+0.25mm 89.22 E12 Pistons

[tonylsmith]

Hello!

Looking for some +0.25mm pistons and rings

I have an original block, e12 '75 head, and 2L crank.

No preference on CR. Primary focus has been getting this thing on the road after sitting for 35 yrs.

I have a set of +0.5mm flat tops lying around but I'd prefer not to skip an oversize if I can help it.

Thank you!

Tony

 

 

Edited February 23, 2022 by tonylsmith

[Conserv]

Tony,

 

Double check that you have an E12 head — which is what all ‘75’s originally had. I say this only because so many members type “E12” when they mean “E21,” and vice versa. And flat-top pistons are, indeed, often associated with the type E21 head, which was the standard issue on U.S.-bound 49-state ‘76 2002’s. Type E12 heads, on the other hand, accommodate piano-top pistons.

 

And a type E12 head — regardless of the year, since they’re all the same — permits a wide range of compression ratios, from 8.1 to 9.5, with increasing heights to the piano tops. I believe the U.S. ‘75 models were originally equipped with 8.3 pistons. Pick your compression and start looking. If you’re looking for NOS examples, the price increases with the compression ratio!

 

Below are photos of some of the E12 piston options: 8.1, 8.3, and 9.5, respectively. I don’t own these pistons; I just have photos of them!

 

Good luck and regards,

 

Steve

 

 

 

 

[tonylsmith]

Sweet! Steve you're the man!!

Confirmed that it's an E12 head, will start looking at my other options.

No preference on CR at the moment, but if I had my pick I'd go with higher CR.

Thank you!

[Conserv]

And… Tony, don’t turn down second oversize pistons (approximately 89.47 mm.), particularly if you’re looking for higher compression pistons, e.g., 9.0 or higher.

 

I agree that we should save our engine blocks for future rebuilds. But if you can’t locate first oversize pistons, you could probably be forgiven by the vintage car gods if you needed to use second oversize. I am assuming that a machine shop has already measured your bores and is confident a first oversize re-bore will be sufficient. If a machine shop — or equivalent — hasn’t yet weighed in on the condition of your bores, that needs to happen before you go piston shopping.

 

Regards,

 

Steve

 

 

 

 

[tech71]

On 2/21/2022 at 6:13 PM, tonylsmith said:

No preference on CR. Primary focus has been getting this thing on the road after sitting for 35 yrs

If the.5 OS flat tops are new, complete..? Consider using them.  Pistons have become as rare as hens teeth. Looking to score a new set from private sellers can take a long, very long time. 

9.5 CR bath tubs are still available at WN if you wish to spend almost $300 a piece

Catalog picture 11/18 - BMW 1502 - 2002 turbo - Engine parts / Cooling system | Wallothesch

WWW.WALLOTHNESCH.COM

 

Dont buy used, its pointless.   Good luck

[Conserv]

On 3/1/2022 at 12:36 PM, tech71 said:

If the.5 OS flat tops are new, complete..? Consider using them.  Pistons have become as rare as hens teeth. Looking to score a new set from private sellers can take a long, very long time. 

9.5 CR bath tubs are still available at WN if you wish to spend almost $300 a piece

Catalog picture 11/18 - BMW 1502 - 2002 turbo - Engine parts / Cooling system | Wallothesch

WWW.WALLOTHNESCH.COM

 

Dont buy used, its pointless.   Good luck

+1

 

A flat-top piston with an E12 head is going to be less than an 8.1 compression ratio (since there’s a very shallow piano-top piston that’s rated as 8.1). That said, “less than 8.1” is likely in the 7.9 to 8.0 range, so it’s probably an imperceptible difference. (Those 9.5 bathtubs probably won’t work with his E12 head.)

 

Best regards,

 

Steve

 

[tech71]

18 minutes ago, Conserv said:

(Those 9.5 bathtubs probably won’t work with his E12 head.)

Oops, my bad. meant to say piano tops?

 

 

[2002iii]

On 3/1/2022 at 9:36 AM, tech71 said:

If the.5 OS flat tops are new, complete..? Consider using them.  Pistons have become as rare as hens teeth. Looking to score a new set from private sellers can take a long, very long time. 

9.5 CR bath tubs are still available at WN if you wish to spend almost $300 a piece

Catalog picture 11/18 - BMW 1502 - 2002 turbo - Engine parts / Cooling system | Wallothesch

WWW.WALLOTHNESCH.COM

 

Dont buy used, its pointless.   Good luck

$241.40 each without VAT, so $1000 for a set of 4.

[tonylsmith]

Thanks everyone. I found a complete engine that will be useable in the meantime to get this thing rolling. The engine build will be a longer term project!