Later Higher compression pistons?
09-20-2011, 05:15 AM
#46
Sounds like it. No offence though - what you're saying actually makes sense - why would Porsche have two lower levels of compression for the USA?
09-20-2011, 09:33 AM
#47
Race Director
09-20-2011, 11:07 AM
#48
Race Car
I feel like the 9.7 pistons are perhaps a misprint in Porsche literature. I don't know anything about a FAQ internet board nor care.
However, I am posing a few questions because there are some subtle differences in the pistons according to who made them. Perhaps an experienced engine builder would have insight.
I would be curious to know what range of motors were allocated Mahle pistons. I do know that the manual/spec books give survey of both throughout all model years. I have found that there are lots of Mahle pistons in the 86/87 years. Early cars don't seem to have mahle as much. This is only anecdotal observations limited to my experience.
Funny thing is, Mahle pistons have the ring grooves grouped about 1mm closer to the crown(this could raise compression if the crown is the same). Another thing is the iron coating. Mahles appear different in color, and of the several sets I've looked at all of them have lost lots of there iron and have galled. KS pistons seem to hold up better.
Also, the wrist pin in Mahles are lighter by about a half oz., and shorter by about 3mm. Both KS and Mahle weigh the same assembled. But if the shorter pin in Mahle would structurally work in the KS(only the length is shorter, all else is the same), it may help in high rpm situations.
Skirt area is way different, and Mahle pistons have an oil groove in the wrist pin bore.
My observations are of NA piston groups only. I'd just like to see what others have found.
However, I am posing a few questions because there are some subtle differences in the pistons according to who made them. Perhaps an experienced engine builder would have insight.
I would be curious to know what range of motors were allocated Mahle pistons. I do know that the manual/spec books give survey of both throughout all model years. I have found that there are lots of Mahle pistons in the 86/87 years. Early cars don't seem to have mahle as much. This is only anecdotal observations limited to my experience.
Funny thing is, Mahle pistons have the ring grooves grouped about 1mm closer to the crown(this could raise compression if the crown is the same). Another thing is the iron coating. Mahles appear different in color, and of the several sets I've looked at all of them have lost lots of there iron and have galled. KS pistons seem to hold up better.
Also, the wrist pin in Mahles are lighter by about a half oz., and shorter by about 3mm. Both KS and Mahle weigh the same assembled. But if the shorter pin in Mahle would structurally work in the KS(only the length is shorter, all else is the same), it may help in high rpm situations.
Skirt area is way different, and Mahle pistons have an oil groove in the wrist pin bore.
My observations are of NA piston groups only. I'd just like to see what others have found.
