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Looking at the JD 930M with the 25.5HP Kawasaki engine to the 950M with the 27HP Kawasaki engine. I have a flat, but bumpy yard that is 5 acres. Would I notice the difference if never running a bagger. Is it worth the extra $800 for the 1.5HP?

Thanks,
Steve

2 hp is a big difference between a engine that has 0 hp and a engine that has 2 hp , but in this instance no you'll never know it except maybe for mileage and that would be pennies . I also think these people are full of it when a 8N ford tractor only has something like 28 hp . May wanna look that one up .

It depends on the year and where you are measuring, drawbar or PTO. 23-27hp. My little brother has one, which I worked on two weeks ago. Spring maintenance and rebuilt the generator.

I doubt while running at full throttle while mowing you would ever know the difference unless you were mowing very overgrown grass or field. More hp would allow for a larger deck if needed. But over a 10-year ownership the $800 is only $6.66/month if you look at it that way.

Also depends on deck size. I work on both these mowers. The 27hp probably has a restrictor plate.

Plus what options are install and if the engine is EFI or carburated does makes a difference too.

HP is a function of RPM and torque. Two identical engines can have different HP ratings if the top RPMs they are allowed to run at are different. You really need to compare apples with apples, and have a torque curve graph to know which works better, or do test drives on an equal surface.

StarTech said:

The 27hp probably has a restrictor plate.

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I'd say the 23 hp has the restrictor plate (If both have carbs) .. Not the bigger hp engine. Same cc's & bore & stroke.

7394 said:

I'd say the 23 hp has the restrictor plate (If both have carbs) .. Not the bigger hp engine. Same cc's & bore & stroke.

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or one was rated at a higher RPM

StarTech said:

Also depends on deck size. I work on both these mowers. The 27hp probably has a restrictor plate.

Plus what options are install and if the engine is EFI or carburated does makes a difference too.

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Is the HP of a carb equal to HP of the EFI if they are Both the same 27HP?

sgkent said:

HP is a function of RPM and torque. Two identical engines can have different HP ratings if the top RPMs they are allowed to run at are different. You really need to compare apples with apples, and have a torque curve graph to know which works better, or do test drives on an equal surface.

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Being most of my experience is with 2,000 HP @ 300 RPM i tend to forget about all the variables .

SeniorCitizen said:

Being most of my experience is with 2,000 HP @ 300 RPM i tend to forget about all the variables .

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BIG diesels,eh? Marine?

Turbocharged TLA Clarks with integral gas compressors .

SeniorCitizen said:

Turbocharged TLA Clarks with integral gas compressors .

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Those Wartzillas(Godzilla's) used to be built close to where I live. A connecting rod nut weighed over 500 pounds. Sometimes,a couple of hp don't amount to much.
On a more serious side, I have several Briggs 500cc engines,one a 19hp and another is a 17.5 engine,the other one has no hp declaration,just a 500cc PowerBuilt. I have swapped them about some and I cannot tell any difference from one to another. Horsepower means little, torque is the king.

Long ago I had a 42" w/ 17.5 hp, & it struggled thru taller grass.. Next & got a 46" w/ 20hp. Breezed right thru same deal..

But agree Torque is the thing.

Your mention of marine engines assisted in my recollection of the MEP engine i operated and maintained . A submarine engine during WWll had 2 cranks , upper and lower and of course , opposed piston so no heads . Worst engine i was ever involved with . I doubt any MEP contributed to winning WWll .

7394 said:

Long ago I had a 42" w/ 17.5 hp, & it struggled thru taller grass.. Next & got a 46" w/ 20hp. Breezed right thru same deal..

But agree Torque is the thing.

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Just think how I am doing with my 42" that had a 16.5 hp which now has a 21 hp on it. Just had to upgrade the deck belt as that 1/2" belt just couldn't handle the power. Started out barely able to cut slightly overgrown grass and now the walks thru 12+" grass.

SeniorCitizen said:

Your mention of marine engines assisted in my recollection of the MEP engine i operated and maintained . A submarine engine during WWll had 2 cranks , upper and lower and of course , opposed piston so no heads . Worst engine i was ever involved with . I doubt any MEP contributed to winning WWll .

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Anything like the Fairbanks opposed piston Diamond engine.
(this probably needs moved to the Front Porch)

7394 said:

Long ago I had a 42" w/ 17.5 hp, & it struggled thru taller grass.. Next & got a 46" w/ 20hp. Breezed right thru same deal..

But agree Torque is the thing.

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Was the 20hp a v twin?

SamB said:

Was the 20hp a v twin?

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No, it was a single cyl B&S..

StarTech said:

Just think how I am doing with my 42" that had a 16.5 hp which now has a 21 hp on it. Just had to upgrade the deck belt as that 1/2" belt just couldn't handle the power. Started out barely able to cut slightly overgrown grass and now the walks thru 12+" grass.

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Yes .
You can go too far down the bigger is better road
Oe of the local makes just kept on putting bigger & bigger engines in their mowers
Originally they were 7 x 24" , 8 x 30" 8.5 x 32
They ran standard polly V belts so were cheap to run and despite having the small decks can out cut most 42" ZTR's & run rings around any tractor style mower.
The name Fast Cut was quite accurate they are way faster than "the worlds faster mower" but that is of course if you accept that the USA is not the entire world.
Any way there things are great and a couple of my part time commercial customers use them particularly for rough cutting 4' tall weeds.
Plain belts , bushes on the deck lift cork plate varidrives so they ru forever and cost nothing to run.
Company got taken over by idiots who just kept on putting bigger engines in them
So the last model, before they went to the wall had a 26 Hp V twin driving the 34" deck
It ate kevlar belts and drive chains to the point that older models second hand were pulling higher prices than the current model new
I have slipped some 10Hp intecks into a few and those customers are pleased as punch with them .