Single Turbo Choice: Street and AutoX Car

[jecr]

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.

[Chadwick]

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

[Rotorypolo]

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.

[IR Performance]

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.

[Mobius]

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

[albertomg]

Originally Posted by Chadwick

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

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).

[sbrian2]

Originally Posted by Chadwick

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

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.

Originally Posted by IR Performance

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.

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.

[hsitko]

Originally Posted by Rotorypolo

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.

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

[IR Performance]

Originally Posted by Mobius

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

A-Spec, Greddy, etc.

[hsitko]

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.

[albertomg]

Originally Posted by sbrian2

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.

How much boost are you guys running on that car?

[sbrian2]

About 15psi.