Explosion

[Lextreme II]

I tried to start my car this morning. It cranked for about 4-5 times and didnt start. Finally it started with an explosion. It backfired. Its was like a little bomb going off. The car shaked and the car sounded terrible. I need I had an exhaust leak. My assume was possible my cross pipe gaskets might be the victim. However to my surprise it more then just gaskets. My mufflers exploded. The left is worst the right. Please see pictures below. The engine didnt experience any damage. I need to retune my start up setting.

 

[Anaema]

i would very much like to know how that happened.

 

[SCV8]

I have done that before when the ignition timing was way out.
Do you use a wasted spark setup?

 

[Smitherz]

That's crazy. This is the car with 450hp right? You should put staight pipes on it so there is no baffleing to stop the firepower.

 

[WDoherty]

my father blew up the mufflers on our van like that when he wired the starter in backwards, it scared the whole neighborhood. Is this another sign in favor of a standalone?

 

[cribbj]

This might be a good time to share my story again about wasted spark ignitions and why I don't like them.

Back in the early 80's, the industrial engine manufacturers were trying to figure out how to get rid of the dual 8 cylinder magnetos for 16 cylinder engines, and they hit on the idea of using a single 8 cylinder unit and double firing it, and waste spark was born for big industrial engines. I was offshore with one of the first experimental units, and we were trying it out on a 9390 cubic inch, twin turbo V16 engine driving a gas compressor. We tried to start the monster several times but didn't have enough air pressure to spin it fast enough for the mag to generate a good spark. Finally we ripped the regulator out of the air supply and gave it plenty of air, and when it did light off, it let out a mighty backfire that shook the platform. Not only that, but it blew the exhaust manifolds, and turbochargers off the motor, and launched the 36" silencer and about 20 feet of 18" exhaust pipe out into the Gulf of Mexico.

Needless to say, experimental waste spark ignition systems were not a big hit that day.

As it turned out, there was an accumulation of unburnt fuel gas in both the intake and exhaust manifolds, and when the plugs fired on the exhaust stroke, with an open path to the exhaust, well, that's all it took.

So now some 20 years later, I'm still not a fan of waste spark ignition systems, because backfires like David's can still occur when there's unburnt gas in the exhaust system.

 

[Smitherz]

That is awesome. As long as no one got hurt!

 

[jibbby]

Dave, sorry to hear about the explosion and destruction of your mufflers...Hope you can fix the problem cheaply...

I too had an explosion happen in my SC a couple of years ago...Early one morning I went to start the car up and BOOOOOOOMMMMMM....I thought the motor blew up, or someone threw a stick of dynomite or placed a car bomb under my car....I jumped out and poped the hood to look for an engine fire and what I found is that the original stock big battery blew up...THe sides of the battery were pancaked out and the insides were gone....Complete battery destruction...The battery explosion threw the battery juice upwards where there is still some evidence of acid damage on the inside of the hood...I never knew a battery could explode like that and make such a loud sound...I was amazed...

I hate early morning car explosions as they can really test your nerves to say the least....:scared:

 

[jibbby]

So what caused the mufflers to blow up? Were you running that car to rich, lack of ignition spark in a few cylinders ? My guess is you were running the motor much too rich.....Exhaust explosion in the mufflers because of unused exhaust fuel....Right or Wrong?

 

[Lextreme II]

Fuel..... lots of unburn fuel.... in the exhuast... due to extreme richness during start up. After few cranks and engine not starting... all those fuel are drump into the exhaust system and once the engine finally start.... Fuel + Air + Ignition = Explosion.

 

[jibbby]

Yeah, I thought so, too rich...

It's unbelieveable how rich these SC's and LS's run during the warm up process... I can smell the raw fuel at times coming out of my exhaust during warmup... Factory ECU setting I believe are set too safe with the 1uz-fe's... My motor runs a little cooler then stock under normal operating conditions so I really had to lean out the fuel mix with the help of my SAFC II piggy back. The motor was running soooooo rich as the stock ECU was still registering my engine as still being cold when it was as warm as it was going to get. I was getting killed at the pumps when I disconnected the piggy for a short period of time.....

 

[Red Supra]

Check out this article on a 1jz that started out with waste spark and ended up with sequential.
http://www.msruns.com/viewtopic.php?t=16721

 

[jibbby]

I was browsing and found this old thread....I was wondering can a big enough back fire in an xuz-fe motor dislodge or blow off the heads or cause damage to the intake manifold? I know that sounds rediculous, but is it possible?

I know the backfires usually just causes damage to the exhaust system only, but can it do more then just that? Maybe if the timing is radically off upon start up in combination with a very rich fuel mix?

 

[Cobolt]

To blow the intake, it must contain an explosive air/fuel mix so with carburator(s) before the intake, it can blow, with injectors near the intake valve in the runners and "no" fuel in the intake, the risk would be slim.

When using a wet nitrous system, especially with single nozzle systems, nitrous backfire is a serious hazard to the intake.

Top fuel dragsters that flood the intake with nitro and methanol also blow their intakes every once in a while.

 

[Tempeheat]

the only thing I've seen blow heads off is nitrous. i've seen the whole engine come out the bottom of the pan too. theres only one thing to say about this. you should've bought a Ford
o wait you have one of those too. nevermind :nutkick:

 

[XR8tt]

Had the same thing happen to one of my cars with MSD ignition...
It goes way better without it...Pita when they play up!!!

 

[jibbby]

Thanks for the replys... I too was thinking a nitrous backfire myself...

The old SBC engines that were carburated that I use to mess with and also had the MSD Ignition would occasionally backfire on me...New carbs, wrong order of spark plug wiring, etc...BOoom, I think I remember a flame coming out of the side headers one time...I can't remember for sure it's been so long...