Rennsport 2.5l FIA Group 4 Motor Completed....

[72group4]

Its done. Even with the restrictions imposed by the 1971 FIA Group4 rules, its making over 260HP and 200 lb-ft at the crank with mild cams (for circuit rallying) and the restriction of the 2.5 litre 10.3:1 Mahle P&Cs. Good enough for its vintage track and rally circuit duties.

Early dyno pull is on You Tube:


YouTube - 1972 vintage Porsche 911 FIA Group 4 engine dyno test


The real test will be on the track.


Thank you Steve Weiner.

[brads911sc]

Wow. Nice. Congrats!

[agrimmitt]

Very nice, wish I still have mine from the late 70's!!!! Much fun and big smiles are ahead for you!!!
art

[atelier14]

Impressive figures. Did Steve build it?

[tom1394racing]

Love the reversion from the carbs.

Very nice!

[304065]

W O W

Is that Series900 fiberglass engine tin?

[72group4]

Yes - this engine was built by Steve Weiner and fuel reversion is pretty evident above the intakes in the video! That was an early run and Steve made a few changes to the setup including jetting and header sizing. In the end we sacrificed some top-end power (it was capable of pulling a higher number) but gained more midrange pull and improved tractability which we needed as part of the mixed-use specification for the build - which means that it can't be an all-out track car. As it stands now we want to keep this below 8,000 RPM for engine durability and max power comes at around 7,800 RPM. We will run this configuration in the car first and see how it goes. Its being used with a short stack gear set to limit top speed at 8,000 RPM to approximately 230 km/hr. The rest of the car is being built by Markus Blaszak to 1971 FIA Group 4 specifications.

[MBEngineering]

HI 72group4
not wanting to put a spanner in the hard work on the engine build, but you may not pass FIA inspection for 1971 with pressure tensioners, just not period then, having to change all my rally/race engines over hear that are running to FIA historic rallying and racing.

regards mike

[manu72S]

HI 72group4

is it a 2.2 or 2.4 crankcase used as basis ?
Is it a short or long crankshaft ?
What type of carburators do you use ?

thanks
Best regards
Manu

[Steve@Rennsport]

Originally Posted by manu72S

HI 72group4

is it a 2.2 or 2.4 crankcase used as basis ?
Is it a short or long crankshaft ?
What type of carburators do you use ?

thanks
Best regards
Manu

I may be able to answer your questions.

Thats a 7R case.
The crankshaft is a custom configuration
46mm Webers

[JohnJL]

Originally Posted by Steve@Rennsport

The crankshaft is a custom configuration

With 200% respect to the workmanship and reputation, does a custom crankshaft meet 1971 FIA Group4 rules?

[Steve@Rennsport]

Originally Posted by JohnJL

With 200% respect to the workmanship and reputation, does a custom crankshaft meet 1971 FIA Group4 rules?

Yessir,..its the same stroke.

[MRD]

That seems pretty well built Love that sound.....