slowZ

I blew head gaskets today on 11psi for some odd reason. I didnt think it was possible on such a low boost level. I have felpro 1074's on there right now, ca any one think of a better gasket to use or just stick with them again?

MikeGyver

I went with Cometics.

slowZ

I was thinking of those, but i have heard you have to have something done to the head surface? Is that true?

MikeGyver

They just need a smooth finish. I think most machine shops go plenty smooth on heads for cars w/o MLS gaskets anyway.

blown94

This topic has been covered numerous times, and just recently, as I had the same dilema. I dont blame the gasket at all looking back. I had a few issues which could have caused it.
To summarize: I dont think I had the arp bolts torqued down enough as they spec higher than factory torque; My meth inj. line burst in the middle of a WOT pull and the wideband hit 12:1 and I let out but unfortunately it was too late; The previous 2 together could have caused detonation with the high intake temps and forced the gasket out.
In the end, I chose to do it again with 1074's as alot of guys are using them with more boost than I have without issue. As someone stated in my thread, its all in the tune. Use the head gasket as a fuse, its better to replace the gaskets than pistons,rods, etc.
Just remembered I was also running 26-7* timing, which didnt seem to be an issue and that car ran like a raped ape, but when combined with my other issues, was probably a recipe for disaster. Chalk it up to **** happens and look into your tune.

slowZ

I like this statement
I will go over the tune and look for something that may need lowered for durability i guess, but i was thinking of just parting the car out due to time and money constraints. college sucks! plus im kinda sick of working on it.

blown94

You know, it also never occurred to me, but i was jst re-reading the post, and you dont state what compression ratio yer running? What dish, what head chamber size, and how much deck is left at TDC? If you're CR is above 9.5:1 thats part of the problem.

I hear ya on being tired of working on an lt1 f-body. It takes alot of patience, alot of time, and a lift is a great help. Without those, I wouldnt have one myself, as its a pain to do most anything to it.

slowZ

The compression ratio is 9.8:1 when i had the short block done the machinist checked the block deck and said it was true enough that it didn't need machined( maybe it had been done by the previous owner?) i believe the dish on the pistons was a -20, i can check my paper work to be sure. I do have ARP head bolts but might not ahve torqued them to ARP's torque specs , i might have used the stock specs???? idk. My brother said to go studs, but i don't think they are the problem. whats your suggestions?

blown94

Well, yer CR is about right for 10 psi from what ive been told. Any lower than 9:1 will hurt off boost perf. in low (<15 psi) applications. On the other hand, you dont want to go any higher thats for sure. Ive got main studs in my 2 bolt and regular ARP bolts in the heads. I noticed ARP wants like 77 ft/lb with arp lube or something like that, check because its different with oil or arp lube, but I know for certain its more than stock, or what most people use (65 ft/lb). Make sure your surfaces are clean as can be, and make sure you torque in the right seq. and double pass the last pass to be sure. Other than that, keep the timing moderate and IAT's down. If you aint runnin an intercooler and yer in higher temp regions, you should at least have a meth kit to help control intake temps and reduce the risk of detonation. And I dont think this needs to be said, but, always run good fuel no less than 91. Try mixing some higher octane fuel if you cant get 93.

slowZ

when you said about the torque specs with the ARP bolts, that got me thinking and i may have used the stock spec and i cannot remember
oh well it happens i guess. the highest intake temps i saw i was in boost for a while climbing up hill was 139 degrees on a 95 degree day, i do not know if that is too hot or not but i don't have an intercooler.

blown94

thats not bad considering 95* day. I too failed to torque the bolts to arp suggested specs, now whether that factored into the issue who knows, but I do know for a fact I did not use arp's specs the first time around. This time I did, and havent had an issue yet with the head gaskets again and yesterday I saw 12 psi @ 6k rpm and it was about 90*+.

One thing to consider: ive heard the intake air temp does not update very quickly, so you're raeding may not be accurate. I remember reading that it only updates like twice a minute or something ridiculous, so I wouldnt count on that. You need a realtime IAT sensor from what ive read.

jsetzer

The computer polls the IAT fairly often. Make sure you are using an open style IAT and not a closed. Closed looks like a coolant sensor.

slowZ

Well I have watched the IAT's go up when I'm in boost and you can see it change probably every two seconds so I am fairly sure it is accurate.
jsetzer- I have an IAT out of a GMC cyclone and the only difference to the stock one is it is metal.

jsetzer

Thats the one I run -

blown94

Ahh, ok, thanks for chiming in because I hadnt the time to research this more and I was very curious as I havent been able to log any of my runs yet so its difficult to watch a scantool while doing a WOT run. I really need to get my laptop setup and do some logging, but the car is running so nice I havent bothered, though it could use some fine tuning.