$150-$200k is some serious money right there! Are there vintage racing classes where these are still highly competitive? Otherwise that's 'real fan' money they're asking. Bet they were a ton of fun to drive. Very light and responsive with some decent power to weight ratio going on there.

ps...are ...

Porsche Weissach gets all the credit for the lightweight 924 D/Production (933) chassis. Only 16 were built to bring awareness to the new front engine model and Porsche put serious effort into the program. Here's lots of info on the cars and the program: https://www.stuttcars.com/wp-content ...

I've often wondered how some people can get their cars down so light? 1970lbs is feather light in my book Michael. My car with single skin metal roof, f/g quarter panels at all 4 corners, f/g nose and bumper. Carbon doors and hood. Lexan rear hatch. Glass front screen as part of rules. Aero add ons ...

Fast951 wrote: Sat Feb 14, 2026 9:29 am To the OP.

The paper gasket, in your posted picture, is damaged or someone modified it. Examine the shape of the drain hole.

Yes, that looks weird John. As if they're trying to fit a square peg in a round hole??

IIRC Duke started with a CR of 9.x:1 then gradually took it down to 8:1 along with fitting ever more aggressive camshafts, ending up with the torque "curve" of a supercharged engine - an almost straight diagonal line peaking at peak rpm.
I wouldn't consider anything higher than 9:1. As Tom said ...

Haha....all are welcome. :)

As far as c/r goes, of course we're seeing much higher ratios than we're used to dealing with re our motors. In the past I've somewhat rejected higher c/r as the cars that I've driven with high c/r and forced induction were too linear. Street cars of course. They were ...

Original build specs here Tom. I don't think 9:5.1 should be too high with this head. 374cfm @ .550 lift / 28". That's significantly higher than even a big 8v.


Engine 4 Cyl in line 4
Engine displacement 3240.30cc
Bore 104.75mm
Stroke 94.00mm
Max RPM 8800 RPM

Block Closed Deck
Deck Ht 229.997mm ...

Just in case any of you are having trouble sleeping... :mrgreen:

I punched in all the specs from the original motor to Ai and advised it that we're moving from 94mm to 88mm stroke while using the original pistons. It advised us to order rods with 155mm ccl. That would lower the c/r from 8:78.1 to ...