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Old 04-27-2003, 11:08 AM
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Tom Wells Tom Wells is offline
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Join Date: Mar 2000
Location: St. Augustine, FL
Cobra Make, Engine: E-M / Power Performance / 521 stroker / Holley HP EFI
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Hi Frank,

Good to hear from you! Sounds like you are going through the "teething" process about like I did

The dyno results shown were limited by the C6, and are taken from the lowest shift point to 3rd onward. Unfortunately the trans won't stay in 3rd below about 3900 rpm at or near WOT, so we were limited to a readout from there upward.

The real test of course is to whack the throttle at 100mph on a dry road and see if the 315/35-17s spin. They do

As to injector size, I have printouts of the fuel pressure and the outputs of the two wideband O2 sensors up to 6000 rpm.

The fuel pressure holds constant at the 44.5 psi setpoint, indicating the fuel supply to the injectors is OK.

The wideband O2 sensors indicate an air/fuel ratio of 13.6 at 4200 rpm, changing to a slightly richer 13.0 at 6000, so my conclusion would be that the 36 lb injectors are at least adequate. Holley claims they'll support up to 575 hp depending on volumetric efficiency.

To answer the duty cycle question directly - no. We weren't recording that, although if I turn on the data log on the laptop next time, I'll try to see what it is. I just forgot to do that this time but when Holley sends the new ECU, I'll take it back to the dyno again, so there is at least another chance for that. It's about 5% at idle

The dyno guy said he uses a 22% loss factor for the C6. I have ~2200 rpm stall I think.

Sorry you are having valve spring problems. That reinforces my switch to a hydraulic roller and appropriate springs to get away from the solid roller which seemed more race-oriented, and kind of high-maintenance for my street purposes.

Let us know when you are in the neighborhood and we'll try to get together!

Tom
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