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View Full Version : 25 hp engine on a 72" deck


puppypaws
03-27-2009, 08:18 PM
How many people would consider running a 25 hp engine on a 72" deck? How much hp is necessary to handle a 72" mower on a normal commercial cutting route and do an acceptable job?

Who mows with 72" decks and what size engines run your mowers?

J&R Landscaping
03-27-2009, 08:31 PM
I ran a 25hp 72" Lazer Z for a previous employer every now and then. The mower was from 02-03 I think. It seemed ok but the pumps were smaller then they are now. It would bog down every now and then. If it were me and I was going for a kohler engine, I would try for the 30hp even though they aren't the best. The 25hp and 27hp kohlers only have 41.0 and 42.0 foot pounds of torque respectively. Not sure about a similar kawasaki unit. The 30hp kohler is putting out 47.1 ft pounds. The newer EFI units are nice. A buddy has one powering a 66" triton and he likes it a lot.

lawnboy2068
03-27-2009, 08:47 PM
Go read the post on the 72" SCAG owners a few threads below. You will ge all the info you need.

James

mag360
03-27-2009, 09:24 PM
A 25 kawi could handle it on a slower ztr. A buddy of mine had one on an early super z 72 and it did pretty well for weekly mowing---a little rough in the spring but the grass here is pretty aggressive.

Walk behinds are a different story. The older machines that had the 72 inch deck (there aren't any new ones that I'm aware of) had a lower blade tip speed than todays machines and the hydros robbed less power. Gear drive would be even easier. We had a 60inch goddall with 18hp and it did pretty well. Same story with an older scag 3 wheel rider, which is basically a walk behind. A 23-25hp kohler would be more than enough for these machines with a 72 inch deck.

More power is nice of course.

djagusch
03-27-2009, 09:32 PM
I didn't think of the 3wheel Scag even though I saw three last week. They run the 23 Kohlers. I guy in town has 5 72" and does the city and a lot of large area mowing. Couldn't get him on a ZTR if we tried (the 3 wheelers cost the same though). He has no problems with them.

mowerbrad
03-27-2009, 09:39 PM
I would never put a 25hp engine on a 72" mower. I would want close to 30hp or more for a 72".

puppypaws
03-27-2009, 09:54 PM
Go read the post on the 72" SCAG owners a few threads below. You will ge all the info you need.

James

I understand where you are coming from now, I just could not picture a 72" walk behind. I guess that is why they stopped making them.

I have no problem seeing a 25 hp engine on a 72" walk behind, there is not the additional weight of a ZTR for it to deal with.

tgaskill
03-27-2009, 10:28 PM
I have an Exmark 72" with a Kohler 25 on it that I've ran for 7 years now. The first 2 of those were only used at my house the next 5 it's on the truck. It was retired back to the house at the end of last season just because I got a great deal on a leftover 72". This thing cuts great really only slows down in super tall stuff (a first time cut on a foreclosure that hasn't been cut in 6 or 8 weeks) no different than any other machine I have. That's why I've never understood why all these guys are always saying I need some monster motor for some 50 or 60ish deck? If youíre doing weekly or even bi-weekly cut it's more than enough of a motor. If you're brush-hogging fields everyday well then you need a different machine not a bigger motor.

David Haggerty
03-28-2009, 10:29 AM
My Toro 325-D' have 25hp Mitsubishi diesels. They are just enough motor. Though the newer ones are 27hp Kubota.
But these machines have power saving features. Belt drive to the deck. Transaxle drive. Wind tunnel decks.

I can mow heavy grass at 5-6 mph with these. Couldn't imagine doing that with a gas motor or a machine with power robbing features like hydro drive etc. But I'm talking about cutting bluegrass in Ohio. Pretty heavy mowing conditions in the spring.

jtkplc
03-28-2009, 11:17 AM
I'm not so much interested in the HP rating but I would want at least a 850-890cc engine powering a 72" deck. I can get a 25hp Vanguard that is 896cc which would be fine with me on a deck that large. But Kawasaki's 25hp is only 675cc and would not be enough power for my preferences. If I had a mower with large pumps like a Super Z or Lazer Z XS I would want a 990cc engine to have the power I need. That's why my 72" XS has the 35hp Vanguard.

puppypaws
03-28-2009, 11:37 AM
I'm not so much interested in the HP rating but I would want at least a 850-890cc engine powering a 72" deck. I can get a 25hp Vanguard that is 896cc which would be fine with me on a deck that large. But Kawasaki's 25hp is only 675cc and would not be enough power for my preferences. If I had a mower with large pumps like a Super Z or Lazer Z XS I would want a 990cc engine to have the power I need. That's why my 72" XS has the 35hp Vanguard.

That 35 Vanguard is a mule, I doubt seriously you ever hear the rpm's drop cutting in any type situations. Those engines are amazingly powerful, most people can't imagine the power until they experience it for themselves.

jtkplc
03-28-2009, 05:16 PM
That 35 Vanguard is a mule, I doubt seriously you ever hear the rpm's drop cutting in any type situations. Those engines are amazingly powerful, most people can't imagine the power until they experience it for themselves.

I've had experience with a 31hp Vanguard on a 60" but when I demo-ed this machine I was blown away all over again. The power is absolutely amazing.

puppypaws
03-28-2009, 05:40 PM
I've had experience with a 31hp Vanguard on a 60" but when I demo-ed this machine I was blown away all over again. The power is absolutely amazing.

I took a 32 Vanguard and cut 30" and some taller Signal grass. I absolutely could not believe this mower would go through this without choking down, my 28 efi Super Z would not get started in this until it would cut off completely.

The 32 dropped about 200 rpm's, the grass was so bad it had to be cut twice. There was so much thick grass, 25% would not get cut in one pass but the engine never slowed down.