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View Full Version : cometic vs oem HG


redline racer510
09-04-2010, 12:19 PM
I have looked around Nico ,skyline AUS and this forum regarding the durability vs price+labor of a cometic HG (stock thickness) vs an oem head gasket that came with by rb25det rebuild kit. To break it down to you guys(and gals) is it worth spending the money on a cometic HG and arp head studs if I am only looking to get say, 300-350whp. How much is the oem head gasket rated for?
P.S. I am not trying to spend the money unless there is a need for it at those power levels

I LUV MY S13
09-04-2010, 12:20 PM
From what ive heard oem is good up to 500hp

Sileighty_85
09-04-2010, 12:35 PM
I would take OEM over Cometic

But yeah The OEM H/G can hold around 500hp

I too am using an OEM H/G with ARP Studs and shooting for 350 on mine.
Tuning is the main thing.

redline racer510
09-04-2010, 12:56 PM
Thanks dudes. lol the simplest answer I have ever got on zilvia.
No but really I appreciate it. mods can shut this down

Silviaoneday
09-04-2010, 11:44 PM
I went with the apexi hg and arp studs. Play it safe and get a real head gasket. I know you guys are saying 500whp, show me some dyno sheets and I will believe it. I run high boost and check the torque on the head randomly and it hasnt bugged for sheeeeet.

anton1o
09-05-2010, 01:55 AM
Get a cosworth head gasket!

Nikeboy355
09-05-2010, 01:16 PM
OEM will work just fine... Clean all your surfaces nicely and torque it down correctly...

eklips3
09-05-2010, 01:25 PM
if you want to use a metal head gasket you MUST get your head planed as well as the block. both mating surfaces MUST be perfectly flat.

OEM head gasket is more forgiving if you only have your head planed but not the block.

even still i would have both head and block planed to avoid any headaches in the future

va240dude
09-05-2010, 09:50 PM
I would take OEM over Cometic

But yeah The OEM H/G can hold around 500hp

I too am using an OEM H/G with ARP Studs and shooting for 350 on mine.
Tuning is the main thing.

This is what I was thinking of setting mine up for. Any reason you chose OEM over a Cosworth metal h/g, or another brand? All my lower block will be stock internals...

Sileighty_85
09-05-2010, 09:55 PM
This is what I was thinking of setting mine up for. Any reason you chose OEM over a Cosworth metal h/g, or another brand? All my lower block will be stock internals...

I had ordered a full rebuild kit, and no point in spending another $250+ when an OEM one works just fine.

Im only looking for like 350whp, so its not really needed.

eh?
09-06-2010, 06:59 AM
This is what I was thinking of setting mine up for. Any reason you chose OEM over a Cosworth metal h/g, or another brand? All my lower block will be stock internals...

Waste of time using a a mls gasket on a stock bottom end. Your ring lands will go before the stock head gasket does.
I had 4 out of the 6 piston ring lands crack yet the gasket was perfectly fine. That's the case with 999 out of 1000 rb25 failures.
IMO: unless your are replacing the pistons leave the HG and head bolts alone. Seems like the only people having sealing issues are the ones with cometic mls gaskets and arp studs. I wouldn't replace the bolts unless I knew for sure they were out of limits.

anton1o
09-08-2010, 10:43 PM
Thought id throw this up there..

http://sphotos.ak.fbcdn.net/hphotos-ak-ash1/hs260.ash1/18767_274613743336_758983336_3278434_7619840_n.jpg