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Hi guys, I’m building a “sleeved/forged” M113k motor and I had spent a considerable amount of time trying to find the exact piston ring end gaps measurements on this board and to no avail I did not find the info.
So I had finally had a chance to get to my other stock M113k engine and tear it down to take the piston ring end gap measurements.
Here they are:
STOCK OEM MEASURMENTS:
Top Piston Ring Eng Gap = 0.020” or 0.50mm
2nd Piston Ring End Gap = 0.026” or 0.65mm
M113K OEM/Factory Top(1st) Piston Ring Gap = 0.020” or 0.50mm
M113K OEM/Factory Top(1st) Piston Ring Gap = 0.020” or 0.50mm
M113K OEM/Factory 2nd Piston Ring Gap = 0.026” or 0.65mm
M113K OEM/Factory 2nd Piston Ring Gap = 0.026” or 0.65mm
To those reading this in the future years from now, there was a youtuber “XF Motorsports” who made a full M113k teardown/rebuild Step-by-step video.
And in his video he also mentions/confirms that the factory piston ring End gap (I infer he was talking of Top ring only) is 0.020” = 0.500mm as well.
But for his rebuild (w/ machined piston heads) he gapped his Too Ring to rings to 0.0275“ = 0.700mm as he planned to run the motor hard during his racing events.
See TimeStamped link below:
The cool aspect of his videos is that he later ran full piston compression tests (both on a cold and a hot engine) on all cylinders (w/ modded lower compression stock pistons) and he still got good compression on all cylinders (Warm Engine: 155psi - 172psi) which is within the spec according to the Mercedes Manual.
I run nitrous on mine with boost. Engine temperature control is also very important. I run a slightly richer AFR at bottom 11's and the engine stays at 180* through entire run. IAT's never above 125-130* on a 1/2 mile run. All this plays a role in end gaps. Could you run .035 to be really safe on the street...sure but now you will have more blow by.
For those reading this in the future, I have found an excellent interview on youtube from the TOTAL SEAL PISTON RINGS channel where they interview Jimmy Barton (experience in NASCAR, Drag Racing, and also set land speed records)..
if true m113k are becoming rare, You can use the non-supercharged mercedes m113 5.0 liter or 5.4 liter blocks instead, and transfer all of your m113k items over and build on a fresher block if need be.
just keep in mind that with the 5.0 liter M113 motors, the blocks oil port is shifted 1/2 an inch in comparison to the True m113K engine blocks.
This means you will need to utilize the oil pump type/style of a 2005 clk500(there may be other models that share this same pump part # which have the oil inlet port shifted 1/2 an inch), and press off/swap the sprocket pulley to your original true m113k oil pump’s sprocket.
a 2nd difference in the m113 vs m113k block,is that on the non-supercharged m113 block, the frontmost and rearmost crankshaft brackets bolt holes(6 of them each crank bracket) are the same between the both m113 and m113k.
But for the 3 middle crankshaft brackets, the bolt hole arrangements on the non-supercharged block, has only 4 vertical bolts holes
There are NO additional side bolts
BUT, for a true m113K, these 3 middles crank brackets possess a 6 bolt hole pattern.
There are enough E-55’s and S-55’s around that engines will continue to be available.
Important thing with end gap for rings being that there be enough gap that rings never close the gap under load and become machine tools that will oversize the cylinders. End gaps are different for intended use, iron or aluminum bore, size of bore. Do your research and get it right.
There are differences between S55k m113k engine and E55/SL55k m113k engines.
I would rather stick to an S55 m113k if I ever had to replace mine.
I believe E55 & SL55 have 2 oil sumps and therefore 2 drain holes in the oil pan. That means such engines also have an extra oil pickup tube in the secondary pan to scavenge oil back to the oil pump. It is this scavenger oil pickup tube that has a seal o-ring which can become brittle and suck air and starved the pump.
There are differences between S55k m113k engine and E55/SL55k m113k engines.
I would rather stick to an S55 m113k if I ever had to replace mine.
I believe E55 & SL55 have 2 oil sumps and therefore 2 drain holes in the oil pan. That means such engines also have an extra oil pickup tube in the secondary pan to scavenge oil back to the oil pump. It is this scavenger oil pickup tube that has a seal o-ring which can become brittle and suck air and starved the pump.
Yes I believe you are right, but the difference here is that darn near every internal thing from an S55 M113k engine can be put in an E55 and SL55 m113k Block…the blocks are practically identical possibly excluding the blocks oil pump inlet port holes (1/2 inch overlapping shift)…
the E55 OIL PUMP style is built with 2 oil inlet sump ports. And the oil pans accomodate this and also match the chassis engine bay frame shape of the E55.
just transfer your S55 upper and lower oil pans and a CLK430/E430 oil pump (of the oil port is shifted/overlapping by 1/2 inch between blocks…and also swap/press-out the CLK430/E430 oil pump sprocket gear and press in the S55 oil pump sprocket gear) over to a used E55 m113k engine block and you are good.
if true m113k are becoming rare, You can use the non-supercharged mercedes m113 5.0 liter or 5.4 liter blocks instead, and transfer all of your m113k items over and build on a fresher block if need be.
just keep in mind that with the 5.0 liter M113 motors, the blocks oil port is shifted 1/2 an inch in comparison to the True m113K engine blocks.
This means you will need to utilize the oil pump type/style of a 2000-2006 CLK430/E430(there may be other models that share this same pump part # which have the oil inlet port shifted 1/2 an inch), and press off/swap the sprocket pulley to your original true m113k oil pump’s sprocket.
a 2nd difference in the m113 vs m113k block,is that on the non-supercharged m113 block, the frontmost and rearmost crankshaft brackets bolt holes(6 of them each crank bracket) are the same between the both m113 and m113k.
But for the 3 middle crankshaft brackets, the bolt hole arrangements on the non-supercharged block, has only 4 vertical bolts holes
There are NO additional side bolts
BUT, for a true m113K, these 3 middles crank brackets possess a 6 bolt hole pattern.
CORRECTION FOR ABOVE POST:
Use oil pump from a 2000-2006 CLK430/E430…
NOT CLK500(mistype)
I had to check my ebay email purchases when I did the swap..
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