All M54B30 internals in m20

[xepa]

Anyone ever tried using the m54b30 internals in a m20? I saw in another forum that it works and it gives you a 3.0 L engine. The only hitch being that they were not sure with the b30 pistons for they were 2mm above deck and so they used JE pistons, but when I looked at the m20, I saw that the stock m20 pistons actually go more than 2mm over deck in a m20. So this could possibly be done with M54B30 pistons and just machining valve relief, what's your opinion?

[reggid]

IMO get custom JE pistons that match the 885 chamber like stock that is the best thing to do. it retains the proper squish and burn characteristic which make it a more efficient engine.

[Andy325i]

If you were boring it could you get the custom pistons a little wider to maybe give you a few extra cc?

All that cost though, surely cheaper to fit the whole M54B30.

[xepa]

If you were boring it could you get the custom pistons a little wider to maybe give you a few extra cc?

All that cost though, surely cheaper to fit the whole M54B30.

I don't want to put a whole m54b30, I want a bigger m20 and I already have an e46. I got those internals for almost free, and since I have a m20 without a cylinder head I'll do a mock up n see how it looks. For the most part, I want to keep it as a m20 e30 but I'll keep the JE pistons idea open.

[DanThe]

The M54 piston is no where near deep enough to machine valve pockets into, custom pistons is the only way to do it IMO

[HairyScreech]

Are the m54 pistons significantly thinner on top than an m52b28 piston Dan?

I know there is ~8.5mm on the top of a m52 piston leaving about 2mm to play with, infact a piston top like below has been toyed with.



Intended to be used with a slightly opened up alpina style chamber (drops squish from 15% to 11% but needs must etc) and the squish band angled to suit the head and other side of the chamber.
Bowl would take out about 1.5-2mm to give around 11:1 and 6.5mm crown thickness which I am reliably informed is fine around this size bore and with good quality stock pistons.
A hard ano coat or a thermal barrier coat would actually be more significant than keeping those 2mm of thickness.
Other beauty of that shape is the valves pass into the bowl, meaning absolutely minimal valve recesses.

2mm above deck is not such the end of the world anyway. After all the squish band is too slack stock by about 0.8mm and there is a recon spec gasket that adds about .5mm to the stock.
If that much is not enough then Cometic do gaskets up to ~3.5mm thick. (stock is ~1.7mm)

Obviously as above I haven't had an m54 piston in my hand to see but flat top pistons don't need too much of a pocket as seen here:

http://www.bmwfanatics.co.za/showthread.php?tid=31659

Obviously cam spec dictates this one a lot.


TBH the above is all really rambling and with the m54 internals then you would either pay good money for custom or just work with what you have.

[HairyScreech]

also, here is pretty much what you are trying to do.
Compression would be my worry. (E85 time?)

http://www.r3vlimited.com/board/showthread.php?t=241011

and for what its worth the piston is a long way down the hole on the m54b30.
so much so its practically quenchless.

http://forum.e46fanatics.com/showthread.php?t=730757