Why did MW dish pistons make soo much more power?

Seems like the turbo dish pistions make the '45 and 17 motors LUG SOOOO much better. Other than displacement, why is that?

It would seem that the heart shaped bowl which is also angled would create good swirl on compression which in theory at least makes for better/more complete combustion.

quench or squish band only starts to show benefits of adding swirl at .030 of the piston striking the head. wrist pin offset can if offset was done for this reason move the piston away from tdc sooner thus creating a depression on the under side of the intake valve sooner .   6.5 hp was all the increase m@w advertised wich is not much of a power increase in my opinion.

Edited by mlpankey - 29 Nov 2010 at 12:06pm

TedBuiskerN.IL. wrote: 6.5 HP may not sound like much, but on a 43 PTO HP tractor that is over 15%.  You are going to notice that in the field.

62 hp as the 175 series has would  be alot easier for me to feal from the seat.

How are you getting more displacement just by switching pistons? The bore and the stroke should be the same...

mlpankey wrote: TedBuiskerN.IL. wrote: 6.5 HP may not sound like much, but on a 43 PTO HP tractor that is over 15%.  You are going to notice that in the field. 62 hp as the 175 series has would  be alot easier for me to feal from the seat.

OK, I'm old so I was thinking in terms of the fifties and sixties before the 170 and 175 was around.  Back when the M&W's were popular.  I don't know if they are even available any more.  And the higher compression 175 pistons would make more power in today's world.

how much comp for these engines and 87 oct gas?

Edited by wi50 - 30 Nov 2010 at 10:18am

the common pump or farm delivery gas is 87 oct, no eth here,

All gas today has 2%to 5% ethanol in it, They dont have to advertize amounts that small.

i ran a wd with 11.1 static with 240 cranking  psi on 93 octane with cold plugs and lower total timing . Add 110 octane bump timming up 10 additional degrees. not a field tractor . A fellow told me that e 85 was withstanding 12 to 13.1 ratios in car engines.  you guys have bp stations in your area they always have gas with a percentage of ethanol . I would tend to think that there is not much market . I can provide you with a forged aluminum piston of any cr ratio up to 4 11/16 bore size. somewhere in the price range of 700. for four. most want a complete rebuild for that price.  You have to realize a guy willing to do field work with a 1950 2500 dollar tractor isnt a big spender. If he was he would be doing his field work with at least a 1980s era tractor. Butch my quote at the bottom of my posts says it all . It did before my time and does still today. kevin they did it with compression and cam change that allowed it to breath at a higher rpm . Its hard to make cam changes to help one breath without needing the compression ratio upped. Ever seen a automobile cam that says needs headers and a compression ratio of ----- for best performance with cam profile. some things just work hand in hand for a better complement.

Edited by mlpankey - 30 Nov 2010 at 11:18am

the extra cost in material of making a longer piston

firebrick43 wrote: Just how much compression will these engines take and still be able to run on 87 octane fuel and not have detonation problems?  I know alot of car engines are in the high 8/low 9's range but realize they are not constant load engines and there are many varibles in head/valves/piston design that can effect that.

Edited by Butch(OH) - 30 Nov 2010 at 11:53am

I thought the main reason to offset piston pins is to reduce piston slap and therefore reduce noise.  A lot of race motors with centered pins have lots of noise when cold due to piston slap.  

The offset piston pin causes the piston side load to swap on the compression stroke when the pressure is light compared to after ignition and on the power stroke. So its much quieter. This can also be accomplished by offsetting the crankshaft. That lets the connecting rod angle be greater with respect to the cylinder bore on the compression stroke than on the power stroke.

My dad told me about family relations coming to SE Missouri from Oklahoma for a funeral when he was young driving a '24 Chevy with cast iron pistons. He said you could hear the piston slap further than the exhaust. As they approached the piston slap was the first thing he heard.

In 1951 he built a garden tractor cutting down model A Ford axles and drive train using a belt clutch and belt speed reduction and a new Wisconsin Model AEN engine. Its run nicely ever since. I have it yet. A couple years later a neighbor bought a heavy duty tiller with that same engine model. It always had piston slap. The dealer took it apart and turned the piston around, thinking the offset was backwards but it had no effect on the piston slap. That was a 7 hp rated engine with a Fairbanks-Morse gear driven magneto with an impulse start like the mags on bigger tractors that made it a really good starter, usually one time through ignition, exhaust and intake and then next time over compression and ignition it was running. Maybe someday I'll look up the shop manual on that engine to see if the piston was drilled offset. Maybe they should have replaced the piston which they may have done since that neighbor was particular about how well his equipment worked keeping his car under a cloth in the garage to keep dust off even with the garage door closed.

Gerald J.

The offset pin doesn't affect piston speed, just the time when it transfers the side load from one side to the other, preferable before ignition so there's only compression pressure on it, not combustion pressure.

The offset crank shaft is another effect.

An offset end on a connecting rod changes the dynamic balance and allows a longer skirt with offset pin or crankshaft position, but it doesn't change the stroke or piston speed any.

Gerald J.