Stock Twin and Ported build recommendations
 

I currently have a stock motor (rebuilt on Atkins kit) running on the stock twins. Mods are Greddy SMIC, Greddy Elbow, Trust Intakes, Catless DP and PFS exhaust. I am running the Petit unlimited ecu and boost settings are at 10 psi and 13.5 psi through a Greddy Profec II boost controller. I currently enjoy the setup and don’t really need the added power but I have the opportunity to start another build and am considering adding a street port to the mix. The final build will be as follows:

Atkins rebuild kit and Apex seals
Mild street port
Stock twins
Greddy SMIC
Greddy Elbow
Trust Intakes
Catless DP
PFS exhaust

Possible items – fuel system upgrade and change to Power FC.

What can I expect in power gain from adding the street port? Am I correct in assuming that instead of maxing out at 13.5 psi I will now be limited to about 10 psi with the Petit Ecu/Stock Injectors? I would think total power would be about the same due to the fuel limitation.

If that’s the case what are the recommended fuel systems upgrades? I probably won’t have the desire to go to a single turbo (I think…) so just whatever it would take to optimize the stock turbos and porting. What kind of power levels would I be looking at here? Basically what is the potential if I upgrade the fuel system?

Finally what is the gas mileage impact? I understand I am driving an RX7 but I’m just curious what kind of impact a street port has on it.

If you pull apart a motor that's working fine just to street port it on stock turbos you are going to be disappointed by the cost benefit ratio.

Porting shifts your powerband higher into the rev range... higher where your stock turbos don't flow without pushing them and hurting their longevity more.

and take it from someone (me) who has written a lot about the power FC: you will never get the driveavility and dependability of a stock/chipped ECU when you go aftermarket. The best tuned power FC will never start, idle, and make power as safe as stock (known stock hesitation is the exception). You lose a lot of failsafes like limp mode.

stick with what you have or bump your budget up and go single. You gotta go all in.

Get rid of the twins and go small to medium single. Go ask on the single turbo forum.
Stock ports that have been blue-printed will give all around better driving experience with increased power.

Upgrades should include larger secondary injectors and a supra fuel pump. With a pfc, you should be able to tune for around 20 hp increase at high rpm with a mild port..

With my pfc, I was able to tune for a smoother idle, better fuel economy, and more hp than with the M2 stage 3 ecu that I had before the change to a mild port..

My car was running around 320 rwhp with an oem cat and smog pump at 13 psi.

Street port (or any port) won't change your peak power potential- that is limited by the CFM flow limit of the turbo(s).

By porting, you will be able to reach peak flow from the turbos at a lower boost pressure though.

The stock twin turbos are good for about 411rwhp dynojet.
dynosheet courtesy @tom94RX-7
https://www.rx7club.com/attachments/...pdynosheet.jpg

Stock fuel injectors/system with upgraded pump and upgraded ECU is good for around 340rwhp.

So, you have ~60rwhp to possibly gain, but very few have refined their set-up to push the stock twin turbos to the 400rwhp mark. Usual max people reach is around 360-380rwhp on stock twins.

So, realistically, you have ~20-40rwhp to gain with porting, injector and standalone ecu upgrade.

I am at the maxed stock fuel system stage and trying to figure out if that is worth the $3,000 or so to make more power.

OP what kind of driving do you do with this car?

It's daily driven, so about 70 miles to work 3-4 times a week. I don't do any drag racing on the strip or street. I may start autocrossing with it but with current life schedules that would only be a 2-3 weekends a year.

Also to be clear the existing engine setup won't be getting rebuilt. I recently acquired another FD with two engines that both need a rebuild. The idea was to swap over my current engine into it for a quick flip and then rebuild the engine(s) that came with the new car. The streetport idea is simply because I will already be in there and to open up the potential down the road (I don't have any plans to go single turbo but you know how these things go...).

Maybe a bit off topic, what is a set of stock turbos in good condition worth these days?

I'm debating if it's best to go single or find a set of used turbos that still have some life left in them. I'm already running a non sequential setup.

T