Ross Racing Pistons

[75Carrera]

Looking deeper into my 3.2 I find it has Ross Pistons in it with very deep value insets. I called Ross yesterday and got these specs from the customer number on the pistons.

400/1000 dome height
3.63 diam.

I'm trying to figure the compression of these. Ross seems to focus on 9.5x1 and 10.5x1 pistons but they do customs too. They really didn't give me what I wanted to know. Who can tell me what compression they are?
I am at 5000+ elevation so I believe the higher compression 9.5 would be great. I doubt they would be 10.5's...

[ChrisBennet]

Just some thoughts:

- I think it would be difficult to tell the difference betweem 9.5 and 10.5 just by looking at a picture. I've had material removed from a 95mm 10.5:1 piston to make and it 9.5 isn't that much.

- 3.62in = ~92.2mm (vs 3.52/90mm for a stock 2.7)

- With a 2.7 (70.4mm stroke) crank and 92mm bore the displacement of your "3.2" would be 2820cc's (2.8L)

-Chris

[75Carrera]

Thanks Chris,

I'm sure these will work out just fine. I'd be reassured to know exactly what's in my motor though. My wrench doesn't have a problem with them at all. Fresh heads and a 964 cam grind are underway along with the SW chip, test pipe and one in two out exhaust should scoot right along.

[ChrisBennet]

You could just CC the motor and know for sure what the compression is.
That said, if this is a single plug motor and the rings aren't broken you can be pretty sure it's not 10.5:1CR.
-Chris