I have problems adding fuel in the 6000+ rpm range , does anyone had have the same problem with more than 450 rwhp ?
I have the stock aps fuel system , what will be the most restrictive part of the system.

 

The injectors are the most restrictive part; however, assuming you are running APS injectors at the APS stock fuel pressure, they sould be good up to about 600hp... which should be closer to 500+whp.

Are you by any chance running a UTEC? I know there were some problems with adding fuel at high power/rpms -- this can be fixed with the addition of their grounding wire.

 

I donīt have a UTEC , I have the unichip.To control my AFRs I have installed an Apexi SAFC2 , between the unichip and the ECU. I donīt have any chance to get an aps dealer here.
If you see my after and before charts , you can see the SAFC2 working great, but the problem is in the top end power, I canīt add more fuel in this range, and with cold temps my boost is raised to 11 psi and my wideband shows around 12-12.2 ,I think this is a fuel amount related problem.

 

what's your fuel pressure at 6000+ rpms or do you not have a fuel pressure gauge?

 

All you are using is an Apexi SAFC2? I would imagine that those are fine for fine tuning the afr on a NA Z, but there's only so much you can do with it. What are you doing for timing? How do you cope with the larger APS injectors and higher fuel pressure? What do you do when the MAF maxes out? You should really consider a more comprehensive piggy back with a MAP sensor IMO.

 

I donīt have a fuel pressure gauge, but I think is not the problem.

 

my money is on the injectors

 

I have the SAFC2 installed "between" the unichip and the ECU, off course I donīt have timimg control , but with the stock map for 91 octane and a CR around 9.3:1.....would be Ok.I have a turboXS Knocklite to check any knock event.

 

Maybe you are right , if you add all the injectors , these only can flow around 180 lt/hr at 58 lb of fuel pressure, and the fuel pump is for 255 lt/hr.

 

You have a piggy back controlling a piggy back controlling the OE ecu. That is not a good combination. The problem you are encountering is that the SAFC2 can only add/subtract up to 50% signal modification. So, in effect, you can only modify the modified signal. Your range of signal modification is decreased.

Remove the SAFC2 and tune it with the UNICHIP only. Your problem should go away. I'm assuming the only reason your using an SAFC is because no one in your area tunes UNICHIP.

BTW, you do have timing control. It's in the UNICHIP.

You are definitely at the end of those fuel injectors as well.

 

you are in the same boat as me.

I peak boost at 14 lbs around 4200 rpms then have to taper to 11 lbs at redline due to fuel. The unichip will not allow you to run larger injectors and I am at the limit of the out of box APS supplied injectors. I am looking into a new EMS and injectors to allow me to hold 14 lbs to redline. And yes, I am at exactly at 450 whp (though Tuan had me up to 460 with 93 oct vs my 92 octane final tune)

 

Woahhh...Your running a super AFC on top of a unichip??Not a really cool idea...But most likely you will max out around 470whp or so on that fuel system.

 

I donīt have a unichip tuner here , and i donīt think that this is a bad idea to control my AFRs, the car runs perfect , even I have a better iddle speed.

 

Good to hear that iīm not the only one with this issue.
When you have the solution , please send me a PM.

 

Ditch the Unicheap and go with a Utec, best move I think I've ever made!

 

I was thinking in get the UTEC , but Iīm a little scared for all the guys having troubles with the UTEC, and Iīm a little far, to get a real support.
I would need bigger injectors for sure.

 

i found that the APS fuel system included with their turbo systems are absolutely maxed out at 450 - 470rwhp on a dynojet. i tried larger injectors in one car and it didnt help. I added an adjustable regulator and improved on the plumbing at the tank slightly and was able to get 515rwhp once again maxed out. thats all she wrote, time for a real fuel system.

 

Say Charles,
Do you know where AL_V could get a "real fuel system" price and availability?

Cheers Amy -

 

I don't get it. I'm putting down 440whp on the stock aps injectors. we had the horsepower up to 470whp(single turbo and cams), but because we couldn't stabilize the boost at 14psi, we decided to work at the boost level we could control. even though that is with c-16, the timing is still pretty conservative. i run the utec and am very happy with the system and the tune i have. i do have a sard pressure regulator instead of the aps regulator in the tank area. once i build the engine, i'll probably upgrade the injectors as well.

 

amy: i dont know much about that stuff really

bullitproof: the over all max will depend on the engines efficiency in using the fuel that it is given... so more aggressive tuning and higher CR's will lead to greater power output... which will explain why guys with stock engines (high NA CR) can hit 500rwhp with the included fuel system.