Full Version: Whats An Sfi Motor
OK what is the SFI stand for..... what is it capabilites..... Whats different about it.... Someone help
SEMA Foundation Inc. The SFI is an organization established to issue and administer standards for specialty/performance automotive and racing equipment.
hmm...I think the SFI in this context is Sequential Fuel Injection, where each injector receives it's own trigger pulse to fire the injector at a different time (similar to a spark plug) versus batch fire where an entire bank of injectors is triggered at once, irrespective of individual valve timing for each injector.
That could be an interesting topic...batch versus sequential...which is better..
That could be an interesting topic...batch versus sequential...which is better..
QUOTE(BeachHead @ Jun 24 2005, 05:25 AM)
hmm...I think the SFI in this context is Sequential Fuel Injection, where each injector receives it's own trigger pulse to fire the injector at a different time (similar to a spark plug) versus batch fire where an entire bank of injectors is triggered at once, irrespective of individual valve timing for each injector.
That could be an interesting topic...batch versus sequential...which is better..
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That could be an interesting topic...batch versus sequential...which is better..
[right][snapback]1040700[/snapback][/right]
Sequential.
QUOTE(Mr. LV @ Jun 24 2005, 06:30 AM)
QUOTE(BeachHead @ Jun 24 2005, 05:25 AM)
hmm...I think the SFI in this context is Sequential Fuel Injection, where each injector receives it's own trigger pulse to fire the injector at a different time (similar to a spark plug) versus batch fire where an entire bank of injectors is triggered at once, irrespective of individual valve timing for each injector.
That could be an interesting topic...batch versus sequential...which is better..
[right][snapback]1040700[/snapback][/right]
That could be an interesting topic...batch versus sequential...which is better..
[right][snapback]1040700[/snapback][/right]
Sequential.
[right][snapback]1040711[/snapback][/right]
Yea, I think this is a no brainer
Any time you have more control of what the engine is doing seems better to me.
well, I think so too...but, I'm sure someone will point out the benefits of having a fully "charged" intake plenum, or better cooling...someone will prefer it for some reason...maybe even simplicity, or cheap..
It could develop into an interesting discussion.
It could develop into an interesting discussion.
Each has their strong points. Each engine is different. Sequential unloads a lot of fuel in one shot and if it all can't be vaproized effieciently in the alotted time event, then it's not being utilized properly.
Batch theory has it more efficiently vaporizing the fuel for more complete burning. You know, 1/2 now and 1/2 later.
Sequentials are usually sized more accurately for a broader range with only one firing Most production systems ARE batch fired until they achieve a closed loop condition.
Batch is also called gang, or bank since the "batch" can be comprised of any formed group of injectors based on almost any reasoning.
I'm speaking with reference to production based systems.
Carl
Batch theory has it more efficiently vaporizing the fuel for more complete burning. You know, 1/2 now and 1/2 later.
Sequentials are usually sized more accurately for a broader range with only one firing Most production systems ARE batch fired until they achieve a closed loop condition.
Batch is also called gang, or bank since the "batch" can be comprised of any formed group of injectors based on almost any reasoning.
I'm speaking with reference to production based systems.
Carl
I'm not sure I agree with all of it. The amount of fuel required should be the same amount regardless of batch or sequential. I understand what you mean about the injector having to unload more fuel in each shot, but it also has to fire way less. It would seem more logical to me, that better atomization would occur as the fuel is being injected at the perfect time instead of sitting on the valve or in the intake waiting to go in which can cause puddling.
However, from my experience with my own cars and some of the cars at the shop, we see a better throttle response and better low load drivability in sequential.
You are also limited to the amount of injector drivers in the ECU. To run in sequential, each injector needs it's own driver. Some of the less expensive ECU's are not capable of running in sequential.
However, from my experience with my own cars and some of the cars at the shop, we see a better throttle response and better low load drivability in sequential.
You are also limited to the amount of injector drivers in the ECU. To run in sequential, each injector needs it's own driver. Some of the less expensive ECU's are not capable of running in sequential.
LV,
Puddling occurs in either situation. Unless there is a high degree of latent heat available for vaproization. The only other way to evaporate large amounts of fuel in one sequential event, is to have a high delta in MAP and that means a closed throttle and that means thet there is not alot of fuel to eveporate in the first place.
But, manufacturers usually use batch to minimize cylinder wash and dripping when it's a cold startup. More time to vaproize, more completely.
Remember that increased pressure RAISES the boiling point. So, Don't overboost!
Carl
Puddling occurs in either situation. Unless there is a high degree of latent heat available for vaproization. The only other way to evaporate large amounts of fuel in one sequential event, is to have a high delta in MAP and that means a closed throttle and that means thet there is not alot of fuel to eveporate in the first place.
But, manufacturers usually use batch to minimize cylinder wash and dripping when it's a cold startup. More time to vaproize, more completely.
Remember that increased pressure RAISES the boiling point. So, Don't overboost!
Carl
QUOTE(Carl P @ Jun 24 2005, 06:27 AM)
So, Don't overboost!
Carl
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Gotcha
However, this is always going to happen in my car!
We'd better move this to Bench Racing.
It's obviously turned into a BATTLE.
It's obviously turned into a BATTLE.
QUOTE(socaldmax @ Jun 24 2005, 07:00 AM)
We'd better move this to Bench Racing.
It's obviously turned into a BATTLE.
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It's obviously turned into a BATTLE.
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Now you're just acting stupid Steve.
gokunbardock
its a good Question ....and not off topic
just ignore the PW`s
its a good Question
....and not off topic just ignore the PW`s
it was started in another section, and moved here...I'll fix the title..
No battle Just good info.
This is afterall, "A TECH FORUM!"
If it's boring to you, then change the channel!!
Some people's kids! Sheeeesh!!
Carl
This is afterall, "A TECH FORUM!"
If it's boring to you, then change the channel!!
Some people's kids! Sheeeesh!!
Carl
I always thought that sequential was better for lower end torque, while batch was better for higher RPM engines.
Seriously, I typed a question and then realized you guys had answered it in the next few posts.
You guys brought out some good points that never occurred to me. I always thought batch fire was used by mfrs because it was cheaper and SFI was more expensive but better for max performance, etc.
I was obviously just joking about the battle. Just wanted to make a point about a tech discussion degenerating into what some might consider bench racing. This is a great discussion, we're learning a lot.
You guys brought out some good points that never occurred to me. I always thought batch fire was used by mfrs because it was cheaper and SFI was more expensive but better for max performance, etc.
I was obviously just joking about the battle. Just wanted to make a point about a tech discussion degenerating into what some might consider bench racing. This is a great discussion, we're learning a lot.
I love this forum 
QUOTE(Mr. LV @ Jun 24 2005, 06:33 AM)
QUOTE(Carl P @ Jun 24 2005, 06:27 AM)
So, Don't overboost!
Carl
[right][snapback]1040841[/snapback][/right]
Gotcha
However, this is always going to happen in my car!
[right][snapback]1040851[/snapback][/right]
I know! Man when I read about the boost youguys run, I thinkit might be cheaper to just run the fuel line DIRECTLY into the manifold!!!
Saves money on the ECU and injectors!
QUOTE(Carl P @ Jun 24 2005, 08:14 AM)
QUOTE(Mr. LV @ Jun 24 2005, 06:33 AM)
QUOTE(Carl P @ Jun 24 2005, 06:27 AM)
So, Don't overboost!
Carl
[right][snapback]1040841[/snapback][/right]
Gotcha
However, this is always going to happen in my car!
[right][snapback]1040851[/snapback][/right]
I know! Man when I read about the boost youguys run, I thinkit might be cheaper to just run the fuel line DIRECTLY into the manifold!!!
Saves money on the ECU and injectors!
[right][snapback]1041160[/snapback][/right]
I still like the drivabiltity and technology that goes with EFI though. There's something to be said about a sophisticated set up!
Let's pick this apart a little bit:
in a four stroke engine there are four events: intake, compression, power, and exaust. For simplicity each event uses 180' of crank revolution--totaling 720' for one complete cycle.
an injector should not be streched past 90% duty cycle-that means that the injector is open 90% of the time and closed 10% of the time. (90% duty usally happens at full throttle/full load).
so if you had sequential injection and were at full throttle (90% duty) the injector would be closed for only 10% of the four events--it's spraying for the other 648 degrees!!! that means if the squirt started during the beginning of the power stroke (180')--all the way through the exaust stroke (180'), all the way through the intake stroke(180'), it would still have 108 more degrees to squirt into the compression cycle.
As you chew on this info it becomes clear the there is no real advantage at full throttle (sequential vs. group vs. batch) or for that matter anything above 50% load (45% injector duty) because the injector is on way past the intake stroke.
thus no real advantage up high. Down low however when the injector is 5-20% duty, and with proper "injection timing" it can enhance idle quality and off idle drivability.
group or batch fire injection does create larger fuel pressure spikes (squential being evenly spaced pulses helps to reduce this problem). some factory manufactures even install fuel pressure dampers (Honda and Toyota)
group or batch is commonly found on less expensive units, they also can run a motor with only a crank sensor (no cam sensor needed) To run a sequential system you must have a cam sensor.
Outback
in a four stroke engine there are four events: intake, compression, power, and exaust. For simplicity each event uses 180' of crank revolution--totaling 720' for one complete cycle.
an injector should not be streched past 90% duty cycle-that means that the injector is open 90% of the time and closed 10% of the time. (90% duty usally happens at full throttle/full load).
so if you had sequential injection and were at full throttle (90% duty) the injector would be closed for only 10% of the four events--it's spraying for the other 648 degrees!!! that means if the squirt started during the beginning of the power stroke (180')--all the way through the exaust stroke (180'), all the way through the intake stroke(180'), it would still have 108 more degrees to squirt into the compression cycle.
As you chew on this info it becomes clear the there is no real advantage at full throttle (sequential vs. group vs. batch) or for that matter anything above 50% load (45% injector duty) because the injector is on way past the intake stroke.
thus no real advantage up high. Down low however when the injector is 5-20% duty, and with proper "injection timing" it can enhance idle quality and off idle drivability.
group or batch fire injection does create larger fuel pressure spikes (squential being evenly spaced pulses helps to reduce this problem). some factory manufactures even install fuel pressure dampers (Honda and Toyota)
group or batch is commonly found on less expensive units, they also can run a motor with only a crank sensor (no cam sensor needed) To run a sequential system you must have a cam sensor.
Outback
QUOTE(glamisoutback @ Jun 24 2005, 09:26 AM)
Let's pick this apart a little bit:
in a four stroke engine there are four events: intake, compression, power, and exaust. For simplicity each event uses 180' of crank revolution--totaling 720' for one complete cycle.
an injector should not be streched past 90% duty cycle-that means that the injector is open 90% of the time and closed 10% of the time. (90% duty usally happens at full throttle/full load).
so if you had sequential injection and were at full throttle (90% duty) the injector would be closed for only 10% of the four events--it's spraying for the other 648 degrees!!! that means if the squirt started during the beginning of the power stroke (180')--all the way through the exaust stroke (180'), all the way through the intake stroke(180'), it would still have 108 more degrees to squirt into the compression cycle.
As you chew on this info it becomes clear the there is no real advantage at full throttle (sequential vs. group vs. batch) or for that matter anything above 50% load (45% injector duty) because the injector is on way past the intake stroke.
thus no real advantage up high. Down low however when the injector is 5-20% duty, and with proper "injection timing" it can enhance idle quality and off idle drivability.
group or batch fire injection does create larger fuel pressure spikes (squential being evenly spaced pulses helps to reduce this problem). some factory manufactures even install fuel pressure dampers (Honda and Toyota)
group or batch is commonly found on less expensive units, they also can run a motor with only a crank sensor (no cam sensor needed) To run a sequential system you must have a cam sensor.
Outback
[right][snapback]1041281[/snapback][/right]
in a four stroke engine there are four events: intake, compression, power, and exaust. For simplicity each event uses 180' of crank revolution--totaling 720' for one complete cycle.
an injector should not be streched past 90% duty cycle-that means that the injector is open 90% of the time and closed 10% of the time. (90% duty usally happens at full throttle/full load).
so if you had sequential injection and were at full throttle (90% duty) the injector would be closed for only 10% of the four events--it's spraying for the other 648 degrees!!! that means if the squirt started during the beginning of the power stroke (180')--all the way through the exaust stroke (180'), all the way through the intake stroke(180'), it would still have 108 more degrees to squirt into the compression cycle.
As you chew on this info it becomes clear the there is no real advantage at full throttle (sequential vs. group vs. batch) or for that matter anything above 50% load (45% injector duty) because the injector is on way past the intake stroke.
thus no real advantage up high. Down low however when the injector is 5-20% duty, and with proper "injection timing" it can enhance idle quality and off idle drivability.
group or batch fire injection does create larger fuel pressure spikes (squential being evenly spaced pulses helps to reduce this problem). some factory manufactures even install fuel pressure dampers (Honda and Toyota)
group or batch is commonly found on less expensive units, they also can run a motor with only a crank sensor (no cam sensor needed) To run a sequential system you must have a cam sensor.
Outback
[right][snapback]1041281[/snapback][/right]
Better disection and explanation than me!
I agree 100%.
[quote=Mr. LV,Jun 24 2005, 09:55 AM]
[/quote]
Better disection and explanation than me! I agree 100%.
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[/quote]
As I look back in history, the high brake specific output engines that were FI used two injectors per cylinder. The LT5 for Chevy comes to mind.
This would allow the correct volume of fuel within the limited time band of the event.
Carl
[/quote]
Better disection and explanation than me!
I agree 100%. [right][snapback]1041322[/snapback][/right]
[/quote]
As I look back in history, the high brake specific output engines that were FI used two injectors per cylinder. The LT5 for Chevy comes to mind.
This would allow the correct volume of fuel within the limited time band of the event.
Carl
I beleive John's explanation, but I'm kinda surprised that injectors are really running at 90% duty cycle at WOT.
If I were designing an FI system, I'd try to do the following:
1. Size the injectors so that it would be on 5% at idle and 50% at WOT
2. Sequential for better control per cylinder
3. Vary fuel pressure from 30psi at idle to 200 psi at WOT (or something similar) to keep duty cycle at or under 50%.
I don't really know how much gas is required to produce say 700 or 800 hp, but if they can make a diesel injection system that can be tweaked to produce 800hp and control the timing very precisely then the same can be done for a gas FI system.
If I were designing an FI system, I'd try to do the following:
1. Size the injectors so that it would be on 5% at idle and 50% at WOT
2. Sequential for better control per cylinder
3. Vary fuel pressure from 30psi at idle to 200 psi at WOT (or something similar) to keep duty cycle at or under 50%.
I don't really know how much gas is required to produce say 700 or 800 hp, but if they can make a diesel injection system that can be tweaked to produce 800hp and control the timing very precisely then the same can be done for a gas FI system.
Sequential pulses each injector every other revolution, once per engine cycle.
Sequential injection has the ability to adjust exactly when the pulse occurs relative to the opening of the intake valve.
Non-sequential style usually pulses all the injectors at the same time and on every revolution.
One problem with non-sequential fuel injection is, when you run very large injectors, this can cause a fuel pressure dip. When all 4, 6, or 8 injectors open at the same time it places large demands on the fuel pump.
The reserve for EFI is the fuel pump; the reserve for a carburetor is the float bowl.
Sequential injection has the ability to adjust exactly when the pulse occurs relative to the opening of the intake valve.
Non-sequential style usually pulses all the injectors at the same time and on every revolution.
One problem with non-sequential fuel injection is, when you run very large injectors, this can cause a fuel pressure dip. When all 4, 6, or 8 injectors open at the same time it places large demands on the fuel pump.
The reserve for EFI is the fuel pump; the reserve for a carburetor is the float bowl.
QUOTE(socaldmax @ Jun 24 2005, 10:22 AM)
I beleive John's explanation, but I'm kinda surprised that injectors are really running at 90% duty cycle at WOT.
If I were designing an FI system, I'd try to do the following:
1. Size the injectors so that it would be on 5% at idle and 50% at WOT
2. Sequential for better control per cylinder
3. Vary fuel pressure from 30psi at idle to 200 psi at WOT (or something similar) to keep duty cycle at or under 50%.
I don't really know how much gas is required to produce say 700 or 800 hp, but if they can make a diesel injection system that can be tweaked to produce 800hp and control the timing very precisely then the same can be done for a gas FI system.
[right][snapback]1041349[/snapback][/right]
If I were designing an FI system, I'd try to do the following:
1. Size the injectors so that it would be on 5% at idle and 50% at WOT
2. Sequential for better control per cylinder
3. Vary fuel pressure from 30psi at idle to 200 psi at WOT (or something similar) to keep duty cycle at or under 50%.
I don't really know how much gas is required to produce say 700 or 800 hp, but if they can make a diesel injection system that can be tweaked to produce 800hp and control the timing very precisely then the same can be done for a gas FI system.
[right][snapback]1041349[/snapback][/right]
Mercedes has a direct fuel injection coming out, this year. (Don’t quote me) Just like diesel engines.
I’ve always said that gas engines fuel injection is not true injection… The diesel engine is true INJECTION. Precisely injected at the right cycle.
QUOTE(socaldmax @ Jun 24 2005, 10:22 PM)
... but if they can make a diesel injection system that can be tweaked to produce 800hp and control the timing very precisely then the same can be done for a gas FI system...
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One big difference is that diesels generally use THOUSANDS of PSI in the injection feed lines where the gasoline injection systems generally have max of hundred(s) of PSI.
The higher pressure gives all kinds of flexibility in increasing flows per injector
I don't think there is much difference between any injector system, or for that matter, carb. at WOT.
What makes injection so advanced is the way it 'adjusts itself' through the power/throttle/RPM range.
I have for a long time thought that it would make the most sense to do what Carl mentioned, but have one set of injectors for Idle/transition, and one (large) set of injectors for 1/4 throttle and up.
QUOTE(hopper @ Jun 24 2005, 10:41 PM)
I’ve always said that gas engines fuel injection is not true injection… The diesel engine is true INJECTION. Precisely injected at the right cycle.
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Is this true?
Wow, this really is a milestone... VW was talking about it a while ago. Takes incredible pressure.
Wonder how this will change the efficiency/power?
The injectors that around these days are amazing. Very good spray patterns and vary good characteristics for precise fuel metering.
Carl, that is a very good point abou the 2 injectors. There are still occasions when 2 is still a good idea. I'm sure Carl is aware of this but for others I'll explain.
For instance, the turbo rotaries require A LOT of fuel to make good horse power. If we tried to run one huge injector per rotor, the thing would have terrible low end characteristics. However, we can stage a small and large injectors to get the required fuel all the way across the rpm range. So the engine runs off of the small injector off the bottom, and the large one ads to it when it comes under boost.
The other application for 2 is when the fuel requirements are much larger than the avilable sizes. This is seen in a lot of high horsepower alchohol engines. Depending on the apliction, you can pair up the injectors or stage them.
Steve, the modern efi injectors are engineered to run at a max duty cycle of 80%. we have pushed injectors past this without failures, but they're designed for 80%. You are able to compensate a little on the fuel pressure, however it is best to stabalize the fuel pressure as best you can. This is true wheather you are running a fixed pressure or a load sensitive pressure, such as cases with forced induction where a rising rate of fuel pressure (1:1 is most common) is desired to help increase fuel flow.
There really is zero application to compare deisel to gas engines. They work completly different, especially in the fuel and air delivery department. Deisels are wide open to air and fuel is metered for engine speed and load. Gas engines meter air and ad fuel required by demand.
Carl, that is a very good point abou the 2 injectors. There are still occasions when 2 is still a good idea. I'm sure Carl is aware of this but for others I'll explain.
For instance, the turbo rotaries require A LOT of fuel to make good horse power. If we tried to run one huge injector per rotor, the thing would have terrible low end characteristics. However, we can stage a small and large injectors to get the required fuel all the way across the rpm range. So the engine runs off of the small injector off the bottom, and the large one ads to it when it comes under boost.
The other application for 2 is when the fuel requirements are much larger than the avilable sizes. This is seen in a lot of high horsepower alchohol engines. Depending on the apliction, you can pair up the injectors or stage them.
Steve, the modern efi injectors are engineered to run at a max duty cycle of 80%. we have pushed injectors past this without failures, but they're designed for 80%. You are able to compensate a little on the fuel pressure, however it is best to stabalize the fuel pressure as best you can. This is true wheather you are running a fixed pressure or a load sensitive pressure, such as cases with forced induction where a rising rate of fuel pressure (1:1 is most common) is desired to help increase fuel flow.
There really is zero application to compare deisel to gas engines. They work completly different, especially in the fuel and air delivery department. Deisels are wide open to air and fuel is metered for engine speed and load. Gas engines meter air and ad fuel required by demand.
It's not possible to find the right size injectors to get the WOT duty cycle down yet still maintain good idle control?
[quote=hopper,Jun 24 2005, 10:34 AM]
One problem with non-sequential fuel injection is, when you run very large injectors, this can cause a fuel pressure dip. When all 4, 6, or 8 injectors open at the same time it places large demands on the fuel pump.
The largest demand on the pump is at full load/full rpm "." (read period) at all other times it is less. If you have a properly sized pump for the hp and pressure you are running then any load less then WOT is easier on the pump and no extra "demands" are on the pump, the gas simply returns to the tank/sump. all injectors starting and stopping at the same time at part throttle is clearly less of a demand then at WOT. At WOT and 90% duty they might as well all come on at the same time (they're practically there anyways) the damper can smooth out the pulses. This problem of pulses with group and batch fire injection pulse can be "tuned out" but a constant ful pressure is always better.
The regulator is the part that actually puts the demand on the pump, without one the fuel pump would have no resistance. When the regulator applies 50psi on the fuel system that is the load. if you raise the fuel pressure to 80psi the fuel pumps load increases. if the pump can't handle 80psi it will fail. injectors merely siphon off fuel that would normally have bypassed the regulator (like when the pump runs and engine is off)
With sequential there is another advantage in that the "pulse width" of each injector could be "trimmed" if you had pyrometers or a/f sensors in each cylinder you may find that there is a lean/rich cylinder because of individual motor characteristics.
One problem with non-sequential fuel injection is, when you run very large injectors, this can cause a fuel pressure dip. When all 4, 6, or 8 injectors open at the same time it places large demands on the fuel pump.
The largest demand on the pump is at full load/full rpm "." (read period) at all other times it is less. If you have a properly sized pump for the hp and pressure you are running then any load less then WOT is easier on the pump and no extra "demands" are on the pump, the gas simply returns to the tank/sump. all injectors starting and stopping at the same time at part throttle is clearly less of a demand then at WOT. At WOT and 90% duty they might as well all come on at the same time (they're practically there anyways) the damper can smooth out the pulses. This problem of pulses with group and batch fire injection pulse can be "tuned out" but a constant ful pressure is always better.
The regulator is the part that actually puts the demand on the pump, without one the fuel pump would have no resistance. When the regulator applies 50psi on the fuel system that is the load. if you raise the fuel pressure to 80psi the fuel pumps load increases. if the pump can't handle 80psi it will fail. injectors merely siphon off fuel that would normally have bypassed the regulator (like when the pump runs and engine is off)
With sequential there is another advantage in that the "pulse width" of each injector could be "trimmed" if you had pyrometers or a/f sensors in each cylinder you may find that there is a lean/rich cylinder because of individual motor characteristics.
[quote=glamisoutback,Jun 24 2005, 11:45 AM]
[quote=hopper,Jun 24 2005, 10:34 AM]
One problem with non-sequential fuel injection is, when you run very large injectors, this can cause a fuel pressure dip. When all 4, 6, or 8 injectors open at the same time it places large demands on the fuel pump.
The largest demand on the pump is at full load/full rpm "." (read period) at all other times it is less. If you have a properly sized pump for the hp and pressure you are running then any load less then WOT is easier on the pump and no extra "demands" are on the pump, the gas simply returns to the tank/sump. all injectors starting and stopping at the same time at part throttle is clearly less of a demand then at WOT. At WOT and 90% duty they might as well all come on at the same time (they're practically there anyways) the damper can smooth out the pulses. This problem of pulses with group and batch fire injection pulse can be "tuned out" but a constant ful pressure is always better.
The regulator is the part that actually puts the demand on the pump, without one the fuel pump would have no resistance. When the regulator applies 50psi on the fuel system that is the load. if you raise the fuel pressure to 80psi the fuel pumps load increases. if the pump can't handle 80psi it will fail. injectors merely siphon off fuel that would normally have bypassed the regulator (like when the pump runs and engine is off)
With sequential there is another advantage in that the "pulse width" of each injector could be "trimmed" if you had pyrometers or a/f sensors in each cylinder you may find that there is a lean/rich cylinder because of individual motor characteristics.
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[/quote]
The largest demand on the pump is at the highest VE. PERIOD.
The regulator is not the part that puts the demand on the pump it’s the injectors. PERIOD.
The “regulator” implies the name of its action. REGULATOR. “ONE THAT REGULATES”
50psi is not the fuel systems load. 50psi is what it says. PERIOD. If you raised it to 80psi you just raised the pressure not the load.
If your pump can not keep up with the demands of the injectors the regulator can not fix this.
Load = flow. PERIOD.
Load is not pressure.
If you have a water hose with an end on it, turn on the valve and adjust to 50psi, there is no load here. The only way you will have load is if you turn on the hose end, then there will be water flow.
[quote=hopper,Jun 24 2005, 10:34 AM]
One problem with non-sequential fuel injection is, when you run very large injectors, this can cause a fuel pressure dip. When all 4, 6, or 8 injectors open at the same time it places large demands on the fuel pump.
The largest demand on the pump is at full load/full rpm "." (read period) at all other times it is less. If you have a properly sized pump for the hp and pressure you are running then any load less then WOT is easier on the pump and no extra "demands" are on the pump, the gas simply returns to the tank/sump. all injectors starting and stopping at the same time at part throttle is clearly less of a demand then at WOT. At WOT and 90% duty they might as well all come on at the same time (they're practically there anyways) the damper can smooth out the pulses. This problem of pulses with group and batch fire injection pulse can be "tuned out" but a constant ful pressure is always better.
The regulator is the part that actually puts the demand on the pump, without one the fuel pump would have no resistance. When the regulator applies 50psi on the fuel system that is the load. if you raise the fuel pressure to 80psi the fuel pumps load increases. if the pump can't handle 80psi it will fail. injectors merely siphon off fuel that would normally have bypassed the regulator (like when the pump runs and engine is off)
With sequential there is another advantage in that the "pulse width" of each injector could be "trimmed" if you had pyrometers or a/f sensors in each cylinder you may find that there is a lean/rich cylinder because of individual motor characteristics.
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[/quote]
The largest demand on the pump is at the highest VE. PERIOD.
The regulator is not the part that puts the demand on the pump it’s the injectors. PERIOD.
The “regulator” implies the name of its action. REGULATOR. “ONE THAT REGULATES”
50psi is not the fuel systems load. 50psi is what it says. PERIOD. If you raised it to 80psi you just raised the pressure not the load.
If your pump can not keep up with the demands of the injectors the regulator can not fix this.
Load = flow. PERIOD.
Load is not pressure.
If you have a water hose with an end on it, turn on the valve and adjust to 50psi, there is no load here. The only way you will have load is if you turn on the hose end, then there will be water flow.
QUOTE(Mr. LV @ Jun 24 2005, 10:59 AM)
There really is zero application to compare deisel to gas engines. They work completly different, especially in the fuel and air delivery department. Deisels are wide open to air and fuel is metered for engine speed and load. Gas engines meter air and ad fuel required by demand.
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Josh,
maybe that changes soon ...
Mitsubishi has an gasoline direct injection engine allready on the market. They still have a throttle body, but more because they need some more time to figure out that whole thing. But they run prototypes without metering the air.
BTW
-the current engines on the market in Europe (don't know they sell them here) run lean down to 40:1 (idle and low loads)
Think about what you could do when detonation is no longer a problem
[quote=hopper,Jun 24 2005, 10:34 AM]
My comments start with ****John and are in blue
Quoted:
The largest demand on the pump is at the highest VE. PERIOD. **** John: this is a more correct statement than mine.
Quoted:
The regulator is not the part that puts the demand on the pump it’s the injectors. PERIOD.**** John: I disagree and will explain:
Quoted:
The “regulator” implies the name of its action. REGULATOR. “ONE THAT REGULATES” ****John: Yes but regulates the pressure which raises the "load" on the pump. fuel pump amps (current) go up as the pressure goes up this would emply a greater stress or demand. Demand is two fold on the pump, 1) demand/stress or resistance on the pump. this is only caused by the regulator (injetcors are not need in this description) 2) the flow demand (or ability to supply under pressure)is whether the pump can maintain a given pressure while losing some of it's fuel through the injectors. If pressure drops during it's highest VE(thankyou), the fuel pump is not sufficent, if the fuel pressure was raised above the design of a pump it will self destruct over time. (some pumps are designed for high pressure low flow, others for low pressure low flow and still others for high flow and high pressure.)
Quoted:
50psi is not the fuel systems load. 50psi is what it says. PERIOD. If you raised it to 80psi you just raised the pressure not the load.**** John: we did raise the stress or load on the pump as seen by the current going up.
Quoted:
If your pump can not keep up with the demands of the injectors the regulator can not fix this. **** John: Yes and no. let's say that at 40psi the pump could not supply the amount of fuel needed and at full VE the pressure dropped off. You would declare this pump "not suffient" however on the same motor the pressure was raised to 90 psi. the injectors would be pulsed for a lot less and the pump may now be suffient "at that pressure". The higher pressure caused more demand/load stress on the pump but it's doing the job. If this pump was designed for 60 psi constant operating pressure it will fail. If it was designed for 130 psi the new higher demand will be no problem. You cannot look at the actual demand without including the working pressure (the regulator).
Quoted:
Load = flow. PERIOD. ****John: Resistance causes load
Quoted:
Load is not pressure. ****John: in our context, Load is pressure
Quoted:
If you have a water hose with an end on it, turn on the valve and adjust to 50psi, there is no load here.**** John: There is load, that is why you have 50psi in the hose. That is why the hose wants to burst. According to my Websters' dic. A load is: A BURDEN: SPECIFICALLY AS MUCH AS CAN BE CARRIED.
Quoted:
The only way you will have load is if you turn on the hose end, then there will be water flow. ****John: Turning on a nozzle at the end of the hose lowers the load/pressure/burden/resistance in the hose.
What we're trying to get across is "supply" under load (burden/pressure. etc.)
p.s. this thread is for instructional content, I am not attacking you, These comments are just my opioin.
John
My comments start with ****John and are in blue
Quoted:
The largest demand on the pump is at the highest VE. PERIOD. **** John: this is a more correct statement than mine.
Quoted:
The regulator is not the part that puts the demand on the pump it’s the injectors. PERIOD.**** John: I disagree and will explain:
Quoted:
The “regulator” implies the name of its action. REGULATOR. “ONE THAT REGULATES” ****John: Yes but regulates the pressure which raises the "load" on the pump. fuel pump amps (current) go up as the pressure goes up this would emply a greater stress or demand. Demand is two fold on the pump, 1) demand/stress or resistance on the pump. this is only caused by the regulator (injetcors are not need in this description) 2) the flow demand (or ability to supply under pressure)is whether the pump can maintain a given pressure while losing some of it's fuel through the injectors. If pressure drops during it's highest VE(thankyou), the fuel pump is not sufficent, if the fuel pressure was raised above the design of a pump it will self destruct over time. (some pumps are designed for high pressure low flow, others for low pressure low flow and still others for high flow and high pressure.)
Quoted:
50psi is not the fuel systems load. 50psi is what it says. PERIOD. If you raised it to 80psi you just raised the pressure not the load.**** John: we did raise the stress or load on the pump as seen by the current going up.
Quoted:
If your pump can not keep up with the demands of the injectors the regulator can not fix this. **** John: Yes and no. let's say that at 40psi the pump could not supply the amount of fuel needed and at full VE the pressure dropped off. You would declare this pump "not suffient" however on the same motor the pressure was raised to 90 psi. the injectors would be pulsed for a lot less and the pump may now be suffient "at that pressure". The higher pressure caused more demand/load stress on the pump but it's doing the job. If this pump was designed for 60 psi constant operating pressure it will fail. If it was designed for 130 psi the new higher demand will be no problem. You cannot look at the actual demand without including the working pressure (the regulator).
Quoted:
Load = flow. PERIOD. ****John: Resistance causes load
Quoted:
Load is not pressure. ****John: in our context, Load is pressure
Quoted:
If you have a water hose with an end on it, turn on the valve and adjust to 50psi, there is no load here.**** John: There is load, that is why you have 50psi in the hose. That is why the hose wants to burst. According to my Websters' dic. A load is: A BURDEN: SPECIFICALLY AS MUCH AS CAN BE CARRIED.
Quoted:
The only way you will have load is if you turn on the hose end, then there will be water flow. ****John: Turning on a nozzle at the end of the hose lowers the load/pressure/burden/resistance in the hose.
What we're trying to get across is "supply" under load (burden/pressure. etc.)
p.s. this thread is for instructional content, I am not attacking you, These comments are just my opioin.
John
I am not going to quote the last quote, it will get to big. Go back and read it if you forget.
Basic electricity 101
On your wall plug were you can plug in your coffee maker, there is 120 volts there. There is no current flow, just 120 volts. If there was current flow your electric meter would spin and you would be paying for electricity that you did not use. If you turned off every thing in your house and went out and looked at your meter and it was moving, you either have a short in your house or something is still on. Current flow will cause the meter to spin. That is how the electric company recoups its money.
The garden hose, you turn on the valve to the hose, there is a hose end at the end of the hose that is turned off. Just pressure no current flow; same principle as the electric theory.
At the substation were electricity is generated, it transfers the electricity to other substations were there are regulators to adjust the voltage because of line loss and demand. Then it is sent to smaller transformers. (Residential and commercial)
Even if there is no load on this transformer the generator has to keep producing electricity.
The generator has to keep producing it to keep the pressure up, or line voltage. This generator could sit idle just producing the line voltage but no demand on it, because of no load.
If there was a great deal of load put on this generator and the generator could not keep up we would have melt down.
Now someone turns on a light in there house, load. The light goes on, this person is happy, and there meter starts to turn. Now we have current flow, all this caused by a resistor. (That is load)
Here is an EZ way to understand this.
You have a small generator, you start to plug tools into it then all of a sudden the motor bogs down or the breaker trips, to much load.
This is how a fuel system works.
Fuel pump = generator = psi or KV
Fuel line = wire
Fuel line size = wire size = Resistance
Regulator = Regulator
Injector = resistor = load
See that small disc that the fuel has to pass thru is a resistor, when it is closed no load when it is open, Load.
This is just off the top of my head, if you like when I have more time I’ll give a complete detail on this theory.
John I took the first respond as an attack, I was fine with this one.
Richard
Basic electricity 101
On your wall plug were you can plug in your coffee maker, there is 120 volts there. There is no current flow, just 120 volts. If there was current flow your electric meter would spin and you would be paying for electricity that you did not use. If you turned off every thing in your house and went out and looked at your meter and it was moving, you either have a short in your house or something is still on. Current flow will cause the meter to spin. That is how the electric company recoups its money.
The garden hose, you turn on the valve to the hose, there is a hose end at the end of the hose that is turned off. Just pressure no current flow; same principle as the electric theory.
At the substation were electricity is generated, it transfers the electricity to other substations were there are regulators to adjust the voltage because of line loss and demand. Then it is sent to smaller transformers. (Residential and commercial)
Even if there is no load on this transformer the generator has to keep producing electricity.
The generator has to keep producing it to keep the pressure up, or line voltage. This generator could sit idle just producing the line voltage but no demand on it, because of no load.
If there was a great deal of load put on this generator and the generator could not keep up we would have melt down.
Now someone turns on a light in there house, load. The light goes on, this person is happy, and there meter starts to turn. Now we have current flow, all this caused by a resistor. (That is load)
Here is an EZ way to understand this.
You have a small generator, you start to plug tools into it then all of a sudden the motor bogs down or the breaker trips, to much load.
This is how a fuel system works.
Fuel pump = generator = psi or KV
Fuel line = wire
Fuel line size = wire size = Resistance
Regulator = Regulator
Injector = resistor = load
See that small disc that the fuel has to pass thru is a resistor, when it is closed no load when it is open, Load.
This is just off the top of my head, if you like when I have more time I’ll give a complete detail on this theory.
John I took the first respond as an attack, I was fine with this one.
Richard
Me too...
john is right !!
QUOTE(bill@accurate injector @ Jun 26 2005, 03:59 PM)
john is right !!
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Bill your opinion means nothing to me!!!
If you were to say “I agree with john” I’d be OK with that, but to come on here and say that John is correct. You are wrong.
I can understand another business trying to get the spot light off another business, by trying to help… but you’re going about this the wrong way.
If I am incorrect, that is fine, but I am not. You and John need to take my Theory apart and explain why it is incorrect and your opinion is the right answer.
And I, my friend, will keep giving the correct answer.
Mr. Hopper,
Your anology of hydraulic theory to electrical flow is flawed to say the least.
I'm not going to write a thesis here but, I would suggest that you study the function of he fuel regulator and actually install a current shunt in a fuel pump circuit.
The fuel pump is ALWAYS pumping under load. Quite the opposite of your "closed injector = no load" statement.
The pump is ALWAYS filling the fuel rail regardless if the injecotr (s) are energized or not. The REGULATOR is bypassing the uneeded volume AND pressure back to the tank: but the pump is very much under load.
You flip the switch, and it's drawing current. Even with the engine dead.
I'm not completely confident on your stated operational scenario of the Fuel regulator. It's a hydraulic/pneumatic device void of electrons; to my knowledge. It's attachment to the intake is to add dynamic range to the injectors by increasing the fuel pressure under what it assumes to be, WOT.
If your going to hijack this "What does SFI mean" thread and start to state Laws of Electricity, that's your choice.
But, please elaborate on the "Hole Theory" and electron flow as well. Just to make sure we've covered the basics of Electricity properly.
I'm definitely no expert here. So if you take offense to what I've stated then let's have another thread to discuss Electicity.
No offense intended, and I hope that I've not mis-stated your posts, or your comments incorrectly.
Sincerely,
Carl
Your anology of hydraulic theory to electrical flow is flawed to say the least.
I'm not going to write a thesis here but, I would suggest that you study the function of he fuel regulator and actually install a current shunt in a fuel pump circuit.
The fuel pump is ALWAYS pumping under load. Quite the opposite of your "closed injector = no load" statement.
The pump is ALWAYS filling the fuel rail regardless if the injecotr (s) are energized or not. The REGULATOR is bypassing the uneeded volume AND pressure back to the tank: but the pump is very much under load.
You flip the switch, and it's drawing current. Even with the engine dead.
I'm not completely confident on your stated operational scenario of the Fuel regulator. It's a hydraulic/pneumatic device void of electrons; to my knowledge. It's attachment to the intake is to add dynamic range to the injectors by increasing the fuel pressure under what it assumes to be, WOT.
If your going to hijack this "What does SFI mean" thread and start to state Laws of Electricity, that's your choice.
But, please elaborate on the "Hole Theory" and electron flow as well. Just to make sure we've covered the basics of Electricity properly.
I'm definitely no expert here. So if you take offense to what I've stated then let's have another thread to discuss Electicity.
No offense intended, and I hope that I've not mis-stated your posts, or your comments incorrectly.
Sincerely,
Carl
Carl like I’ve said before, I can keep poking holes in this.
I wrote the theory off the top of my head, in a laymen’s term so everybody could understand it.
Here one more thing to think about…
If you have 8 120 volt single phase motors, when running they draw 10 amps. There (I’ll keep this simple) LRA (Lock Rotor Amps) is 20 amps.
That means when one of these motors start up it will have an inrush of 20 amps.
So just starting one motor at a time is no big deal. (Sequential)
But starting all 8 motors at the same time (very big in rush, 160 amps) you would dip your neighbors lights, until the motors were up and running. (Non-sequential)
You guys can believe what you like, it’s a free country.
I wrote the theory off the top of my head, in a laymen’s term so everybody could understand it.
Here one more thing to think about…
If you have 8 120 volt single phase motors, when running they draw 10 amps. There (I’ll keep this simple) LRA (Lock Rotor Amps) is 20 amps.
That means when one of these motors start up it will have an inrush of 20 amps.
So just starting one motor at a time is no big deal. (Sequential)
But starting all 8 motors at the same time (very big in rush, 160 amps) you would dip your neighbors lights, until the motors were up and running. (Non-sequential)
You guys can believe what you like, it’s a free country.
Carl why would I install a current shunt on the fuel pump circuit? I would just clamp the wires to check load.
A shunt is used for protection, you must be think of installing a in line amp gage?
A shunt is used for protection, you must be think of installing a in line amp gage?
QUOTE(hopper @ Jun 26 2005, 08:43 PM)
Carl why would I install a current shunt on the fuel pump circuit? I would just clamp the wires to check load.
A shunt is used for protection, you must be think of installing a in line amp gage?
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A shunt is used for protection, you must be think of installing a in line amp gage?
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A shunt is a device used in instrumentation applications for reading minute current fluctuations. A "clamp" is used in the field for seeing if there is current or not.
We install shunts for seeing changes in current (in all loaded circuits) as low as 1 milliamp. It's that critical when dealing with control software for engine management systems.( See Googled definition below).
It would show you that the pump is loaded all the time. The exact opposite of what you stated earlier. Then you promptly jumped to "wall outlets."
You're not addressing the topic of "Fuel Systems."
You keep jumping around going back to AC Electricity.
With all due respect, the example only clouds your point on the topic under discussion.
Please stay on subject for clarity to the readers!
Carl
[""The Application
I have chosen a common industrial measurement to illustrate the importance of isolation. We’ll measure the current delivered to the armature winding of a motor, which can be used to derive the torque it delivers while operating under a load. In most such applications, current is measured using a current shunt. This device acts as a resistor that provides a precisely calibrated, constant, and known resistance. When inserted in series with the armature power supply, the voltage developed across the shunt is directly proportional to the current delivered to the armature. Ohm’s Law precisely defines this relationship:
Armature current = Ia = Vs/Rs
Where: Vs is the voltage developed across the shunt and Rs is shunt resistance.
Current shunts are typically designed to deliver 100 millivolts at full scale current, which can be hundreds of amperes. ""]
ouch 
my head hurts from reading
..........i think i need another
my head hurts from reading
..........i think i need another
Here's my analogy:
Let's take a 55 gallon drum of fuel and connect a hose between the drum and a manual pump with a crank. From the pump we have another hose (the fuel rail). At the end of this hose we have an adjustable regulator (0-100psi). We then have a clear return line leaving the regulator and dumps back into the 55 gal drum (closed system). teed into the side of the line between the pump and the regulator are 4 fuel injectors that we can control by a switch. There is a pressure gauge in the fuel rail for observation.
1) A man starts to crank the pump at 60rpm's. the regulator is set to zero psi. He notices the this is an easy job. He is only circulating the fuel. He sees the fuel returning through the clear line. We energize the 4 injectors--they just dribble. We know we need more than a dribble.
2) We turn the regulator up to 50psi, the man continues to crank at 60rpm's but notices some resistance (load applied to pump, pressure=load). We still see the fuel returning. We then start to energize the 4 injectors. The man doesn't notice any increase or decrease of load when the injectors are pulsed. The rail maintains 50 psi. In fact, as long as he can see fuel returning from the regulator the pressure can not not drop below 50psi, even if the injectors are on all the time. The key is that there is still fuel leaving the regulator, fuel can only return when the rail pressure is above 50psi! (as you said, that is what a regulator does- IT REGULATES)
3) We add 2 more injectors to the rail (now 6 total)and turned them on. We now notice no more fuel returning to the drum. We can conclude that the fuel pressure is at 50psi or less. The pump is no longer capable of supplying the rail because the fuel demand was too great.
Also we note that if the rail pressure is maintained at 50psi, the man cannot tell by his load (pumping) weather the fuel left the injectors or the regulator!
In example 2) if the man now increases to 80rpms he is only recirculating more fuel back to the tank, he is wasting energy because with his 4 injectors wide open there was still sufficient "fuel return" at 60rpms.
In example 3) The 80rpms (we read "bigger pump with more gpm") could now be suffient with all 6 injectors on if there is fuel returning to the drum.
Motec has just introduce a variable fuel pump controller. It varies the voltage to the pump. It can be controlled by a map in the ecu. In example 3) this pump is huge and returns a lot of fuel back to the tank (more at idle, less at full V.E.) This controller would allow the tuner to drive the pump (less fuel pump noise/less work) so that at any given rpm there is just a minimal amount of fuel returning to the tank. As long as there is fuel returning from the regulator---then rail pressure is being maintained. As long as the pressure is being maintained, The pump works the same weather the motor is off, idling, or at full throttle.
John
Let's take a 55 gallon drum of fuel and connect a hose between the drum and a manual pump with a crank. From the pump we have another hose (the fuel rail). At the end of this hose we have an adjustable regulator (0-100psi). We then have a clear return line leaving the regulator and dumps back into the 55 gal drum (closed system). teed into the side of the line between the pump and the regulator are 4 fuel injectors that we can control by a switch. There is a pressure gauge in the fuel rail for observation.
1) A man starts to crank the pump at 60rpm's. the regulator is set to zero psi. He notices the this is an easy job. He is only circulating the fuel. He sees the fuel returning through the clear line. We energize the 4 injectors--they just dribble. We know we need more than a dribble.
2) We turn the regulator up to 50psi, the man continues to crank at 60rpm's but notices some resistance (load applied to pump, pressure=load). We still see the fuel returning. We then start to energize the 4 injectors. The man doesn't notice any increase or decrease of load when the injectors are pulsed. The rail maintains 50 psi. In fact, as long as he can see fuel returning from the regulator the pressure can not not drop below 50psi, even if the injectors are on all the time. The key is that there is still fuel leaving the regulator, fuel can only return when the rail pressure is above 50psi! (as you said, that is what a regulator does- IT REGULATES)
3) We add 2 more injectors to the rail (now 6 total)and turned them on. We now notice no more fuel returning to the drum. We can conclude that the fuel pressure is at 50psi or less. The pump is no longer capable of supplying the rail because the fuel demand was too great.
Also we note that if the rail pressure is maintained at 50psi, the man cannot tell by his load (pumping) weather the fuel left the injectors or the regulator!
In example 2) if the man now increases to 80rpms he is only recirculating more fuel back to the tank, he is wasting energy because with his 4 injectors wide open there was still sufficient "fuel return" at 60rpms.
In example 3) The 80rpms (we read "bigger pump with more gpm") could now be suffient with all 6 injectors on if there is fuel returning to the drum.
Motec has just introduce a variable fuel pump controller. It varies the voltage to the pump. It can be controlled by a map in the ecu. In example 3) this pump is huge and returns a lot of fuel back to the tank (more at idle, less at full V.E.) This controller would allow the tuner to drive the pump (less fuel pump noise/less work) so that at any given rpm there is just a minimal amount of fuel returning to the tank. As long as there is fuel returning from the regulator---then rail pressure is being maintained. As long as the pressure is being maintained, The pump works the same weather the motor is off, idling, or at full throttle.
John
Carl you’re so funny!!!!
Since you cannot visually see the flow of electrons, current, etc... And you need to see the relationship between voltage, current, and resistance, let’s do it with some terms which you are more familiar with, using water.
Water------Electricity
Pump-------Generator
Pipe------Conductor
Pressure-----Voltage
Flow of gallons--------Amperes
Restriction--------Resistance
Generator is like a water pump, the prime mover.
The conductor is like the water pipe, the larger the conductor, the less resistance and the more flow.
The voltage is like the water pressure, the force pushing.
The amperes are like the flow of water, an amount of current flowing is like the gallons per minute, as would the resistor in an electrical circuit.
The resistance is like the restriction in the water pipe. A reduction in the water pipe size would cause opposition to the amount of gallons per minute, as would the resistor in an electrical circuit.
Watts (power) is expressing the rate of work involved; the power required. With water it requires more work to pump ground level. Wattage is the rate at which the electrical energy is changed into another form of energy, such as light or heat. The faster a lamp changes electrical energy, the brighter it will be.
Regulators are a form of autotransformer which will increase (boost) or decrease (buck) the unregulated voltage applied to it. The percent regulation is the amount the regulator can boost or buck the voltage above or below its source voltage.
Carl, go back and do another search on Shunts. I am not going to give you that answer.
Since you cannot visually see the flow of electrons, current, etc... And you need to see the relationship between voltage, current, and resistance, let’s do it with some terms which you are more familiar with, using water.
Water------Electricity
Pump-------Generator
Pipe------Conductor
Pressure-----Voltage
Flow of gallons--------Amperes
Restriction--------Resistance
Generator is like a water pump, the prime mover.
The conductor is like the water pipe, the larger the conductor, the less resistance and the more flow.
The voltage is like the water pressure, the force pushing.
The amperes are like the flow of water, an amount of current flowing is like the gallons per minute, as would the resistor in an electrical circuit.
The resistance is like the restriction in the water pipe. A reduction in the water pipe size would cause opposition to the amount of gallons per minute, as would the resistor in an electrical circuit.
Watts (power) is expressing the rate of work involved; the power required. With water it requires more work to pump ground level. Wattage is the rate at which the electrical energy is changed into another form of energy, such as light or heat. The faster a lamp changes electrical energy, the brighter it will be.
Regulators are a form of autotransformer which will increase (boost) or decrease (buck) the unregulated voltage applied to it. The percent regulation is the amount the regulator can boost or buck the voltage above or below its source voltage.
Carl, go back and do another search on Shunts. I am not going to give you that answer.
EFI injectors are rated @36psi of fuel pressure for a determined flow (lb/min or cc’s)
So our fuel pump’s job is to maintain 36psi at idle. That is its job.
When we open the throttle we put a demand on the injectors to accelerate the engine. The fuel pump has a demand on it now, the injectors asking for fuel. Load. This is above its standard job. What every the static fuel pressure is, that is the fuel pumps standard job. Any thing above this is load.
So our fuel pump’s job is to maintain 36psi at idle. That is its job.
When we open the throttle we put a demand on the injectors to accelerate the engine. The fuel pump has a demand on it now, the injectors asking for fuel. Load. This is above its standard job. What every the static fuel pressure is, that is the fuel pumps standard job. Any thing above this is load.
QUOTE(hopper @ Jun 26 2005, 11:06 PM)
EFI injectors are rated @36psi of fuel pressure for a determined flow (lb/min or cc’s)
So our fuel pump’s job is to maintain 36psi at idle. That is its job.
When we open the throttle we put a demand on the injectors to accelerate the engine. The fuel pump has a demand on it now, the injectors asking for fuel. Load. This is above its standard job. What every the static fuel pressure is, that is the fuel pumps standard job. Any thing above this is load.
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So our fuel pump’s job is to maintain 36psi at idle. That is its job.
When we open the throttle we put a demand on the injectors to accelerate the engine. The fuel pump has a demand on it now, the injectors asking for fuel. Load. This is above its standard job. What every the static fuel pressure is, that is the fuel pumps standard job. Any thing above this is load.
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My comments start with ****John and is in blue
Quoted:
EFI injectors are rated @36psi of fuel pressure for a determined flow (lb/min or cc’s)****John, But can use pressures up to 100psi, and often do.
Quoted:
The fuel pump has a demand on it now, the injectors asking for fuel. Load. This is above its standard job.****John, This is incorrect, do you think the pump speeds up, or magically puts out more fuel when the injectors are "demanding more fuel"? if your answer is yes, then how does the pump know?----it doesn't know, when the injectors open the regulator restricts the fuel return and maintains constant, stable pressure! The fuel pump load is always the same! In fact a properly sized fuel pump doesn't even know that the injectors are opened! FUEL PUMP LOAD IS NOT DEPENDENT ON INJECTORS AT ALL, INJECTORS HAVE NO CONTROL OVER FUEL PUMP LOAD. THE REGULATOR PROVIDES THE LOAD. And did I say the regulator provides the load?
Quoted:
What ever the static fuel pressure is, that is the fuel pumps standard job. Any thing above this is load. ****John, First you said "Load is flow" now "Load is anything above it's standard job"
Could you please poke some holes in my previous post, you didn't respond
John
p.s. what does turning on 8 -20amp motors have to do with fuel supply and demand. When Angel stadium turns on all their lights my lights do not dim. I think we're feed by the same grid.
"<<Carl, go back and do another search on Shunts. I am not going to give you that answer."">>
Mr. Hopper,
We were not talking about shunts and wall outlets or most of the analogies you've dug up so far. The shunt example was to enlighten you about an instrument you incorrectly identified, in usage and function. I really don't need to search for them; I have three sitting on my bench!
It seems that you're not very accepting of any position other than yours. John has pointed out real world examples in today's performance vehicles. Of which I've noticed over the years that he's a fantastic source with an undisputable reputation for being a knowledgeable source.
Carl
Mr. Hopper,
We were not talking about shunts and wall outlets or most of the analogies you've dug up so far. The shunt example was to enlighten you about an instrument you incorrectly identified, in usage and function. I really don't need to search for them; I have three sitting on my bench!
It seems that you're not very accepting of any position other than yours. John has pointed out real world examples in today's performance vehicles. Of which I've noticed over the years that he's a fantastic source with an undisputable reputation for being a knowledgeable source.
Carl
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