Single Turbo Choice: Street and AutoX Car
 

I've been trying to make a decision on a turbo setup for some time now. I was originally going to go with BNR twins, but I've committed now to a single turbo setup (read: sold all of my stock twins stuff).

My first impulse was to jump on the GT35R bandwagon. After driving a 400whp GT35R FD, I changed my mind. The car was not for me at all. I beat my own time around an autoX course in that FD by 2 seconds with a stock S4 N/A.

I want something like what can be had from the Apexi RX-6 turbo setup, but hopefully without the price tag. Namely, full boost by 3k RPM, 350whp @ 12-15lbs of boost.

After a conversation I had today, my options seem to be the following:

GT3076R 53trim w/ .82 a/r turbine
OR
T3/T04E 60trim w/ .82 a/r turbine

Opinions?

This is relevant to my interests. To you have a preference on wastegate? I've heard that the 3076 will run out of breath on the top end and that 350 is about the most you'll get out of it. i'd at least go with the bigger turbine section.

just hearsay though.

I'm going to try out the Synapse Engineering wastegate, we'll see how that goes.

I've heard the same thing about the 3076 not having the top end, but I'd rather sacrifice 50whp on the top end for full boost at 2800-3000 rpm.

Which brings me to the T04E. How much difference does the whole ball bearing thing make? It's half the price, has more 'breath', but I don't know what the spool is like? I don't know anyone who has one.

Get the GT35R with the .82 AR turbine. You most like drove what I have, GT35R 1.06 AR.

I have driven a lot of single turbo fds, I always hear claims of people saying x turbo hits x amount of boost by 3-3500rpm and it never seems true. If you are shooting for 350rwhp and want great response just go with the stock twins or BNRs in sequential mode. Use the PFC to adjust the transition point of the secondary to make it more controlled and you will have the fastest spooling setup period.

This is just my opinion obviously, take it for what it is worth. If you want autox performance stay with the twins.

+1

The twins will do 350whp no problem and it is much cheaper and easier than going single.

If you definitely want to install a single turbo then look at the GT35R with the .82 turbine housing. I'm almost positive the FD you drove had a larger housing (more lag).

Really - dyno torque plots are going to tell you more than boost numbers will.

I have built an FD with the 35R .82 Housing - and it made boost fairly quick - but felt laggy compared to my GT3071R in the RX8; but I make over 200 lb/ft of torque at 3000 RPM...

I think comparing some torque graphs would help you pick the right snail for your car.

I'll have to ask what the a/r was on the car I drove. It could have had the 1.06. But still, what is the upside to going with the 35R?

David, I am going to take a look at going with the BNR's again, but it will be more money to do so than the 3076.

Anyways, thank you everyone for your responses and input.

I could see a 3076 being a really good street turbo.

It really shouldnt be any more money. You dont need a custom downpipe, it already has the wastegate, you dont need a custom manifold, custom oil feed/drain lines. They are hard to beat for simplicity/performance/price.

Like I mentioned before, I sold/gave away all of my twins stuff to other local FD owners already, after my last set of twins ate itself at 15lbs. The initial purchase price plus all of the components to make a reliable, functioning sequential system will be significantly more, and it will be more complicated.

$2600 for everything I need, fab up a downpipe, bolt on and attach a couple of vacuum hoses. Oil lines are minor, I probably have enough stuff just lying around here to finish those off.

I think I'm pretty set on the 3076. I'll post up some pictures ect. in the spring when it's done.

I'm sorta in your boat too. I originally went with a T-78 single to during my rebuild swap, to simplify the process and I got the kit for a good price. I tried my first auto-x and now I'm considering something smaller, I'd like to find something that has an external W/G since I want to try and reuse some what I can like my GReddy manifold and type-R W/G after reading what you are considering I'm going to start looking into those myself. Best of luck to you =)

For AutoX/street I am with David... stick with the Sequential Twins. I haven't bought and sold and many FD's as David, but I have quite a few pass through my hands. There is no better set up for AutoX/Street IMO then Sequential Twins... whether it be stock, BNR Stage 3's, or 99spec. I currently have 3 FD's... a sequential, a T78 Single, and a full nonsequential car. I'd rather drive the sequential any day and time on the street or autoX. Track Days though... T78 all the way :D

I been thinking about this for awhile... And to be honest.. I'm a fan of twins and fan of BNR turbos.

My blk FD will have BNR stage 3s in seq. and my MB has stock twins in seq.. I also have a BIG T-76BB that's been sitting in my living room.. Newly rebuilt.. with all the junk to put in minus the DP. But I just can't seem to put that in there as I like No lag :)

Throw that baby in there, nothing a 75 shot of nitrous couldnt spool up :)

Phil, you need to build the black car into a 600+rwhp fd or bust.

I've been autocrossing my stock twins for 8 years and prefer the more linear response then a single turbo setup. Also, a single turbo setup would also automatically bump you to SM2.

I also have to weigh in with the Twins crowd. I have yet to run across a single that can come online as quick as properly tuned twins. I personally run the 99's but am considering going to BNR's when they die. I actually need to talk to Brian about the possibility of making a set that keeps the smaller primary and a larger secondary.

Dan

I am contemplating going BNR III's in seq. form and maybe a GT35R w/ .84 AR. Something that can achieve around 400-430 rwhp and still get decent spool. I am not sure if the BNR seq. will do the trick. Most I have seen people with BNR seq. get about 360-380 rwhp with 15 lbs?? To be honest, if I am gonna spend close to 3K to upgrade to BNRs (seq. of course) and get about the same hp as my stock twins can put out, I might as well get a set of used stock twins and call it the day...unless people can prove me the BNR's in seq. form can handle more in moderate boost level like 15-16 lbs on pump.

For autocross you'd be happy with a T3 gt35r with the smallest hot side option. You will be limited in top end power, but you will want the spool to get you out of the tight turns. Otherwise you could go with the Apexi RX6 but I have never liked that kit. BNR's are great for those wanting to keep costs down and stick with twins, but the very non-linear power band will be difficult to manage at autocross. Even stock twins exhibit the same problems once you have too many mods. There is just too big of a sudden power surge when they transition and it can send you right into a wall.

Does anyone know of anyone who produces/sells T3 flanged manifolds for the FD? Or if there is a FC manifold that would work?

Let me know how that works out. I'm contemplating moving to BNRs but am concered that it will be a bit laggier than my current 99 twin setup (running seq).

In with the twins too. Dan's car is so good with the 99's it is hard to imagine that the power band could be better, but we have discussed the idea of a BNR hybrid setup if it could be made.

I disagree. While most FDs I have driven have this characteristic, it can be tuned out. Dan's car has a very smooth power curve and the only real way you know that you are in the 2nd turbo is by the change in the pitch of the engine and the fact that everything looks like it is in fast forward :). I was able to hop in his car and be very fast out of the box despite the fact that I have driven a low horsepower (114 to the wheels) E Stock Miata for the past 6 years.

I'm not so sure about these things that you are talking about. I have a 35r with a mild streetport and all of the supporting mods necessary to make Great power. And i make 380whp on a brand new self sampling dynojet with 40c intake temps. On a dyno dynamics with 60c intake temps i made 360whp My friend chance with a freshly broken in large street port in great condition stock twins with all the necessary supporting mods made 317 whp at 14psi on the dyno dynamics which steve kan told us was one of the highest numbers he had ever seen on stock twins. Both of our setups were tuned by steve on a dyno dynamics. Where are you getting 380 on stock twins from? That is crazy. Those things turn just about useless past 14psi. The only thing they do past there is make a hotter air charge. I hit 15psi at about 3.8k in my car. Which is pretty damn spectacular. That puts me within 50lbf of my peak torque at 3.8k and only 1.4k away from it. It is way more than satisfying. That and it weigs less, is simpler and makes less heat than the stock twins. That and i dont have to worry about the in and out of transition of the sequential system (which in my opinion is the only way that the twins should be run).

Non sequential can be proven to be a bad idea with the reading of dyno charts. Nonsequential gains a minimal amount of hp on the top end and the losses in torque and spool on the low end make the car technically slower than one with a functioning sequential system. You cant argue those points. There is some info for you.

As for the 99 spec twins. They have something called an abradiable compressor housing. Which is actually just a plastic insert in the housing that the compressor wheel actually wears a groove into to increase the tolerances in the housing. The only benefit that has been reported by the 99 spec twins are a faster spool time and the obvious benefit of having brand new turbos. Otherwise the power increase comes from other modifications made to the rest of the power plant such as the efini y pipe and different engine management. Some of the internals of the 99 spec rotary engine are different as well. Namely the "bath tubs" on the rotors.

Picking your turbo with spool times in mind is a great idea. Just make sure you dont listen to people who tell you that 380 is a reliable number to make on stock twins. Its just not. Low 300's are the maximum safe area for the stock twins.

Any questions on my setup please feel free to pm me.

--Hank

A-Spec, Greddy, etc.

Greddy does not. The only ones i have seen come from a-spec. For this reason i had mine custom made by clr motorsports for less than half the cost of the a-spec one.

How much boost are you guys running on that car?

About 15psi.