I started a turbo build a while back, so the car has full TII rear and trans, beefy clutch, and now Im trying to decide on what Im going to do, I plan on 4 port plates, s5 N/A guts, defined autoworks header, and this throttle body
https://sdparts.com/i-24133478-holle...0aAnvoEALw_wcB

I need IACV and such, my car has A/C and PS, the question I have, using my 4 port holley intake and that t.b., am i going to see a noticeable power gain over 4 port lower with FD upper or am i wasting money? I already have 4 port lower and fd upper and i already have a holley 4 port intake.
thoughts?

 

Short answer- yes, significant (for an NA build) gains with the Holley style intake manifold and 4 barrel 4150 TB.

Long answer, I will find and link the Aniversary Racing Factory dyno page. They used to specialize in NA rotary circuit builds and so have NA FD dynos with stock intake and NA FD dynos with NA style aftermarket intake.

 

Google translated arf site

Looks like a jump of 25hp between stock FD intake and TWM throttlebodies.

The over the top of engine manifold with primary and 2ndary ports per runner shared on two TB of the TWM might have a little under the curve power advantage over the shorter Holley ITB set-up, though I would expect the Holley to be able to make ad much or more peak power with the right header length and top hat volume.

Have you considered bridge or semi-p port? Eiter is "easy" with 4150 intake manifolds available and should net you another 20-50hp depending on ezhaust.

 

Also, you dont need that fancy injector throttle body.


You could do-
$200 JW 4150 TB from summit/jegs/ebay
$150 speedmaster 4150 TB from ebay/amazon
$150 boost hat or a cheaper aircleaner.
Use 1st gen turbo rx7 720cc primaries in the intermediate plate in the stock rail
Or get fancy and get aftermarket rail with 1000cc, 1300cc or 2000cc ev14 injectors (up to 400rwhp potential there).

Or you could try something like the holley sniper/stealth that combines 4150tb, injectors and ecu. Guy on youtube seems to have holley sniper running his p-port.

 

The only reason I was suggesting using that Holly throttle body is because it has the IACV built in, I do not want to lose the ability for my car to run and drive on the street. My car is currently running naturally aspirated on Haltech PS1000, I'm using ID injectors on the primaries and currently not having to run secondaries. I already have a four barrel throttle body for my intake manifold but like I said, it has no means for IACV. Bridgeporting or at least a half bridge will probably happen, if not it will just be a large streetport.

 

Header

https://www.definedautoworks.com/mazda-rx7-parts.html

 

IAC is generally overrated on a naturally aspirated rotary. I have never used one and haven't had issue.

I still feel that the S4 NA intake manifold is better than the Holley, but a Holley and throttle body gives better immediacy to throttle response, and that is a higher priority for me.

 

You can run an old school external iacv if you like, iacv is just a fancy ecu controlled vacuul leak.

 

Between us guys, I don't really give a **** about IACV but my tuner is kind of a diva and he works for free so I try to give him what he wants lol. He's a close friend, I believe his exact words were, if you're going to keep your air conditioning then I'm not tuning your car without an IACV because you want to be a little bitch.

 

you could use something like the 12A (might work better on a holley) it had a throttle opener thing, and when the A/c is on, it applies vacuum to the thing and it literally just pulls the throttle open a little