i am thinking about a t04r, t04z or t04s garrett, spa, or presicion turbo. I want to know about ARs. There are .63 , .70 , .83 etc......I want to make boost at 3500rpm, fast spool. Which AR do you recommend for 400whp (all supporting mods of course)? the car is mainly for street use and some ocasionly drag racing.

Is it true that HKS don't make a wastegate that fits their iron cast manifold? which wastegate will fit?

 

"make boost" means nothing. you will make boost at 1500 rpm, but where will you hit your target boost or full boost is the question. gt35r with a .84 or 1.00 turbine housing is the ticket for you.

and yes it is true that hks doesnt make wastegates for there cast manifolds anymore. just buy a used one.

 

i want to stay below 1.00. Lets lag as posible. not looking for more than 400whp but fast spool is critical. seeing to hit full boost as low as posible maybe 4500 rpm

 

I wouldn't go below the .8X and the gt35 will hit full boost way before 4500 rpm at 15 psi even with the larger 1.00 housing. If you're running the cast manifold the .96 undivided would be a good way to go if they make it for that turbo. The turbine housings you listed are too small for a rotary.

 

The A/R is half of the battle. Choosing the turbine wheel size is also critical. Generally rotaries require a larger turbine housing and naturally coupled with a larger wheel. A divided turbine housing will allow for a quicker spool up. I would use a 35r or equivalent turbo on your setup...

 

It will only allow faster spool if the manifold is divided also. The cast ones i don't think are divided. So a divided turbo housing could theoretically hinder performance given the extra blockage in the airflow path.

 

lets recap so we have a
gt35 turbo with a .86 AR divided exhaust
stainless steel manifold with a divided flange

How about the t04s or t04r turbos? i have seen some of these turbos up close on a few rotaries . i was thinking about a t04r with a ,70 AR. your thoughts?

 

too small hotside. if u want to go with a to4r or any turbo for that matter plan on going with a .8X or larger hotside. The gt35 is basically the same size as a to4r except its dual ball bearing so it spools faster. which is what you want. Thats why everyone is saying go gt35. Though the cost is higher. Stop asking about the .70 a/r it isnt good for a rotary. Unless you are talking about the compressor side, which is fine. But no one really talks about the compressor A/R because its usually matched well to the size of the turbo and doesnt factor in like the turbine side of things

 

and a 35r with a .84 housing, they dont offer a .86. you would be suprised at how fast a 1.00 housing will spool. i had the 1.06 with a 35R on my car with STOCK PORTS and was hitting 18 psi by 3800. remember rotarys like big exhaust housings. hell, my new turbo is a 1.32

 

^^Yeah, my 1.06 hotside will hit 15psi by 3500 and it will do 18psi by 3800 as well. This is also on stock ports. Rotaries are not piston engines and require a pretty good sized hotside and associated wheel.

 

If your going to run a 67mm turbo and want as quick a response as possible I would run a BB unit, running a TO4R is not going to be your most responsive 400whp turbo. Otherwise look into something smaller. Most power for your response is going to be a larger wheel in a tighter A/r nine times outa ten. My suggestion would be if your looking at our 35R T4 .84 or 1.06 also take a look at our GT3574 but in our new BB version. This would run a GT35R compressor wheel with a 74mm turbine wheel in a .84 divided housing. Power numbers are available in our section but it will easily hit 400whp, most people are seeing lower mid 400's at moderate boost levels on standard port work. As for response the non BB unit is very close to 35R response. So it will only improve with the BB unit. Hope that helps you a bit please PM or email sean@a-spec.com if you have any questions.

 

A/R is AREA / RADIUS not air/ratios. I agree with most of the recommendations thus far especially Sean's (A-Spec). He sells great products/turbo systems that have been researched and tested and the perform well.

~Mike..............

 

what manifold are you running to get 18 psi by 3800? i am getting the same boost at the same rpm but with a .82 T4 housing.

 

I believe the 1.06 A/R turbine he is reffering to is a open valute (non divided) T3 footprint unit.

~Mike..........

 

Man I just want a replacement turbo for my old rayjay. bolt in and go, anyone who knows turbos ill have to send it to you for a match

 

How about this combo? It is a non-ball bearing turbo. Where could i see boost on street ported engine?

T04R turbo with 1.0 A/R divided exhaust housing
HKS cast manifold

 

Is the hks cast manifold divided? If not it will do no good to put a divided housing on it. It would only add a restriction in the pathway for the exhaust. I think if you did some searching you could find spool prefer for that turbo. That would give you a general idea. On an undivided manifold i would go with .96 undivided turbine. Or whatever the next smallest undivided is. Divided turbines will only increase spool speed if the exhaust pulses are kept seperate with a divided manifold.

 

originally you stated you wanted 400 hp with the fastest spool possible. you also said full boost by 4500 rpm.....but 4500 rpm isnt really fast for full boost. I'm guessing you want to run a reliable street setup on 93 pump gas. So that limits your boost to 15 psi without Aux injection (AI) or race fuel.

What i said earlier about the gt35 being the same size as a to4r wasnt accurate, i meant the to4z is basically the same as the to4r only DBB, although different manufacturers have different wheel combination for their to4r.

The gt35 is basically the same as a t60-1 only DBB. For a 400 hp ported engine running 15 psi and the fastest spool possible without choking on top, you should go with the gt35r with t4 housing. Full boost will be under 4k.

If you don't want to spend as much and sacrifice some spool then another good choice is the t60-1. Both will make 400 hp on a ported engine and spool faster then the to4r.

The to4s would also be a better choice then the to4r due to its peak efficiency being in the 15 psi area. The to4z really wont give you much more power until above 16 psi.

The t60-1, gt35r, and the gt35XX combination's that a-spec sell are all in their efficiency range at around 15psi, if you go with a bigger turbo it will just slow the response down and not make much more power until higher boost levels. So unless you plan on running a 3 bar map sensor, and either race gas or meth injection going with a to4r wouldn't benefit you.

 

excellent post!!!

 

the hks cast manifold is divided. Thanks for the detailed post. it was a used turbo......thought i could use it.....must keep on looking

 

If you can get a good deal on it and you're ok with full boost prob around 4500. (depending on your ports, exhaust, intercooler and tune) then it would be a good purchase. But def a smaller turbo will get you there with faster spool.

 

Excellent post. So a T60-1 and gt35r will get me 400whp @ 15psi on a ported engine. What would be the max boost they could handle?20psi? What would be the whp at this level?. I will probably run 15psi on the street with Alcohol injection and raise the boost with c-16 race gas at the track.

 

Yeah they will get you in the 400's @15psi with a well ported engine. 20 psi seems to be about their limit after that the efficiency really drops off. How much power you make will depend a lot on the porting and tune, but I would expect high 400's @ 20 psi. There was a thread somewhere called maxing out gt35r and it seems like they got close to 500 hp running 20-23 psi. Either turbo will make a great street turbo. I recommend going with a larger exhaust housing since you plan to run 20 psi.

 

what exhaust housing would it be? What about A/R, was thinking 1.00 because rotaries like big A/Rs. It will be mainly street turbo wih ocasional strip use.

 

yeah something like that.... 1.00 - 1.15 divided preferably if your manifold is.