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Trying to find out what the tolerable compression numbers are for a healthy engine.
BMW says 10 to 11 bar. They tend to be low of course as they don't want to fix stuff. Other suggest numbers should be in the 200+lb range.
Lowell - you guys see these things? (early S38 euro engine... the 10.5:1 variety)
If 10.5:1 it is an S38B35.Quote:
Originally Posted by Jeff N.
M535, M635 from 1981 all had these with Motronic. Later cars (M5 & M6) had the catalysed S38B36 and S38B38), except the euro ones which stayed S38B35 (with updated Motronic?) - I'm not 100% of this. If 10.5:1 that would make it one of the non-catalyst versions- the best of all... due to the higher compression and more aggressive cam.
If not S38 it could only be a BMW designated M88/1 (M1 cars only) unless it is an an experimental engine for the e26 M1 (circa 1977) M49/5, or perhaps an even earlier M49/? twin cam from a 3.0CS/CSL... all these used Kugelfischer injection and dry-sumps though. Any idea about the engine's history?
Nice engine history, you're pretty much spot on. The M88 is the designation for a non-cat S38.
Got any idea what "good to better" compression is? It was pushing about 180 to 190 across.
Quote:
Originally Posted by genphreak
Sorry Jeff, I'm no practical expert with M88s, I've never worked on one. If I was in the US I would be tho, they are just so rare here in Oz. One day I will buy one tho and do a blueprint and slow, careful rebuild. These engines deserve preservation as they were the best in their era. No doubt Whit will know the pressure numbers you need- which reminds me, I have to test my M30B35s bores too... they just looked good to me when I had the head off the block, all the original honing was there and I couldn't even detect a lip worn anywhere towards the top of the bores... which was good enough for us to finish the job with no more adieu at the time.:) nickQuote:
Originally Posted by Jeff N.