CoffeeMug 6 Report post Posted February 18, 2021 Sorry if I have posted this in the wrong place.. (This may sound not so smart) After looking at the bore and stroke of a M52 2.5 & 2.8 is the 2.8 just simply a stroked 2.5, no other differences between the two? Sounds stupid (I know) but I've been thinking about it for a while.. Quote Share this post Link to post Share on other sites
Herbmiester 923 Report post Posted February 18, 2021 The M52 B25 lacks the rich torque curve the B28 has. Ironically the M50B25 has similar power to the M52B28 but again its in a torque hole, that being said if they are buzzing past 4k rpm there is little to differentiate them As to the M54b30 vs the M52B28, having owned both I am unsure why the B28 would be more highly regarded, both rev cleanly to redline and the B30 has very nice torque delivery. putting an M54 crank rods and pistons into a B25/28 is a popular swap. 1 Quote Share this post Link to post Share on other sites
CoffeeMug 6 Report post Posted February 18, 2021 Thank you guys, that clears up a lot of clouded thought I had with it, I have been thinking about what to do to my poor old bimmer, swap in a crank and rods out of something then get the benefit of a (sorta) new engine and maybe try my luck at making some ITB's Quote Share this post Link to post Share on other sites
CoffeeMug 6 Report post Posted February 18, 2021 1 hour ago, Herbmiester said: The M52 B25 lacks the rich torque curve the B28 has. Ironically the M50B25 has similar power to the M52B28 but again its in a torque hole, that being said if they are buzzing past 4k rpm there is little to differentiate them As to the M54b30 vs the M52B28, having owned both I am unsure why the B28 would be more highly regarded, both rev cleanly to redline and the B30 has very nice torque delivery. putting an M54 crank rods and pistons into a B25/28 is a popular swap. Just to be annoying again, I cant seem to find anything online about it but is it really as simple as dropping in M54B30 rods, crank and pistons into either B25/28? do you need to change the cams or would they still work? I think I've convinced myself that it surely cannot be that straightforward and there is some BMW witchcraft in there somewhere.. Sorry for peppering you with questions, just trying to learn as much about it as I can Quote Share this post Link to post Share on other sites
Herbmiester 923 Report post Posted February 18, 2021 If you do a crank swap to go to 3l then you may as well play with the cams. A bit of googling will show you how M5x engines can use each others cams and a bit more lift and duration can wake up the 3l stroker combo. As mentioned headers and ITB's would be well worthwhile. With 3L capacity the M50B25 intake swap starts making sense and it wont have the capability of ITB's it is proven in 240HP+ stroker setups. There is also a bit of scope with tuning the 3L stroker combo, raising the redline a bit and adding a bit more timing, The end result is a very responsive engine with decent power and torque. Quote Share this post Link to post Share on other sites
Herbmiester 923 Report post Posted February 19, 2021 Don't get hung up on specific power output per cc, its completely irrelevant when you consider the engines weight and external dimensions are all but the same. You could consider a straight M54 swap. There is a bit of fiddling with the DME but all the fixes are out there. The Getrag 220 will live behind a 3l engine, maybe not forever but plenty see duty in similar applications. If you go to a ZF for the trans then safely pushing the M54 past its 170kw stock rating is reasonably easy with a good exhaust system and DME tune. I have had the pleasure of owning and or driving E36's with M50's, M52's and M50 3l setups. By far an away the 3l Stroker was the best of the lot, it just had more everywhere. It did have a tuned DME that allowed it to rev a bit higher and with a nice set of headers it was enthusiastic and had a very nice note as well. Don't get caught up in the Purist BS, longer stroke motors can rev and be full of character, just look at the S54. 1 Quote Share this post Link to post Share on other sites
CoffeeMug 6 Report post Posted February 19, 2021 You guys have both given me a lot to think about and a lot of different options, I think for now I might try and make a set of ITB's up, test my luck at that, I am definitely still interested in stroking what I have to get a little more. More so that I can freshen up what I have, just gone past 300k so might try give it a bit more life (still goes strong and pulls well however there are some odd sounds starting) Might even try stroker with ITB's, bit of a rip off M3, maybe even put an M badge on there 1 Quote Share this post Link to post Share on other sites
Blackie 510 Report post Posted February 19, 2021 Bear in mind, this will cost you a fortune and you will still get owned by Hondas 1 1 Quote Share this post Link to post Share on other sites
dirtydoogle 383 Report post Posted February 20, 2021 M52b25 uses the same valve and cam package as a m50/52b20, not worth putting money in to. M50b25 or b28 head is where the difference is 1 Quote Share this post Link to post Share on other sites
