i have recently installed an apexi avcr i have wound the boost up to 15 psi wat power increases do i have over running at 1o psi .2000 model with stock twins, power fc, avcr, dual pod intake, standard pre cat ,mid pipe ,4" cannon jasma exhaust,diff locker,hks 2 plate clutch

 

only 15psi? stock setup can take 17psi eaaaaaaasy. Crank it up to at least stage IV and report back.

 

but how much extra power at 15 psi i will run no higher or est power at this boost level

 

Whoa. What fuel system mods do you have? Are you monitoring AFRs?

Unless you southern hemisphere types have different injectors and fuel pumps than the rest of us, the stock fuel system is good for a whole lot less than 17psi. More like 12psi.

 

With stock ports, you are probably somewhere between 330-340rwhp at 15 PSI (depending on the health of your engine and everything else being equal).

 

17 psi is borderline engine popping due to detonation and hardly safe... unless he is running auxiliary injection.

 

At 15psi those twins are really taking a real beating that’s pushing those twins to the max. As far as KFC3S goes I sure hope he was only kidding both stock twins and fuel system cant handle no 17psi. Plus I belive he is still running the stock IC and by standard pre cat I hope he doesnt mean stock pre cat.

 

2000 model years don't have a pre-cat. Just a downpipe.

 

maybe the jap model especially a series 8 has an improved fuel system etc ,duty cycle is 57% to achieve 15 psi ,intake temps are around the 40-50 deg c but it is 30 degc ambient, have stock intercooler and am running 98 octane pump petrol. on my previous series 8 i ran it at 15-17 psi for about 7 months till i wrote it off, on it i forgot to remove all the pipes when i installed the avcr it boosted to 24 psi and didnt blow up

 

Do you happen to know what size injectors the series 8 come with? Our S6 US models have 550 primaries and 850 secondaries.

 

i wouldnt have the faintest but when it did boost at 24 it would splutter, but seems 2 b happy at 15 psi goes like a champion have the start duties set at +2% in all gears and it just wants to go yeah baby

 

If you get any detonation doing this your engine is toast, I hope you realize that.

I'm not saying 15psi is wrong if it turns out the fuel system on a 2000 turns out to be different than my 94, but I can say with certainty that it would be a very bad idea on a US Spec FD. I suggest you research this further or talk with a tuner who is familiar with the fuel system capabilities to be sure.

 

i foresee a part out thread in the near future.

 

fixed

 

You spiked to 24 psi on the stock twins/fuel setup? I'd look around for a Scottish guy named Scotty to narrate from the back seat while you drive, cause she's gonna blow.

 

This will most certainly end poorly.

 

ru guys serious i drove my last car a1999 model series 8 for at least 7 months on 15 psi and it didnt miss a beat until it hit a few signs and fences. even this one will run just as hard to 9000 rpm, engine has done 90000 km.this car and my last are driven daily and i rack up over 300km per week so it gets a fair run

 

The series 8 (jap spec) has the same sized injectors as all other s6 S7 and S8 models out there.


I see an engine blow incoming

 

I drove my 94 on stock injectors running 14psi on stock twins with a stock ECU. Only thing added was a rising rate fuel pressure regulator. I ran 42 road course track days with the set-up and also drove it on the street. Never missed a beat. Not even once.

Only thing that killed the motor was when I overheated it at a race. I even did another two event's after overheating it. Didn't give any signs until months later, when it started using coolant.

The idea that you need an aftermarket ECU to run up to 14psi, is highly over sold.

This is not just my opinion it is also my experience.

 

you do realize the stock FPR is a rising rate FPR too right?

 

So how does your stock ECU not hit fuel cut?

Dave

 

Don't let the terminology confuse you. A traditional FPR, like the factory one and your typical Aeromotive one, maintain the same pressure differential between the fuel and the manifold. So at 0psi boost you may have fuel pressure of 36psi. At 10psi boost you will have fuel pressure of 46psi. The fuel pressure increases at the same rate as the manifold pressure. This can be called a 1:1 FPR, although people sometimes mistakenly refer to it as "rising rate."

On a "real" rising rate fuel pressure regulator, the oldschool kind, the fuel pressure increases faster than the manifold pressure. So at 0psi you may have 36psi fuel pressure. At 10psi boost, instead of having 46psi fuel pressure you might have 50psi. I refer to this as an "oldschool" mod because back in the day when engine management was more limited people had to do it this way rather than having a computer to calibrate.


The fuel cut varies with rpm. Here is the graph for the series 6:



The ceiling could be higher on the later models. Do the '99+ models run higher boost from the factory?

 

another lesson learned

 

here's info on a "real" rising rate fuel pressure regulator, courtesy of a wise old sage by the name of Google.com http://www.cartech.net/fmu2020instruc.htm

 

The "high output" option models do run slightly higher boost and probably have a higher fuel cut to match.

On US FDs with stock ECU it's strictly limited to the chart you produced above.