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DMax Piston Specs

buddy

buddy

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California, central coast
Hello,

Does anyone have the specs/dimensions/weight on the stock pistons? I know diameter, but....

stock weight: with or without pins/rings/rods

How tall are they from skirt bottom to piston top?

Compression height: center of pin to top of piston?

The distance between the top compression ring and the piston top?

And volume of the center dish/bowl with the dome?

Thanks for any help, this stuff is nowhere I can google.
Tom
 
Not all Dmax pistons are the same. LB7 and LLY were made by Mahle OEM, they were 17.5:1 compression ratio. LBZ and newer are different and have a compression Ratio of 16.8:1. Wrist pins are different between them as well. There were small running changes during different production years of all the pistons so your not going to find a one ssize fits all measurement set.
 
Thanks
How about on an 07 LLY or LBZ? Not concerned with what compression ratio they ended up making the engine. Just their actual dimensions.

Anyone have one laying around they could measure? Or one busted or not I could have
:)
 
There is no 07 LLY. That would be the later style piston not made by Mahle. It's used in the LBZ and LMM.
 
I have pre production LB7s?? Not going to help you at all either.

Are you trying to make your own piston??

Im pretty sure LBZ pistons are cast in the same factory as "Hot Wheels" Only difference is the hot wheels hold up better.
 
I'm kind of wondering how I might be able to manipulate one :Justwait2:

If youre wanting to get rid of those preproduction ones I might be interested if you had the specs on them. :D
 
No you wont be able to use them for anything, they have a completely different bowl design for the pre production injectors, which means stuff isnt gonna work if you put them in something.

Plus from the info ive gathered, they had issues and I could tell, two of the eight have hairline cracks in the skirts.
 
Thats too bad. From what I gather the LBZ pistons are supposed to be "better" than those previous, which is why I was asking about them.

Do you think you could measure the compression height on that preproduction piston? Distance between center of pin and the top of piston. Doenst have to be perfect measurement. It could not have changed much, or at least gotten any higher with the compression drop in later years.

Thanks
 
buddy said:
Thats too bad. From what I gather the LBZ pistons are supposed to be "better" than those previous, which is why I was asking about them.

Do you think you could measure the compression height on that preproduction piston? Distance between center of pin and the top of piston. Doenst have to be perfect measurement. It could not have changed much, or at least gotten any higher with the compression drop in later years.

Thanks
Click to expand...

No 01-05 LB7 and LLY are the pistons you want. NOT the LBZ & LMM ones.
 
I have some LMM pistons with 16k on them...

$25 bucks shipped via paypal each :smile5:

I dont really have time to go measure them all up precisely though.
 
Thanks MMLMM, the value I am most interested in is the compression height if you could eye that up to within like a mm or two that would be very helpful. I just may be interested those pistons.
 
Here is what Alldata gives me:

Piston Diameter: 102.948 - 102.960 mm
 
Yep, bore is easy enough to come by, its just the compression height I'm curious about.

Distance between top of piston and the center of the rod pin.

Anyone happen to eye it up with a ruler or caliper? within a mm is good enough for me.

Can also calculate it if you know the deck height, piston to deck distance at TDC, rod length and the stroke.

I know rod length and stroke, but not the deck height (crankshaft center to top of deck) or how far the piston is from the deck at TDC. Piston sticks out at TDC right?

Thanks
 
IIRC the top of the piston is perfectly flush at TDC. Providing the rods arent bent.

But it is different on every duramax. Thats why there are three different thickness headgaskets. and one side of the motor can be different from the other side of the motor.

Im not at home around my manuals but ill see if i can find the deck height for you.
 
Piston protrusion should be .0088" to .0148" on all models. The various thickness gaskets correct for where they are within that specification. If they are flush with stock pistons then you have bent rods.
 
Diesel Tech said:
Piston protrusion should be .0088" to .0148" on all models. The various thickness gaskets correct for where they are within that specification. If they are flush with stock pistons then you have bent rods.
Click to expand...

Awesome, now I just need deck height, from crank center to top of deck. And then can caluclate piston compression height.
 
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