Trying to figure out what the best options are. Was running the stock 325is m20b25 until I lost compression in 2 cylinders. After pulling the head I saw that one of the cylinder bores had a slight groove worn where it appears a ring gave way. Found an 86 325 engine with good compression. It's my first rebuild and from what I have read so far I'm thinking that I should be able to use the 86 block and my b25's head and rotating assembly. My goal is to put together a reliable daily driver. My stock engine and boost setup had lasted over 4 years including regular oil changes and an occasional race. Any suggestions for things I can do during the build that will give me the most engine life?
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Originally posted by i_build View Post. Any suggestions for things I can do during the build that will give me the most engine life?
Hope that helps.
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Originally posted by i_build View PostCan the m20 b25 head be used with the 325 block and rotating assembly? The top of the Pistons are fairly flat on the m20 b27 versus the Pistons on the b25.89 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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Originally posted by i_build View PostThanks. I'm doing a bunch of reading. It seems like it might be the way I want to go as I am reading that it will lower my compression and that's what I'm looking for with my turbo setup.Last edited by digger; 08-29-2018, 12:50 AM.89 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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I definitely don't have the budget to do it "properly" was thinking if I got over 4 years of 30 miles a day driving with a stock b25 and my tune I should be able to get at least that much with fresh rings gapped for forced induction new bearings and the b25 head with b25 rotating assembly. Didn't realize compression would drop that much with the b27 Pistons. Just don't have the funds for a new crank and Pistons. Best I can do is rings, bearings, arp fasteners, arp head studs and gaskets. Will measure the bores to make sure they are in spec and hone. Already checked block and head surfaces. Was hoping to ask about rings and gaps.Last edited by i_build; 08-29-2018, 04:28 PM.
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Originally posted by e30davie View Postwhy the m20b25 is only 8.8:1 but the m20b23 is 9.5:1? (according to wikipedia...)
Some versions of the M20B25 are 9.7:1.
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