bored and stroked m20

[85e325]

after reading the latest issue of eurotuner which featured a 2002 powered by a punched out m20. I curious to learn how much of a power gain that gives you. Has anybody else done this? Here are the engine mods listed in the article.
85 mm pistons
S52 crankshaft
Regroung 272 degree cam
Honed intake
Forged rods
Headers and chip

If i did do this i was also thinking of swapping for a I head and having a five angle valve job done as well as having it port matched and polished. Am i dreaming or would these mods be worth the cost of machining?

[acolella76]

http://www.e30tech.com/forum/showthread.php?t=48288

I suggest you read up. Many people have built stroked M20s.. a 2.8L is your most 'cost effective' since it uses all OEM parts and bore sizes. If you're going to be using custom forged pistons, might as well go all the way and go 3.2L

[einstein57]

You'd be much happier with a top end refresh, eta bottom end and boost. Sure your not going to have as much torque off the line as a franken motor but you can do have a lot more fun and save on gas, parts, etc. Unless your worried about the po po.

[delatlanta1281]

When going to a 3.2 build, you need to be very careful as to what you do exactly. Alot of these bigger builds yield gains at the lower end of the rev cycle, but fall flat on their faces after 5500 rpms. Without the right exhaust, cam, headwork (which is pretty hard on an 885 head), you won't have a solid HP torque gain through the rev range. I have been told that the euro head for the m20 has a better profile for porting (more like the M10) and can be manipulated better to breathe at higher rpms.
The thing is, there are ALOT of combinations for an m20 stroker out there. It all depends on what you want. I wanted to build a big ass 3.2 stroker with a super aggressive cam profile until I spoke with the right people. Turns out, none of what I wanted to do matched the way I wanted to drive my car. Yes it could be built, but robbing Peter to pay Paul becomes the theme when you aggressively stroke the bottom end. All kinds of things come into play at that point, IE: Ring pack size to overkill on compression when compared to head flow. If you do decide to go to a 3.2, make sure you are asking questions of the people who are building your parts. I would like to see actual dyno numbers from the boys that boast the 3.2 swaps. I would find someone with that motor and ask them what they REALLY think of it. People who build motors and refuse to show you the actual results are blowing smoke up your ass. Don't trust them, and don't trust what you read online, talk to someone personally.