911 ST Engine Specs

[CanuckRS]

Falling down the slippery slope...In my quest for more horsepower I am considering building one of the ST spec motors for my Vintage racer...I am looking to the collective knowledge of this forum to help me fill in the blanks... I am trying to keep it as close to original specs as I can...This is what I think I know based on Bruce Anderson's Performance Handbook and Patrick Paternie's Porsche 911 Red Book...Is there any other reference books I should pick up ??

2.3 - 2247 cc
Bore - 85 mm
Stroke - 66 mm
Compression ratio - 10.3
Twin plugged heads ???
Intake Valve - 46 mm ???
Exhuast Valve - 40 mm ???
Cam - 906
Case - Magnesium or aluminum ??
Cylinders - Biral or Nikasil ??
Rods - S ??
Fuel Injection or Weber 46 IDAs

2.4 - 2380 cc
Bore - 87.5
Fuel injection
Everything else same as 2.3 ??

2.5SS - 2466 cc
Bore - 89 mm
Cylinders - Nikasil
Everything else same as 2.3 ??

2.5LS - 2492 cc
Bore - 86.7 mm
Stroke - 70.4 mm
Mechanical injection
Everything else same as 2.3 ??

TIA

[Flieger]

Paul Fere's Porsche 911 Story is another good reference.

[CanuckRS]

Thanks...on the list...

[CanuckRS]

I know there has been some incredible examples of ST cars built by members (Milou and Gabe's come to mind) of this forum with a tremendous amount of information on period correctness but very few details on the engines....If anyone is building any such engines it would be nice to know the build specs which would be a great reference for others going forward...There is a vast amount of knowledge on this forum, let's document this....
The hot rodders and vintage racers on this forum, please feel free to add your 2.3 and 2.5 motor build specs here as well (Chad P, Mark S, Kenikh...)

[Flunder]

The 2.5 short stroke
Cams: 906 (center lube) with mfi
Crank: 66mm
P&C: Mahle 89mm Nikasil providing 10.3 CR
Rods: Nitrided steel S - Ti rods not homologated for ST
Heads: twin plug; 46mm intakes; 40mm exhausts; 41mm i&e ports
Induction: 2R High Butterfly with Bosch mechanical fi pump
Distributor: Marelli twin spark with 30mm neck
Case: mag
Chain box covers: mag/center lube
Oil cooling: case mounted cooler replaced by 906 grenade filter; bi lateral fender mount coolers
Fan: small 225mm 906 style fan
Exhaust manifolds: spageti

[CanuckRS]

Thanks Tom...That's the type of info I'm looking for !!!

[Flunder]

Mike Keyser spotted this one at the factory race dept (scan courtesy of Jim Calzia). Note the proto drilled exhaust carrier and non-drilled engine mount bar.

[Flieger]

I responed to your Pelican thread.

Give me a minute and I will copy and paste

[Flieger]

The 2,3 and all of the other ST engines were Magnesium crankcase.

They had Biral cylinders until the 2,5 liter with 66mm stroke was introduced as the very last variant. This was made possible by the 89mm Nickasil cylinders. The 66mm stroke revved faster and lessened the vibration problems in the crankshaft on the 70.4mm stroke crankshaft, which had caused flywheels to come loose.

ST engines all had 10,5:1 compression ratios, though there may have been some special factory cars (916 engine?).

According to Paul Fere's Porsche 911 Story:

911/20 and 911/22: 2,247cc (85mm bore x 66mm stroke)
power: 230 PS @ 8000 rpm
valve diameter intake/exhaust: 45mm/39mm
valve lift intake/exhaust: 12.1mm/10.5mm
911/20 = injected 911/22 = Webers

911/21: 2,380cc (87.5mm bore x 66mm stroke)
power: 250 PS @ 8000 rpm
valve dia. intake/exhaust: 45mm/39mm
valve lift intake/exhaust: 12.1mm/10.5mm
injected

911/70: 2,494cc (86.7mm bore x 70.4mm stroke)
power: 275 PS @ 8000 rpm
valve dia. intake/exhaust: 46mm/40mm
valve lift intake/exhaust: 12.1mm/10.5mm
port diameter intake/exhaust: 41mm/41mm
injected

911/73: 2,466cc (89mm bore x 66mm stroke)
power: 275 PS @ 8000 rpm
valve dia. intake/exhaust: 46mm/40mm
valve lift intake/exhaust: 12.1mm/10.5mm
port diameter intake/exhaust: 41mm/41mm
injected

[CanuckRS]

Great info Flieger...Did Paul Fere say if all the ST motors were twin plugged ??
All photos I have seen idicate that they were...

There is some confusion on Compresson ratios...According to what you posted, Paul Fere stated that they were 10.5 where Patrick Paternie in the Porsche Red book have them at 10.3...

What about cams...Did they all use the 906 cam ??

Thanks again for sharing...