I had a nitrous backfire....
I had a nitrous backfire.... Well, I just got my kit installed and was using it for the second time when I had a horrible nitrous backfire, it blew my lid off and broke the clamps, and blew a hole in the back of my intake. It was the weirdest thing, seconds before the backfire happened it sounded like my car was hitting the rev limiter (but it wasnt, it was at about 6000 RPM and my limiter is set at 6600) and then BOOM! I have a heads/cam car and was using a TNT 100 shot with a window switch. I dont know why the hell this backfire happened.
I have a few guesses why it happened can anyone confirm these suspicions:
1. I didnt pull any timing while using the 100 shot, I was under the impression I would be ok with that size of a shot.
2. I am still using a stock fuel pump with a wet kit and a heads/cam car. I dont see why a lean condition would cause a backfire, but does this possible have anything to do with it?
3. I was only using premium octane, and my compression ratio is 11.1:1, should I have been using race gas?
I have a few guesses why it happened can anyone confirm these suspicions:
1. I didnt pull any timing while using the 100 shot, I was under the impression I would be ok with that size of a shot.
2. I am still using a stock fuel pump with a wet kit and a heads/cam car. I dont see why a lean condition would cause a backfire, but does this possible have anything to do with it?
3. I was only using premium octane, and my compression ratio is 11.1:1, should I have been using race gas?
TECH Resident
Joined: Dec 2003
Posts: 797
Likes: 0
From: Long Island, NY
Hmm Im interested also.
Did you spray at a higher psi? like 1100+?
How muching higher than stock timing are you running with the heads and cam setup? I know stock timing works with a 100 shot. 150, 2 less.
I dont think fuel pump has anything to do with it.
I think its because of compression and too much timing....
Let see what others say as this is just my guess.
Did you spray at a higher psi? like 1100+?
How muching higher than stock timing are you running with the heads and cam setup? I know stock timing works with a 100 shot. 150, 2 less.
I dont think fuel pump has anything to do with it.
I think its because of compression and too much timing....
Let see what others say as this is just my guess.
On The Tree
Joined: Jan 2004
Posts: 107
Likes: 0
From: layton ut
I live in salt lake city with an alitude of 4400 feet, so i was spraying with a bottle pressure of about 1250 psi, but that should be fine in utah because of the altitude. also, the only timing change i have done is from 800-1200 RPM because of bucking issues. I advanced it about 2 degrees in this range, I did not change any timing anywhere else.
I dont have a shift light, but I was definetly shifting at about 6000. I dont know what the hell the problem was. It seems everyone I know who has an ls1 and has used nitrous has had backfiring issues and I dont even want to deal with it again, it's ridiculous. I'm going to sell my nitrous kit, forge my motor, lower my compression, get new heads and turbocharge my motor. I thought I could use nitrous as an inexpensive means to powerful runs, but have learned that it is much to finnicky. I guess it's true that nothing good comes cheap. 
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There's something else that is wrong, I know TONS of people runnign alot more then 100 shots and having no problems. Do you have a window switch, fuel pressure safety switch? I'd guess that at higher RPM your fuel pump couldn't keep up and it went way lean.
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Yep you likely went lean....Thats why I preach wideband....Could have either been because the fuel pump couldnt keep up or a common fuel noid failure. Id bet the "rev limiter" you describe was heavy detonation...
its not the fault of the LS1 or the nitorus... **** with everyone around here you would figure it came stock on LS1's.. no what gear were you in.. 1st and 2nd motor revs so quickly the stock tach can't keep up.. hell i blew the tires off once and hit the limiter.. the tach was still at 5700.. and my limiter is over 7k..
Originally Posted by blacktransam
its not the fault of the LS1 or the nitorus... **** with everyone around here you would figure it came stock on LS1's.. no what gear were you in.. 1st and 2nd motor revs so quickly the stock tach can't keep up.. hell i blew the tires off once and hit the limiter.. the tach was still at 5700.. and my limiter is over 7k..
what RPM does your window switch deactivate the nitrous?
Jon
Originally Posted by LoWeLL216
Why would a lean condition cause a manifold explosion? (just wondering for my own knowlege)
stock timing and a 100 shot is fine, as is stock timing for a 150 tnt shot (i get ZERO KNOCK during my runs- the only knock i may get is one "ping" or spike when the nitrous activates- which im going to tune out).
im running a racetronix fuel pump also though. i'd be willing to bet the stock fuel pump is the issue. a friend of mine is running a zex 125 shot on a si ls1 (zex `125 shot= about the same as tnt 100 shot) and he was dropping fuel pressure as the rpms got higher during a nitrous pass on his stock fuel pump. he had the same cutting out issue like you described but i guess didn't stay into it enough to get a backfire.
don't sell the kit- buy a fuel pump and get some sort of tuning equipment (i reccomend hptuners) so you can log and see what is going on, then make changes accordingly. you can't expect to just slap the kit onto a h/c high compression motor on the stock fuel system and expect everything to work out perfectly.
edit- i just saw that you have hptuners. how did the log of the run look? WHAT was going on with the car will tell the story.
im running a racetronix fuel pump also though. i'd be willing to bet the stock fuel pump is the issue. a friend of mine is running a zex 125 shot on a si ls1 (zex `125 shot= about the same as tnt 100 shot) and he was dropping fuel pressure as the rpms got higher during a nitrous pass on his stock fuel pump. he had the same cutting out issue like you described but i guess didn't stay into it enough to get a backfire.
don't sell the kit- buy a fuel pump and get some sort of tuning equipment (i reccomend hptuners) so you can log and see what is going on, then make changes accordingly. you can't expect to just slap the kit onto a h/c high compression motor on the stock fuel system and expect everything to work out perfectly.
edit- i just saw that you have hptuners. how did the log of the run look? WHAT was going on with the car will tell the story.
I believe you hit the rev limiter before the factory tach could read it and then went lean which will cause this problem. I had a similar situation and it took out the back of the intake, maf, lid, 4 valves and punched a whole in heater core housing. I set my window switch 2 to 4 thousand rpm's below the rev limiter just to be safe. Also like other people said, get a fuel pump as the stock is not designed for spikes in hp levels. Good luck
Nitrous backfire?? IOh... I know all about that! Luckily I didn't have my new hood on at the time... Beleive it or not, there was no motor damage, the lid didn't even break!!!
Originally Posted by 00Z28SS
Well, I just got my kit installed and was using it for the second time when I had a horrible nitrous backfire, it blew my lid off and broke the clamps, and blew a hole in the back of my intake. It was the weirdest thing, seconds before the backfire happened it sounded like my car was hitting the rev limiter (but it wasnt, it was at about 6000 RPM and my limiter is set at 6600) and then BOOM! I have a heads/cam car and was using a TNT 100 shot with a window switch. I dont know why the hell this backfire happened.
I have a few guesses why it happened can anyone confirm these suspicions:
1. I didnt pull any timing while using the 100 shot, I was under the impression I would be ok with that size of a shot.
2. I am still using a stock fuel pump with a wet kit and a heads/cam car. I dont see why a lean condition would cause a backfire, but does this possible have anything to do with it?
3. I was only using premium octane, and my compression ratio is 11.1:1, should I have been using race gas?
I have a few guesses why it happened can anyone confirm these suspicions:
1. I didnt pull any timing while using the 100 shot, I was under the impression I would be ok with that size of a shot.
2. I am still using a stock fuel pump with a wet kit and a heads/cam car. I dont see why a lean condition would cause a backfire, but does this possible have anything to do with it?
3. I was only using premium octane, and my compression ratio is 11.1:1, should I have been using race gas?
I really want to know the plugs you were running.
Originally Posted by Big Mike
Nitrous backfire?? IOh... I know all about that! Luckily I didn't have my new hood on at the time... Beleive it or not, there was no motor damage, the lid didn't even break!!!
