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ltpyro

Honda turbo size

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What size turbo(s) would you recommend for a j35 Honda?  I really want to make a twin turbo car, so I'm leaning that direction.  Looking for 400+hp.  

 

I've never sized a turbo to a motor and not sure how to properly do that.

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Gt35r with .82 hotside is supposedly the ticket. I'm running a ball bearing t3/t4 hybrid with billet wheel. 

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i have some trick little turbos that would work  $850 for one but would do 1500 for a pair.  even have SS exhaust housings.  good for up to 600hp. you are being too bashful thinking you're only doing 400.  a gt35 is only for a single turbo application and still too big unless its a gen one ( i have a brand new one of those for a great price)  also talk to Kraut_n_rice, Brandon on the board. he may have the ticket for your motor build too

Edited by John@Outfront Mtrsprts

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9 hours ago, John@Outfront Mtrsprts said:

i have some trick little turbos that would work  $850 for one but would do 1500 for a pair.  even have SS exhaust housings.  good for up to 600hp. you are being too bashful thinking you're only doing 400.  a gt35 is only for a single turbo application and still too big unless its a gen one ( i have a brand new one of those for a great price)  also talk to Kraut_n_rice, Brandon on the board. he may have the ticket for your motor build too

There is a little "+" behind that 400 :) .  My original goal was 500, but scaled my expectations back for the moment to see how much this is going to cost me.  I just got the new transaxle and will start the process of tearing down the car for a rebuild this summer as soon as the engine I have for sale goes away.  Was going to send Kraut_n_rice a PM, he is very knowledgeable on these Hondas.

Right now I just want to plan out parts and costs.

Can you tell me more about those turbos?

Edited by ltpyro

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1 hour ago, ltpyro said:

There is a little "+" behind that 400 :) .  My original goal was 500, but scaled my expectations back for the moment to see how much this is going to cost me.  I just got the new transaxle and will start the process of tearing down the car for a rebuild this summer as soon as the engine I have for sale goes away.  Was going to send Kraut_n_rice a PM, he is very knowledgeable on these Hondas.

Right now I just want to plan out parts and costs.

Can you tell me more about those turbos?

they are T28 based turbo, good forup to  300hp each so 600 would be obtainable in the future.  they small, designed for a 2.0-2.5 liter so it would spool quickly. brand new, 3" inlet and 2" discharge on the cold side. They come with a special SS exhaust housing so no jet coating needed.  brand new, journal style bearing.  Of course you will need an intercooler regardless.

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GTX or GT2860RS with the 0.64 turbine housing if 500whp is your goal.  0.86 housing if 600whp or want to run weaker fuel (not sure what the knock resistance on the J35 is) and are willing to sacrifice a little response.  

That being said, unless it's for looks or packaging problems behind the engine, you'll get way more performance out of a single GT30/GTX30 or GT35/GTX35

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44 minutes ago, Rockwood said:

GTX or GT2860RS with the 0.64 turbine housing if 500whp is your goal.  0.86 housing if 600whp or want to run weaker fuel (not sure what the knock resistance on the J35 is) and are willing to sacrifice a little response.  

That being said, unless it's for looks or packaging problems behind the engine, you'll get way more performance out of a single GT30/GTX30 or GT35/GTX35

he wanted dual turbos, putting two gt2860rs would be too much turbo  the turbos I have are smaller then those

the GTX30/71 would be the right turbo for a single, the 35 way too big for a duner

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Could the Turbo size recommended a single GT30/GTX30 or GT35/GTX35 be used in a similar displaced motor such as the 3.5l Honda but on a GM LFX 3.6L v6 engine application ? 

Thanks and i'm not asking for a friend. 😁

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35 minutes ago, GROPER said:

Could the Turbo size recommended a single GT30/GTX30 or GT35/GTX35 be used in a similar displaced motor such as the 3.5l Honda but on a GM LFX 3.6L v6 engine application ? 

Thanks and i'm not asking for a friend. 😁

I would assume so since I believe you size a turbo for the size of the motor and the desired HP you want.  But, that's about as far as my knowledge of turbo sizing goes...

 

1 hour ago, Rockwood said:

GTX or GT2860RS with the 0.64 turbine housing if 500whp is your goal.  0.86 housing if 600whp or want to run weaker fuel (not sure what the knock resistance on the J35 is) and are willing to sacrifice a little response.  

That being said, unless it's for looks or packaging problems behind the engine, you'll get way more performance out of a single GT30/GTX30 or GT35/GTX35

Mostly I just wanted a twin turbo car.  Most everyone I know runs a single because its a cheaper solution.  How would a single turbo get more performance than a twin?  I'm assuming you have to sacrifice a little low end response to get a single to flow a higher volume at top end, and with twins you could retain some of the low end quick spool and keep a little more top end because you could split the flow between two turbos.  Educate me...…  :)

 

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2 hours ago, John@Outfront Mtrsprts said:

  they small, designed for a 2.0-2.5 liter so it would spool quickly. 

Are they designed as a twin set for a 2.0-2.5 or as a single turbo for that size?

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1 hour ago, ltpyro said:

I would assume so since I believe you size a turbo for the size of the motor and the desired HP you want.  But, that's about as far as my knowledge of turbo sizing goes...

 

Mostly I just wanted a twin turbo car.  Most everyone I know runs a single because its a cheaper solution.  How would a single turbo get more performance than a twin?  I'm assuming you have to sacrifice a little low end response to get a single to flow a higher volume at top end, and with twins you could retain some of the low end quick spool and keep a little more top end because you could split the flow between two turbos.  Educate me...…  :)

 

Twice the moving parts.  Most turbos have about the same bearing and shaft sizes, so with a single turbo, more of the compressor's wheel is dedicated to airflow instead of attaching to the shaft.  

You'll also only need one wastegate, so simpler/cheaper.  @jtmoney714's turbo J35 sounds like a V8 when you start it, then plain pissed off under boost.

2 hours ago, John@Outfront Mtrsprts said:

he wanted dual turbos, putting two gt2860rs would be too much turbo  the turbos I have are smaller then those

the GTX30/71 would be the right turbo for a single, the 35 way too big for a duner

Guess it depends on what the OP is looking for: "I just wanna dune in 3rd" or "I want everyone around me to fear for their lives". :bigrin 

GTX2860RS with the 0.64 turbine would spool pretty damned quick and likely clear 300lb-ft by 2500rpm.  Revving to 7k, this would make for a fairly wide powerband.  

Smaller than that, you could just throw a couple of ball bearing straight T25s on there and max out around 500whp and spool a little quicker.  Something like a GT2560 could make 550-600whp maxed, but those will be a little less efficient than the newer stuff and it's the same 46mm in/60mm ex compressor, just 90s tech and a smaller turbine.  YMMV, but I've never been a huge fan of super small turbos running lots of power on VTEC motors because you either have to disable the big cam or you have to take a lot of timing out due to shitty delta P.  3.5L V6 with VTEC is a lot of exhaust energy to spool shit up, so we usually tried to take advantage of it. :bigrin 

Compressor map for the GT2560 (aka S15 turbo):

GT2560_COMP.jpg

And the GTX hotness:

GTX2860R.JPG

Same physical size wheel, way more flow and efficiency.  Figure a J35 @500whp will be right on that 76% mark, which will make for a very low stress and free-flowing set of turbos.  If running an AEM Infinity or similar, just crank the timing on the off-boost maps and keep the compression reasonable on whatever piston you get.  Regular J35 isn't a wimp NA anyway.  Both of these are "1.4-2.5L" turbos per Garrett.  

Edited by Rockwood

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1 hour ago, ltpyro said:

I would assume so since I believe you size a turbo for the size of the motor and the desired HP you want.  But, that's about as far as my knowledge of turbo sizing goes...

Mostly I just wanted a twin turbo car.  Most everyone I know runs a single because its a cheaper solution.  How would a single turbo get more performance than a twin?  I'm assuming you have to sacrifice a little low end response to get a single to flow a higher volume at top end, and with twins you could retain some of the low end quick spool and keep a little more top end because you could split the flow between two turbos.  Educate me...…  :)

 

It's funny you mentioned that you want a twin turbo motor, I have a twin turboed 416ci LS3 in heavy 4 seater, but for my lighter 2 seater I want one turbo that spools up faster.

The LFX 3.6l I'll be installing is available with factory bolt on twin turbos that came on the Cadillac CTS's.  I just want something with less weight, moving parts and plumbing.

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1 minute ago, GROPER said:

It's funny you mentioned that you want a twin turbo motor, I have a twin turboed 416ci LS3 in heavy 4 seater, but for my lighter 2 seater I want one turbo that spools up faster.

The LFX 3.6l I'll be installing is available with factory bolt on twin turbos that came on the Cadillac CTS's.  I just want something with less weight, moving parts and plumbing.

Aren't the NA LFX motors a little explody though? Never modded them...

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3 minutes ago, Rockwood said:

Aren't the NA LFX motors a little explody though? Never modded them...

What I've read there good for 6-7lbs and to 10+ with Timing Chains & Cams. It's a pretty popular motor for RX8 Conversions and smaller Hot Rod's. There are several available with very low miles from $1k to $2500 depending on miles.

Edited by GROPER

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On ‎2‎/‎14‎/‎2020 at 8:04 AM, Rockwood said:

GTX or GT2860RS with the 0.64 turbine housing if 500whp is your goal.  0.86 housing if 600whp or want to run weaker fuel (not sure what the knock resistance on the J35 is) and are willing to sacrifice a little response.  

That being said, unless it's for looks or packaging problems behind the engine, you'll get way more performance out of a single GT30/GTX30 or GT35/GTX35

Mostly because I want twins but in order to put a single I would have to mount it off one side down low since my cage is right behind the engine and I don't want to re-fabricate it unless I absolutely have to.

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3 hours ago, ltpyro said:

Mostly because I want twins but in order to put a single I would have to mount it off one side down low since my cage is right behind the engine and I don't want to re-fabricate it unless I absolutely have to.

Word. If you can still merge them, try to. Sounds a lot better that way. 

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On ‎2‎/‎14‎/‎2020 at 10:49 AM, Rockwood said:

Same physical size wheel, way more flow and efficiency.  Figure a J35 @500whp will be right on that 76% mark, which will make for a very low stress and free-flowing set of turbos.  If running an AEM Infinity or similar, just crank the timing on the off-boost maps and keep the compression reasonable on whatever piston you get.  Regular J35 isn't a wimp NA anyway.  Both of these are "1.4-2.5L" turbos per Garrett.  

What would be "reasonable" compression???  Since the J35 comes at 10:1 stock I was hoping to get pistons that would allow me to drop to 8.5 or 8:1, does that seem like a good place to shoot???

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Gonna run corn or race mix? 9-9.5:1 is reasonable as long as you keep the coolant temps in the 170-180 range. 

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I would love to keep it at pump fuel, but willing to go to 50/50.

The whole engine area is getting a make over this summer.  Got a new 2D, going to get a new radiator and a few other goodies...

I'll be making a few more posts with questions that I have once I get the car out of the trailer and in the garage to begin the work.

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