Hey guys, I have been searching but having a hard time finding the info I need, if anyone can direct me to a thread that will answer my question that would be great. I am building an 87 Iroc 5.7 L98 TPI v8, single Holset wh1c, internal gate w/ adjustable actuator, plan on running around 6psi with no intercooler so the charge pipe won't be long maybe 2 feet into the oval 3.75"ish throttlebody, compressor outlet is 2.5" would I be better off running 2.5" pipe to the throttle body or would I benefit from using a 3" ? My theory is considering i am wanting low boost and the TPI is infamous for low rpm torque and this turbo is made to produce 20-30psi on a diesel Cummins 5.9 at low rpms would I benefit from the larger pipe? I don't want it spooling up and making 6psi without being into the throttle much etc. Thanks guys

 

I forgot to add the turbo specs 56mm inlet with 12cm exhaust housing

 

You won't notice any difference in the two. I'd go with the 3" though.

 

I also do have access to an hx40 compressor housing and I have read that I can change my turbine housing to a larger 14 or 16cm would you recommend any of these modifications right off the bat or should I just go ahead and try the stock 12cm with 56mm and if I am not spooling and producing power at the rpms I want play around with things? Apparently my tune and stock maf are limited to around 400hp so I have been instructed to get a wideband and run low boost and raise the boost until I achieve max safe reliable power levels so I'm not going crazy with it I am building a reliable torque monster camaro

 

Your going to find that turbo small no matter what. Yes, its made to go on a 5.9l, but the 5.9l is peaking at 2600-2800 rpm. It will be out of mass flow very quickly as soon as it sees rpm. You really need 2 of them for the gas 5.7l. Once it runs out of go, the engine is going to feel like its hitting a wall.

Run what you've got to start, tweak once you know how it behaves.

 

I was going to say the same thing, but then remembered that these were something like 160 hp, and all done by 4500 rpm. The T3 sucks for future upgrades, but that can be changed pretty easily.

 

The T3's are generally bad, but some of the T3 diesels are pretty darn big. The Holset 18cm T3 is like a 1.37 T4. The 14cm is like a 1.05 T4

Unfortunately that compressor is too tiny for the job. I wouldn't bother trying to fit/use that unit when you can get a new "GT45 clone turbo for $140 shipped. Or a 78/75 billet turbo for $270 shipped.

 

Personal preference would be to run the turbo outlet size to the throttle body, the reason for this is it will reduce lag very slightly.

The turbo is small so you won't be aiming for top-end power but instead driveability, I think that would suit your needs better.

 

Hey guys so I acquired a good used HX40W with 7 blade compressor wheel and a 16cm exhaust housing, this sound like it would be better for my application? All tips and tricks and advice are welcome thanks!

 

prob not... The exh housing and wheel aren't the problem. Think those are a 57mm compressor? (some had a 60mm). Pop the cover off and measure it, But either is too small for a v8 IMO. A simple GT45 clone is dirt cheap.

 

V8 doesn't really matter, what matters is its na torque/hp. Some modern 4 cylinders make more power than that v8 in stock form. Plenty have run 60mm compressors on 225 -250 na hp engines.