GT-ER

I have a car at home that may have a cracked piston but I'll find out for sure on saturday. Anyone have a set?

GT-ER

Also, does anyone know if e55 pistons will drop into an SLK55?

e55amgrocket

I've got a set with rods. They will fit SLK55 also.

blackbenzz

Yes they will fit. Might as well do the rods if you're digging into the car

Hulk

GT, what happened??

GT-ER

To me, nothing. But I have a car at home that has a bad misfire and it SEEMS like the only thing I haven't checked is the compression which I will be doing saturday.

GT-ER

Aren't the rods the same? They apparently are forged from what I've read but I don't know if they are identical or not.

Robert AMG

iTrader: (1)

The E55K and slk55 with 55/NA engine(2003 and up) has different pistons and rods, i have a good review in the thread below in my signature, the 55k pistons is higher then the 55n/a(11:1CR) by 0.7mm, that mean if you install the 55k piston on the 55n/a rod the piston will hit the heads, also if you install the 55k piston and rod you get a lower compression ratio cause the shape of the 2 pistons are different, look at the picture attached, on the right the 55k piston and near it to the left is the 55n/a(11CR) one.

GT-ER

Very good to know. Thanks!

blackbenzz

The rods are different because the na 55 has a oil port through it and 55k does not. They are both forged as you mentioned.

I can measure the pistons when i get home but i don't see why the lower compression pistons would be taller.

GT-ER

I'm guessing it's because they use a shorter rod.

Sir-Boost-a-Lot

iTrader: (1)

And have a taller compression height for strength.

Robert AMG

iTrader: (1)

32K piston= 89.9mm bore, weight 518g, CR=9:1
55K piston= 97mm bore weight 582g, CR=9:1 and are 1.3mm lower then 32K piston
55N/A piston(2003 and up)= 97mm bore weight 532g, CR=11:1 and are 2mm lower then 32K piston

i used the above 55N/A pistons with 32K rods in the 3.72L V6 from Ml350 2004 and i got a CR=8.5:1
with 32k crankshaft and ml350 heads with 32k cams and double springs and valves from the 55k
then i installed the 55k supercharge on the engine with some cut and weld
and with stock pulleys now i am at 555 crank hp 740n.m torque crank.

i have 6 55K pistons and rods if you want.

blackbenzz

Here's an old pic i have. 03 e55 (left) vs 01 Clk55 (right)The differences i saw were oil port in rod, bigger dome on e55 piston for lower compression, and different wrist pins. I didn't measure them but visually rod length and piston height were the same
http://m41.photobucket.com/albumview....jpg.html?o=11

GT-ER

I have the C55 and the E55 pistons and rods next to each other and see no difference in height either. The rods are shaped differently so if you measure the ENTIRE rod it'll be different but from center bore to center bore I see no difference. Granted, I'm eyeballing it...no scientific data here.

Robert AMG

iTrader: (1)

i was mentioning the difference in pistons only, not pistons with rods, of course 55K pistons and rods will have same height as 55N/A pistons and rods, but if you installed 55K pistons on 55n/a rods they'll have different height, they'll hit the heads.

GT-ER

Ah yes, I see what you mean. My bad.