joe morreale

I bought a "built" vvt head from someone a few years ago. He said the combustion chambers were opened up to drop compression, allowing him to run more boost. Can a hamfisted guy, who has a hard time understanding stuff, figure out how much it drops compression? I got it cheap and it had 1500 miles on it. He dropped a thrust bearing. Cams don't have any scoring, so I'm assuming that it's a good head. I'm trying to decide if I want to keep it for a forged build or sell it. I just want to know what I have. Original owner is out of the picture.

HarryB

You can measure the combustion chamber volume quite easily. From there, static CR calculation is straighforward.

Blkbrd69

https://motoiq.com/how-to-measure-yo...n-chamber-ccs/

https://auto.jepistons.com/blog/how-...d-displacement

joe morreale

Thanks for the link. I can get my head around that and figure out what I have.

joe morreale

Hate to sound dumb but if the cams are still in the head can you just close the valves to measure the volume with the oil. I would think if it holds compression it should hold oil.

Blkbrd69

Correct.