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Injector Staging/Sizing for 12lbs supercharged 13b NA?

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Old 11-30-05, 11:40 PM
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Injector Staging/Sizing for 12lbs supercharged 13b NA?

Would a 350cc (33.66lb/hr) primaries, and 2 720cc injectors (67.32lbs/hr) be sufficient for a staging setup for a 12-15lb supercharged S4 NA motor? Wondering if I calculated it out properly. Estimating about 340hp from ~12lbs on a Vortech V-2 trim supercharger. If I got this wrong, someone help me out here, we start off with 450cc injectors, which I don't understand why it's not enough fuel for that much power in the first place.
Old 12-01-05, 01:33 AM
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First off, is this custom? Other then Camden no other company makes a supercharger kit for the 2nd generation RX-7.

Second, why are you DOWNGRADING your primaries? You have 460x4 all around stock. http://rx7.com/cgi-local/2ndgencalc.cgi. According to that you're good for around 178 FLYWHEEL horsepower.

I don't think you have a clue of what you're doing and should stop and re-think what is going on.
Old 12-01-05, 03:06 AM
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Alright, It was my misconseption of the injector sizing, however, replacing the stock ecu with a megasquirt will allow 80% duty cycle as opposed to 68% and allow timing retard on boost..

Using a supercharger calculator/formula, you take the 170bhp, and the 12lbs and result with 334hp at the crank, resulting in 297rwhp. For 335hp @ the crank, I will need 550cc primaries and 900cc secondaries, and a full retard of 4-6 degrees, does this sound right to anyone, or am I going on the thermodynamics of a piston engine too much here, if anything I got the assumption it would make more power exponentially as long as the supercharger doesn't overspin and still has the potential to make boost?

BTW this is a custom setup, vortech V2 trim running at 12lbs should not even need an intercooler, but a safety blow off valve is planned. Ports will actuate off the throttle body/sc intermediate pipe. That should be more than enough to make sure they open at the right time. I just want to make sure I'm going on the right idea here before I blow anything up
Old 12-01-05, 03:12 AM
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do you have a turbo drivetrain? 'cause your n/a one can't take much over 200bhp.
Old 12-01-05, 09:16 AM
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12 PSI? You'll want 550 primaries, 720cc secondaries and an upgraded pump to match.
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