1650cc injector and pump/e85 question

[jrohner]

Originally Posted by blackrosenova400

No way 1600's would be good enough for 900 wheel hp. I was at 68% duty cycle with 1350's at 38 base fuel pressure, making 380 on Map's dyno (e85). Maybe if you ramped up fuel pressure but I would still highly doubt it.

My cousin is at 321hp with 680's on E85; look where I'm at with 750s. There's also a guy on tuners with like 440 with 750's. Your 1350's at 38psi are actually like 1260's. Also, there's a big difference between 68% (856cc) and 80%(1008cc) duty cycle, but how much fuel you are using depends on your tune not just your hp (and if the fuel is actually getting to the injectors). Most people I've seen on tuners seem to run E85 really rich - like 11:1 gas afr, which is actually 7.3:1. I can hear my car misfiring if I go even close to that crazy rich and I know I loose power as I go richer (even before misfiring). How I drive, if my tune wasn't safe my engine would be gone -- I could never be as hard on my engine on a drag strip as I am on the road.

I pretty much consider the duty cycle a theoretical number; some people have claimed at times to see higher than 100% duty cycle with no issues-- is that actually possible - NO.

[Kracka]

Originally Posted by jrohner

I pretty much consider the duty cycle a theoretical number; some people have claimed at times to see higher than 100% duty cycle with no issues-- is that actually possible - NO.

Yup; IDC definitely isn't exact with the stock ECU's. I saw a max of 119.5% with my stock injectors and Scheides saw almost 130%.

[jrohner]

Originally Posted by Kracka

Yup; IDC definitely isn't exact with the stock ECU's. I saw a max of 119.5% with my stock injectors and Scheides saw almost 130%.

Anyone know why, is there just something wrong with the formula used to calculate it? I would never go by IDC alone, I say richen it up some and if your AFR's still match up you're good.

[Kracka]

Originally Posted by jrohner

Anyone know why, is there just something wrong with the formula used to calculate it?

I'm guessing that must be it; or maybe 100% IDC as logged by the ECU is what they feel the ideal maximum to be? It seems like anywhere above ~115% and fueling issues begin to occur.

[jrohner]

Originally Posted by Kracka

I'm guessing that must be it; or maybe 100% IDC as logged by the ECU is what they feel the ideal maximum to be? It seems like anywhere above ~115% and fueling issues begin to occur.

Is it that way with evo's also? So on some cars 115% is actually around 100% maybe, and some are even more off?

I don't really see why mitsu didn't go by IDC's for fuel cut instead of airflow (or in addition to), maybe it is because the IDC's aren't accurate; although I guess you could use fuel cut to prevent overboosting if you set it just a little higher than the max airflow you'd ever see.