pistons that fit m42??

[keggy]

guys cans yas tell me what pistons fit an m42 wen bored out to raise the cc?

[appletree]

american spec m36 m3 evo ones will fit IIRC but they cost alot and will take it to just under 2.1ltrs, JE pistons can make you some and you can have any CR you want.

tim_S has them in his 2.1 so he would be best to talk to, i know he said they were deffinatly different to UK ones though

[keggy]

must have a chat with tim then

[stuartgallafant]

go custom, its so much more worth it for your money. as said US S50 B30 pistons work, but they need machining

using the pistons alone will not give you just under 2.1 litres matt. the engine must be stroked aswell

[appletree]

i cant remember exactly what was said but me and tim talked about quite afew different conversions using different bits. some M44 bit aswell IIRC

if you want loads of info on 2.1 builds you could check out this site

http://www.m42club.com/forums/forumdisplay.php?f=17

quite afew people on hear seam to have different ways getting the CC up

[DanThe]

Ive got some nice 2.8 pistons and rods for sale

http://www.e30zone.net/modules.php?name ... ic&t=61230

[stuartgallafant]

the rods would fit, as long as they're not too long. the big end size is the same as the M42.

however, the pistons are too small. the pistons on the M52 are 83.980mm, where as the pistons on the M42 are 83.985mm

sorry if i kicked you in the balls dan!

[DanThe]

sorry if i kicked you in the balls dan!

With 0.005 mm

Thats got to be a record of some sort

[stuartgallafant]

no, i meant with your sale, or whatever! didnt wanna upset you or nowt!!

[DanThe]

Surely thats within tolerance?

Wouldnt some oversize piston rings make up the difference?

[keggy]

prob if teh bores were in new brand new condition but mines prob has wear

[DanThe]

prob if teh bores were in new brand new condition but mines prob has wear

Err, hello,,

this is a BMW, my recent 230,000 mile M50 block still had the original honing pattern on the cylinder bores

[stuartgallafant]

dan, thats way outside the permissable range

as said, go custom. im gonna be using custom pistons in mine. i found a really good site in America that would supply and deliver custom pistons, to any spec, with rings and small ends for about £500

sods law now that i cant find the poxie site!!

[keggy]

wen u find that site gime a buzz mite be worth wile getin a set the same time for cheaper shippin?

[stuartgallafant]

i was gonna suggest something like that keggy

i'll see if i can email the guy and see if we can get a discount coz we're on a club!! ya never know.

failing that, i'll see if i can get either my friend, who has his own company, or the guy thats doing my machining, to order them, that way, they can be sent as "test samples" and we can avoid import tax!! then i'll just send your pistons to you???

i'll have a think mate

[DanThe]

dan, thats way outside the permissable range

I know nothing about piston swapping, but I cant see how 0.005mm is going to make a blind bit of difference

Please tell me your joking...........

Realoem lists piston rings of up to 0.5mm larger than standard

[stuartgallafant]

dan, thats way outside the permissable range

I know nothing about piston swapping, but I cant see how 0.005mm is going to make a blind bit of difference

Please tell me your joking...........

Realoem lists piston rings of up to 0.5mm larger than standard

if 0.005 didnt matter, BMW would have put these in the engine already! when i stripped my M42 block, after 160'000 miles, i measured the bores, pistons and big-end bearings. everything was fine bore-wise, i only had about 0.03 conicity and ovality on all cylinders. however, when i measured my pistons, they were measuring at about 83.95, 83.92, figures like that...

this shows that the pistons just arent as durable as the bores, and when i did the calculations to find the permissable value of clearance, mine exceeded the value by about 0.6mm. just putting rings in was not an option.

dan, your pistons will also be worn, and considering that they're too samll anyway (albeit by only 0.005mm) this will not help

im not trying to be completely anal, but if you are going to do something, do it properly

[DanThe]

I see what your saying but I aint going to be buying no god damn pistons! I will take some measurements and see what the crack is with em

[keggy]

i was gonna suggest something like that keggy

i'll see if i can email the guy and see if we can get a discount coz we're on a club!! ya never know.

failing that, i'll see if i can get either my friend, who has his own company, or the guy thats doing my machining, to order them, that way, they can be sent as "test samples" and we can avoid import tax!! then i'll just send your pistons to you???

i'll have a think mate

yeh that sounds gr8 find out

[stuartgallafant]

I see what your saying but I aint going to be buying no god damn pistons! I will take some measurements and see what the crack is with em

have you got an m42 then?