78.4 ?

Santas Brother · Post by **Santas Brother** » Sat Jun 24, 2006 4:19 pm

Jake: where did the 78.4 mm stroke come from ?
All other sizes are in whole mm sizes.
Seems like a strange number.

My guess is that is the max stroke
that will clear the stock base circle cam.

Yes,no ?

Thanks.

tuna · Post by **tuna** » Sat Jun 24, 2006 8:53 pm

Actually the 78.4 stroke is a holdover from the Type 1 days. Why that particular number, I don't know. I think it may have started with the Okrasa cranks, but I could be wrong.

Tuna

R2.0 · Post by **R2.0** » Sun Jun 25, 2006 6:37 am

IIRC, it is what one winds up with when a crank is offset gound to Chevy bearings.

R2.0

Kelley · Post by **Kelley** » Sun Jun 25, 2006 9:28 am

Deck height?

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Sun Jun 25, 2006 9:43 am

actually it came from Oettinger in the early days of VW stroking... I used to remember the story but I had to "Recycle bin" some of that old memory to make room for the new stuff or my brain would have locked up from overload!

Santas Brother · Post by **Santas Brother** » Sun Jun 25, 2006 12:27 pm

90 x 78 = 1985

90 x 78.4 = 1995cc

If you were racing in a class with a 2000cc limit,
some people would want that extra 10cc.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Sun Jun 25, 2006 12:42 pm

Yes, back in the day the 90mm NPR piston kit was very popular in the 2.0 class and used with this crank

Wally · Post by **Wally** » Sun Jun 25, 2006 11:06 pm

MASSIVE TYPE IV wrote:Yes, back in the day the 90mm NPR piston kit was very popular in the 2.0 class and used with this crank

I think it is more likely that the 90,0mm Oettinger Nikasil cylinders/Mahle pistons were used for that size 'back in the day', but I'am talking type 1 here

The Oettinger type 1 Nikasils were 90,0mm, not 90,5mm, so thats rather distinctive

(the porsche 2,7 911 engine has 90,0mm alu barrels as well

)

Walter

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Mon Jun 26, 2006 4:58 am

Here in the states the 90mm NPRs were very typical with the Type1. I used these all the way up to 1993 when the supply dried up.