M W vs OEM

[MapleStone]

Starting to look for an engine rebuild kit for my 550 and was wondering if there is much difference between the M&W vs the OEM style pistons and sleeves.

Also any tips on buying an engine kit for a 550 would be appreciated.

 

[e]

I put the M&W's in my 880 and love 'em to death. With a bigger carb, high energy electronic ignition and a port/polish job, it will just about out pull my 1755D. Definitively worth it IMHO.

 

[Anonymous-0]

I am going to give you the other point of view. If this is going to be a normal use tractor I would not consider them. When I worked for a dealer we took about 8-10 sets out for each new set we installed. I would keep it 3.-5/8 bore. Questions send me an e-mail

 

[e]

No reason to keep secrets so let's keep it out in the open for everyone to read. What are the details as to why would you not consider them?

 

[Dick W.]

I just put a set of M&W in my Super 55 gas. I had trouble getting the sleeves into the block. I had new lower block sleeves installed where the o-rings stop. The machinist has a standard Oliver sleeve for fittng the lower sleeves in the block. The M&W sleeves were .002 to .0035 bigger than the oliver sleeve he had. He turned the M&W to fit the sleeved block that is standard oliver size with the lower sleeves installed. I'm also installing a late 550 head and manifolds and had the head surfaced .100,also decked the block .007. I'm hoping to make 50 hp at 2400 rpm.

 

[BM]

The M&W high domes are like having sneakers that say turbo on them. They seem great compared to your old wore out pair but it"s all about the catch phrase.
Go with flat top pistons whatever bore size you choose. If you decide to go with 3 3/4 bore make sure your head gasket has at least a 4" hole in it. I"ve heard alot of complaints about broken sleeves, it"s because the off the shelf gaskets only have a 3 3/4 hole in them. This loads the inside of the sleeve too much where it does not have block directly supporting it. This has not been a problem up until the last 5 years or so, sleeve quality must be going down. You did not mention gas or diesel, obviously if you have a diesel flat tops are your only choice and 3 3/4 is highly reccomended, the extra compression really helps them start.
A little explanation on the high dome thing. They have a dome, then they drop the head of the piston down about 1/8" into the bore. There goes the compression the dome gained. With a 880 head 3 7/8 high domes are 8.5:1 compression. 3 7/8 flat tops are 8.4:1. The m&w kit lost your quench area, and you now have a big turd on top the piston blocking flame travel.

 

[Anonymous-0]

The odd head gasket mentioned above is one reason. 3.625 bore in the 4 cylinder 550 works good and the head gasket will be around longer than some of the 6 cylinder Oliver engines because the basic design 550 engine was used in lift trucks. We used to have trouble with more top ring wear in an engine equipped with M &W sleeve sets than with Oliver sleeve sets. Most farmers with gas tractors complained the increase in power cost to much extra fuel. We were a diesel minded dealer. My employer sold olver Super 88 tractors new. Three were gas. A friend on mine was restoring a super 88 diesel he purchased. It had a set of M & W's. One piston was bad. We could not find one that matched and we had 3 different 3.750 bore M & W pistons. We finally weighed them all and made a ballanced set. They also had a 77 in their shop one time with M & W 9-9/16 inch bore. One sleeve was bad. We finally found an old 3-1/2 inch sleeve out of a Super 55 and then bored it to the correct size. Some of their odd diameters also creates more problems finding ring sets. My 2 cents worth.

 

[e]

Mine does like the fuel, but I beat the tar out of it when I drive it since it's quite the blast to bomb around on. Having a bigger carb with an accelerator pump sure doesn't help any either.

The big question is if the extra work done by upgraded engines justified the extra fuel consumption.

 

[e]

Hrmmm, I think your math is off. Going from a 3.75" bore to 3.875" bore only results in a volumetric increase of 6.78%. Stock 880's had a 7.3:1 compression ratio (Super 88's had a 7.0:1 compression ratio just for reference). Therefore, going from a 3.75" bore on an 880 to a 3.875" bore will only increase the compression ratio to 7.79:1. This will be true unless the distance from the piston pin to the piston top increase when going to the overbore pistons (which I don't think is the case)

What we really need is some comparative dyno data from a stock engine outfitted with M&W's. There is enough dealers with dyno's out in the world that if M&W's were really a spoof, then it would have been widely know for quite sometime.

I really don't buy your "big turd" argument seeing how the spark plug is located directly above the top of the dome. The flame front will travel down both sides of the dome and then out to the flat regions of the pistons. Much like what occurs with a hemispherical combustion chamber.
880 Nebraska tractor test report

 

[BM]

Good point. My math was off. I was giving M&W too much credit. The M&W book states that a stock 880 was 7.3:1. That comes to 115cc in the head and gasket. 880 High domes are 7.8:1. Using 3 7/8 bore flattops and 115cc comes to 7.72:1. Dyno Comparisons are challenging because big bore flattop kits have not become available until fairly rencently.

 

[e]

Ya, 8.5:1 is really rather high for an industrial engine of that vintage.

Ah, ok, things are making more sense now. It's been years since I've rebuilt a gasser and had to look into new jugs and slugs. I've been more intent on stuffing Cummins into these things than rebuilding the original engine. So, back "in the day" the high domes were really the only performance trick out there if big bore flat tops didn't exist. That would explain why M&W became associated with "performance" and hence it was easy for them to differentiate from stock.

Now, if what you say is true and the difference between the M&W and big bore compression ratios is really that small, then I would tend to lean toward big bore flat tops especially if they were made by a reputable manufacturer (like Federal Mogul, etc.).

 

[BM]

The 3 7/8 flattops are a genuine waukesha kit for another engine that i do some machine work to. power seal makes the 3 3/4 kits for the smaller engines and no longer makes the high domes. on the small ones the flat tops are actually more compression than the domes.