mill head + thin gasket?

[ptownTSI]

So i'd like to mill my head down by about .025 or .03 along with run a thin head gasket to get the compression ratio up to about 9.5-9.75:1 or so. I know i would need to run premium but these bad boys have aluminum heads and should be able to do it fine.

where can i get the thin gaskets?

[92 mtechnic cabrio]

The design of M20 heads actually cause a lot of detonation problems, even at a low 8.8:1 compression. Our heads have lots of hot spots or something. Many E30 owners are pinging even on 91 octane gas. Good luck running 9.5 compression in California.

[homegrone30]

arent you supposed to run premium ne ways in these bad boys

[strad]

My 92 E30 owner's manual says 87 minimum AKI, 91 RON is required.

I don't know about others' experiences, but my own has been that my completely stock 158k M20b25 runs perfectly fine on 87, not a hint of pinging.

If it were me, I'd go with chipping and camming before milling to get horsepower results, since with the former one can reverse the operation if it doesn't yield the desired results.

[MattE30]

Mine ran fine on 87 octane (stock).

[ptownTSI]

i can mill a certain amount and stay SCCA legal in my class, i can't do a cam swap. also the timing is not going to be affected very much.

[nando]

be careful about valve to piston clearance... there isn't very much there.

[asubimmer]

yeah only the m42 and s14 take 91. The m20 and m10 take 87.

[SandyEggoE30Girl]

I have to run 91 in my 1987is. If I don't it pings really bad? Especially on a warm day.

[ptownTSI]

you need to do an upper engine treatment.

take the plugs out and pour a tablespoon of seafoam down each of holes, let it sit there for an hour or two. then crank the engine over with the plugs out of it to eject all the solution that didnt seap past the rings.

put the plugs back in the motor and pour the rest of the bottle down a vacuum tube, sucking it up as fast as possible so the motor starts to run rough, when you get to the end try to pour it in quickly and then shut it off immediately. the goal here is to get it liquiefied into the motor, on the valves and pistons.

let it sit for 15 mins.

go for a really hard drive and then change your oil.

that should do it. if you need to run 91 something is wrong with your motor or it is modified. excessive deposits on the internals can cause it to ping and need higher octane. you are only covering up the problem.