tt408 first dyno fun
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Staging Lane
Joined: Aug 2005
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tt408 first dyno fun Hp performance just got my c5 finished up and is dynoing it with the stage 2 turbos.
8 psi netter 630hp/670 tq
valvefloat seems ot be a problem as the motor wont rev past 6000 rpm.
I have comp 921's, what springs are boosted guys running??
8 psi netter 630hp/670 tq
valvefloat seems ot be a problem as the motor wont rev past 6000 rpm.
I have comp 921's, what springs are boosted guys running??
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Staging Lane
Joined: Aug 2005
Posts: 69
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Originally Posted by Boostaholic
wtf that seems awful low
what kind of setup do you have for intercooler? what were your AFRs and knock at?
what kind of setup do you have for intercooler? what were your AFRs and knock at?
its only 8 psi, and on a msutang dyno, and it floats the valves at 5800 rpm.
My main questions is what valve springs work well for boosted cars?
What gap plug are you running? Close the gap to .025 if you haven't yet, could be experiencing spark blow out. You could also adjust the dwell time.
I highly doubt it's valve float at that low of an rpm.
I highly doubt it's valve float at that low of an rpm.
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At 8#, those springs should be fine, they're 135# on the seat and 400# at their peak - I don't think the boost will be holding open the valves at all, unless the cam is super-radical and right on the edge of lofting them already. I also doubt the spark is being affected unless you've really fouled your plugs.
Jim
Jim
Last edited by DeltaT; Jun 16, 2006 at 01:21 AM.
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Staging Lane
Joined: Aug 2005
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Originally Posted by DeltaT
At 8#, those springs should be fine, they're 135# on the seat and 400# at their peak - I don't think the boost will be holding open the valves at all, unless the cam is super-radical and right on the edge of lofting them already. I also doubt the spark is being affected unless you've really fouled your plugs.
Jim
Jim
it has the comp shaft mount rockers, and comp-r lifters.
It had the comp 918's on it when it was n/a and I had this exact same problem, but switching to the 921's fixed the problem..
Originally Posted by kindaslo
Hp performance just got my c5 finished up and is dynoing it with the stage 2 turbos.
8 psi netter 630hp/670 tq
valvefloat seems ot be a problem as the motor wont rev past 6000 rpm.
I have comp 921's, what springs are boosted guys running??
8 psi netter 630hp/670 tq
valvefloat seems ot be a problem as the motor wont rev past 6000 rpm.
I have comp 921's, what springs are boosted guys running??
You know I made the same power at 6000 as I did at 7350? Maybe you will make more at a higher rpm. What's the rest of your set up?
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Staging Lane
Joined: Aug 2005
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Originally Posted by MIGHTYMOUSE
got a way to measure your exhuast backpressure? are there pictures of this set up?
As far as pics go, this is what I have.
Thread Starter
Staging Lane
Joined: Aug 2005
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Originally Posted by LASTLS1
You know I made the same power at 6000 as I did at 7350? Maybe you will make more at a higher rpm. What's the rest of your set up?
Originally Posted by kindaslo
Measure backpressure... negative. It's straight pipe though lol.. Redneck style. I'll get video up of it soon enough.
As far as pics go, this is what I have.
As far as pics go, this is what I have.
Stick? How much max timing, just to give us an idea?
I am running 977's right now I think, I'm kind of forgetting. You want to run a lot of spring for blower cars, and even more so for a turbo car. I had Crane 832's but when I stepped up my cam my car fell off at 6100 rpms. Last time it peaked at 6600, T400, ~754rwhp, conservative tune C16 + 21 degrees of timing.
I am running 977's right now I think, I'm kind of forgetting. You want to run a lot of spring for blower cars, and even more so for a turbo car. I had Crane 832's but when I stepped up my cam my car fell off at 6100 rpms. Last time it peaked at 6600, T400, ~754rwhp, conservative tune C16 + 21 degrees of timing.
Originally Posted by kindaslo
I have comp 921's, what springs are boosted guys running??