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OE BMW 10:1 pistons


Stuart

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What cyl head do you have in your 02, 121, E12, or E21?  tii or regular 02?  What are your plans for your 02, street or track use?

 

Reason I ask is below, source for this info is http://www.bimmers.com/02/

 

Recommend you read the part on go fast upgrades, engine section before you place an order for pistons. This sentence is from this section. A Schrick 304 cam should be run using at least 10:1 compression to really make the engine come alive.  Going with 10.0:1 on a street car with a high duration cam and dual carbs is not highly recommended unless you are rebuilding an early Euro spec tii motor with the pistons you desire.

 

121 Cylinder head:

8.5:1 CR U.S. "Spec" piston on 1968-1972 2002's
         42.3 mm pin-to-deck, flat top

9.0:1 CR U.S. "Spec" piston used on '72 US-model 2002tii's

9.3:1 CR European 2002TI (twin-carb model)
         42.1 pin-to-deck, 5.2mm dome

10:1 CR Early euro-spec 2002tii
        42.5 mm pin-to-deck, 4.4 mm dome

 

E12 Head:

6.9:1 CR Factory "Turbo" pistons (used on 1974 2002 Turbo)
         42.0 mm pin-to-deck, 3.7mm dish

8.1:1 CR flat-topped piston (much like the 8.5:1 CR used on the
         121 heads)  used on '75 US-model 2002's, also on most
         US-model 3-liter cars of the era. (keep in mind that
         the 2-liter 4-cylinder with the E12 head and 3-liter
         6-cylinder cars can interchange pistons)

8.3:1 CR U.S. "Spec" piston on mid 1972-1974 cars

9.0:1 CR U.S. tii pistons

9.5:1 CR European tii pistons

 

E21 2.0 Head:

8.3:1 CR flat-topped pistons (used on 49-state '76 2002's,
         US 2-liter 320i's)

9.3:1 CR domed pistons (used on european 4-cylinder 320i's)

 

Note: compression ratios given are with a stock head, and zero deck height.

 

My tii engine is stock but when it was rebuilt a few years ago, the only upgrade was Euro tii spec, 9.5:1 CR pistons.

 

G-Man

74 tii (many mods)
91 318i M42

07 4Runner

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Stuart,  the truth of it is you will be hard pressed to find a set of Mahle oversized high-comp. pistons for anything close to a reasonable price.

 

I know you do a good job of researching, but for posterity.

 

9.5:1 Compression pistons

292 Cam

decent header

decent ignition

38/38 or dual 40DCOE's 

 

....is an excellent recipe for a fun, 91octane-friendly, street hotrod.

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I suspect you will have to sell a testicle to find an OE 10:1 piston.

 

Ross will build you a set for a lot less... separation.. than that.

As will J&E, Veniola, etc...

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Who are these people buying these testicles?

John

Er! I remember a Brit Army WW2 song,

 

Hitler has only got one ball,

Göring has two but very small,

Himmler has something sim'lar,

But poor old Goebbels has no balls at all.

 

heheh.

Les

'74 '02 - Jade Touring (RHD)

'76 '02 - Delk's "Da Beater"

FAQ Member #17

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