M20 2.3 pistons - crank

Post Fri Dec 19, 2014 12:07 am

Hello
I am in the US and have a euro E30 baur that i started to do an engine refresh after a bad headgasket issue. The engine is apart and I have found that one of the pistons is cracked between the rings. In the US we only had the 2.5 and 2.7 L . From what I have found on Wikki the 2.0 and 2.3 L not sold in the US are 80mm pistons, with a 76.5 stroke. VS the is 2.5 with 84mm pistons and a 75mm stroke. And the ETA engine with a 81 MM stroke.
I am guessing there is no way to bore the block and use the 2.5 pistons because of the stroke.. Does any know if there are different length rods?
If not then is there a good place to buy 2 used 80mm pistons?
Since the parts are not available here in the USA.

Regards,
Barry

Post Fri Dec 19, 2014 12:56 am

2.5 has a 135mm rod, 2.0 2.3 & 2.7 have a 130mm rod, you should be able to bore the 80mm to a 84mm bore and use the 2.7 crank & pistons. the 2.5 pistons are domed and will not work with your head though.

Post Fri Dec 19, 2014 2:16 am

find a running B25/B27 there should be hundreds in the states, and swap the whole kit and caboodle

Post Sat Dec 20, 2014 6:08 pm

Either of the above or just ask someone in the uk to send you a couple of pistons and keep the 2.3 if originality is important.

Post Sat Dec 20, 2014 6:11 pm

JB Weld FTW.

Post Mon Dec 22, 2014 4:55 am

Thanks.. I think I am going to use a 2.7L shortblock with the 2.3 head.. since the 2.7 as flat pistons..
I also have the 524 Diesel crank and could build a stroker engine..

I appreciate the info..

Post Mon Dec 22, 2014 7:37 am

2.3L head needs some massaging, in stock form they are very restricting

Post Mon Dec 22, 2014 11:13 am

As above, but with the biggest 43mm valves easily available and some work they are a cracking head. (885 owners pardon the pun)

Post Tue Dec 23, 2014 1:23 pm

A 323i has the same 731 head as the 320i. It has identical chambers, valves and exhaust ports to the Eta '200' head and whilst it doesn't have the best flow for high rpm, it will give tremendous torque. Use the 323i inlet manifold and throttle body as well - I had a 2.7 using these bits and it went very well. It all depends on what you want from the engine.

No point in modifying a 731 - the 885 already has the bigger valves and inlet ports and it gives a similar CR to the other heads, especially with a skim.