VAFC
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Joined: Oct 2000
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From: San Juan
Also to consider. If you go with force induction you need to raised the pressure in the fuel system relative to the pressure in the manifold otherwise you end up with less fuel. If you put 2PSI on the manifold you need to raise your fuel pressure 2 PSI over you base pressure at WOT to counteract.
You could correct with the V-AFC but doubt that it will allow such a large correction considering the 6 PSI of the SC.
You could correct with the V-AFC but doubt that it will allow such a large correction considering the 6 PSI of the SC.
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Joined: Jan 2001
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From: Monterey
If we could get a harness built for us at a reasonable price including a group buy price for the VAFC I would be extremely interested in this mod. Just out of curiosity and my own ignorance, is this something you install and leave along? or do you have to adjust it often?
Mingster- I live pretty close to where you bought your car, in La Verne, if this goes as planned we might want to set up a date so that all of us L.A. owners can get together and do the install at the same time. What do you think??
Mingster- I live pretty close to where you bought your car, in La Verne, if this goes as planned we might want to set up a date so that all of us L.A. owners can get together and do the install at the same time. What do you think??
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Joined: Feb 2001
Posts: 2,895
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From: You wish
Rev is right on keeping the boost dependent regulator on a SC car. Here's why. If you kept the stock fuel pressure, your injectors would be maxed on pulsewidth long before you hit full boost or high rpm. That's because the injectors can only supply so much fuel at a given fuel pressure (usually 45 psi standard). I'm betting the F20C injectors are about 300cc/minute.
By upping the fuel pressure, the injectors can deliver more fuel, to the tune of the square root of the new pressure over old pressure (double the pressure would give you about 41% more fuel).
The downside of increasing fuel pressure is that as you increase pressure, pump capacity (don't care what pump you have) goes down. The stock fuel pump could probably supply the necesary fuel for a SC'd car, but it can't at 100 psi of fuel pressure. Thus, you have to go to an upgraded fuel pump.
It's a nasty cycle of upgrades and suspect tuning that can be avoided by simply putting in a boost sensitive ECU and some larger injectors. My CRX makes 70% more power than stock while still using the stock fuel pump by using this approach.
BTW, Pepe, all FPR's, stock or boost dependent, use a reference vacuum signla from the intake manifold. This ensures that differential pressure between the injector rail and the intake runner remains the same. Boost dependent just changes the ratio as boost rises.
UL
By upping the fuel pressure, the injectors can deliver more fuel, to the tune of the square root of the new pressure over old pressure (double the pressure would give you about 41% more fuel).
The downside of increasing fuel pressure is that as you increase pressure, pump capacity (don't care what pump you have) goes down. The stock fuel pump could probably supply the necesary fuel for a SC'd car, but it can't at 100 psi of fuel pressure. Thus, you have to go to an upgraded fuel pump.
It's a nasty cycle of upgrades and suspect tuning that can be avoided by simply putting in a boost sensitive ECU and some larger injectors. My CRX makes 70% more power than stock while still using the stock fuel pump by using this approach.
BTW, Pepe, all FPR's, stock or boost dependent, use a reference vacuum signla from the intake manifold. This ensures that differential pressure between the injector rail and the intake runner remains the same. Boost dependent just changes the ratio as boost rises.
UL
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Joined: Oct 2000
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From: Baltimore
Originally posted by pnty drpr
Whats the difficulty in installing it without the harness?
I remember seeing a wiring diagram, but it wasn't in English. If I pick one up, can anyone help me out?
Whats the difficulty in installing it without the harness?
I remember seeing a wiring diagram, but it wasn't in English. If I pick one up, can anyone help me out?
the reason why i would want the harness is so that it can be removed without signs of tampering. this thing instantly voids any warranty we got, so splicing the wires is not an option for me.
derryck, you there?