2.4 crank for a 2.2
 

I've read about putting the 2.4 crank in the 2.0 and I've read about putting the 2.2 pistons in a 2.4. Each for their unique advantages. But what about putting a 2.4 crank in a 2.2? Wouldn't that be about the same as putting the 2.2 pistons in a 2.4? Use the rods on the 2.4 crank as well, correct?

Yup. The only difference is that putting 2.2 pistons on a 2.4 doesn't require cracking the case. Changing the crank will.

If by this you mean use the 2.4 rods with the 2.4 crank -- yup. You don't want to mix and match the rods will the crank.

Thanks for the reply. Yes, that's what I meant, get a 2.4 crank and rods together to install in the 2.2. So, what CR do I end up with?

The increased stroke length will give you a .55 point compression ratio increase over what it was as a 2.2 liter. But, since Porsche apparently overstates their compression ratios, it will work out to a number actually less than what the 2.2 claims to be.

Example: 2.2S is 9.8/1 CR. So, when these pistons are used with the 2.4 crank, it should work out to 10.35/1. But it doesn't. It measures out at 9.66/1.
What this means is that the 2.2S isn't really 9.8/1, but something less to start with.
This is from an excerpt from Bruce Andersen's 911 Performance handbook.

In Wayne's Engine Rebuild - Top Engine Modification Picks (page 112), he also lists putting a 2.4/2.7 crank in a 2.2 case with E pistons & E cam with a CR of 10:1. He also confirms Tyron's figure above, that a 2.2S pistons and cams with a 2.4 results in a CR of 9.6:1.

This might be an error - I consulted with Bruce on this, and he mentioned (after the book was published) that he wasn't too sure. I think it should be about 10.3:1 or so...

-Wayne

Sorry once again. The engine in question is a "T." No S pistons to use.

Milt, what cams are you using? Those T pistons won't allow andything other than T cams unless you cut the valve pockets deeper, and even then, only E cams will clear since there isn't sufficient dome thickness to cut them any deeper than 1.8mm.

If you use the 2.2T pistons with the 70.4mm stroke, you'll end up with a little over 9:1 CR. 2.2T had 8.6:1 plus .55 for a net of 9.15:1

Wow! Interesting stuff. So, if the E cams get into the piston, how in the world did they get a high CR with S pistions and S cams?

BTW, I didn't buy the 2.2 motor I was looking at. So this whole thing might be moot. But, it's good to know these things. I'll get Wayne's 2nd book before I ask any more questions. I WILL BUILD A HOT ROD (someday).

Milt, the pistons match the cams. S pistons have relief pockets for S cams, so when you do this, you need to either get E or S pistons for E cams, and S pistons for S cams. Or machine the valve pockets if there is enough meat in the piston crown.

2.2S pistons will go right in a 2.4S motor because those pistons were designed to clear S cams already.

another clarification on this.
2.2T engine
add 2.4 crank
T cams
2.2 T pistons
2.2 rods

will this work. I wanted to bump up my commpression usinf the 2.4 crank, but I hoped I would not need to replace the rods too.

The 2.2 rods have different sized jounals than the 2.4 crank -> won't work.

You can use the 2.4 crank and rods with this setup, and it should work okay. I have a used set of rods for $150 ($25 each) if you're interested...

-Wayne

I may do that wayne. i will call ya if I can't find some local.

Drop me an email - I'm not at my phone these days. Wayne@pelicanparts.com

-Wayne