rb20 metal headgasket

[xdream]

anyway now that i have to take the head off to see if i have any head damage i might as well buy a metal gasket....

the thing im wondering is the FET 1mm Metal Head Gasket - RB20 RB20DET Skyline good at all??? or should i go with the RB20DET Head Gasket Cometic Nissan Skyline 1.2mm RB20. (both are on ebay)

another factor im not sure about is... i might do some work on my block and possibly bore it out just enough to have new cylinder walls, would that affect the bore mm size??? ( ex. 82mm, 84mm, 80mm ??) and would i still be able to use say for example the cometic or Fet gaskets?

or should i just get different brand gaskets?

[Gold Digger]

Speaking of head gaskets.

What is the stock size for the RB20 turbo head gasket? Will increasting the size of the gasket make a dramatic change in compression, resulting in having to change your boost. If I remember correctly, lower compression = higer boost capability. And vice versa for high compression.I have thought about upgrading to a different head gasket but,1. Don't really have the place or the tools and knowhow to do it myself,2. Don't have the coin to pay someone else to do it for me.

[Bronze MFP]

unless you are pushing a ton of power is an upgraded headgasket even nessisary? also, don't go dropping your compression ratio just to run more boost. remember, you have to live with the engine off boost too (assuming its your daily driver). dropping your compression ration will make the engine more sluggish off boost.

[the_momo]

done bore your walls. pointless unless you have destroyed cylinder walls. ball hone for the win.

also......you need to deck your head and block so they are parallel surfaces. if they are out of true, youll waste a lot of time and money.

[themadscientist]

Don't lower the compression, it's fine. The metal headgasket is a nice upgrade since you are in there anyway. Not completely needed but might as well for the future. I THINK, I would have to confirm this, but I think 1.2 is the OEM gasket thickness. Thinner = higher, thicker = lower compression.

[the_momo]

im pretty sure the fact one is 1.0 mm. i have a cometic mls hg at 1.2 and it was thicker. not by much...like .2 mm actually im pretty sure the fact one is 1.0mm

[xdream]

so im better off getting the metal 1.0 mm for 170ish shipped? i plan on having around 350hp max.

or should i just play 215 for the 1.2 cometic?

also why would u want to lower compression to run more boost... cant you just raise compression a bit and make the same power?

[themadscientist]

You run a higher risk of dotonation.

[Carl H]

dont buy either, tune the car right and it will be fine.when i tore my motor down after i blew a hole thru the piston the hg was still mint, pretty impressive that some serious detonation had gone on in its poor life thus far.std gasket holds up surpsingly well with arp studs, have fun getting the cometic gasket to seal.

[xdream]

well carl,

can i use the gasket i just compressed with my arp head studs. i put the new gasket on and then did the compression test.... then it messed up my motor i think.

im gonna take that head off this weekend and see whats wrong but can i still use that gasket or no?

[Carl H]

once a hg has been compressed, or any gasket for that matter its useless...you will need to find a new hg.

[xdream]

well i see....

so you say im better off just buying an stock head gasket for $80 than buying the metal one for $160 1.0mm?

i just dont want to ever do a headgasket... and you also say its hard to seal those metal headgaskets?

how would i seal the metal ones properly?

[the_momo]

my cometic hg sealed just fine, but i decked my head and block. thats pretty much the only way. if you call cometic thats what theyll tell you. "put it on dry, there is a thin film of sealant already on the hg, and make sure the block and head have been planed square and true." thats what they told me. its not cheap, or easy. but itll hold more than the stock hg, and i needed to do it anyway. my head was warped a little.