I want to run 14psi of boost because I don't have any ignition yet. I read Corbins page but the formula he uses is based on HP not boost pressure. How much HP will I get out of 14psi of boost? I will be getting a S-FAC, SFMU, and injectors very soon but what size injectors should I go with at 14psi of boost? Should I go with 440's, will they be enough? Sorry about such a lame question but I am a little weak on fuel systems. Thanks for any help, Patrick
Patrick 96 GS 13.54 @ 106.94 mph on 15psi 21 May.04 HRC kit, S20G, FMIC, Howell bottom end 8.6 pistons, S-FMU, Blitz BOV, P&P head, SS valves, lots more little goodies
#25226, "RE: Confused on injectors and boost HP" In response to Reply # 0
Your power output is going to be dependent on which turbo and compression ratio you have, in addition to the boost (and other factors). And if you use a S-AFC to lean things out, you may need an ignition to retard timing. When you lean with the S-AFC, the ECU will advance timing beyond normal levels. So you may need the ignition to cancel out some of that advance.
Corbin
'95 ESI-T HRC+FMIC+ETC...
Gimme fuel...Gimme fire...Gimme that which I desire
#25227, "RE: Confused on injectors and boost HP" In response to Reply # 1
Well I have a super 20G with 8.6 compression and a p&p head. Why would you have to redard timing if you use the s-afc? I thought that the s-afc tricked the ECU into not knowing that there were bigger injectors, because our ECU can only handle up to 315's. Why does the ECU want to advance timing with the s-afc? Patrick
Patrick 96 GS 13.54 @ 106.94 mph on 15psi 21 May.04 HRC kit, S20G, FMIC, Howell bottom end 8.6 pistons, S-FMU, Blitz BOV, P&P head, SS valves, lots more little goodies
#25228, "RE: Confused on injectors and boost HP" In response to Reply # 2
I'm sure someone else can comment on what HP to expect from the combination (I still have a 16G on a stock engine). The problem with the S-AFC is that it tricks the ECU. It sends it false inputs and the ECU makes decisions based on that. One result is the ability to run bigger injectors while staying in the adjustment range of the ECU. The other result is alterations in ignition timing. Lowering the MAP signal voltage will lead to increases in timing advance. I don't remember the exact reason why the stock ECU does this, but its a logical thing to do. The designers didn't make the ECU with the expectation that you would strap a turbo and S-AFC to it.
Corbin
'95 ESI-T HRC+FMIC+ETC...
Gimme fuel...Gimme fire...Gimme that which I desire
#25229, "RE: Confused on injectors and boost HP" In response to Reply # 3
Ok, well I guess I will wait untill I get everything and put it all on at once. This will take a little longer than I had wanted but oh well better to safe then sorry. I wanted to be done by August for hot import nights in Enis TX. This will be close to done on time. How about if I just threw in some 32lb injectors till I get everything ready, this should make me run safely at 10psi right? Well I appritiate all the help Corbin, with out the knowlege of others we would never learn. Thanks, Patrick
Patrick 96 GS 13.54 @ 106.94 mph on 15psi 21 May.04 HRC kit, S20G, FMIC, Howell bottom end 8.6 pistons, S-FMU, Blitz BOV, P&P head, SS valves, lots more little goodies
#25230, "RE: Confused on injectors and boost HP" In response to Reply # 4
I see 32 lbs is the biggest you can go before the injectors get really expensive (with Accel at least). Those are about 336 cc/min. With a S-FMU, you could have a low idle pressure (no S-AFC needed), keep a reasonable fuel pressure at max boost (to use a Walbro), and spit out a good amount of fuel with the 336's. I think you could run 10 psi on low comp with those. That would at least work until you figured out your fuel needs at 14 psi (then you'd probably need bigger injectors and S-AFC).
Corbin
'95 ESI-T HRC+FMIC+ETC...
Gimme fuel...Gimme fire...Gimme that which I desire
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