nitrous back fire
ok plugs look good...........i checked the compression.1 and 7 are showing compression when i was cranking the motor. #2 while cranking the motor, and the intake valve going down then going up.once up there is air rushing through the intake and out the tbody.so i guesing the valve is bent or i have a broken seat........there was some stooting stars flying out of the exhost.
On The Tree
Joined: Nov 2008
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ok plugs look good...........i checked the compression.1 and 7 are showing compression when i was cranking the motor. #2 while cranking the motor, and the intake valve going down then going up.once up there is air rushing through the intake and out the tbody.so i guesing the valve is bent or i have a broken seat........there was some stooting stars flying out of the exhost.
ok i pulled the driver side head off and could not see any visual damage.i was wrong when i said #2.......my bad i ment the #3 cylinder wasnt making any compression.
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What ever caused the detonation, it was multiplied by spraying so low, IMO. The lower in the RPM band we go, the bigger chance we have of hurting parts should something go whack with the tune. Hitting a motor with a 180rwhp shot at 2900rpm is still quite an increase in cylinder pressures, besides the full 300hp is all in by .5 out. What is the RPM when the full 300 hits?
Now, the cause of the detonation? I would like to see pictures of the plugs? Might have some traces of oil on them? A big source of detonation on these motors when spraying big hits is oil getting into the cylinders. Now I say this not knowing if your running a vacuum pump, but just thought I would through it out to get the diagnostics started. I didn't see where you stated your timing, and how you were pulling it and if it was stepped. Anyway, i am sure glad it looks so far as though you didn't hurt anything major. I would have done a complete cylinder leakage test prior to tear down, and could have really helped in the overall diagnostics. Keep us apprised on what you find as the root cause of your problem.
Edit: I borrowed your video to add to my collection, hope that is OK? It's not to try and make you look bad, but rather to show that even a tune that has been previously used can cause problems should something act up. Trying to keep the street guys from running a more race like tune, where there is not much safety blanket should something go amiss.
Robert
Now, the cause of the detonation? I would like to see pictures of the plugs? Might have some traces of oil on them? A big source of detonation on these motors when spraying big hits is oil getting into the cylinders. Now I say this not knowing if your running a vacuum pump, but just thought I would through it out to get the diagnostics started. I didn't see where you stated your timing, and how you were pulling it and if it was stepped. Anyway, i am sure glad it looks so far as though you didn't hurt anything major. I would have done a complete cylinder leakage test prior to tear down, and could have really helped in the overall diagnostics. Keep us apprised on what you find as the root cause of your problem.
Edit: I borrowed your video to add to my collection, hope that is OK? It's not to try and make you look bad, but rather to show that even a tune that has been previously used can cause problems should something act up. Trying to keep the street guys from running a more race like tune, where there is not much safety blanket should something go amiss.
Robert
Last edited by Robert56; Feb 2, 2010 at 04:31 AM.
What ever caused the detonation, it was multiplied by spraying so low, IMO. The lower in the RPM band we go, the bigger chance we have of hurting parts should something go whack with the tune. Hitting a motor with a 180rwhp shot at 2900rpm is still quite an increase in cylinder pressures, besides the full 300hp is all in by .5 out. What is the RPM when the full 300 hits?
Now, the cause of the detonation? I would like to see pictures of the plugs? Might have some traces of oil on them? A big source of detonation on these motors when spraying big hits is oil getting into the cylinders. Now I say this not knowing if your running a vacuum pump, but just thought I would through it out to get the diagnostics started. I didn't see where you stated your timing, and how you were pulling it and if it was stepped. Anyway, i am sure glad it looks so far as though you didn't hurt anything major. I would have done a complete cylinder leakage test prior to tear down, and could have really helped in the overall diagnostics. Keep us apprised on what you find as the root cause of your problem.
Edit: I borrowed your video to add to my collection, hope that is OK? It's not to try and make you look bad, but rather to show that even a tune that has been previously used can cause problems should something act up. Trying to keep the street guys from running a more race like tune, where there is not much safety blanket should something go amiss.
Robert
Now, the cause of the detonation? I would like to see pictures of the plugs? Might have some traces of oil on them? A big source of detonation on these motors when spraying big hits is oil getting into the cylinders. Now I say this not knowing if your running a vacuum pump, but just thought I would through it out to get the diagnostics started. I didn't see where you stated your timing, and how you were pulling it and if it was stepped. Anyway, i am sure glad it looks so far as though you didn't hurt anything major. I would have done a complete cylinder leakage test prior to tear down, and could have really helped in the overall diagnostics. Keep us apprised on what you find as the root cause of your problem.
Edit: I borrowed your video to add to my collection, hope that is OK? It's not to try and make you look bad, but rather to show that even a tune that has been previously used can cause problems should something act up. Trying to keep the street guys from running a more race like tune, where there is not much safety blanket should something go amiss.
Robert
Yes indications of oil. I was wondering if you may have old plugs that you pulled that you could snap a picture? Without the backfire we are looking for shiney black, or wet black as the the oil indicator. Or maybe go to the projected vs non-projected plug thread and look at some of the early plug pictures as they have the oil on them, then does yours ever look like this? IMO, the only way we can keep oil out of the combustion chamber on a heavily sprayed car is by going vacuum pump. Guys can use all the inline puke cans they want, even redundant, but it will not cure the oil getting into the chamber. It will help under certain conditions, a puke canned PCV system, and/or vented covers, but will not eliminate the issue of the oil getting past the rings into the chamber on the intake stroke. There is more to this story, and it gets somewhat complicated, but that is for another thread on blow-by and the LSx. 
Robert
Robert
Where's yours set at now? I feel a little safer with my window set at 3400 rpms.