Loss of power please help

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Jun 9, 2012 | 02:24 PM

halljo

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Loss of power please help

So I took my car to the dyno today after a toquer V3 cam upgrade, L/T and ory. The first run it made 354hp, the second run made 331hp, and the third run only made 320hp. my tuner says everything is set right but the car is still losing power bad. He says it almost has to be something internal, so what could cause this kinda of power loss. I also installed .650 dual valve springs and pushrods with the cam. The car sounds good and runs good until about 5000rpm and then it just falls on its face. Any suggestions?

Jun 9, 2012 | 02:40 PM

Darkman

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From: Spring, Texas

I would pull the valve covers and check the valve train. Which valve springs are you running, i.e. how much open spring pressure? What other valve train components are you running?

Jun 9, 2012 | 02:51 PM

halljo

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they are PRC .650 dual spring, im not sure how much open spring pressure there is.

Jun 9, 2012 | 02:53 PM

halljo

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also have 7.425 hardened push rods, rockers are stock

Jun 9, 2012 | 02:54 PM

LSXFEIN

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does your engine burn motor oil? if so it could be fouling up the plugs or maybe it could be running to rich, i had the same problem losing power on the dyno!

Last edited by LSXFEIN; Jun 9, 2012 at 02:55 PM. Reason: misspelled

Jun 9, 2012 | 03:07 PM

Darkman

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From: Spring, Texas

Quote:

Originally Posted by halljo

they are PRC .650 dual spring, im not sure how much open spring pressure there is.

Quote:

Originally Posted by halljo

also have 7.425 hardened push rods, rockers are stock

If those are the new design springs the open spring pressure is 450 pounds. In my opinion that is too much pressure for stock rockers, but that has more to do with long term reliability. Otherwise, those spring will bring out any other weakness in the valve trains such as failing lifters. As I said before, I would at least want to look under the valve covers for problems.

Additionally, I assumed (without asking) that your dyno runs were done with external fans running. If the dyno set up has inadequate air flow, heat accumulation can drive down results. (Although I have not seen the kind of nosedive in numbers that you report.)