I drove it to the track last Wednesday. First run, 11.57 @ 123 (200 shot direct port). I have run about 10 runs like this in the last couple of weeks. Next run, big fireball out of the cowl hood. Died, barely started back up. Drove it to the pits, but it was running pretty bad. So, decided to go ahead and nurse it home. Did it blow the head gasket at the track, and the drive home destroyed my head because it was leaking there? The block is stock 4 bolt. The heads were LPE CNC ported. Let me know what you think. Here is a link to an index of the pix.


http://82lt1.cz28.com/damage/

 

Looks like you did pop a head gasket from what I saw in the pics. The fireball from the motor is a nitrious backfire. They tend to be quite violent when they happen. It usually occurs when n20 starts to puddle up in the intake but Ive never seen it happen with a direct port.

 

I think I probably popped the head gasket and then, the drive home took a little more with it. The next cylinder wasn't too far from going too. I think the head gasket could have blown causing the backfire. We'll probably never know. I was using the mr. gasket head gaskets. I don't think I'll use those again though.
Todd

 

Would the head erode that much from a little low load driving after the gasket blew? Isn't it more likely that the head gasket was blown for a while, and the intense heat of the nitrous eroded/melted the head material? No expertise here... just trying to think my way through what happened.

You can get a fairly decent intake manifold nitrous explosion even with a dry system. Again, if the hole was open connecting the two cylinders, isn't it possible that the A/F mix from one cylinder on a compression stroke could have been blown out through an open intake valve on the adjacent cylinder? That would load the intake up with air, fuel and nitrous..... add a little heat and.... big boom. I've had a manifold "pop" due to a leaking nitrous solenoid between the water box and the line.... enough force to give the 58mm throttle blades an interesting "L" shape.

 

I talked to a friend that said the damage was probably done at the track. I don't really think it could have eroded that much from a 20 - 30 mile drive home. If it eroded that fast, I would think any cylinder head would wear from normal driving, but they don't. The drive home could have smoothed the hole out though. We are going to try to repair it and see what happens. He has repaired some similar damage before. Hopefully I'll be back up and running. I may have a direct port nitrous intake for sale though.
Todd

 

Crossfire - It's not just a cool children's game.

I've seen where sbc stuff was overheated & lost the gasket between the adjacent exh ports fairly often, and the damage can be pretty severe. I saw one poor block that was trashed after it had over .200" material blown out.

Another reason that if you suspect you've lost a head gasket, stop driving it.

 

Very interesting, no?

SkarodoM, It wasn't the adjacent exhaust. It was the adjacent intake. Though the the #3 and #5 exhaust area looks like it 's about to go also.

Injuneer, Guess which intake is open when #5 cyclinder fires.

 

Looks like it just got way to hot, more than likely from running lean.

The only time I have seen anything close to that was on a solid roller LS1 car that someone had put the head gasket on upside down blocking off some of the coolant holes. It was on the dyno for about 5 really hard 7500rpm pulls and started to run badly. It lost the ends of the spark plugs in the two middle cylinders and blew a hole thru the head between the two, but not as big as this one. Just looked like someone had taken a plasma cutter and blew a hole thru it.

 

Pretty simple, you blew it the f*** up

Adjacent cylinder doesn't matter. If you were spraying that big of a shot, the heat from the combustion process just goes over into the other cylinder, no matter which on it is (intake/ exhaust).

I'm surprised your pistons are still intact if they are the stock castings

-Shannon

 

Yeah I can tell the difference between intake and exhaust valves ; )

I was giving an example of what happens oftentimes with NA stuff. Either way, running it like that is f'd. I've seen a set of LS6 heads that someone installed the gasket on backward & blew a hole through as well, LOL.

 

what kinda head gaskets are those? impy or maybe the mr. gasket .026?
might wanna invest in some better gaskets.... better suited for sealing under a 200 shot, i mean.

just curius... what was your launching technique? spraying out of the hole im sure, but at what rpm do you begin spraying?
and, also, are you leaving off of a rev limiter?
jeremy

 

They are the Mr. Gaskets. I think that was a lot of my problem. I really think I blew the head gasket while spraying. I possibly could have went lean. I have a fuel pressure safety switch, but it's set at 35 psi. I am definitely not using the same head gaskets. From what I've read, I think I'll go with the Fel-Pro 1074's. I think I will also upgrade my fuel system. I have an intank walbro 255 lph. But, I remember standing behind the car the other day, and thinking the pump sounded a little strange. I didn't think much of it because it was running fine. But, when you're putting that much spray to it, I know it needs a bunch of fuel.

I have one of the Mallory boxes with rev limiter, window switch, retard and all the goodies. I was retarding 6 degrees, window switch from 3000 to 6800 (I think) and shifting about 6900. I have been leaving about idle or so. I haven't been to the track a lot, so I've been just kind of experimenting. I hadn't really gotten a good burnout until that run. I was really hoping to see a good time, until the fireball popped out from the hood.

I'm going to send the head to TEA for repair. Probably have them flow them and see what I got. Then, build the short block. Hopefully it will last a little longer this time.

Todd