# Combustion chamber volume?



## vr2jetta (Dec 16, 2007)

Does anybody happen to KNOW the combustion chamber volume in cc's for the various heads? Counterflow, crossflow? Any of these? I have searched for a while but cant seem to find any information.


----------



## ABA Scirocco (May 30, 2001)

*Re: Combustion chamber volume? (vr2jetta)*

They vary slightly but a close ball park figure is 30cc for 1.8L-8v heads and 32.5 for ABA crossflow.


----------



## vr2jetta (Dec 16, 2007)

*Re: Combustion chamber volume? (ABA Scirocco)*

What about deck heights and piston cc's? Nobody seems to get this technical when discussing motor builds, everybody just wants to know "what parts from 'said magazine' will make my car fast?"


----------



## ABA Scirocco (May 30, 2001)

*Re: Combustion chamber volume? (vr2jetta)*

The deck heights are typically very close to zero and piston dish volumes vary depending exactly which engine you have, they only one I've got good numbers on is the early Mk3 2.0L engine (ABA obd1), the dish volume on that is around 16.5cc. 
BTW, if you're reading VW technical specs and you see a compression ratio, be aware that it's very common for VW to overstate the compression ratio by 0.3 to 0.5 points that why if you do the math with the numbers I've given you so far to calculate the compression ratio of the ABA engine you'll come up with 9.6:1, the published spec is 10:1.


----------



## vr2jetta (Dec 16, 2007)

*Re: Combustion chamber volume? (ABA Scirocco)*

Cool man, thanks!
Edit: does anybody have the cc's for the 16v pistons? I know they are flat top but the valve reliefs add up to something.


_Modified by vr2jetta at 12:39 PM 6-20-2009_


----------



## Prof315 (Jan 5, 2009)

*Re: Combustion chamber volume? (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_The deck heights are typically very close to zero and piston dish volumes vary depending exactly which engine you have, they only one I've got good numbers on is the early Mk3 2.0L engine (ABA obd1), the dish volume on that is around 16.5cc. 
BTW, if you're reading VW technical specs and you see a compression ratio, be aware that it's very common for VW to overstate the compression ratio by 0.3 to 0.5 points that why if you do the math with the numbers I've given you so far to calculate the compression ratio of the ABA engine you'll come up with 9.6:1, the published spec is 10:1.


I just cc'd my ABA from a 95 Jetta : dish volume was 16.5cc, combustion chamber was 30cc. compression came out to 9.93 to 1


----------



## ABA Scirocco (May 30, 2001)

*Re: Combustion chamber volume? (Prof315)*

Interesting, I've cc'd 3 ABA heads, all early OBD1 heads like yours, and mine all came in at about 32-32.5 cc's. It would seem there's a fair bit of variability to these things; yet another good reason not to take anyone's numbers at face value and measure stuff for yourself.


----------



## vr2jetta (Dec 16, 2007)

*Re: Combustion chamber volume? (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_Interesting, I've cc'd 3 ABA heads, all early OBD1 heads like yours, and mine all came in at about 32-32.5 cc's. It would seem there's a fair bit of variability to these things; yet another good reason not to take anyone's numbers at face value and measure stuff for yourself.

Yea, that would be the best thing to do, but I do not have a burette. I do have a large syringe for.....well I dont know what it is actually for but I normally use it for pulling brake fluid out of the resevior, and it is marked in cc's. Thanks for the ball park #'s though.


----------



## B4S (Apr 16, 2003)

*Re: Combustion chamber volume? (vr2jetta)*


_Quote, originally posted by *vr2jetta* »_Cool man, thanks!
Edit: does anybody have the cc's for the 16v pistons? I know they are flat top but the valve reliefs add up to something.

_Modified by vr2jetta at 12:39 PM 6-20-2009_

There is actually a slight 'crown' at the point where the reliefs are cut. It comes out above the deck slightly when the piston is at TDC.


----------

