mega eta

[dave525]

I have an excellent m20 b20 engine.I also have a 2.8 crank.Would it be possible to combine the two,using 2.7 eta pistons and boring to suit, and the 2 litre head.I already have an m20 b28 but I was just wondering what the result of this combination would be.The two litre valves and ports are supposed to be too large for the standard engine so it might make a nice torquey motor suited to an auto?

[Speedtouch]

http://www.e30zone.net/e30zonewiki/inde ... ding_a_2.8

http://www.e30zone.net/e30zonewiki/inde ... roker_Info

[reggid]

What you are proposing for the bottom end is ”aessentially”a taking an ETA and adding 3mm stroke (1.5mm extra throw). This means the ETA piston will sit 1.5mm higher at TDC than designed. This could be addressed in several ways none of which are ideal IMO.

I would go the regular 2.8L option as above. Even with big ports of the 885 it is still a very torquey engine when you set it up to be that way.

[dave525]

As I said I already have an m20 b28 with bbtb in my 320 auto cab.I just wondered if there was a way to use the original engine and spare crank I have. It seems a waste but my genuine 80000 mile 2.0 engine is no use for anything. I could have it bored to 84mm and use an 885 head I suppose.

[Speedtouch]

Another option would be to slip a 323i crank in, which should give you around 140bhp.

[reggid]

machine some off the ETA piston tops (nominally 1.5mm) so there is 1mm clearance between top of piston and head when the head gasket is fitted. might need to deepen the valve reliefs to compensate depending on the cam.

this will get it to work there should be more than enough meat in the piston