JE pistons with cast iron barrels?

[porschetub]

Thinking ahead but looking @ gathering parts up in advance for refresh/upgrade on my 2.2T.
Can I use JE 86 mm pistons in bored out stock cast iron 2.2T barrels ? is the expansion rate correct or are these for Biral cylinders only ?.
Secondly..are the rings supplied by JE oem quality?
Thanks.

[tom1394racing]

There is no issue with running JE pistons in cast iron cylinders. Both the Biral and cast iron cylinders have a cast iron inner bore. Some recommend having the cast iron bores Nikasil plated.

[Steve@Rennsport]

You can do this, but you shouldn't.

Piston-to-cylinder wall clearances will need to be very large to prevent scuffing and seizure due to widely different expansion rates. .004-.005" and that means noise and smoking. If you decide to use iron cylinders, I'd use the JE 4032 pistons, not the 2618 ones.

You would really be far better off with Nickies or Mahle cylinders.

[bgyglfr]

aren't the original Pistons aluminum? Wouldn't they have the same expansion issues?

[RedCoupe]

Originally Posted by bgyglfr

aren't the original Pistons aluminum? Wouldn't they have the same expansion issues?

Aluminum pistons that are designed to run in cast iron or steel bores are designed differently than piston designed to run in aluminum bores. Piston manufacturers have been coming up with solutions to the differential expansion rates of pistons and cylinders since the days of the Model T, but I believe that Steve's point is that you don't want to use a piston designed for an aluminum cylinder in a cast iron cylinder.

[ganun]

Different aluminum alloys in their forged pistons, the type with a lower expansion is a more brittle alloy, the reverse is true for the other alloy. I suppose you should be OK with the first, the second is more for turbo applications where boost spikes could crack the pistons. Ask me how I know. So in order to compensate for large expansion rates with temp a larger than usual clearance like was stated above is required and it will cause noise when cold. 3 to 4 thou vs the usual 1.5-2

[porschetub]

Originally Posted by Steve@Rennsport

You can do this, but you shouldn't.

Piston-to-cylinder wall clearances will need to be very large to prevent scuffing and seizure due to widely different expansion rates. .004-.005" and that means noise and smoking. If you decide to use iron cylinders, I'd use the JE 4032 pistons, not the 2618 ones.

You would really be far better off with Nickies or Mahle cylinders.

Thanks Steve,I did think there would be an issue with piston to barrel selection hence the question.
Are these pistons a custom order from JE I don't see them on the website?,AA list them but not the 4032 as you recommended.

[tom1394racing]

Originally Posted by Steve@Rennsport

You can do this, but you shouldn't.

Piston-to-cylinder wall clearances will need to be very large to prevent scuffing and seizure due to widely different expansion rates. .004-.005" and that means noise and smoking. If you decide to use iron cylinders, I'd use the JE 4032 pistons, not the 2618 ones.

You would really be far better off with Nickies or Mahle cylinders.

Steve

Just to clarify, running JE's in Biral cylinders with 0.002-0.003" clearance is OK because the thermal expansion of the Biral cylinder is much closer to the expansion of the JE piston? Cast iron cylinders, although running hotter than the Birals, would still not expand as much as the Birals and thus would require a larger build clearance. Am I correct?

[bgyglfr]

Aren't the sleeves in Biral cylinders still cast iron? Wouldn't they also expand just as much as the T cast cylinders?

[tom1394racing]

The outer shell in the Birals is an Aluminum alloy. In theory, the combined Al/Iron Biral cylinder will shed heat at a faster rate than a cast iron cylinder and thus not heat up as fast. Also, at steady state operating temperature, the Biral should run cooler than the cast iron. The key question is, how does the inner bore diameter react to the temperature transient from room temp to operating temp in both the Biral and cast iron cylinders?

[bgyglfr]

While we are talking pistons and cylinders, I have a couple sets of Arias Pistons. One set is mated with 2.7 mahle aluminum cylinders and the other with 2.2 cast cylinders. I'm curious if anyone has any information on them. I would assume they are pretty similar to JEs?

[Steve@Rennsport]

Originally Posted by tom1394racing

Steve

Just to clarify, running JE's in Biral cylinders with 0.002-0.003" clearance is OK because the thermal expansion of the Biral cylinder is much closer to the expansion of the JE piston? Cast iron cylinders, although running hotter than the Birals, would still not expand as much as the Birals and thus would require a larger build clearance. Am I correct?

Correct, and especially so for any 2618 piston.

[Steve@Rennsport]

Originally Posted by porschetub

Thanks Steve,I did think there would be an issue with piston to barrel selection hence the question.
Are these pistons a custom order from JE I don't see them on the website?,AA list them but not the 4032 as you recommended.

Yessir, custom order for sure. They can make anything you want in either alloy.

[porschetub]

Thank you sir,what is the issue with the supplied pistons with the AA 86mm kit (non JE),I note there has been QC issues....are they as bad as people say and I understand engine builders don't use them as they have to stand by their work,......just asking .