The 325i pistons are not domed there concaved, dish in type allthou i was told the early 325 pistons were flat top but i cannot tell you that as im not sure of it, the early say 525e 1980-1986 are slightly domed giving it a nasty threatning 11.1 comp ratio, after 1986 the compression ratio dropped to 10:1 using a slightly concaved piston BUT is flat top u only notice it slighlt... ALSO uses the 885 or is it the bloody 886 casting cylinder head (cant remember now)but as said the early 525e 1980-1986 used lesser cam journels and that head was no use if building a 2.7.. so from what it seems you could get away using that lump, also u need to change the ECU to a 325i from what i believe this way it will give you full RPM`s... been there and done all that shit headache but worth it.... check the casting on the cylinder head if its the 885 or 886 (like i says above) sweet, count the cam journals aswell.... some guys like to use the 320/323 head,cos of small head chamber which is good.. but personally i like to know i have bigger valves opening and closing... personal chioce.
524td i had a crankshaft and pistons for which i was lucky to get hold of, u wont find them they are rare in this land, if you do then consider ur self luck like i was, but got rid of it, its heavier than the standard 525/325e crankshaft..... that crankshaft is good for turbos conversions cos its build solid .. thats what alpina used in there C2 2.7, the gearbox side... not sure if its the same, BUT check the cast numbers, if not the same stick a 325 gearbox on......
pistons... i done 3 different conversions, the second was a trial and error, i used 325 pistons and 325 conrods which when on TDC the piston was higher then the block by 3-4 mill which tightened the comp ratio so the 325 valves was 3 mill away from the top piston vlave slot this gave me power i needed. if you wanted to build a turbo the use 320 conrods and 325 pistons which will lower the compression and port the cylinder chamber larger....
The LSD is good for the power control in the wet and the power u produce, i heard and dont quote unless some one else says but the 325e diff is better.....not sure....
i would use the 325i loom setup including 325i ecu and a nice chip and induction... nor sure if the 325e loom is the same setup ...also what i did was i changed my injectors to lime green E36 323/325/328 cos they dont lean out at top speeds and feed the bores with plenty of juice to keep it going, ive done it felt the difference and love it... shove an FSE booster up the pressure when fitting only withcams and 6 Branch manifold...
If you dont like all this, settle for NissanMicra, they make beautyfull cabriolets now..
goodluck mate
jimi
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