Big nitrous back fire=bent valve, Need HELP
Thread Starter
Launching!
iTrader: (119)
Joined: May 2008
Posts: 220
Likes: 0
From: Jefferson City, MO
Big nitrous back fire=bent valve, Need HELP --------------------------------------------------------------------------------
I had a nitrous back fire out racing the other night,it happened right before the end of the quarter,am i running my fuelrail and fuel line dry ? It busted the air filter and bent a intake valve on #1 cylinder,that sparkplug was messed up and #5 plug,Any help would be good,i may have had a little much timing after 3600 rpm its 22-23 degrees,im using a .083 nitrous jet,a little about my setup
1999 Silverado 2wd ECSB
LQ9 6.0
Ported L92 heads
ARP rod bolts,stock shortblock
L92 intake,fast 90mm throttle body
headers,3"y-pipe,single 3"muffler and tailpipe
Comp cam 581/598,224/234,112
3800 fti converter,built 4L60
3.73 gears
Single Walbro 340 fuel pump in tank
All stock fuel line,L92 fuelrail
with 99 corvette fuel filter that hooks to fuelrail and stock feed and return line,and i also have the factory inline filter
93 octane
What caused this
Any help THANKS
I had a nitrous back fire out racing the other night,it happened right before the end of the quarter,am i running my fuelrail and fuel line dry ? It busted the air filter and bent a intake valve on #1 cylinder,that sparkplug was messed up and #5 plug,Any help would be good,i may have had a little much timing after 3600 rpm its 22-23 degrees,im using a .083 nitrous jet,a little about my setup
1999 Silverado 2wd ECSB
LQ9 6.0
Ported L92 heads
ARP rod bolts,stock shortblock
L92 intake,fast 90mm throttle body
headers,3"y-pipe,single 3"muffler and tailpipe
Comp cam 581/598,224/234,112
3800 fti converter,built 4L60
3.73 gears
Single Walbro 340 fuel pump in tank
All stock fuel line,L92 fuelrail
with 99 corvette fuel filter that hooks to fuelrail and stock feed and return line,and i also have the factory inline filter
93 octane
What caused this
Any help THANKS
Last edited by 70ls1chevelle; May 19, 2011 at 03:59 PM.
Valve could have floated and caused the backfire, could have been too lean, too much timing, fuel jet could have clogged...
I think you don't have enough octane for that power level with a stock motor IMO... alot of people get away with that, but I wouldn't do it myself.
I think you don't have enough octane for that power level with a stock motor IMO... alot of people get away with that, but I wouldn't do it myself.
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I had a nitrous back fire out racing the other night,it happened right before the end of the quarter,am i running my fuelrail and fuel line dry ? It busted the air filter and bent a intake valve on #1 cylinder,that sparkplug was messed up and #5 plug,Any help would be good,i may have had a little much timing after 3600 rpm its 22-23 degrees,im using a .083 nitrous jet,a little about my setup
1999 Silverado 2wd ECSB
LQ9 6.0
Ported L92 heads
ARP rod bolts,stock shortblock
L92 intake,fast 90mm throttle body
headers,3"y-pipe,single 3"muffler and tailpipe
Comp cam 581/598,224/234,112
3800 fti converter,built 4L60
3.73 gears
Single Walbro 340 fuel pump in tank
All stock fuel line,L92 fuelrail
with 99 corvette fuel filter that hooks to fuelrail and stock feed and return line,and i also have the factory inline filter
93 octane
What caused this
Any help THANKS
I had a nitrous back fire out racing the other night,it happened right before the end of the quarter,am i running my fuelrail and fuel line dry ? It busted the air filter and bent a intake valve on #1 cylinder,that sparkplug was messed up and #5 plug,Any help would be good,i may have had a little much timing after 3600 rpm its 22-23 degrees,im using a .083 nitrous jet,a little about my setup
1999 Silverado 2wd ECSB
LQ9 6.0
Ported L92 heads
ARP rod bolts,stock shortblock
L92 intake,fast 90mm throttle body
headers,3"y-pipe,single 3"muffler and tailpipe
Comp cam 581/598,224/234,112
3800 fti converter,built 4L60
3.73 gears
Single Walbro 340 fuel pump in tank
All stock fuel line,L92 fuelrail
with 99 corvette fuel filter that hooks to fuelrail and stock feed and return line,and i also have the factory inline filter
93 octane
What caused this
Any help THANKS
There is no telling until we get a little more communication going sir.
That was kind of what I was getting at. With the timing he's running, and on 93 fuel.. I don't think it's going to make a ton of difference what fuel jet or bottle pressure is being run. The heads and cam that are in the truck, probably are making 430+ rwhp I'm sure, combine that with a good bit of nitrous, and the load that the motor's seeing from the weight of the truck..... that's a recipe for putting a hurt on something.
I'm sure, that there's more then just a valve bent. I bet if you pull the heads and look at the pistons, you will see something that's not too pretty.
Maybe not if he's lucky... but something is telling me that won't be the case.
Only confirmation I need that the motor has big problems, is what plugs were in it. if I hear anything more then a #8 heat range the motor's probably toast.
I'm sure, that there's more then just a valve bent. I bet if you pull the heads and look at the pistons, you will see something that's not too pretty.
Maybe not if he's lucky... but something is telling me that won't be the case.
Only confirmation I need that the motor has big problems, is what plugs were in it. if I hear anything more then a #8 heat range the motor's probably toast.
I ran a .073 jet with 91 octane and -9 plugs at 20* and all the plugs looked great with the timing just starting to show on the end of the strap. I wasn't making the power he prolly does NA, but it was a 6.0 with some 59cc chamber 243s and stock truck intake. I'd say 23* was way too much with I'm going to guess prolly tr6 plugs.
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Brett Foote Thread Starter
Launching!
iTrader: (119)
Joined: May 2008
Posts: 220
Likes: 0
From: Jefferson City, MO
That was kind of what I was getting at. With the timing he's running, and on 93 fuel.. I don't think it's going to make a ton of difference what fuel jet or bottle pressure is being run. The heads and cam that are in the truck, probably are making 430+ rwhp I'm sure, combine that with a good bit of nitrous, and the load that the motor's seeing from the weight of the truck..... that's a recipe for putting a hurt on something.
I'm sure, that there's more then just a valve bent. I bet if you pull the heads and look at the pistons, you will see something that's not too pretty.
Maybe not if he's lucky... but something is telling me that won't be the case.
Only confirmation I need that the motor has big problems, is what plugs were in it. if I hear anything more then a #8 heat range the motor's probably toast.
I'm sure, that there's more then just a valve bent. I bet if you pull the heads and look at the pistons, you will see something that's not too pretty.
Maybe not if he's lucky... but something is telling me that won't be the case.
Only confirmation I need that the motor has big problems, is what plugs were in it. if I hear anything more then a #8 heat range the motor's probably toast.
The head is off,the combustion chamber looks good besides the bent intake valve,the piston looks ok,lots of shiny specles on top of piston,one spot very small looks like it might have got melted a little on outer edge you cant see the ring,can this seize the ring to the piston ?
Make sure you do a compression test.
If you have something that looks like that.... the piston is probably shot. You probably had some oil getting by, causing some detonation, or it was from too much timing, not enough octane, or a combo of the above.
That plug should be o.k, but I like to run the ngk when anything is first getting set up, they have alot weaker ground strap and show heat alot quicker/easier then autolite plugs do....
General rule, is if you melt an autolite plug you definitely hurt something.
That plug should be o.k, but I like to run the ngk when anything is first getting set up, they have alot weaker ground strap and show heat alot quicker/easier then autolite plugs do....
General rule, is if you melt an autolite plug you definitely hurt something.
Thread Starter
Launching!
iTrader: (119)
Joined: May 2008
Posts: 220
Likes: 0
From: Jefferson City, MO
2 Plugs the ends were gone,the cylinder on that side is a little black,im going back to a 5.3 in the truck and selling it,you think put another stock LQ9 piston in there and go with it,im parting everything out to many projects.
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I had a nitrous back fire out racing the other night,it happened right before the end of the quarter,am i running my fuelrail and fuel line dry ? It busted the air filter and bent a intake valve on #1 cylinder,that sparkplug was messed up and #5 plug,Any help would be good,i may have had a little much timing after 3600 rpm its 22-23 degrees,im using a .083 nitrous jet,a little about my setup
1999 Silverado 2wd ECSB
LQ9 6.0
Ported L92 heads
ARP rod bolts,stock shortblock
L92 intake,fast 90mm throttle body
headers,3"y-pipe,single 3"muffler and tailpipe
Comp cam 581/598,224/234,112
3800 fti converter,built 4L60
3.73 gears
Single Walbro 340 fuel pump in tank
All stock fuel line,L92 fuelrail
with 99 corvette fuel filter that hooks to fuelrail and stock feed and return line,and i also have the factory inline filter
93 octane
What caused this
Any help THANKS
I had a nitrous back fire out racing the other night,it happened right before the end of the quarter,am i running my fuelrail and fuel line dry ? It busted the air filter and bent a intake valve on #1 cylinder,that sparkplug was messed up and #5 plug,Any help would be good,i may have had a little much timing after 3600 rpm its 22-23 degrees,im using a .083 nitrous jet,a little about my setup
1999 Silverado 2wd ECSB
LQ9 6.0
Ported L92 heads
ARP rod bolts,stock shortblock
L92 intake,fast 90mm throttle body
headers,3"y-pipe,single 3"muffler and tailpipe
Comp cam 581/598,224/234,112
3800 fti converter,built 4L60
3.73 gears
Single Walbro 340 fuel pump in tank
All stock fuel line,L92 fuelrail
with 99 corvette fuel filter that hooks to fuelrail and stock feed and return line,and i also have the factory inline filter
93 octane
What caused this
Any help THANKS
This is the guy you were racing 03-termi on mwce
