1SIKZ31

iTrader: (5)

Keeping it short...
Forged 346 LS1
PRC stage 2.5 5.3 heads
LS9 Headgaskets
Fresh motor... Around 3,000 miles on it...
76mm turbo... 13psi... 11.0 a/f... 15 degrees timing...

Mid race on the highway running this SUPER fast GTR after going through a few gears... In the middle of 4th gear I felt the car studder (misfire?) and then stayed in it for MAYBE 1-2 seconds after that... As soon as I let off the gas and hit the brakes engine died... Car POURED white smoke from the exhaust... I tried starting it but it was just POURING white smoke again and had coolant in the cylinders...

I'm getting it towed and will take off the heads soon but what the hell happened?!??? ... Blew my Headgaskets? How?!
Makes no sense!!!!
Detonation caused the weak link to let go?
Or ?

yelo04goat

iTrader: (11)

lifted head maybe...?

1toofastlt1

iTrader: (4)

What kind of gas? Are you running head studs?

1SIKZ31

iTrader: (5)

ARP head bolts.

This happened after 3 back to back races with about 30 second cools is periods, coolant temps were 190 when this happened if that matters...

Any ideas?

How why it lift the head??

93 octane Shell gas

yelo04goat

iTrader: (11)

arent the prc 2.5 heads milled down a bit on an already thinner deck.. ?

4 bolt heads can "lift" or just kinda bow up over the cylinder. causing coolant to go places it shouldnt.. just an idea not an expert by any means

stock48

iTrader: (17)

This is most likely your answer starting with the 93 octane. Need to run 160 deg coolant temp, low iat's and be really careful with that stuff.

novaflash2002

iTrader: (51)

Whats the casting # on the heads?

typhoon1015

iTrader: (5)

I would guess the 1-2 seconds of detonation causing very high cyl pressures lifting the head.

TheLS1Lover

You need some head STUDS, without a doubt.

MUSTANGBRKR02

iTrader: (91)

That's what I was thinking. I bet IAT's were through the roof.

got-a-ls1

iTrader: (12)

hopefully its just the gaskets and you didnt break a liner. people push water all the time but doesnt usually result in water rolling into the bores from what ive seen. if you detonated really hard i can see a liner getting taken out

1SIKZ31

iTrader: (5)

Just pulled the plugs. 3rd cylinder's electrode was closed shut.
Oh the car does have a 160 thermostat. But the motor stays around 175-180 degrees... After a pull it goes to 190 but goes back down to high 170's after cruising for a few minutes...
Pulled the head and found a ******* broken ring land on the 3rd cylinder from the front on the drivers side...
This sucks! It's a fresh motor!!!!!
Those 1-2 seconds I stayed in it were catastrophic..

How can I keep this from happening next time?
I think my heads are 706 castings...

Oh ****... The cylinder head got pitted up... The cylinder liner appears unharmed... But where is the piston?!
I reallyyyyy hope of didnt slam in to my $2400 comp turbo

T/ALT1

iTrader: (3)

Thats very hard on any engine, 30seconds cool down after each race. You detonated the piston for sure. I would put some heads with a bigger combustion chamber (243 castings) along with alky/water injection to keep this from happening agan.

MUSTANGBRKR02

iTrader: (91)

expensive lesson

Johnv

Can you see if the head gasket did let go ? if not have a very close look at the cylinder bore for cracks, hope you can salvage the block..
What pistons were you running ?

I'm picking detonation, repeated 4th gear pulls would produce very high IATs and EGTs.
Definatly add a meth kit to help this thing live next time around.

TrickrTreat

iTrader: (3)

In my opinion its a combo of your compression being too high for your driving style, the boost level with the 5.3 heads on your cubes, running straight 93, and no cooling of iat's other then ambiant air , is what poped your motor.

In the same situation , with 93 octane, and methinol inj , and at least a ls1 or a 317 head , this would have had a lot larger chance of Not happening at all.

I8UR4RD

iTrader: (16)

sounds like she was a little hot. alot to ask of any stock piston. cant be too upset though, thats quite a beating for a stock motor @ those specs to deal with. still a pretty amazing motor. at least its not a high dollar longblock.

MUSTANGBRKR02

iTrader: (91)

First post says it was a forged bottom end.

Sales@Tick

iTrader: (3)

Long highway pulls like you were doing are THE most taxing on any combination. What happened here was probably a combination of several things and not just one. For starters, as others have pointed out already, for that long a period of load and the amount of cylinder pressure seen in 3rd and 4th gear on the highway you didn't have enough octane. Possible that you have the incorrect heat range plug in the motor as well as no one has asked what plugs you were running yet. Your heads may of not had the proper clean up or surface finish causing a bad head gasket seal and it was exposed under higher cylinder pressures. Bolts aren't going to cut it on a boosted turbo set-up with stock heads doing what you were doing. Your ring gap may of been too tight and not loose enough for your power levels. This list could literally go on and on.

What I would personally do is have the heads checked out, run a looser ring gap, run a colder plug, get a meth kit and spray a lot of it...as in dual 10-15# nozzles and get some head studs. This will probably fix your issues for good at least until you really start leaning on it again in the upper 800rwhp range when the heads really want to start to lift and not at the power level you're at now.

1SIKZ31

iTrader: (5)

Thanks guys!!!!