Cant rev past 5800. Help needed
Cant rev past 5800. Help needed Here are some specs on the car.
BS3
402 LS2 + F1C
ETP 245 heads with Patrio Dual valve springs(unshimmed)
Mitchubishi Truck coils
111 octane race gas
TR8's gaped at .020
Ignition voltage at WOT was getting down to 12 volts
16.2 psi
The car was dyno tuned today by a very reputable tuner. One of the problems it is having is that it can't rev past 5800. Its almost like its hitting a rev limiter, but its not bouncing off it. It pulls very clean, and then it smoothly stays at 5800 rpms. We changed the plugs to a fresh set, no difference.
Here is a list of things that I am thinking could be causing it:
Bad coils(they are brand new)
Valve float(seat pressure is too low for FI)
Converter(doubt it as Neal Chance converters are prety reputable)
Crank sensor
Reluctor wheel freespining.
What do you guys think we should try first? I have a set of stock coils that we can toss back on and see if that helps. I am aslo thinking if its worth to try shimming the valve springs, or just buy some higher quality springs. Any advice is appreciated.
I dont have the dyno graph, but can possibly get it. Thanks!
BS3
402 LS2 + F1C
ETP 245 heads with Patrio Dual valve springs(unshimmed)
Mitchubishi Truck coils
111 octane race gas
TR8's gaped at .020
Ignition voltage at WOT was getting down to 12 volts
16.2 psi
The car was dyno tuned today by a very reputable tuner. One of the problems it is having is that it can't rev past 5800. Its almost like its hitting a rev limiter, but its not bouncing off it. It pulls very clean, and then it smoothly stays at 5800 rpms. We changed the plugs to a fresh set, no difference.
Here is a list of things that I am thinking could be causing it:
Bad coils(they are brand new)
Valve float(seat pressure is too low for FI)
Converter(doubt it as Neal Chance converters are prety reputable)
Crank sensor
Reluctor wheel freespining.
What do you guys think we should try first? I have a set of stock coils that we can toss back on and see if that helps. I am aslo thinking if its worth to try shimming the valve springs, or just buy some higher quality springs. Any advice is appreciated.
I dont have the dyno graph, but can possibly get it. Thanks!
FormerVendor
Joined: Mar 2006
Posts: 1,540
Likes: 0
From: Hell AFB
Here are some specs on the car.
BS3
402 LS2 + F1C
ETP 245 heads with Patrio Dual valve springs(unshimmed)
Mitchubishi Truck coils
111 octane race gas
TR8's gaped at .020
Ignition voltage at WOT was getting down to 12 volts
16.2 psi
The car was dyno tuned today by a very reputable tuner. One of the problems it is having is that it can't rev past 5800. Its almost like its hitting a rev limiter, but its not bouncing off it. It pulls very clean, and then it smoothly stays at 5800 rpms. We changed the plugs to a fresh set, no difference.
Here is a list of things that I am thinking could be causing it:
Bad coils(they are brand new)
Valve float(seat pressure is too low for FI)
Converter(doubt it as Neal Chance converters are prety reputable)
Crank sensor
Reluctor wheel freespining.
What do you guys think we should try first? I have a set of stock coils that we can toss back on and see if that helps. I am aslo thinking if its worth to try shimming the valve springs, or just buy some higher quality springs. Any advice is appreciated.
I dont have the dyno graph, but can possibly get it. Thanks!
BS3
402 LS2 + F1C
ETP 245 heads with Patrio Dual valve springs(unshimmed)
Mitchubishi Truck coils
111 octane race gas
TR8's gaped at .020
Ignition voltage at WOT was getting down to 12 volts
16.2 psi
The car was dyno tuned today by a very reputable tuner. One of the problems it is having is that it can't rev past 5800. Its almost like its hitting a rev limiter, but its not bouncing off it. It pulls very clean, and then it smoothly stays at 5800 rpms. We changed the plugs to a fresh set, no difference.
Here is a list of things that I am thinking could be causing it:
Bad coils(they are brand new)
Valve float(seat pressure is too low for FI)
Converter(doubt it as Neal Chance converters are prety reputable)
Crank sensor
Reluctor wheel freespining.
What do you guys think we should try first? I have a set of stock coils that we can toss back on and see if that helps. I am aslo thinking if its worth to try shimming the valve springs, or just buy some higher quality springs. Any advice is appreciated.
I dont have the dyno graph, but can possibly get it. Thanks!
I have in it the EPP blower cam, 232/240. I am not sure about free reving it, I will have to try that. . It was doing the same thing off the trans brake. It would stop right at 5800.
It does not spit or sputter, and no black smoke. It revs very clean. There is methanol injection setup on the car, but it was turned off. The mixture was 100% meth, no water.
It does not spit or sputter, and no black smoke. It revs very clean. There is methanol injection setup on the car, but it was turned off. The mixture was 100% meth, no water.
Teching In
Joined: Jan 2006
Posts: 15
Likes: 0
How big is your air filter?
I've been having the same issue with my sbc/YSi trim setup. I changed the springs, plugs, gaps, coils and tuned the hell out of it to no avail.
I decided to check for air filter restriction with a filter minder and found 25" of vac at 15 psi boost and 6k rpm! I tried it without the filter today and it flattened out again at 6k, but when I looked at my data log, it made 3psi more boost and leaned out to 13.5 afr ( by the way, I did add fuel before this test).
Hopefully, more fuel= more rpm. I will keep you posted.
Steve
I've been having the same issue with my sbc/YSi trim setup. I changed the springs, plugs, gaps, coils and tuned the hell out of it to no avail.
I decided to check for air filter restriction with a filter minder and found 25" of vac at 15 psi boost and 6k rpm! I tried it without the filter today and it flattened out again at 6k, but when I looked at my data log, it made 3psi more boost and leaned out to 13.5 afr ( by the way, I did add fuel before this test).
Hopefully, more fuel= more rpm. I will keep you posted.
Steve
I found out that the BS3 wire that is supposed to be wired into 12v+ ignition, was barely making contact. We fixed that, then took it for a spin and did a few data logs. It did pull up to 6700 rpms in second, were it was at 18.3psi. I didn't want to get too much on it in 3rd gear while on the slicks. I can put the drag radials back on tommorow and then do some 3rd gear pulls and see if that solved the problem. Regardless if this fixed the issue or not, I will still be ordering some new springs.
Do you guys know of a spring pressure tester that can be used while the heads are on the car? We had someone bring one by, but it couldn't work on the LS1 head.
Jim, "override Cam sync test" was already checked . Did you mean to un-check it?
Its a good size filter. I dont think that was the problem, although I was planning to remove it towards the last of the runs, to see if would make any more HP without it on.
Do you guys know of a spring pressure tester that can be used while the heads are on the car? We had someone bring one by, but it couldn't work on the LS1 head.
Jim, "override Cam sync test" was already checked . Did you mean to un-check it?
How big is your air filter?
