L-Jet fuel pressure reg. question
12-11-2006, 12:33 PM
#1
Racer
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L-Jet fuel pressure reg. question
L-jet cars have 1 fuel damper and 2 fuel pressure regulators. The regulators reduce fuel pressure under manifold vacuum (32 psi versus 36 psi @ atmospheric) via the internal diaghragm. Does anyone know if that diaphragm serves to add fuel pressure under boost and if so, by how much?
12-11-2006, 01:06 PM
#2
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sure, the more pressure put on the diaphram, the more the valve allowing fuel to return to the tank is closed. the more its closed, the more the lines approach pump pressure. with vacuum, the valve is opened even more, allowing more fuel to return to the fuel tank (reducing the line pressure) I suppose since 14psi vacuum is used to pull back the pressure 5psi of fuel, i suppose that 5psi of pressure could increase fuel flow by 2psi (a guess) . interesting thought. maybe we could use some special pressure attachment and hand pump that could be rigged to apply pressure at WOT to the fuel reg. (1-2 bar!)
Hacker, dont see why your blower would effect idle, since the pressure is bled off on the intake . if it didnt bleed off the pressure, you would have pressure in the intake and that means more than idle throttle position. (ie part throttle, etc)
mk
Hacker, dont see why your blower would effect idle, since the pressure is bled off on the intake . if it didnt bleed off the pressure, you would have pressure in the intake and that means more than idle throttle position. (ie part throttle, etc)
mk
12-11-2006, 02:08 PM
#3
Inventor
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Hack-er,
How much resistance are you adding to the Temp II? I realized that when I tried it, I didn't have enough range to make a difference.
You should do a thread on it.
How much resistance are you adding to the Temp II? I realized that when I tried it, I didn't have enough range to make a difference.
You should do a thread on it.
12-11-2006, 02:09 PM
#4
Racer
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Hacker,
just trying to understand your situation...is it your exhaust that cuased the L-jet to run lean during normal driving, the addition of the blower, or was it just your L-jet that for some reason didn't maintain good AFR during cruising? My L-jet seems to maintian my AFR very well despite my exhaust mods (which surprised me) and thats whats cuasing to me question if the mild boost will add enough fuel pressure via the diaphragm in the stock regulators?
just trying to understand your situation...is it your exhaust that cuased the L-jet to run lean during normal driving, the addition of the blower, or was it just your L-jet that for some reason didn't maintain good AFR during cruising? My L-jet seems to maintian my AFR very well despite my exhaust mods (which surprised me) and thats whats cuasing to me question if the mild boost will add enough fuel pressure via the diaphragm in the stock regulators?
12-11-2006, 06:06 PM
#5
Rennlist Member
regarding fuel flow at cruise .(anytime not at WOT) its quite alright to have mixtures very lean, even at 14.7. the mass flow can be low enough where even complete burning, doesnt create much heat.
very lean is ok too, as its common to operate aircraft engines at "lean above stoich" for fuel economy. generally, go as lean as you can before you start running rich. this is all handled by the maps in the ECU. ( and with some modifications of the fuel regulator)
MK
very lean is ok too, as its common to operate aircraft engines at "lean above stoich" for fuel economy. generally, go as lean as you can before you start running rich. this is all handled by the maps in the ECU. ( and with some modifications of the fuel regulator)
MK