I need some help selecting a GT35R for my car.

This car as all necessary modifications and I am running a standalone and a HKS manifold and wastegate. The car has a ported S4 TII motor. The car is an FB widebody. I last dynoed at 365 RWHP with 320lb of torque.

My goal here is quick spool up with a little over 400 rwhp (maybe 425). Car is a street/track car as I take it HPDE at the loval race tracks and it is not a DD. I have my heart set on the GT35 series due to their fast spool up.

Dave at KDR told me that I should look for a GT35 with a .64-74 hotside and a .70 coldside. I would like to know everyone elses recommendations as well.

I was lookg at both the RX-7 store:

https://www.rx7club.com/newthread.php?do=newthread&f=23

and A-Spec:

http://www.a-spectuning.com/store/in...&products_id=8

Any help here and any one with experience with the GTX turbos?

Thanks!

 

Think your goin the right way w/that GT35R BALLBEARING bro. I'd call Jason @
RX7 Store and tell him what your tryin to do and he will hook you up. I love my GT35R which came from Jason.

Good luck w/that.

 

Several ways to go about it. With an HKS manifold I would go with a 60 trim To4E .84, it will spool faster than a GT35R, just take a couple more psi to make up the rwhp difference...

 

Yeah, I have dealt with Jason before and purchased turbos from him for my FD. However, every tine I ask him about anything turbo for an FC engine, he tells me that he is not familiar with the FC setup and is not confident in recommending anything. That being said, I have not posed this specific question to him.

I am currently running a T04E that I had custom built by BNR. I don't remember the specs, but I was under the impression that the GT35R spooled faster and made more power.

 

Not in my real world experience, but there are other factors that greatly affect this. Are you talking about a BNR hybrid To4E based on a stock frame turbo?

I never recommend anything less than the 1.06 for the Gt35R on an 2 rotor. You won't see any real difference in spool, just kill your top end..

 

I custom built a turbo which was designed to support 370rwhp (1.2bar) operating on the ragged edge. My idea was minimal wheel sizes combined with 1.0 A/R turbine and a 60trim 70mm OD compressor wheel.

I actually hit 330rwhp using 18psi midrange, falling to 13.5psi @ 7300rpm. The idea was to get the thing spooling as quick as possible. Under these conditions would be operating around 105000RPM. Using electronic boost control or even stiffer springs in my wastegate (and putting up with the absolute MOUNTAIN of torque at 4000rpm that 20+psi gives you) I could get it to hold closer to 1.2bar/17psi @ 7300rpm and make the 370rwhp. That would be spinning the turbo to 125000RPM and absolutely maxed out completely verticle lines on the compressor map.

There will always be a huge rise in power on a twin rotor wankel around 4000RPM when using evalated boost pressures. I feel that is one of the reasons the factory was using boost pressures around 0.5bar.

I would not use a turbine housing smaller than 0.84 on a P-trim turbine wheel(65mm exducer). I would not use a turbine wheel smaller than a 55mm exducer (found in stage3-t3/gt30r/stock FC turbine). And for either 55 or 62mm exducer turbines I would use the 1.0 turbine housing.

If you compare most 300-500rwhp turbos on a rotary you will see that you very rarely get 18psi happening much earlier than 4000RPM. The bigger turbos have larger turbine wheels so more fin and harvest more of the waste heat.

When using smaller turbos what you do find is faster throttle response in the areas where there is not an abundant amount of waste heat, you also find the turbo is more eager to get going in the 2000-3000RPM band when you go smaller. You need to decide first on your PEAK power goal, and then decide if you care about throttle response between 2000 and 3500rpm or throttle response between 4000RPM and 7500RPM.

 

[QUOTE=Turblown;10526211]Not in my real world experience, but there are other factors that greatly affect this. Are you talking about a BNR hybrid To4E based on a stock frame turbo?
QUOTE]

No, I started with a hybrid and gave up on that. I sent it back to BNR and had him build it as a full T04E. As stated, currently running a HKS manifold and HKS 50mm external wastegate.

Pic of my current setup



My turbo before going in:





As you can see, not a hybrid.

 

Thanks for the good information. My peak power goal is juat over 400 between 14-18psi max. I want fast spool up, but throttle response is needed above 3000 RPM. I tend to keep my engine boiling when I am driving on the track.

 

Bump!

Any one else with any advice?

 

This is good advice, I started with a .82 open volute and later changed to a 1.06 divided and experienced no change in spool, 10psi by 2800 on both housings. I did get better boost control and the car feels better on top end.

 

Ok, so 1.06 A/R it is. I don't really understand the two dropdowns. I selected the 1.06 A/R and then on the turbine housing style I guess I need to also select the 1.06 A/R T04 with the V-band clamp?

Also, it it worth it to get the ported shroud (anti surge)? Does it really make a difference?

On a unrelated note, I got the Dinan Stage 2 software in my DD 335i DD yesterday. Holy hell, 400+lbs of torque is crazy. Makes gear shifting almost irrelevant. And that was suposed to be my "civil" car.

 

1.06 GT 35R on order from Jason!

 

Nice. Im currently running a jb+ @ 75% and bms dual cones on my 07 335i, the torque is awesome even with my mild setup. I think im switching to the cobb AP when its released for 07 models.

 

Yeah, I have always loved the rotaries and a beemers and I usually have at least one of each

Cheers!

 

all i gotta say is one of my fav turbos

 

Cool. Dropped it off last Saturday.

I soon hope to have one of the most unique WB FBs out there (without going 20B).

Currently getting painted Spirit R Titanium Grey and the getting the BBS RS refinished.

 

updates? would love to hear your impressions on the difference btw the three kits you have used.

Iam in a similar boat. I have a TII swapped fb that ive been researching turbos for.

The current turbo was a hybrid that gave up the ghost, now im trying to decide if i want to go bnr hybrid, t04, or something else like a BB gt35.

 

First ask yourself how much power you want and how are you going to plant it on road
I would guess that T04E 60 Trim with P-Trim 1.0 A/R turbine on tubular manifold will be able to push out more than car would transmit effectively

 

yes, its a good amount of power, the fb could handle the 300whp i had with sticky rubber. future goals will be wide body to stuff some bigger wheels and tires. but if the power is smooth it should be okay.

traction was one of things I was hopping the OP could comment on. seeing as he has an fb for track duty

 

The turbo I had in my FB was a T04E with a p-trim and a 1.0 A/R. I was seeing 365rwhp at 14psi. Traction was an issue as I could spin the wheels in third. That is why I went widebody. While the car was in the shop, I ended up buying the GT35R for no real reason besides boredom. I will sell the T04 for a couple hundred shiped if somone needs it. It only have about 300 miles on it and was custom built by BNR for about $1k.

I have not driven my new setup yet as there were some paint defects that I wanted fixed. Dave does the dyno tuning last so as soon as they correct the paint defects, I will be picking that bad boy up (see my sig).