MLS gaskets are available from Cometec, Lextreme sells them. The cometec ones are available in several thicknesses which will lower your compression, which would be good in your turbo jet.
How come new gaskets, have you blown them or are you building a hotter engine?
Andrew, the reason for new head gaskets, I had a injector problem & a lean out
on one cyl that burned a hole in the piston. The standard Toyota head gas
kets show no signs of failure, considering 20 psi boost @7500rpm.
I dont know how much abuse the standard will take but I'm very happy with its performance.
It kind of depends on the gasket & has alot to do with what the torque / shifting / expansion of the heads & blocks work out to be.
For traditional pressed gaskets - you'll find Honda's & everything that swear up & down they're ok up to 24psi of boost.
Then again, even with the newest pressed grafite gaskets (Better than the old pressed paper ones). You only see the best quality pressed gaskets rated out to a 12:1 CR.
Sure you can far exceed that, but to me - 12:1 is My "set in stone" rule for any type of non-all metal gasket AFA 100% certianty that it will not be a problem (If the head/block/torque etc agree). When talking boost - it's a different story because you're really fighting the peak effective compression ratio. I tend to get a 14-17:1 leway without much regard on pressed gaskets.
It's not like they're all going to fail the higher the PE CR goes, the risk just goes exponentually higher.
You guys will probably fight me all day on that with the uz's great track record (Almost all Toyota engines - even with the old gaskets & known problems post asbestos ban - have great track records on boost), but like I said - my opinion, on 100% certianty.
Rough numbers on a stock 1uz-fe for a quick refferance:
5psi - 13:1 CR
9psi - 15.5:1 CR
12psi - 17.25:1 CR
14.5psi - 18.75:1 CR
20psi - 22:1 CR
24psi - 24.5:1 CR
You can see, *peak* effective compression ratios rise quickly with boost. I'm stopping at 24psi because frankly, even the "kids with turbos" i4 guys know to stop by 24psi.
So a quick recap:
For full time drive around power. You need to stop at 12:1. With something like a turbo, or centerfugal blower, you can let the ratio slide up a good bit all things considered - because that ratio is only going to be a *peak* ratio that isn't experianced all the time.
14-20's is where I like to pull the reigns & say whoa based on all the factors related to the particular engine.
Like I've said a hundred times in this post already LoL! Just my opinion, on the entire scope of the pressed gasket issue. Some go much farther than others.