1jz turbo choice help

My friend is after a upgraded turbo for his jzx100 chaser (1jz vvt) car is a street car and hp goal will be around 450-500 , we were advised to use a gtx3071 would this sound like a good sized turbo for the job , thanks for any help

What fuel will it be running on? When you say 450-500hp I am assuming at the wheels and on petrol? If so, I'd suggest it may be slightly on the small side and cutting it a bit close - that is quite a bit of power and I'm not sure you'd even comfortably do it on the stock cams, I have in my head the 1JZ VVTi motor has quite small ports and conservative cams from factory and need a bit of work to make a fair bit of power. If you are looking for a Garrett turbo which will do 450-500whp then I'd be looking at the likes of a Garrett GTX3582R or perhaps consider a GTW3476R.

I know some people in the UK insist on using "flywheel power" numbers which makes things difficult to call when you don't know what calculations people have made up in order to estimate it... given it seems that different tuners don't seem to agree on it. In terms of "real" crank hp the GTX3071R will move more than the area of 50lb/min required to make 500hp @ crankshaft on 98 octane RON fuel, on a 2.5litre I'd use a .82a/r turbine housing and it'd do it with pretty decent response.

There are plenty of other good options which will give very good results, too.

On a non VVTi 1JZ I've used a GTX3076r and made 459bhp at the hubs running approx 1.9bar boost, I really wouldn't advise going this far with a street car as the temps were starting to cause all sorts of issues.

For street use I'd probably run about 1.3-.5bar, it'll make your 450bhp at the fly target no bother and have lots of response, my one concern would be the gearbox, what will you be using?

Fly wheel hp on 97ron fuel , that's sounds perfect Chris the gear box is stock jzx 5 speed what size of housing was on it the gtx3076 ?

Is it the R154 that's stock on them? If so I'd go for a bigger turbo, GTX35 kinda size, to slow down the torque delivery

Yeah it's a r154 are they really that weak ?

https://youtu.be/KmyjEB6v2ho

To further back this up, my MR2 (2.0 3SGTE) runs a GTX3076 and made between 450 and 480 bhp "flywheel" bhp according to the dyno (at approx 1.8 bar), therefore give or take some percentage you're in the right area. Mine spools up ok, but you'd do better with a bigger engine. I have power coming on at 3500 and full power from 4000 rpm.

I also struggled with cooling though and have had problems with this, partly because the engine's in the back so getting cooling to it is a problem - charge cooling (I hope) is the answer and is current project.

Car used for circuit racing - could do with a little more oomph out of the corner when just off boost, however with a bit more displacement to help spool you up you might be ok.