I'm a big fan of sequential twins. The setup in my car is all about response - 99 twins at 14 psi, boost controller set up for fast spooling, transition dialed in so it's a flat power band with no sequential transition dip. Also 4.44 rear gears for more response.

All that said, I drove a friend's (Stephen) FD with the 8374 setup this year at Deal's Gap. Holy hell. I was AMAZED at the response, it really does spool and respond like the twins, then goes on to KEEP MAKING POWER, it just pulls like a train. IMHO it's the perfect weekend warrior street turbo, by far.

Here is his build thread -

https://www.rx7club.com/build-thread...-base-1140779/

I think with your current setup you can totally swap to the 8374, get it dialed in, then figure out where you want to go from there.

Personally I would go that route but I just can't justify sinking the money down on that setup - car needs other things, like a good paint job, first.

Dale

 

Yes I think it's the right move. Just need to figure out my heat management solutions, pumping out another 100+hp isn't doing the car any favors, and that inconel shielding is crazy expensive..

 

As I said before, thx for the kind words. Means alot coming from you.
Anytime you wanna drive her just say the word 👍


Also, Big time YES to the EFR 8374iwg its a awesome street turbo for those wanting a balance between spool and power.

Steve

 

Do you have a stock or ported engine?

 

Stock port

 

Any noticeable benefit with a turbo smart BPV upgrade? They claim better boost response? Or in reality is it just a reliability upgrade for turbos seeing hard use?

 

It's been just over a year since I started this thread. Car hit the dyno today. 436whp @1bar, 300ft/lbs by 3,700k. Started the pulls at 3k, super excited to dial it in and beat on it. Need to street tune for the low end. Thanks for all the help.

 

nice and congrats
.

 

Thats awesome!

I found hillclimbs themselves are the easiest way to improve turbo response/spool. So much more load on the engine/slower rpm sweep.

"Hillclimbing is a turbo sport".

Our local hillclimb is 1,160ft elevation change in 2.2miles and the top is relatively flat. A weekend racing there and the car feels unresponsive on flat ground.
______

If /when you are still looking for ways to pick at gaining response on your current set-up...

I ran many set-ups on the same turbo 2001-2012 (and then swapped turbos to efr 7670 for 2014).

I found-

Biggest downpipe/midpipe diameter possible for greatest turbo exhaust pressure differential.

A velocity stack on end of turbo inlet and the longest oiled (dryflow flows less) air filter on the end you can fit.

Balance ignition retard/high egts for spool VS ignition advance for engine acceleration- must be done on street with an accelerometer or load dyno tracing torque over time as a parameter.

Low timing split in the spool range (anything to raise egts in spool).

Hot ignition system and lean 16:1-15:1 afr cruise for high egts pre warming your exhaust components. 13 yrs of 1,000C preturbo egt cruise never hurt anything on my car (700C on boost).
Dont do this with catylitic and dont expect anyone to follow run you (extreme NOx in exhaust).

Combine or substitute the above with shorter rear end gearing (4.3:1 or 4.78:1 from RX-8).

 

I have a greddy v mount core on the way, it’s shorter than my current core, should allow a straight shot to the turbo instead of the 90* inlet I have now. I’ll also be able to rework the turbo to intercooler pipes to be a lot more efficient. 4” downpipe will happen at the same time I think. I can’t get too insane with the spool tuning, it’s primarily a street car so high egts at 3k will be my freeway cruising zone.

Nice to move on past the initial build and tune, back to driving for a while instead of waiting on parts. I’m going to enjoy it.

 

The FD after mine put down 545whp on a T51R… puts my build into perspective lol. This is a slow FD by Thailand standards, everything here has a massive bridge port

 

A 90 degree turn in the turbo inlet is beneficial to spool though it reduces peak flow.

The phenomenon is counter rotation of the air column against the compressor blades. There are sae papers and patents on this by OEMs. You can find my thread on that as well.

Or you can use veins to accomplish this.
I think Bullsey Batmo turbo inlet is the only example of this available over the counter.

Luckily, patent infringement is only for selling stuff- so we can use all this simple patented stuff on our race cars without legal issues.

 

Weird, I never would have expected that. Definitely something to test out. Might not be worth the reduced flow up top, only one way to find out.