Yup, there's the big rub as far as stock-based turbos. Heat on the track. Sure you can make great power with twins, but after 10 mins on track you're staring at IAT's in the 70's (C)!

 

Very true. And you're also making more heat than the stock setup, as well as more power. That's probably the biggest disadvantage i've seen so far. To make the same hp, a single setup would run significantly cooler (IAT's and coolant) than bigger twins. But then again, bnr's *are* half the price of a complete single setup...

 

I will, eventually, track this car in DEs regularly (15-20 weekends a year). Right now I am relegated to tracking my daily (a 325is)...and it is depressing when the RX7 is sitting at home Just for reference...I have been tracking cars for many years and work as an instructor for NASA and AZRA, when I can get out to the track .

In my research the single GT35R from A-spec was the way to go...in fact I just ordered it this week. I trouble shot the stock twin setup, fixing it twice, both times it fell on its face again with some solenoid or another malfunctioning. Maybe I have a cursed car...

For me though, the heat that the twins...in any form...introduce into the engine bay is their biggest detriment. I can push the same volume through a GT35R as the BNRs but do it with 10 degrees cooler IATs. Cooler IATs are just the start as all the crap surrounding the engine is removed as well, giving you cooler engine temps (oil and coolant) due to the improved air flow. You take that into account, you eliminate the vacuum hose mess under the intake manifold, and also produce a more linear boost curve....and you have me sold. 400whp with a relatively reliable tune is my goal on this moderately aggressive ported engine.

I passed emissions here in AZ without the airpump hooked up, so I am not worried about that. You can keep the emissions gear on the car with GT35 so with it all functioning I am sure I will pass the sniffer just fine.

They don't do much in the form of visual inspection here. Last time I went a kid just looked under the hood, came back to me with a big grin and asked me what was done to the car....how fast it was...and if he could have a ride in it sometime...

 

10 degrees cooler? More like 20+ degrees... celcius... from what i've seen from single turbo cars on track vs. twin turbo's with similar supporting mods.

 

Wow great numbers rynberg!


Oh and to this dude:

sucks that you don't get to drive you car in the winter ha ha

 

 

good numbers Rynberg, now let see some pics of the cage and the rest of all the mods..wanna see those big brakes too..

 

It sucks even more than you think... We only have 91 pump.

 

BNR's!

 

About the heat discussion. Wouldn't it help a lot with IAT's with a vented hood like the N1, and a vmount?

 

The IATs aren't the critical problem, at least not with a larger SMIC (although, they do get in the high 60s C on a HOT track day). It's the water temps from those two blazing ovens strapped to the motor.

A vented hood would probably reduce temps a little bit, but I've yet to see solid documentation as to how much.

 

I haven't had coolant temp problems with either of my pairs of BNR 3s (old style and new style). This includes a track day in September in Texas at Motorsport Ranch, when my peak temps during 30 min hot lapping sessions at 14 psi only reached 99 degrees C. Of course, I have had my A/C removed for awhile now, but this is with stock hood and no fancy v-mount

 

I have the old style BNRs 3 on my car now (just finishing it up), with the stock exhaust turbines and bigger compressor turbines (or whatever the technical jargon is), I've heard these will spool a little faster, is that true?

 

IM going BNR !

 

I would call Bryan up and ask him. He can be reached pretty easily during the day from 10am to 5 pm, eastern time. His shop # is 205 640 1193.