BMW

I am  not a BMW only specialist, but I did already a lot of 4 cyl engines

based on the M10/S14.

This engine is one of the greatest 4 cyl designs ever.

Just the fact that it served the BMW F1 turbo so well, tells everything. It

has the best stock lubrication system I am aware off, is light and very

reliable.

But, even the simpler 2V version is not absolutely a project for your

home garage if you want to exceed 150Hp seriously…

The layout of the combustion chamber needs experience, a skilled hand

and also some serious machining equipment.

if you want to exceed a certain amount of cam lift, the 2 front camshaft

bearings need to be machined to a bigger diameter, also here, no job for

home.

On high end engines the layout specs are getting really tight, like valve to valve on overlap, valve to piston and even valve to bore and guide clearance. Very much the same problems like on NSU engines, all parts need to be designed within 10th of milimeters. Even with a seemingly odd and oldfashioned intake runner design, flow values are pretty good with very low turbulence. This in particular ensures consistent power all the way up to high revs. With 125 HP/liter specific power output the engine is not at the limit, but the valve train is touching its limits over 9000 rpm without titanium parts. Kugelfischer MFI becomes almost madatory at this point, of course with a custom camshaft and also a custom actuation cam. The M10 legend will be topped with the even more famous S14 4V successor. I am rather conservative with power output statements about it. There is too much information and rumor around from back in the all famous DTM and STW days. Those back then indicated 400 plus HP will never be measured on my dyno…. Taking into account the hardly availble parts in case of a failure, one should not eceed 9000 rpm too often. Accepting this as the limiting factor, 290 HP for the 2,0 version and 330 HP for the 2,5 are reasonable numbers. The almost unlimited amount of parts for intake, exhaust and airboxes are not always providing what they were supposed to be back in the day. The combination of head design, camshaft choice and those parts, has to be validated on the dyno to achive good results. Therefore, dyno tuning is a must to achive results even close to the ones from the early days. While blocks are rare, there are now at least aftermarket crankshafts available. They offer good opportunities for street engines, for both engine types.

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