Will a 993 Crankshaft fit in an '84 case?

[Dennis Kalma]

Hey guys, I am musing.

My Porsche parts guy says he has a 993 crankshaft available (apparently in pretty good shape) and was wondering if I wanted it.

For background, I have a new (as in brand new, never used) 1984 case that I am using as a basis for my engine build. General plan was to use the 74.4mm crank as used standard in the '84 case, 98mm Mahle P/C's and the heads from my 930/03 donor motor. From what I have read, this is a pretty good combo with TWM intakes, SSI's and something like a TEC 3 engine management system.


I must confess ignorance on the 993....but I am suspicious that it is different enough that it is not suitable....can anyone offer a definitive yes/no on whether it will work?

Thanks

Dennis

[YTNUKLR]

The flat answer is "yes," it'll work.

The general consensus is not to, from what I've heard and seen...

[strokher racing]

I am running a 964 crank in my 3.3. The 964 crank is the way to go if you are looking to stroke it in my opinion. Keep in mind the 993 crankshafts are not the correct journal size for a 964, 3.3 or 3.2 rods. If you go that route you need the matching rods and have to then figure out compression ratio with the pistons you choose

Eric Hood

[Bobboloo]

I would think you have to change rods regardless since your changing the stroke.

[Wayne 962]

In general, you have to keep the rods with the crank if the stroke is the same - it's an almost universal rule with all of the engines:

2.0/2.2
2.4/2.7
3.0
3.2
etc...

-Wayne

[Carrera3.5L]

Originally posted by Wayne at Pelican Parts
In general, you have to keep the rods with the crank if the stroke is the same - it's an almost universal rule with all of the engines:

2.0/2.2
2.4/2.7
3.0
3.2
etc...

-Wayne

That's true as a general rule of thumb, but like you alluded to there are exceptions...

For example, increasing the displacement of a 3.2L to 3.6L uses Mahle 100mm pistons/cylinders (the same used in a 3.5L conversion) along with the 76.4mm 964 crank. This conversion retains the standard 3.2L rods. The 100mm pistons are specially machined to work. There are/were alot of these conversions running around (both normally aspirated and turbo) in the late '80's/early '90's before transplanting a 3.6L became both more cost effective and a better starting platform.

Ralph

[Bobboloo]

That's true as a general rule of thumb, but like you alluded to there are exceptions...

For example, increasing the displacement of a 3.2L to 3.6L uses Mahle 100mm pistons/cylinders (the same used in a 3.5L conversion) along with the 76.4mm 964 crank. This conversion retains the standard 3.2L rods. The 100mm pistons are specially machined to work.

Hmm, so the small end of the rod rides higher in the piston to compensate for the longer stroke. Just shows to go you, there's more than one way to skin a cat.

[Jeff Alton]

The 3.2 and the 3.6 964 rods are dimensionally identical....

Cheers