|
Ahh...I found one of the posts about this Supra power pump...(heh) 
Apparently, it works for some, and flows too much for others, while others say the FPR holds, but the pressure rises too much b/c the fuel pump naturally flows more at the same voltage; here's the relevant post, anyways, with the whole string site attached:
http://www.dsmtalk.com/forums/showthread.php?s=1273136f89354f65b237730203db13fd&threadid=10307&highlight=supra+fuel+pump+flow+rate
"Are you monitoring an EGT? What boost levels? turbo? FMIC, other big mods?
Anyone can say they run mod X and it works great, but does the car _RUN_ great? No one ever questioned the performance of the Supra pump.
my setup:
97 GS-T Spyder
ported big 16G
2.5" turbo back
Supra fuel pump
12psi boost (sometimes 15psi)
stock clutch, injectors, and SMIC
The main problem with the supra pump is that the fuel rail will be running approx 15psi more pressure than stock. i.e. for 2G it's ~45psi. The fuel system is now forced to operate at ~60psi fuel pressure. This is because the stock FPR's return line cannot flow enough fuel to keep pressure at ideal levels. An aftermarket Adj FPR like the SX, Paxton, or Extreme are ideal FPR's that have larger return line openings. Note, the B&M Commandflo is a piece of junk so don't even look at it; it cannot lower pressure, only raise it.
The ECU does its best to recalibrate but will often times throw a CEL over fuel trim malfunction (I get this). This is because the ECU can't adjust the injectors well enough to get a consistent fuel mixture. This is because the injectors are overtaxed with more pressure than the ECU thinks. The injectors will also spit more fuel on minimum pulsewidth. The secret to tuning an EFI car is to get the ECU to run at a fuel trim of 0%, which will give optimal timing and fuel maps.
The other issue is running boost. The fuel rail pressure increases proportionally with manifold pressure. This is the job of the FPR. I believe it's a 1:1 ratio, but don't quote me. Assuming it is, that means at 15psi, the fuel rail has ~75psi of fuel. You run into two possible limitations: One is injectors will no longer flow more fuel as pressure in increased. Kinda like turning up the water pressure thru a small garden hose. As pressure increases, eventually the hose will stop increasing water flow. Second, and more likely, is that the fuel pump begins to flow less as the pressure increases past its acceptable limit. It is said that a pump will stop flowing at a certain pressure (perhaps 80-90psi?) because it spends all its energy simply maintaining the pressure level and not flowing fuel thru the lines. This can be seen on RRE's page where they did flowrate benchmarks on several popular pumps:
http://www.roadraceengineering.com/fuelpumptechtip.htm
Toyota Supra Twin Turbo In Tank Pump
(Adj FPR required)
260 lph @43psi @12v, 220 lph @58psi @12v
290 lph @43psi @14v, 260 lph @58psi @14v
So if rate drops from 290lph to 260lph when raised to 58psi, then imagine what it could be at 75psi! The flowrate drop could be linear or proportional. My guess is the latter. So now you have a risk of running dangerously lean. The higher the boost, the more fuel you need, the less fuel the pump flows... My EGT will demonstrate this when I switch from 12psi to 15psi boost.
THIS, my friends, is why the supra pump requires an Adj FPR. If you don't get one, your car is not going to run in ideal conditions. BUT, it will run. Money is better spent on a pump that doesn't require an Adj FPR, such as the $160 150lph pump RRE sells (ND 0990).
Hope I cleared this up.
*whew*"
_____________________________________
Jason ESi-T
04' BMW 325Ci
91' Nissan 240SX
98' Eagle Talon ESi (sold)
|
Search
Printer-friendly copy
1 User in Chat
