I pressed on the gas and WOT when nitrous was on and the car was off. I then attempted to start the car, gas puddled in intake and ignitited.
UPDATE
I think the cause of the backfire was one or both solenoids were stuck on.
The car revving was just the nitrous, and gas flowing into the intake.
Turned car off...still flowing, car turned back on it ignited
Found a blown out manifold in front and rear,blown out air inlet duct (stock accordian style) blown out radiator, holes were created from heat, not the shards.
I pulled the manifold and replaced with a new stock LS6, replaced air inlet, and replaced the radiator,also refilled with coolant.
Go to crank it over and:
It starts, tried to let idle, sounded vey loud, like exhaust off or something
Notice no oil pressure, zero
Turned off car........
Tried one more time and same thing.

Cause of problem now?
oil pump?
timing chain?
blown piston?
blown out galley plug?
All of them ?
Anything else?
Bearing?

I would like advice as to what I should do next....
What would you do next?

7/15/06
I did a compression test today, on the front four pistons, and they all read 120 to 150, my battery was dying so didnt get to the back four yet.

From what I have read, so far that compression is ok. ???











the way it it sits now

 

Are you sure the oil pressure sendng unit is OK?

 

You have a lot of deviation in the compression on cylinders.

I don't have the manual handy, but the compression in each cylinder should be around 160 PSI. You may have a blown head gasket or valve damage.

As for the oil pressure, is there a lot of mechanical noise indicating the lack of oil pressure.

 

Yes when it first started, there were some odd mechanical sounds.

 

Man, you are learning basic nitrous lessons the expensive way. I'd agree that the oil sending unit was likely damaged by the explosion. The MAF and throttlebody may also be toast.Obviously you are lacking the safeguards that are absolutely required to prevent the explosion that you experienced. If you lucked out and didn't do any serious internal engine damage, and it's quite possible that you didn't, you need to re-engineer your system to lock out the nitrous unless you want it to activate.You need a window switch to sense both WOT and rpm.You also need a fuel pressure switch to drop out the nitrous if the fuel pressure drops below a set point in addition to the main arming switch. Any one of those safeguards would have prevented you from violating the first law of nitrous which is-never shoot into an engine that is not WOT and spooled up. That ALWAYS causes an explosion. In your case, having shot nitrous into a non running engine, there is a purge procedure to clear the engine before trying to start it.That would have prevented the damage. Back to square one or you will do this again. JMHO-Chuck.

 

Thanks BUD! I appreciate the knowledge you have shared!
I hope I have helped you in my experience

Now to the current issue determining what to trouble shoot next!
Anyone know what the compression numbers should be?

Next step, takes heads off?
or
Change timing chain and oil pump?
or
Pull motor then play?



UPDATE
NO compression #7.........

 

Uh oh...perhaps the piston said see you later...pull the head and have a look.

 

Pulling the entire engine.
The rad tubes clearly show they were ruptured from very high PSI from the inside, out. This tells me that the extreme PSI created by the backfire, blew the head[s] off the deck,[and/or split a cyl wall] at least long enough to put tremendous PSI into the coolant. This is further confirmed by the compression on #7, being at zero...
An explosion of that magnitude, could bend rods, break pistons, break the cam, and generally destroy the engine...

Do yourself a big favor, and pull it out, and inspect every piece....

 

Yes I think thats where I am now. Pull the motor out, and go from there.....

 

Sorry if you thought I was trying to be anything but helpful. since you have located a problem with a cylinder, It's still possible that the problem is in the head or head gaskets. I'd pull them both before actually pulling the engine.Chuck.

 

Thanks,
I am going to pull he heads tonight, and i will let you guys know what I find!

I think I am having fun

 

Is Port Richey near Port St Joe? James

 

If you just pull the heads and don't find a busted piston make sure to check the TDC hieght on all the pistons you could have some bent rods. I bent one of my rods with a nitrous backfire and a couple valves as well.

 

Wow, I bet that was a huge kaboom! That is what keeps scaring me away from a wet shot system! From what I understand from reading the post is the kaboom happened on start. I don't think there is going to be anyway you damaged a piston, rod, or valve with nitrous at startup with a plastic intake. Obviously the intake is the weak link here. But it is very likely that there is a small (or large) piece of plastic from the exploded intake stuck in the #7 valve. And if there is something stuck under one of these valves there is not much extra room in there so it would be very likely that the piston contacted the valve.

You shouldn't have been able to damage anything in the oiling system except the sending unit which is right there behind the missing chuck of the intake.

I would pull that left head and see what you find.

 

He said the nitrous was foged into the engine while it was off, and then he tried to start it. So it is very likely that he has bent rods and such. I've seen cars blow the oil pans off from the same situation. When nitrous is injected without the engine running it can go throughout the engine, if you just try to start it without purging it you will have an explosion just like this.

 

that sucks.... seeing the exterior parts took a good beating and the fact the car starts leads me to believe internally you might be super lucky... pulling the motor (never done, but undestand whats involved) or removing the head... i'd say heads would be an easier way of going.... I think with an uncontroled explosion like this you could have damaged a the valve train...

I dont' think c5chines was trying to be a jerk about it... but with all of todays technology you should have problems like this... things can still go wrong... but you can lessen the chance of it... I dont' have to question if you decide to use juice after this that you will have more safty equipment than you know what to do with..

Good luck and sorry to hear about this... I hope you get lucky and the damage does not result in a new bottom end.

but what i don't understand is why the radiator "blew up" intense heat yes... but how was the heat transfered to the radiator?

 

QUICK UPDATE!
I got compression on all cylinders!
I found intake parts holding up the #7 and # 6 intake and exhaust valve, respectively.
AND
BAD oil sensor...replaced it....

Still working on it...

 

Did something hit the radiator? I first thought flying parts took out the radiator but looking close it looks like the front of the radiator as all the holes, is that correct?

 

The explosion came out from the front, through the air bridge, and shot down looks like it hit the radiator.?

Someone mentioned possibly the deck of the head lifted and cause pressure to seep into the coolant part of the block.

 

I would recommend to do a coolant system pressure check as soon as you set the heads back on the motor. Just to be sure you don't have some other problem. It may save you some work. From looking at the holes in the radiator photo it looks like it may have been pressure.

I still say from what I have read here there is no way the nitrous explosion could damage the engine internals. Figure the pressure inside the cylinder under normal operation. You have several hundred pounds perfectly mix fuel and air inside the cylinder then it is lite at the point of max pressure. Then you have the occasional detonation which is many time more pressure than normal. Now no matter how much nitrous and fuel you put in the intake you can't make more pressure in the cylinder than under normal operation. The plastic intake will desegregate way before you even get remotely close to pressures it would take to damage the pistons, head gaskets, valves, or rods. BUT what likely happened in your case was after the motor was shut off the first time and fuel and nitrous kept flowing into the intake. When the motor was refired there was probably pooled fuel in the intake. As soon as the engine turned is would have sucked this fuel into one or two cylinders which could have very easily hydra locked one or more cylinders which could very easily rise a head off the deck, blow a head gasket, or bend a rod. Depending on your compression it will only take 60-65cc of liquid to hydra lock a cylinder. If a head gasket was compromised then it wouldn't be a problem for your nitrous explosion to put 100+ psi in your cooling system which could have been your cause of the radiator problem. But I would think the coolant tank would explode long before the radiator would let go.

Did you pull both heads?