Help:: on Dyno peak hp at 5k and flatlines
Help:: on Dyno peak hp at 5k and flatlines Had my car on the Dyno and I'm having a strange issue, car made 428hp/494tq...the hp hits 5k and just flatlines and holds right around 430hp till 6k where we let off, peak tq was at 3900/4k...I knew the valve springs were tired so I put new pac springs on and it didn't change a thing. I changed cams over winter and I'm starting to think the cam is off a tooth, even tho I was very meticulous with installing it. I'm on my phone right now but will post a screen shot of the graph when I get to a computer. Any other ideas or input?
370ci lq4
Tea stage 2 243 heads
Si5 cam (231/237 112+4)
Fast102
Nw 102 tb
Built 4l65
Yank 3600
Xpipe
85mm maf
FTP lid
The car is down about 30 - 40 hp, could the cam being off dot to dot kill hp? Or does it just shift the curve?
Have to figure this issues out ASAP.
370ci lq4
Tea stage 2 243 heads
Si5 cam (231/237 112+4)
Fast102
Nw 102 tb
Built 4l65
Yank 3600
Xpipe
85mm maf
FTP lid
The car is down about 30 - 40 hp, could the cam being off dot to dot kill hp? Or does it just shift the curve?
Have to figure this issues out ASAP.
im starting to think that also.. even if the cam timing is off it would peak earler and fall off... he ran it out to 6800 on the run after the valve springs and it was flat almost exactly the same.
I wonder if it's the cam...mine is a 230/238 113+2 at peaks at 6300 in a 5.7l
Yours is a similar size cam in a decently larger engine which will bring the RPM peak down but it is also a 112+4 which will also bring it further down. I would think it would be higher than 5k but wouldn't expect it to be over 5900-6000 peak.
Normally my next thought would be intake or exhaust restriction but your mods there look up to par. Any chance the transmission is slipping under peak HP (I would expect it to slip under peak TQ if anywhere though)?
EDIT: you beat me to posting with the graph, that doesn't look right at all...looks like it flatlines well before 5k rpm.
Yours is a similar size cam in a decently larger engine which will bring the RPM peak down but it is also a 112+4 which will also bring it further down. I would think it would be higher than 5k but wouldn't expect it to be over 5900-6000 peak.
Normally my next thought would be intake or exhaust restriction but your mods there look up to par. Any chance the transmission is slipping under peak HP (I would expect it to slip under peak TQ if anywhere though)?
EDIT: you beat me to posting with the graph, that doesn't look right at all...looks like it flatlines well before 5k rpm.
Yeah I mean you are peaking way sooner than even a bone stock LS1 would, so I can't even possibly comprehend how it would be the cam or any of that. If you could find another dyno for a cheap quick pull it would be interesting to see if there was a difference
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From: Mooresville, NC
What did the AFR look like? Timing? You don't have a rubber silicone part in the intake sucking shut do you?
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well i didnt drive it all winter and over winter i swapped out the old cam (228/230 .578 112) and put under drive pulley on put in built trans and yank3600 (took out edge 3400 which was real tight). To me it feels great and feels like it pulls strong. im hoping to go pick it up tomorrow and if the rain holds off i will run it at the track to see what she does.
After seeing those ridiculous torque numbers like that graph is showing, it's blatantly obvious the dyno is fucked up. You might have an issue with your engine, but don't base that upon that graph. Get your money back and go somewhere else.
