I don't suppose anyone knows the standard compression height of 2WD vs 4WD pistons? Mahle seem to think that they're the same at 40.8, whilst burtons think its 40.5 for one and 38 for the other. Needless to say this doesn't help me get everything machined consistently.

 

Mahle only list one piston for all applications (the 4wd one) so I would be surprised if they are different. Especially bearing in mind they make all the OE pistons for 2wd and 4wd

 

I've now got a load of pistons to compare, the 4wd are substantially more dished, so if you're buying new mahle pistons to go in a 2wd block you'll be dropping your compression ratio whether you wanted to or not. Hohum,

 

I have fitted 4wd pistons into my 2wd engine. The compression height is the same for both piston.

As cng1 stated the 4wd pistons do have a larger dish. Once everything was measured up it worked out that the 4wd piston with a 2wd head has a compression ratio of approx 7.6 to 1. (Exact figure depends on head gasket thickness and how much of a skim the head has had).

 

4wd pistons have a 4cc larger bowl than 2wd pistons (and conversely the 2wd head has a 4cc larger chamber)