Exotic-metal55

Took a few pictures of a stock Piston from an E55 that had a nitrous explosion in the chamber. At least that is what I was told. As you can see it blew the lands off. (See PICS Below)

I cut the Piston in half to measurments and compare to the custom forged pistons put in my motor. (Got the idea from PTE)

From what I have learned recently the hard way and reading up on Piston design, our stock pistons are pretty trick. The have thin and anrrow rings to lower friction, increase bore seal and are pretty light for stockers. They are pretty tuff but I think still on the britle side.

I was hoping from this thread to learn more about the forged pistons I installed and help avoid design mistakes , as tuners start to have custom pistons made for our engines. I will be ahppy to MIC anything on the stock pistona nd post my forged spec sheet to talk about. I have seen pictures of a few other custom 55 pistons but thought those cars had engine build issues or soemthing like that.

Stock piston Deck thickness: .325 Wiseco forged .475 , if the deck thickness is measured in the middle of piston.

Stock top land thickness .2545 VS Wiseco .2500

Stock second land thickness .1700 Vs Wiseco .1600

There is so much to modern piston desing that just having people kind of guess what what we may need , can really cause lots of issues with a 48K motor. Pin offset, pin design, gas hole angle and location, deck thickness, ring thickness, ring material , land thickness, skirt lenght, skirt tapper, forged material used, silicone content, Ring gap spec , piston clearance, and the list goes on and on..


Example of some really cool JE piston options . http://www.lnengineering.com/pistons.htm

Exotic-metal55

To technical of a post or just a bad topic?????`

MRAMG1

Not for a junky like me my friend.

To quote XXX, " I live for this sh-t"

What suprises me the most is how SMALL the oil ring land is. I am guessing this was for reduced friction, but I am AMAZED that there is enough cooling/lubrication from such a SMALL ring. I guess the squirters underneath REALLY do a good job of cooling.

See yeah

PS: Keep up the good work

Exotic-metal55

Yes, stock oil ring is really narrow and thin. AMG looks to be using leading edge performance ring and piston tolerances. I showed these rings to a top area in engine builder and he was also amazed how thin they were..

Stock oil ring width is only .760!
Top ring is only .480
Second ring is thicker at . .690

The stock wrist pin is heavy at 124 grams and .866 dia. x 2.357 long. Pretty beefy for stock.

The Wiseco`s , 89grams , little longer at 2.500 x .866

MRAMG1

I also enjoy the rather large gap between the two compression rings, with the first one being placed WELL BELOW the top of the piston. They did this to try to keep the rings cooler form the heat no doubt thanks to mr supercharger

Good luck, again, and thanks for the info on the top guided engine. I can honestly say I didn't know that about AMG's. The gap between the rods would have had me tearing it apart in a heart beat thinking I did something wrong.

Heck, I have NEVER seen that on ANY engine I have rebuilt, but granted most were US made, okay US sold sorry.

See yeah

PS: The pin would HAVE to be beefy as it is guiding/holding the rod. And YES, that is a BIG pin for a stocker, IMHO.

bobgodd

You should have included WHEELS in your topic description, it would have gotten you more traffic

Ghostrider

What would it take to make a stouter rotating assembly, based on stock. Just better.

Ex-m55, what part of Texas are you from?

Exotic-metal55

I thought 55 piston would refer to brakes and forged =wheels..

I think a great set of modern designed, forged pistons would pretty much do the trick. Heat retention, friction, weight , sealing and oiling could all be improved. Even piston tops could be re-worked for more valve clearance for larger cams. Most engine builders that have seen our rods and crank feel they are pretty stout. You could call that stage one build.

Stage two: Custom stroker crank, custom rods and forged pistons for stock bore.

Stage three: Bore stock block and install larger siamese metal sleeves. Use domestic size bore for 4" plus pistons, custom stroke crank, custom domestic rods and pistons. Low cost and high power! Make a nice sqaure block stroke and max out cubes! Going to send my bad block to inspect for sleeving and stroke.

AMGSC

Very ambitious. Do you need a guy to custom tune it? Vadim will have mine completed by July 31st. Going deep into the 10's hopefully.

Yacht Master

I could see the Siamese Sleeves and Forged pistons, If done right, it is rebuild kit for 55s that have suffered loss of piston lands and scored walls. The cu$tom $troker crank (a real one, not a welded stocker) would be nice to have, expensive but nice. The pistons can be fly cut for valve clearance (duration) but I recall not having much room for higher lift cause of rockers/rocker shafts.

Exotic-metal55

What do you mean by the first sentance above? The rebuild kits have suffered for the 55? Sorry, just not clear on your statement.

Yes, I recall the same thing. Not much room for larger cam but piston room, may help some.. I would rather put my money in head porting than cams, on a SC engine anyway.

If you steel sleeve the block and use high quality race domestic parts, the price could be under 10K.. I was just out 16K , for waaaaaaaay less of an engine. Custom cranks are pretty cheap these days. I guess a top guided motor would be off the table then..

I am still having a hard time getting over, that our blowers are made in Japan and our intercooler in mexico.

shardul

iTrader: (1)

interesting did not know that

Marcus Frost

It would be interesting to see how much displacement could be had given the R&D budget. I would personally like to see a few more RPM out of these engines, maybe in conjunction with a properly sorted head and valvetrain (obviously taking into the account limitations of a 3valve SOHC head). We should NOT need more displacement to hit 1khp.

-m

splinter

Appreciate you sharing your findings.
Fact is our OE pistons are pretty stout pieces. Seldom does one hear of them failing, even when subjected to ~19 psi of (C32) boost. Proper fueling is essential to avoid the meltdowns of which we’ve all read.

The only real advantage of forged pistons is their increased strength over our cast hypereutectic hardware - owing to their superior modular structure. They’re frowned upon by most road car manufacturers because of their relatively large cylinder wall clearances and the attendant cold-start noise/oil consumption issues. Never mind the ‘63 contingent. Seems BMW’s M division has been able to strike a reasonable compromise.

Once you’ve elected to increase displacement, the aftermarket is your only option.

Exotic-metal55

I totally agree on the strenght of our motors and even pistons. Most of us will just bolt the 3-4 mods on and be happy as hell.

My point is,, that our engines are getting 7 plus years old now. More people moding them now. As our car values decrease from 100K plus to 25 plus K,, then we get more and more people buying them to race! More blown motors, more wore out motors and more poeple wanting to push the envelope. The hard part is, how to economically re-build these motors? A new bottom end is 20K from MB and whole motor is 48K.. You could buy 2 more AMg cars for that, on today`s market.

We need aftermarket pistons that work and we need people that can re-coat our blocks for these pistons. Most of all, do it with the Quality we expect.. If re-coating does not work, then we need top quality sleeving vendors that can use high quality low cost domestic race parts for our blocks. At some point, it would be nice to have aftermarket heads available too.

Just looking to the near future, since my motor rebuild came way sooner than expected.. As PTE said, a motor can blow from doing a simple air filter change, having an air tube ring come loose and go into the blower. 48K, Kaboom!

Yacht Master

[QUOTE=Exotic-metal55;3622634]What do you mean by the first sentance above? The rebuild kits have suffered for the 55? Sorry, just not clear on your statement.QUOTE]

What I meant was, It would be nice to have a Sleeve & Forged piston kit, for rebuilding an engine. Especially for one with a burned/cracked piston that has damaged the cylinder wall beyond MB-AMG + sized pistons. So if you chose to do it and all the home work / R&D it would be a valuable item to market as a "standard" kit.

You could call them "Exotic Metal Cylinder Kits"

Ghostrider

I knew what you meant!