2003cobraH/C

iTrader: (1)

sooooo...... we were testing out our fully built ls6 motor with full bolt-ons and more with FORGED internals with some spray (200 shot).
We were in 3rd gear on the freeway and when the spray hit the tires spun REALLY bad, it was crazy!!!
Something didnt feel right and the car was shooting out white smoke everywhere!!! we knew it WASNT a blown motor because the motor still had a good idle.....
so when we took the motor apart we saw the the driver side head gasket had blown. the shitty thing is that the gaskets were COMETIC gaskets with ARP head bolts!!!
The motor is about 11:1 compression with 18degrees of timing and about 11.3A/F with TR-6 plugs gapped to 35.
YES we will be using ARP head studs with cometic gaskets and NGK 7's next time.
But has anybody heard anything like this.... let me know what you think....
IT DOESNT seem to be detonation because the pistons are still better then PERFECT and the block also was untouched!!!!
THANKS FOR THE INFO!!!!
ALSO provided is the video when the car was racing and pics of the head and plugs... it is a convertible trans am WS9 vs a buddies BAD *** VETTE!
the trans am spun real bad and he short shifted into 4th & 5th....

briannutter

When intense cylinder pressures lift the head and the gasket can't expand enough to hold the seal, the combustion takes the shortest path to Oxygen... which acts as a blow torch. That wasn't the heads fault. You'll need to have the heads welded and resurfaced. What's really fun is seeing this action though IRON heads and blocks. That's when you know you've done a really good job With compression, even pulling timing isn't enough sometimes. I'm a big proponent of running a secondary fuel system to the fuel solenoid and having it filled with race gas.

ryan@rpm

iTrader: (5)

I would def. go with a diff. plug next time. Probally would not hurt to go down to a AR93 in that set up. Like the guy above said some race gas would be good also !!

edcmat-l1

iTrader: (10)

The plug heat range has nothing to do with that.
Probably not really anything wrong with the tune up either. Just a typical 4 bolt head with too much cylinder pressure.
I'd o-ring the heads.

2003cobraH/C

iTrader: (1)

just to let everyone know the nitrous set-up is a direct port kit with a stand alone fuel system which had 100octane in it!!!
ANY suggestions on what timing should be run on this kind of set-up? AND what is this O-Ring the cylinders????

stevieturbo

detonation plain and simple.......been there done that

I wish my block had been as lucky and survived !!!!

ATVracr

iTrader: (5)

A 347 with a 200 shot is not to much cyl. pressure.
Looks like there may have been something missed during assembly.

You should not be running TR6 with a 200 shot.

We have sprayed ALOT more and I have never seen that happen, definatley not a faulty head.

98Camarod

iTrader: (43)

it melted the head but not the block? What does the surface of the block look like?

venom ws7

iTrader: (13)

ATVracr what plugs you think will be better for 200+shot???

ATVracr

iTrader: (5)

AR94 is a good plug. you want something in the 7 heat range for a stockish motor and 8 heat range for a 400" motor. (non projected tip for N20)

I run the AR94 on the motor and NGK 11's on spray.

to cold of a plug wont hurt anything, to hot..... melts ****!

87silverbullet

iTrader: (11)

^^^^ I'm with him. Did you clean out the bolt holes good when you put the heads on? You might had enough clamping force on the motor but not enough on the spray and you lifted the head.

edcmat-l1

iTrader: (10)

The amount of nitrous in a specific size engine isn't the only factor in cylinder pressure.
And, I never said it was too much nitrous.

DrkPhx

iTrader: (15)

Good question. What does the block deck look like? Looks like a sealing problem. Cometics with copper spray works really good, but the surfaces must be perfectly clean. The good news is the head can be repaired. Call WRE they are experts at this type of repair. They fixed one of my heads. It has 4K miles without a problem.

stevieturbo

Send them back to Trickflow, they built the heads, so you can guarantee any repairs will be 100%

2003cobraH/C

iTrader: (1)

the block was COMPLETELY untouched, only one side of the Cometic gaskets had been blown out, the explosion did not go all the way through to the block......... we will be using ARP head studs instead of head bolts this time with of course a much better plug!!! and yes we got out as much out of the holes as possible and then put the bolts in..... any suggestions on the BEST way to install the head studs??? seems like there is no way to get out all the **** in the holes no matter how much i blow out!!! also would anyone copper spray the cometic gaskets or just put them on???

stevieturbo

no gasket or spark plug will prevent that damage from happening IMO.

brad8266

iTrader: (23)

I agree 100%. It had to have been extremely hot in there to do that to the head. Did you log air/fuel by chance??

An 11:1 200 shot isnt very hard on a built 347, especially with the timing bumped way down like you had.

FranCisco

O-ringing is a good idea with high cylinder pressure applications. a reciever groove is cut into the head and a loc wire is put in place allowing for better head to deck sealing. Best explanation I can give in a nutshell.

DAVESS02

iTrader: (30)

Had the block been decked? I blew gaskets on a H/C 346 twice in the same places. The first time it was due to me not re-torqueing the head gaskets after heat cycling. The second time was with SCE coppers and copper spray with Dart heads. After that, they seeped between the lower bolt holes after a few thousand miles. I swapped in AFR's wilth SCE Titan o-ringed copper gaskets and used indian head sealer. Took the motor apart last month and while it didnt show signs of a blown gasket, there was a little carbon between the cylinders. Re-torqueing the studs TWICE the last time, I watched the socket and I wound up getting 1/4 to 1/3 more turn on the studs the first re-torque after heat cycling and another 1/8 turn after the second re-torque. Still though, I wonder if the block was warped a bit.

oange ss

iTrader: (50)

relativley mild setup for the components involved, i'd bet it was weak head bolt install resulting in lifting the head, i would also up the gas for the stand alone to 110...my .02