Head spacer

[shEck3lls0]

Because the m42's compression ratio is high.... and I am doing a turbo and wasn't smart enough to put forged pistons in when I rebuilt(didn't plan on turbo at the time), what do you guys think about this head spacer? It is very iffy to me, but until I have the time and money to rebuild another motor... or another car, might as well try something.

http://www.amazon.com/Cylinder-Head-.../dp/B004HH5BXI

[Massimo]

IDK I think I would be more inclined to use the thickest head gasket I could get. Something like this I know its not cheap but comes .140 thick

http://store.vacmotorsports.com/vac---m42m44-multi-layered-steel-head-gaskets-mls-p1023.aspx

[Dj Buttchug]

Massimo is right. the gasket pictured in the Op's link will not fit. The more parts the more chance of fail.

.140 is the best (cheapest) way to do things. consider some better fastening hardware as well. thicker Hg tend to have problems

[bwawuz02]

What's the resulting C/R from running a .140 MLS gasket?

[shEck3lls0]

Very true. Especially with a turbo. How much will that lower compression? Either way, I will eventually be doing forged pistons.

[Massimo]

that .140 head gasket should give you about 40cc more. Then as for hardware you have two choices ARP bolts which are the same as stock just stronger.

Or you can get a stud kit from ARP the good thing about these are they are stronger and are reusable about 3 or 4 times but they are pricy.

[Ian Bowers]

.140 MLS lowers comp to right about 8.5:1, it's the route I went. I also got ARP headstuds. Be warned, though, setting the timing is a major bitch with the MLS, the profile gasket has to be doubled up with RTV/gasket maker, and (supposedly) it alters ignition timing.

[bwawuz02]

I already have the ARP studs. I don't see how it would alter ignition timing. Yeah, I think i'll just wait for turbo until the current engine comes out and the new one is well broke in. Hoping to find an M47 crank while i'm in germany. I really gotta start parusing the yards here, but I don't have any tools :(

[Ian Bowers]

What's the head thickness? If you get it too tall or short it will throw off the valve timing and therefore the ignition timing won't be right either.

That's what was said in my thread when I asked for help with my timing.

[shEck3lls0]

What about just running stock head gasket and cr on 8-9 psi until I build up another motor? It would be awhile though before I could do that though. Or should I spend the $200 on gasket amd hardware until I can drop a new engine in?

[nando]

not a good idea.

there are other solutions:
-get an agressive cam set. this will reduce dynamic CR and the tendancy to knock at peak torque/high boost.
-use a very efficient, large turbo (something new and modern, from 2011 - no 20 year old junkyard crap)
-make sure your exhaust is as restriction free as possible (4" downpipe, dual bypass valves, 3" tubing and freeflow mufflers)
-careful tuning (standalone - no jimmy-rigged AFMs or stock computers with ebay "turbo" chips)
-make sure your intercooler setup is efficient (high IAT = more likely to knock)
-build your fuel system for E85 (if available). E85 has cooling properties that are highly beneficial for boost, especially with a higher CR

you don't really need super low CR just because it's boosted. That's just an easy way around some of the things I mentioned above - you can get away with a lot less efficiency. However, a highly efficient setup with a higher CR will be overall better, it's just more difficult to setup because you have to take each step carefully.

things like thick headgaskets or spacers are a poor bandaid at best. They affect the combustion chamber in other ways that are not desireable..

[bwawuz02]

not a good idea.

there are other solutions:
-get an agressive cam set. this will reduce dynamic CR and the tendancy to knock at peak torque/high boost.
-use a very efficient, large turbo (something new and modern, from 2011 - no 20 year old junkyard crap)
-make sure your exhaust is as restriction free as possible (4" downpipe, dual bypass valves, 3" tubing and freeflow mufflers)
-careful tuning (standalone - no jimmy-rigged AFMs or stock computers with ebay "turbo" chips)
-make sure your intercooler setup is efficient (high IAT = more likely to knock)
-build your fuel system for E85 (if available). E85 has cooling properties that are highly beneficial for boost, especially with a higher CR

you don't really need super low CR just because it's boosted. That's just an easy way around some of the things I mentioned above - you can get away with a lot less efficiency. However, a highly efficient setup with a higher CR will be overall better, it's just more difficult to setup because you have to take each step carefully.

things like thick headgaskets or spacers are a poor bandaid at best. They affect the combustion chamber in other ways that are not desireable..

this guy knows how to read. love it. E85 has less power output/mol, and a higher octane rating. Which translates to spraying more liquid fuel (bigger injectors, greater cylinder cooling) and less tendency to pre-ignition. Check out MITs direct injection of E85 w/port injection of pump gas, pretty neat.

[tom d]

i've seen mention of the M42 having cast pistons a couple of times now, from what i understand, the E30's M42 has forged pistons. i might be wrong, but i've read it a few time in tech manuals.

[Ian Bowers]

They are cast.

[bwawuz02]

They are cast.

+1. Most BMW pistons are. I think all rods are forged, some cranks are cast.