|
|
|
|
| Author |
|
|
Registered User
Join Date: Aug 2010
Location: Küsten, Germany
Posts: 175
|
JE Piston Wrist pins
Hi there,
when i compare the wall thickness of the pins which are coming with the JE pistons i notice a significantly smaller wall thickness compared to Mahle piston pins. Is there any report of a piston pin fail of a JE pin? Thanks and greets, Robert |
||
08-22-2012, 04:54 PM
|
|
|
Registered
Join Date: Oct 2008
Location: Nash County, NC.
Posts: 8,467
|
Years ago the different shops would drill the center out of the Mahle to lighten them.
The strength of the wrist pin has little to do with the thckness since its running in aluminum. What you need to ask is why are the circlips twice as heavy as the Mahle. Bruce |
||
|
08-22-2012, 05:08 PM
|
|
|
Registered User
Join Date: Aug 2010
Location: Küsten, Germany
Posts: 175
|
Bruce, i thought the same but i was wondering also why Mahle put about twice the material in making them much heavier. Different steel quality? And why have Diesel pins typically again much bigger wall thicknesses...
So no issues known with JE pins, also @ high revs (stroke 70,4mm)? Yes the circlips JE's are coming with are weird, seems a standard DIN part. I am modifying the grooves to accept Mahle clips. Actually i am after a set of 85mm JE pistons. Has anyone got some for sale? Thanks, Robert |
||
|
08-23-2012, 02:25 AM
|
|
|
Registered
Join Date: Oct 2003
Location: Central Fla
Posts: 1,864
|
JE pins
We use on the non boosted 911's a .150 in straight wall pin that depending on the forging is 2.25 to 2.50 in in length, we used to use a tapered wall pin but seen the results of pin flexing and pistons cracking as a result. The .063 dia. clips are tough but they don't cause the problems that the mahle set up does when the pins bump into the clips and pound out the groove. the chamfer on the end of the Je pin work with the clip and groove to keep the pin from floating and working at the groove/clip. On the boosted engines we use a .210 in wall pin and that works well. If you lighten up the assembly with Ti rods, light weight pistons the pin dia. and wall thickness can be less. One of the best circlip install tools I have used is from Stomski Racing, it is very simple works with the clips with the tail or with out and they are dia. specific but very reasonable
Mike Bruns
__________________
The two most useless things to a driver are the braking distance behind you and nine-tenths of a second ago. |
||
|
08-23-2012, 05:19 AM
|
|
|
Registered User
Join Date: Aug 2010
Location: Küsten, Germany
Posts: 175
|
Mike, do you manufacture the pins by yourself? .150 wall thickness (~3,8mm) seems to me quite sportive. What do you understand as "boosted" or "non-boosted" 911s? And at what point do you distinguish?
Why do you estimate a straight pin more stable as a tapered pin? I used to taper pins for other applications in the past, is the 911 pin "machineable"? Thanks, Robert |
||
|
08-23-2012, 06:30 AM
|
|
|
Registered
Join Date: Oct 2003
Location: Central Fla
Posts: 1,864
|
Pins
We buy our pins from Je, Boosted is turbo or supercharged application. we did use the tapered pins for a long time but after their engineers determined the pins were deflecting enough to cause piston issues we went to straight wall design, They are machinable but tough. most all of our work is 911 based full race engines and we see them back in cycles to be refreshened often, so you get quick feedback on changes
Mike Bruns
__________________
The two most useless things to a driver are the braking distance behind you and nine-tenths of a second ago. |
||
|
08-23-2012, 06:59 AM
|
|
|
