Cochezz

Does anyone know the part number for the later 2.5NA higher compression pistons? I think it was in '88 they bumped it up.

Looking to change out the '85 model 9.5:1 for the latter 10.2:1 (i think thats the CR).

Thanks

MAGK944

I don't know the part number of those but I will have a set of 10.6 euro na pistons removed this week, pm if you are interested.

V2Rocket

euro pistons are worth about 5-6hp over the 88 pistons, for the record.

Paulyy

cant you buy higher CR pistons that are aftermarket and lighter and stronger then stock?

V2Rocket

yes, but the factor is price. 10.2 pistons probably 150-200 for the set, euro pistons probably 200 for the set, custom pistons ~700 maybe more. plus you'd probably have to change your tune to reflect that kind of change. but i'd like to see a 11:1 or higher NA motor someday..

MAGK944

Yep, and a nice 20hp over the stock US na pistons.

Paulyy

once josh finishes the SD-Tune, i think it wouldn't be as hard to go 11:1 or higher while running e85 with that help from the extra octane

elzergone

I do not get why its so hard to find euro NA pistons. Even searching ebaymotors.co.uk, and .de I find nothing :P

MAGK944

Most breakers there want to sell you the complete engine so they won't remove the pistons. I scour the Porsche breakers in the UK twice a year when I go over and ship back a bunch of stuff. I'll be there later this year

M758

Yes they were increased in 88 to 10.2:1. I don't have the part number either, but they are easy to spot visually. The 10.2:1 have small dime sized depression in the top. The Euro 10.6:1 are flat topped and the 9.5:1 pistons have large dish 3/4 the area of the piston top. Turbo pistons are 8.0:1 and have very large oval shaped carving out of the top.

M758

11:1 is easy... use 10.2:1 pistons or even better us 10.6:1 and then shave the head. You can shave the head on 9.5:1 pistons and bump compress by 1 full point. Going much father can result in a thin head, but do that same shave with 10.6:1 pistons and you are right at 11.6:1.

M758

Not really... It is a long story, but that 20 hp bump from 143 SAE net ot 163 DIN is not really 20 hp. 7 or 8 of that HP is due to the difference betwee SAE rating method in the USA vs DIN rating standards. If you look at the native kW rating for both motors the gap is closer to 10 hp. Some of which comes because the euro cars did not use a CAT either.

MAGK944

FYI: Euro 10.6 pistons are not flat top.

M758

The photos that I have seens show them to be flat topped, but if you have photo I would love to see it.

JohnKoaWood

I will see if I have beter pictures at home this evening... but here is a pic from my 88.