Piston Tolerances
03-20-2004, 02:21 AM
#1
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Location: Savannah, Georgia
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Piston Tolerances
I was looking through the PET program and noticed that under my 1983 there were three different piston tolerances available. Those were 0, 1, and 2. I was wondering why there was a "1" stamped on top of my pistons and figured this was probably the answer.
I'm wondering if anybody knows why there are three groups and what the differences between them are.
Did all of the cars in 83' have the same pistons, or did some other factor dictate what piston went where.
I hope everyone has a great weekend!
I'm wondering if anybody knows why there are three groups and what the differences between them are.
Did all of the cars in 83' have the same pistons, or did some other factor dictate what piston went where.
I hope everyone has a great weekend!
03-20-2004, 02:43 AM
#2
Nordschleife Master
Do you have the factory manuals?
It's explained in there...
I'm not sure why they did it; but they did.
Each piston tolerance group corresponds to a certain cylinder bore tolerance group (stamped on the block, near each cylinder on top).
It's explained in there...
I'm not sure why they did it; but they did.
Each piston tolerance group corresponds to a certain cylinder bore tolerance group (stamped on the block, near each cylinder on top).
03-20-2004, 03:21 AM
#3
Rennlist Member
Good old German engineering. The groups represent pistons and bores that fall into three different size ranges. I assume that they did this so that they could get away with a slightly greater variation within the manufacturing process, while still maintaining their tight piston to wall specs -- rather than ensuring that each piston and block was made to exactly the same size. We're talking about very very slight variations among the groups (which other manufactuers might ignore?).
03-20-2004, 08:07 AM
#4
Race Director
Originally posted by Tom M'Guinn
Good old German engineering. The groups represent pistons and bores that fall into three different size ranges. I assume that they did this so that they could get away with a slightly greater variation within the manufacturing process, while still maintaining their tight piston to wall specs -- rather than ensuring that each piston and block was made to exactly the same size. We're talking about very very slight variations among the groups (which other manufactuers might ignore?).
Good old German engineering. The groups represent pistons and bores that fall into three different size ranges. I assume that they did this so that they could get away with a slightly greater variation within the manufacturing process, while still maintaining their tight piston to wall specs -- rather than ensuring that each piston and block was made to exactly the same size. We're talking about very very slight variations among the groups (which other manufactuers might ignore?).
And you're right, the tolerances are so tight that simply accounts for variation in machining. Remember, we're talking clearances in the ten-thousandths - much tighter than a cast iron block.
03-20-2004, 09:57 PM
#7
Rennlist Member
Originally posted by Geo
I wouldn't be so quick to credit German engineering. I think you'll probably find this will most if not all aluminum block engines. The Nissan SR20DE engine has the same thing.
I wouldn't be so quick to credit German engineering. I think you'll probably find this will most if not all aluminum block engines. The Nissan SR20DE engine has the same thing.