Is it a 2.4 or a 2.2?

[TWJ]

My '72 911T 2.4L has a popular period upgrade of 2.2S P's & C's to raise the compression (making it a fun car!)...my question is: Is it still a 2.4 or is it now a 2.2?

I know that the difference between a 2.4 and a 2.2 is the length of the stroke but how did they do this? Crankshaft? Length of the rods? Pistons?

Thanks in advance for any input!

[trdking]

My '72 911T 2.4L has a popular period upgrade of 2.2S P's & C's to raise the compression (making it a fun car!)...my question is: Is it still a 2.4 or is it now a 2.2?

I know that the difference between a 2.4 and a 2.2 is the length of the stroke but how did they do this? Crankshaft? Length of the rods? Pistons?

Thanks in advance for any input!

I would most certainly think it is a non stock version of what ever the case says it is.

[Jules Dielen]

meet in the middle and call it a 2.3

[767driver]

Knowing the bore and stroke you can use this...

http://performancetrends.com/Calcula...splacement.php

Using the 2.2L bore of 84mm and 2.4L stroke of 70.4mm you get 2.341... or 2.4L in Porsche-speak. Both the 2.2L and 2.4L use the same bore. The 2.4L has a longer stroke at 70.4mm vs 66mm for the 2.2L.

[TWJ]

Thanks for sharing the knowledge Lee!

[767driver]

Thanks for sharing the knowledge Lee!

Anytime...I just hope it's correct!!!

[majordad]

But is the larger cc got by longer rods or longer crank throw ?

[john rice]

Gents, You are making this too hard. The 2.2 to 2.4 is via longer throw crank. The 2.4-2.7 use the same crank and this crankshaft is the first use of the forged crank for all versions. In terms of the specific engine that started this discussion, think of it as what it is- higher compression pistons. With Porsches it is usually done as a piston/cylinder "kit", which is a simplier way to get the clearances right. A 2.4S with 2.2S pistons will make a 2.7 RS driver miserable and has a much sportier feel. [I have a 2.4S long block in pieces and got a set of 2.2S pistons for the day I get off my duff and build it. :-> ]

[trdking]

nerds........

[davep]

No change in displacement from the 2.4 since they used the same bore and stroke of the 2.4; the 2.2 evolved into the 2.4 via the longer stroke crankshaft. Rods did change I think. However the big deal is that the piston crown is bigger which magically increases the compression ratio over both the 2.4 and the 2.2. Thus you have a fairly high compression engine with more power with stock parts.