So, I wanted to have a place where I can create links to good info I have found.
FPR for NA or FI
Posted 04-24-2008 at 03:39 PM by gamiller
http://www.contour.org/ubbthreads/sh...=&sb=5&o=&vc=1
Quote:
Originally Posted by Stazi 11/16/05 10:06 AM
On my returnless setup, there is probably less chance of heaving one cylinder leaner than another due to a dead head setup in the fuel rail, but for return-style rails, I bet money that the last injector before the pressure reg is a smidge leaner than the first injector on the rail - this is because unless the FPR clamps shut under boost (thus creating a dead head) the allowed fuel flow out of the rail will cause the pressure at the last injector to be lower than the first - there' no way around that - otherwise you defy fluid dynamics and physics. I.e. you have to have a low and high pressure variation to cause the fuel to flow into the rail and out again.
Quote:
Originally Posted by warmonger 11/16/05 07:10 PM
Stazi, well that makes sense when you explain it like that. But in my case the FPR diaphragm recieves positive boost pressure so it should be clamping it shut.
That also reminds me that injector pressure would be reduced by the boost pressure present in the intake.
I wonder if it balances out. The FPR keeps fuel pressure a rock steady 55psi without boost under WOT. If it adds 10psi boost to both the diaphragm and the intake system, does it balance out and still inject at 55psi?
That also reminds me that injector pressure would be reduced by the boost pressure present in the intake.
I wonder if it balances out. The FPR keeps fuel pressure a rock steady 55psi without boost under WOT. If it adds 10psi boost to both the diaphragm and the intake system, does it balance out and still inject at 55psi?
Total Comments 1
Comments
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Fuel Pump LimitsLimit of the stock fuel pump in a return car.
Quote:
Originally Posted by warmonger
That number comes from my testing back in 2003 and is based on a 1999 Contour SVT return-style system. The setup was a 3L engine with water-air intercooler on about 6psi boost setting down 300wHP. Testing was done on the dyno at Streetflight, now called ADC. I was there with Keith as we were trying to add fuel to the car just to see what it would do to the power. We started trying to richen up the air fuel through the tune and it only got a little bit more rich in the midrange but the top-end got no better. We added more fuel and in the low-midrange the engine got more fuel and the very top end stayed a bit lean. We came to the assumption that at high volume the stock pump just wasn't able to supply the added fuel. This was backed up by the results I had when I switched to the Walbro 255LPH pump. Same tune but with just a swap on the pump and the top end went very rich after that, to the point that I had to use the emanage and lean out some of the fuel. So that basically told me that at least MY fuel pump was limited to around 300 whP, or about 290-300ft-lbs of torque at higher rpms. As long as you are careful during testing you should be able to establish the limits of your fuel pump yourself but I imagine it would be similar to what I had experienced. |
 
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