Yet another 2.2T owner seeking sanity check on adding displacement

[rgupta250]

Hello Ravi , I like your engine except for the crankshaft , the stroke is just out of proportion to the bore , more like a tractor engine , the connecting rod angle is too much . 3.0 SC engines have the same stroke and things are back in proportion .
Porsche made the 2.4 liter to compensate for detuning the 2.2 for emission requirements , detuning that was antiquated by todays knowledge and standards such as lowering the C R . Your engine redline may be 7,200 but it will not easily go there . The 2.4 is basically a smog dog , but bore and stroke became better proportioned with the 2.7 liter engine . Porsche tested several 2.5 liter engines for the ST ,one with 66mm stroke and one with 70.4 stroke ,
the 66mm stroke was used . or 68mm I think .

Thanks Rich for your feedback. I appreciate your wisdom and experience. At least, you can’t critique my brake, fuel, heating systems since you are the one restoring/reinstalling them on my 71 sports purpose build.

[teenchy]

Well the motor is finally in the car but the gearbox needs fettling. Apologies for the sorry condition of the latch panel, the grime, and the paint job generally. There's a hole where an old alarm system sensor was removed, and whoever scraped the stickers off the latch panel and didn't clean up behind themselves before shooting paint deserved a shot of another kind.



Cosmetics are last on my list once the drivetrain is complete.

[Richy]

I really don't like the " sports purpose build " cliche . The car was a sports purpose product when created by Porsche . I think " track or racing modifications " would be better .

[teenchy]

I really don't like the " sports purpose build " cliche . The car was a sports purpose product when created by Porsche . I think " track or racing modifications " would be better .

Guessing that's directed at Ravi, as I didn't use that term in describing my car. I don't think it'd fit, either, unless you flipped open the decklid.

[rgupta250]

Yes, Richy’s comment were for me

In any case, I ended up altering my engine build to a S-spec engine:

Case: matching numbers 3R case (71T)
Cylinders: Mahle 84mm biral (moon cut)
Pistons: Wossener (CR - 9.5:1)
Crankshaft: 66mm counterbalanced (knife edged)
Rods: CP Carillo
Cams: Dougherty Racing DC-40 (Mod-S)
Cylinder Heads: Rebuilt to S-Spec (36mm/35mm)
Distributor: Bosch S Distributor (007)
Fuel Delivery: Webers 40IDA
Oil Pump: 4-bar SC pump


I know Richy would approve of this engine build. Ask me how I know!

Best,
Ravi

[teenchy]

Sounds nice, Ravi. Looking forward to the results.

[cwrm4]

Well the motor is finally in the car but the gearbox needs fettling. Apologies for the sorry condition of the latch panel, the grime, and the paint job generally. There's a hole where an old alarm system sensor was removed, and whoever scraped the stickers off the latch panel and didn't clean up behind themselves before shooting paint deserved a shot of another kind.

Looks great. What did you end up with for the transmission and torque converter? I believe you had posted you were going to convert a 3-speed 925 to 4-speed? Are you going to use a 911S torque converter with the higher stall speed?

[teenchy]

Looks great. What did you end up with for the transmission and torque converter? I believe you had posted you were going to convert a 3-speed 925 to 4-speed? Are you going to use a 911S torque converter with the higher stall speed?

925 conversion is in progress. Torque converter will likely be the 911S. Kennedy Engineering clutch disc a possibility.