So i have been researching a this topic for a while. And When spare money comes up, I am wanting to build a stroker m20. I have heard that i can use a m20b25 block, and get a 2.7 crank and then I rods and I pistons (shaved 3mm) as well, and that will put me at around a 2.8L? Anyone else have any info on this topic? i know I.E makes kits for this, but i am on a budget.
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i dont think anyone has really tried to build a stroker M20 before89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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those are some big dreams OP
1991 325iS turbo
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So you want to use a 2.7L crank and not increase the bore yet expect it to be a 2.8L?
My advice is do some research on the subject. If your car is already a M20B25 I'd leave it as is. If it's a M20B27 car I recommend keeping the bottom end as-is and swapping to a M20B25 head, intake, and all electronics/sensors/etc.Comment
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Stock eta bottom end with i head and other stuff is not worth the trouble. Seta ftw. Make a true 2.7i and actually get one up on an i car. I had a "budjet" 2.7 with a g260 and s4.10 and could not catch my buddys chipped eta g260 3.73 combo. I was so disappointed after the build.-Andy
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You can use the a 2.7 crank in a 2.5 M20, after all, 2.3 is a stroked 2.0L, the same as a 2.7 is a stroked 2.5L. The bore is same in each respective motor, as well as the rod length, the crank is the difference.
Shaving the pistons would increase capacity but would reduce compression and therefore rob you of any potential gain. If you want more capacity with a still relatively small stroke, you bore out 1mm oversize a make a gain that way.
IMHO the key to seeing horsepower gains would be the 885 casting head, and using oversize valves to allow the whole engine to breathe better. A mild cam will wonders as well. I am running a 276/284 degree cam in my E34 525i and it boogies from 3000rpm.
If you want some straight honest answers to any of this, call Jeremy at I.E. The man is a Guru on all things engine-wise.Comment
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Here is some stuff to get you started.
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1989 325is Raged on then sold.Originally posted by JinormusJ
1988 325 SETA 2DR Beaten to death, then parted.
1988 325 SETA 4DR Parted.
1990 325i Cabrio Daily'd, then stored 2 yrs ago.Comment
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nope, 130mm eta vs 135mm i
After countless hours of researching various M20 motor builds, I think it's safe to say that you get what you pay for. When guys say they're 'on a budget', in most cases it means custom pistons are out of the question. This is a huge limiting factor when it comes to actual gains. There are only so many combinations you can toss together utilizing stock pistons, and at that you're most likely gonna sacrifice compression ratio and rod length for increased displacement unless you start machining valve reliefs (for a higher lift cam) and piston skirts (for a stroke > 84mm).
I've tried to think of ways to beat the system when it comes to using stock pistons, but I keep coming to the conclusion that if I'm going to build it at all, I might as well build it right. It may take more money (think 1k for custom pistons and 1k for machining) and possibly more time, but in the end I know I'll be happier with the results.
You can always skip the stroker build altogether and try to maximize your stock displacement by refreshing the engine, adding a slightly more aggressive cam (like a Schrick 272), MAF conversion, chip, and a free flow exhaust. You might be surprised and it will probably run a lot better than a lot of 'mickey mouse' strokers out there.
my .02Make the bastard chase you.Comment
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Thanks a lot guys! ill be reading up a lot, and if i have any more questions ill just post here!sigpicInstagram: bir_madhatter
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