Need advice m20 turbo build.

[timmyr77]

So I've started to to build my head on my m20 and I have read that for na porting and polishing a head is basically as far as $$/powergain. So is it worth porting and polishing the head if I'm boosting it.
Plannin to have
272 camshaft
Possible heavy duty rocker arms
IE valve springs
And stainless steel valves
Most likely not running more than 18 psi


(I'm new to turbo set-ups so sorry if this is a stupid noob question)

[timmyr77]

Oh and a 2.7 bottom end

[ColdAsLife]

What is your power goals? At 18 psi depending on your tune your HP can vary from 375 to 450 on that setup. There is recorded accounts of the swedes getting up to 650HP on untouched 885 heads so I personally would stay away from porting the head as its not a bottle neck in what I can assume are your goals are. Currently the least capable piece of your build will be the eta pistons in the 2.7 bottom end which will hold you back before the 885 head will IMHO.

I'm running a Ireland 272 cam and if I were do it again I would run a Z45 turbo cam from Pure Performance Factory.

Hope this helps.

[timmyr77]

so porting wont do much hp wise. well once i have the seta pistons ill be good to go, just need to rebuild the head. ill look into the z45 cam. and if i dont pollish and port that will save a good 400-800 bucks.
any other thoughts on this?

[Good & Tight]

so porting wont do much hp wise. well once i have the seta pistons ill be good to go, just need to rebuild the head. ill look into the z45 cam. and if i dont pollish and port that will save a good 400-800 bucks.
any other thoughts on this?

Don't waste your money on port and polish for a stock bottom end turbo setup.
Now if you had forged rods and pistons and wanted to run over 25psi then yes port and polish would be worth it along with a good tubular manifold and a cam.

[timmyr77]

ok thanks

[pantelones]

One BIG thing that most people don't realize about a turbo set up is that the cam really needs be custom ground for your set up... Read this....

http://www.hotrod.com/pitstop/hrdp_1011_cams_for_turbocharged_engines/viewall.html

"In truth, Godbold says 99 percent of Comp Cams' turbo grinds should be custom profiles because "pressure differential can be all over the place. The reason we don't have a lot of catalog turbo cams is because there are not a lot of catalog turbo systems." Every turbo installation is unique."

[JTapper]

Do the heavy duty rockers, and ARP studs top and bottom, and you should be good to go.

I ran 20psi on an ebay .63ar T3/T4 turbo and had nothing but fun with it. All stock internals, only upgraded to studs. I had an SETA bottom end with an 885 head, cometic MLS head gasket.

[1owNslo]

not trying to steal this thread... but where do you go about getting a custom ground cam? and where do you start in respects to that? do you give them your end HP goals and your set up and they grind you a cam????

[einstein57]

http://www.bimmerheads.com/

[pantelones]

not trying to steal this thread... but where do you go about getting a custom ground cam? and where do you start in respects to that? do you give them your end HP goals and your set up and they grind you a cam????

Did you read?

http://www.hotrod.com/pitstop/hrdp_1...s/viewall.html


Then read...

http://www.forcedinductions.com/help.htm

http://www.tildentechnologies.com/Cams/index.html

Then AFTER you have done all your homework, and have your set up compiled you can go about getting something to suit your set up.

Any power goal under 300'ish HP is fine with the stock cam. Anything that deals with power goals and PSI over, lets say 15+PSI SHOULD have a custom ground cam. Again, this is at your discretion and knowledge of engine design. My honest opinion is that if you plan to make 350+ WHP out of an m20 you better be doing your homework, and know that cam design is very important. It's right behind having a proper tune.

Also, don't quote me on those numbers either. Personally, I would have a custom ground cam even if I was only running 6 PSI...

[1owNslo]

+1 thanks!

[1owNslo]

++1 really good read and makes a hell of a lot of sense.