So I have to bore my cylinders...

[flagoworld]

9 minutes ago, Hans said:

Try Pelican for 90mm pistons.

 

Sadly they only have them for the 121 head.

 

If I can't find pistons in the next week, I might buy the forged ones from IE. Second-to-last resort, though. They are pretty expensive.

[kbmb02]

20 minutes ago, flagoworld said:

 

Sadly they only have them for the 121 head.

 

If I can't find pistons in the next week, I might buy the forged ones from IE. Second-to-last resort, though. They are pretty expensive.

 

I sent you a PM - might have a set of 90 mm piano tops. -KB

[flagoworld]

On 3/23/2017 at 4:19 AM, wegweiser said:

And here's a tip....that will save you the HOURS of research I spent, last year.

 

If you use the +1.00 (89.97/90mm pistons) and need rings - either because the ones fitted are damaged or rusty, or if they gat damaged during installation - you can use the std size piston rings from a BMW R90 motorcycle. I insisted on using OEM Goetze/Mahle rings on a used set I had acquired, and the ONLY ones I found were these. I checked dimensions, diameter, profile, alloy...and found them to be identical to the original 2002 rings...but in the +1.0mm oversize...which BMW never offered for automobiles. I ended up NOT using the used pistons, and re-sold the new rings later on. 

 

You can get a decent price on these rings from companies like "Motobins" in the UK - still cheaper that any BMW cycle shop in the US - even with postage.

 

And regarding the above ebay pistons... one set is marked "8.3" as in 8.3:1 compression. You might consider searching for 9 or 9.5 compression units....or have the seller verify their claims of "high compression" application, by comparing measurements to true tii pistons. There's no substitute for displacement...except maybe compression.

 

These bad boys?

 

 

[EvilEmpire]

We are new the 2002 scene - We just tore down the engine on our new project car - pulled E12 head (looked clean with new looking stock HW) and oil pan - found nice H-Beam con rods. Mahle 89.97mm 9.5:1 piano top pistons But the pistons had lots of burned oil- so started taking them out and skirts were burned oil too. Pistons measured out at 89.97- rings looked a little funky but intact. Measured cylinder bore - aver 90.127 with taper of .012mm - but looking at the book piston/cylinder clearance we are way off... book .045 ours .157 - YIKES! That might explain the oil. Put in the piston ring to measure gap with a tape measure 

 

So gonna need some new pistons - should I just plan to bore to 91 or 92 mm - get forged pistons for that bigger size and then have them bore the block?

 

Have a nice set of Mahle 89.97 piano tops gonna be available. 

 

 

[flagoworld]

When I was researching pistons on the FAQ I came across someone mentioning that they used 92 bore in their race engine without issue. So, theoretically you should be able to do that. Not sure if you can go bigger, so maybe you want to do 91 so there's an extra mm there in the future? I almost got these... They might be what you're looking for? http://www.iemotorsport.com/bmw/2002-engine/m10forged-custom.html

 

Thanks for the offer on the 89.97, but kmb02 did provide me with some and I am all set.

[EvilEmpire]

4 hours ago, flagoworld said:

When I was researching pistons on the FAQ I came across someone mentioning that they used 92 bore in their race engine without issue. So, theoretically you should be able to do that. Not sure if you can go bigger, so maybe you want to do 91 so there's an extra mm there in the future? I almost got these... They might be what you're looking for? http://www.iemotorsport.com/bmw/2002-engine/m10forged-custom.html

 

Thanks for the offer on the 89.97, but kmb02 did provide me with some and I am all set.

IE forged pistons ordered for a 90.5mm bore and 9.75:1 compression.

[Preyupy]

Make sure you get an oversize head gasket. Normal stock gaskets are 90.4mm and if you leave any of the gasket sticking into the cylinder it will fail very quickly.   

[EvilEmpire]

3 hours ago, Preyupy said:

Make sure you get an oversize head gasket. Normal stock gaskets are 90.4mm and if you leave any of the gasket sticking into the cylinder it will fail very quickly.   

Thanks for heads up - I did order a custom MLS gasket 

[EvilEmpire]

So when we took off the head we saw the black pistons...

 

And then found out why..... can you say measure ring gap with a yard stick

 

[wayne pwombat2]

Naz, if  u have those rings for the 89.97 pistons Ill take em ...let me know how much and contact info... thks..Wayne 978 962 1102 text is best...im new here and dnt know  if this will get to you,thks

[stephers]

That is just set real loose for lots of high rpm's  Ha HA

[stephers]

That is just set real loose for lots of high rpm's  Ha HA