Single Turbo V8 Sandrails - a rarity? a good idea? fast is fast right?

[Grease Monkey]

I’m a single turbo guy. Love it. That’s what I would do!

Been thinking Subaru and Honda engines thru this whole thread. All single turbo.

 

[John@Outfront]

It always cracks me up when v8 turbo guys say they have lag. I mean like a v8 is already massive torque non turbo so I just can’t relate. I’m like how fast can you go? What I think most guys are really saying is “ my car is too heavy” it does not “ move” as fast as I want therefore it must be turbo lag.

That being said , sure there could be real situations of turbo lag because people are picking turbos that are way too big But I believe the first comments are more true

 

[Sutton]

I have done 10 single turbos kits on LS motors, 3 of them have been on a DD car, Works good, Typically all the parts come close to $5000 depending on sales during the year,

What size turbos are you putting on most of the ls1/ls2 cars?

 

[Rockwood]

I have seen a couple setups where the turbo feeds directly into the intake manifold without an intercooler.

I know there is the option of using a water cooled intercooler in the intake manifold (Tick or Shearer)
View attachment 170293

But i have seen some without it. How are they managing to keep intake temps cool with a setup like that?

E85. No need really for an intercooler unless you’re going crazy with boost.

 

[J Alper]

Turbo setup looks killer! I wonder how bad (if there is any) the lag is. Turbo looks pretty big.

It not big,

 

[J Alper]

What size turbos are you putting on most of the ls1/ls2 cars?

Depends on the Motor size, The smallest is a 415 and the largest was a 485 tall deck

 

[John@Outfront]

Depends on the Motor size, The smallest is a 415 and the largest was a 485 tall deck

he wasn't asking for motor size, he was asking for turbo size you use for LS motors

 

[Goatpoker]

I’m also entertained by the concern about 1 big turbo vs. 2 smaller ones. I mean, it’s just math. 4 cyl feeding 1 properly sized turbo… or 8 cyl feeding a 2x bigger turbo is the same thing. LOL.

Yes, it takes more pressure and flow to move the bigger turbo, but you have more pressure and flow from 2x the cylinders.

Now, if we get in the weeds, you are loosing efficiency due to the distance from the exhaust valve to the turbine being longer. So, under ideal conditions 1 turbo will be less efficient than 2 close the to valves. Might be able to see it on a dyno… not the way most people drive.

Which leads me to the lag discussion on these “1200HP” twin turbos. When the turbo is sized to feed 7000rpm and max hp… it will be sluggish at 3000rpm. If you wanna drag or run the hill that’s good. But you will feel it coming out of a turn pulling from 3000-5000. I’d gladly sacrifice high end for strong mid-range

 

[Kraut_n_Rice]

An easy cure for lag is Nitrous..lol

 

[Cookie]

It always cracks me up when v8 turbo guys say they have lag. I mean like a v8 is already massive torque non turbo so I just can’t relate. I’m like how fast can you go? What I think most guys are really saying is “ my car is too heavy” it does not “ move” as fast as I want therefore it must be turbo lag.

That being said , sure there could be real situations of turbo lag because people are picking turbos that are way too big But I believe the first comments are more true

ME TOO, but I always thinks it comes from the people that don't shift at all as well. For myself, I started on 2 stroke MC and then graduated to an VW 1835cc, they lag big time unless you are on the powerband. Sam at Rancho told me years ago, never lag the car, too much stress on the tranny.............run it like you stole it and there is no lag

 

[J Alper]

he wasn't asking for motor size, he was asking for turbo size you use for LS motors

I know what he was asking, the Turbo size really depends on the motor size,

 

[Rockwood]

I’m also entertained by the concern about 1 big turbo vs. 2 smaller ones. I mean, it’s just math. 4 cyl feeding 1 properly sized turbo… or 8 cyl feeding a 2x bigger turbo is the same thing. LOL.

Yes, it takes more pressure and flow to move the bigger turbo, but you have more pressure and flow from 2x the cylinders.

Now, if we get in the weeds, you are loosing efficiency due to the distance from the exhaust valve to the turbine being longer. So, under ideal conditions 1 turbo will be less efficient than 2 close the to valves. Might be able to see it on a dyno… not the way most people drive.

Which leads me to the lag discussion on these “1200HP” twin turbos. When the turbo is sized to feed 7000rpm and max hp… it will be sluggish at 3000rpm. If you wanna drag or run the hill that’s good. But you will feel it coming out of a turn pulling from 3000-5000. I’d gladly sacrifice high end for strong mid-range

Yeah. I think the "twin turbo is better" thing is because of 90s cars that touted them as the solution to turbo lag (which, they didn't). Everything modern is turbocharged and you almost never feel lag with an OEM turbo setup.

Exhaust efficiency is lower with a single turbo, but in buggy form you'd be hard-pressed to really kill efficiency given the engine's already at the back of the car.

Spinning up 4 wheels, shafts, bearings, then the drag those cause, is less efficient as well, so in the end, it's basically a wash. SIngle will absolutely save money/complexity however. Middle ground is twin scroll.

Any turbo setup will be sized for a powerband, and this comes down to user preference and power goals.

A good, modern turbo (GT or GTX) will be responsive at 3,000rpm and still hold strong at 7,000rpm. Biggest issue is for an LS that revs to 7k is it usually isn't awesome at 3,000 and should've been downshifted anyway. A turbo is just going to elevate the powerband that already exists, except in parts where the turbo just can't respond.

I know what he was asking, the Turbo size really depends on the motor size,

That LS flexibility. Is it 292? Is it 454? Dunno.

 

[Kraut_n_Rice]

Yeah. I think the "twin turbo is better" thing is because of 90s cars that touted them as the solution to turbo lag (which, they didn't). Everything modern is turbocharged and you almost never feel lag with an OEM turbo setup.

Everything modern also has VG turbos controlled by the ecu to maximize the power band.

My wife has a Chevy Equinox with a turbo 1.5. It moves pretty good.

She bought the car without me. She just brought it home. Whatever, her money. I had only driven it a few times in the first couple months. When it came time to change the oil was the first time I even opened the hood. I was like, WTF? T1.5?

 

[Rockwood]

Everything modern also has VG turbos controlled by the ecu to maximize the power band.

My wife has a Chevy Equinox with a turbo 1.5. It moves pretty good.

She bought the car without me. She just brought it home. Whatever, her money. I had only driven it a few times in the first couple months. When it came time to change the oil was the first time I even opened the hood. I was like, WTF? T1.5?

Diesel, yeah. VGT and gasoline cars is a bit more rare. Most are electronically actuated, but standard single geometry turbos, like the 1.5 in the Civic SI:

 

[Kraut_n_Rice]

Diesel, yeah. VGT and gasoline cars is a bit more rare. Most are electronically actuated, but standard single geometry turbos, like the 1.5 in the Civic SI:

View attachment 170388

Be curios to know the ECU logic on the gates function. Closed for fast spool/low RPM situations. Varying degrees of open to manage boost and not overspeed it? VG~ish?

 

[Rockwood]

Be curios to know the ECU logic on the gates function. Closed for fast spool/low RPM situations. Varying degrees of open to manage boost and not overspeed it? VG~ish?

Torque management. DBW means you can do torque request and the ECU does the calibration calcs on requested load vs. how to execute it. Means for very smooth driving with the AT and engine below just figuring out what you meant.