cablebandit

iTrader: (37)

I'm with Harlan.....timing...or a/f. Too many people are making that power or more with forced induction and not lifting heads anymore since we got enuff fuel and better tunes now. I use cometics.....with this rebuild (hydrolocked) it will be my 4th-5th time using those same headgaskets. I am gonna bet the farm on some detonation somewhere.

LOnSLO

iTrader: (15)

Sever detonation is likely the culprit. You don't need copper gaskets at that power level. The quench height change is negligible. You don't need to o-ring the block, and you don't have too much compression. I would do 2 things, one of which is mandatory:
1. Change to a different head gasket- you need to replace them anyway since one of them will be ruined.
2. Go through your entire fuel system. Check fuel pressure at WOT at torque peak.
Something seems amiss. Were you logging on the dyno runs?

SAM98WS6

Just a thought....If you didnt go over the ARP heads studs final torque value for at least 1/2 hour then the studs werent torqued properly. I waited 15 minutes and they had backed off 1/2 turn..or needed another 1/2 turn...went over them another 2 or three times after they sat until they didnt turn anymore.

If you only did it once then that is your issue probably.

Hysteria

I am with the head stud thing. All of ARP's stuff like their rod bolts and stuff require a 3 time torque routine. It is very easy to over look. Cometics are good gaskets, just like anyone elses top name gasket.

Nickn20

Ditto, what fuel octane, timing and AFR were you at?

I plan on running 104 URL whenever I spray, its just cheap insurance, and timing with a 200 shot will be around 18ish for my motor(10.7:1) and the AFR will be low low 11s, to start out with, I think I will be safe.

383LQ4SS

iTrader: (33)

Ditto on the Detonation.
I believe that most people that have head gasket issues or head lifting issues are really having detonation issues.

Gold Z

iTrader: (3)

Lots of good info. Thanks for all the responses.

99HUGGSS

I have 11.8 to 1 compression, stock head bolts, MLS gaskets, and spray 3000-6800 RPM's with 31.9 degrees of timing on 93 octane gas and haven't had any problems. That's not to say I won't, but I don't have any detonation or anything. I have to agree with the head gasket theory

383LQ4SS

iTrader: (33)

How much do you spray? Whats your total HP?

Sure you can spray a 100 shot with your combo...but I do not believe you could spray a 200 shot that way.

On my 383 I would get detonation around 600 rwhp on 93 octane and 27 degrees of timing.


Also...to the original poster...what rpm did the juice come on...what was your TQ? Many times for nitrous cars...its not the peak HP where the problem occurs...its at peak Tq...which is usually as soon as its activated. That where cylinder pressure is greatest.

Ben R

Lifting a cylinder head is the result of detonation.

You need more octane, less timing, or a better tune once on the gas. It might also be a combination of all three.

LASTLS1

iTrader: (7)

93 octane and nitrous is a set up for problems. You NEVER know what your getting out of the gas station fuel pumps! When using nitrous I ALWAYS buy drums of fuel. I bought 200 gallons of 104 for $2.30 a gallon. I was before the prices for fuel went up. Good fuel is the cheapest insurance you will ever buy. Good luck, let us know what you find.

99HUGGSS

I spray a 150 shot, so far so good

Brian Tooley Racing

iTrader: (13)

We always set our A/F ratio on the wide band at around 10:1, never leaner then 11:1, 116 octane, o-ringed heads, stock GM graphite gaskets, ARP studs torqued once , not much timing , NGK V-power #8 plugs, etc.

O2bqwik

iTrader: (6)

yep thats why my nitrous system will be running off a stand alone fuel system with some high octane gas in it