any ideas on this? graph inside
Thread Starter
Joined: Nov 2001
Posts: 10,018
Likes: 51
From: Virginia
any ideas on this? graph inside this is from the w2w mustang dyno
the horsepower / tq peak was roughly at 17psi no meth, 100 unleaded
after this my friend rob and i added .060 valvespring shim to the comp 921's as prescribed by kurt and this did not change the graph
i'm pm'ing jose to see if this is something to do with the t-4 pte-88 i got from him
the idea is that it is either that the turbo is surging, or that the cam (stock z06) is just wrong for the combination (or some mix of the two)
the second attachment is a local dynojet for comparison (had the old larger w2w turbo cam, and a turbonetics 76mm t-4 turbo (bost cooler results)
im working on getting ahold of the old cam to put back in
the horsepower / tq peak was roughly at 17psi no meth, 100 unleaded
after this my friend rob and i added .060 valvespring shim to the comp 921's as prescribed by kurt and this did not change the graph
i'm pm'ing jose to see if this is something to do with the t-4 pte-88 i got from him
the idea is that it is either that the turbo is surging, or that the cam (stock z06) is just wrong for the combination (or some mix of the two)
the second attachment is a local dynojet for comparison (had the old larger w2w turbo cam, and a turbonetics 76mm t-4 turbo (bost cooler results)
im working on getting ahold of the old cam to put back in
Dave the turbo is unrelated in erratic curves like that. Only time we see problems like this is engine misfire, or the wastegate is fluttering. Also surging like you asked in your PM would be noticed loudly when under that high of boost. Can you hear anything under boost at the top end??
Jose
Jose
Thread Starter
Joined: Nov 2001
Posts: 10,018
Likes: 51
From: Virginia
this is the low setting
we saw no indication of anything abnormal with the engine, could you post your graph with the misfire?
i switched to truck coils, and it didnt go away, even switched back to the car coils and same thing. i also had a couple sets of wires and plugs in the car with no change
we saw no indication of anything abnormal with the engine, could you post your graph with the misfire?
i switched to truck coils, and it didnt go away, even switched back to the car coils and same thing. i also had a couple sets of wires and plugs in the car with no change
Hmm, I would check then the plugs if you have checked all your other options. Does this happen under low boost conditions as well?? Also have you tried to see if this happens on race fuel alone??
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Verdad Gallardo Thread Starter
Joined: Nov 2001
Posts: 10,018
Likes: 51
From: Virginia
yes, ive been workign on this since november
ive put new plugs in before, and the power is smooth when i drive around town so i would say very very low boost as in vaccum is not affected.
yes. the wheel dyno is race fuel alone, and the previous work was all done on pump gas or pump gas and methanol
ive put new plugs in before, and the power is smooth when i drive around town so i would say very very low boost as in vaccum is not affected.
yes. the wheel dyno is race fuel alone, and the previous work was all done on pump gas or pump gas and methanol
Thread Starter
Joined: Nov 2001
Posts: 10,018
Likes: 51
From: Virginia
here is the thread i made from before i switched cams
https://ls1tech.com/forums/forced-induction/384407-help-me-pick-another-cam.html
https://ls1tech.com/forums/forced-induction/384407-help-me-pick-another-cam.html
Thread Starter
Joined: Nov 2001
Posts: 10,018
Likes: 51
From: Virginia
a/f is 11.5 plus or minus. 100 is way plenty at this boost, i have knock control and it was at 0 the whole time. (19* advance)
also at this boost pressure of 17 my exhaust backpressure was 25 = 1.47:1
also at this boost pressure of 17 my exhaust backpressure was 25 = 1.47:1
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
How much lifter pre-load is there ?? Could valve "clearances" be too tight ? perhaps causing them to hold some valves open slightly at higher rpm causing it ?
Maybe try a shorter pushrod, or shimming up the rockers.
Unlikely, but should be pretty easy to try.
Maybe try a shorter pushrod, or shimming up the rockers.
Unlikely, but should be pretty easy to try.
It looks like valvetrain to me. I had some serious valvetrain issues and my graph looked exactly like that but I was n/a.
http://img.photobucket.com/albums/v6...rainissues.jpg
http://img.photobucket.com/albums/v6...rainissues.jpg
Thread Starter
Joined: Nov 2001
Posts: 10,018
Likes: 51
From: Virginia
that is how the graphs were given to me by the dyno operator.
country boy.. what did your valvetrain 'issues' turn out to be
kurt checked the lifter preload to be OK..
country boy.. what did your valvetrain 'issues' turn out to be
kurt checked the lifter preload to be OK..
TECH Apprentice
Joined: May 2005
Posts: 300
Likes: 0
From: Boise Idaho
on mine, I happened to miss one of the grounds that I had undone, and would only miss on the top end, on boostaholics, a fouled plug was causing a low end miss, so mabey something with your ignition would be my guess.