Spectrum24x

Hi guys, i've been reading around and doing some searching, and like many things this seems to be a case by case basis you get different answers so i thought i'd post in here with my car's specific setup and goals and see what you guys think...

right now my car is a 91 n/a with a jdm s5 turbo 2 motor swapped using my n/a harness converted for n370 ecu. the car is basically stock with a downpipe, full exhaust, hks bov, and intake...

My next step is to put 720cc injectors and im hoping to up my boost a bit, i'd really like to reach 225-250 rwhp...
i've been doing some reading and it seems like mostly the fd guys have no choice but to use power fc because of issues with stock ecu but i havent seen a whole lot of issues concerning fc's and power fc...

i'd really like to get away with buying a used s-afc and a "home depot" boost controller do some basic tuning, get about to ~12-14psi on my boost and see some hefty gains... is this practical without blowing up my motor, or do i need to fork up the extra 800 and get a full stand alone?

thanks in advance!

cloudzero

iTrader: (1)

you can go full stand alone if you want, but if those are your only goals something like a RTEK might be more up you alley.

fc3s91

iTrader: (23)

I have a AP Engineering pfc fs. Just for the S5 t2.

RotaryEvolution

iTrader: (30)

you can probably get by with the SAFC and 720's, many people have done it but it is hardly optimal. the SAFC is tricking the ECU so your timing will be too far advanced with the SAFC in which case you can retard it by the CAS but then you are losing out of boost timing for low end power and mileage.

Spectrum24x

how about a microtech lt-8? found one cheap, under 400
sorry for all these questions, im new to ems on rx7s and i've done plenty of searching and learned quite a bit, but still have so many unanswered questions as there seems to be so many options for engine management...

Banzai-Racing

iTrader: (11)

The S-AFC only controls fuel by tricking the ECU, it has nothing to do with timing or boost.

To raise your boost higher than stock, you need an FCD which also tricks the ECU, this greatly effects ignition timing as the ECU does not retard the timing beyond stock. This means by 12-14psi it will be too advanced.

The little electronics for "tricking" the ECU start to add up and you still have a system dependant on the AFM. Before EMS systems were readily available (economical), people used these "tricking" devices because that is all they had. They also blew engines regularly.

If you do not care about the longevity of your engine then just slap in the 720's, S-AFC, FCD and Home Depot boost controller. It will be fun for a little while.

Half of the secret to having a reliable turbo rotary is tuning.

RotaryEvolution

iTrader: (30)

perhaps you are right, i was thinking of the AFM causing the timing issue versus the craptastic FCD. to delete fuel cut an Rtek 1.7/1.8 chip can be installed without affecting the timing curve by tricking the ECU.

Banzai-Racing

iTrader: (11)

Yes, but he wants to do all this on the stock ECU, which makes the FCD manditory. That being said 550/720cc is not enough fuel to safely support 14psi anyway.

With the Rtek + S-afc, might as well buy a Power FC and have full tunabilty as well as ditching the AFM and OEM boost sensor. Not to mention the ability to upgrade the injectors to support the desired boost levels.

arghx

iTrader: (3)

They have an Rtek 2.1 available for the s5 now. In terms of hardware capability, that will be fine for your immediate needs (fuel and timing control with nearly stock driveability). You will have to hassle with a Palm or an emulator to connect to it though. You can't easily share maps with it and you still will have to pay someone to tune it. If you plan to go with more upgrades in the future the Rtek will start to hold you back because it does not control big secondary injectors well.

Microtech is a completely different setup, you will have to rewire the car for that.

RotaryEvolution

iTrader: (30)

you're thinking of the Rtek 2.1i assume, which is their $500 "standalone" ECU. the Rteck 1.7/.8 chips cost less than a hundred bucks and allow 720's to be used in the secondary position without any ill effects and gets rid of the boost cut and the ECU is still "stock". many of used this as our starting point and it worked fine.

if it was a ported motor with FMIC i would probably say that that fuel setup won't be enough but with minor mods then with just a fuel pump on top then it most definitely IS enough.

a used microtech is probably his best bet but we also don't know if he wants to keep the car relatively stock for emissions purposes, in which case the Rtek 2.1 or PowerFC is the best options, the Rtek being a royal pita though to tune with those 4000 little cells you have to manage one by one with that shitty palm pilot..

Spectrum24x

Oh sorry it does have FMIC

Spectrum24x

And I do need to pass emissions for at least the next 5 yrs

Spectrum24x

i can get all of this for 300 shipped, the guy says it plugs right into the rx7 harness.. thoughts?

arghx

iTrader: (3)

If it plugs right in, where's the harness adapter? I don't know much about Microtechs though. Maybe you should make a separate thread in that section.

slpin

iTrader: (9)

I'll take that

mrb63083

iTrader: (4)

And he also has a FCD.