3.0 RSR pistons. Will they work?

[PMNorris]

I am finalising plans for my 3.0 SC upgrade. It has 40mm PMO's. John recommends the the GT2-102 cam with the carbs and i can get some 3.0 RSR Mahle pistons. The pistons are 10.5:1. The engine is a 79 Euro SC, so has larger ports than the US spec.

Page 145 of the performance handbook states that the combustion chamber these pistons create is smaller than the SC and they should be avoided. Does anyone have any experience of installling them in a Euro spec 3.0 SC engine?
Alternatively i can go with the JE pistons.

Thanks

[0396]

I've been told that the spacing of the cylinder is larger than the S/C.

[carrerarsr65]

just got done with a 79 row engine big port twin plug,hpv-1 ign, j&e 10.5.to1 on these je pistons take the sharp edge off the top ,something to do with combustion,steve at rennsport sold me mine,any way 964 cams wich I think suck,bad choice on my behalf.weber 40idas header and a couple exhaust choices ,the megaphone are straight out bad ass sounding, I like the je though no smoke on start up

[Henry Schmidt]

Originally Posted by PMNorris

I am finalising plans for my 3.0 SC upgrade. It has 40mm PMO's. John recommends the the GT2-102 cam with the carbs and i can get some 3.0 RSR Mahle pistons. The pistons are 10.5:1. The engine is a 79 Euro SC, so has larger ports than the US spec.

Page 145 of the performance handbook states that the combustion chamber these pistons create is smaller than the SC and they should be avoided. Does anyone have any experience of installling them in a Euro spec 3.0 SC engine?
Alternatively i can go with the JE pistons.

Thanks

The Mahle 3.0 RSR piston has a theoretical compression ratio of 10.4:1 when used with the RSR head.
When you combine it with an SC head with a larger combustion chamber the result is a much lower compression ratio. If memory serve me, that number is under 9:1. If you can live with the resulting compression ratio they will work just fine.

[camgrinder]

Originally Posted by Henry Schmidt

If memory serve me, that number is under 9:1.

Way too low.

[Henry Schmidt]

After some quick calculations I came up with 8.6:1
31.2 cc dome
77.2 chamber =10.4:1
31.2 cc dome
90cc chamber= 8.6:1

[JV911SYDNEY]

Originally Posted by carrerarsr65

964 cams which I think suck,bad choice on my behalf

too mild?

[PMNorris]

Too mild. Maybe the JE pistons will be a better choice. Many thanks for the feedback.