PDA

View Full Version : Diesel vs. Gas engines on ZTRs


gbparn
05-04-2011, 01:14 AM
I am looking to buy a new mower and leaning toward a diesel (Ferris IS2500). But a small engine guy told me that he preferred a big gas engine to diesel engine because of torque. He said it was his experience that a gas engine could maintain blade speed better in thicker grass and he attributed that to the amount of torque the engine could produce. I had always understood that a diesel motor produced more torque over a gas engine, but he went on to say that was true only when you got into the higher horse powers (65hp and higher).

The other issue with a gas engine I wonder about is ethanol. The higher ethanol blends (E15, E20 etc..) are coming in the not to distant future and conventional gasoline will be harder and harder to find. I have been hearing the service guys (and recently EPA) telling me how hard ethanol blended fuel is on small engines. I don;t want to buy a machine that wont have an easily available and compatible fuel supply in 5 or 6 years.

Take costs out of the discussion and what are the advantages or disadvantages of either engine type.
Is there a cut difference?
Does a diesel "pull" better and keep on cutting on hills or rough terrain better than a gas engine or vice versa.
Does anyone know how the engine manufacturers are planning on dealing with the ethanol levels? Will fuel injection engines help resolve the problems ethanol causes in small engines?

Ridin' Green
05-04-2011, 02:00 AM
I can't answer the ethanol question for you, but I can speak to the deisel vs. gas issue a little.

I have owned a few deisel compact utility tractors in the 21-26 HP range, and one in the 40 HP range(4110,4115,4500 JD's. I still own the 4115), and all of them would/will out torque my comparable gas tractors equipped with identical mowers. (my 4110(21.6 HP) compared to my 445 (22HP) for one example). Not even close. The deisel wins by a noticable margin in thick or weedy grass.

I have never run a deisel ZTR, but I seriously doubt that having a gas engine on a ZTR could somehow make the gas engine superior all of a sudden. My ZTR has a gas engine, but if I had the funds to buy whatever I felt like, I'd buy a deisel without question. They're more fuel efficient too.

Both Deere and Kubota tout their deisels as the way to go for seriously heavy cutting.

Curtis
05-04-2011, 07:55 AM
I've always thought diesels were heavier, giving you a better chance to rut a residential yard in a rainy period. The diesels and fuel injected engines are looking more attractive with the price of gas these days .

MOHUSTLER
05-04-2011, 09:13 AM
I am a firm beliver in a gas engine. Diesels are more cost and more headache. On the plus for a diesel engine, they will run for thousands of hours. But so will a properly maintained gas engine.

The only people still buying Diesel mowers are farmers with fuel barrels. Other then that go with a gas engine.

vinny_a
05-04-2011, 11:19 AM
The only people still buying Diesel mowers are farmers with fuel barrels. Other then that go with a gas engine.

I disagree with that, lots of people are buying diesel mowers who aren't just farmers with fuel barrels.

My uncle who is the Highway Superintendent for a town up in MA just bought several diesel JD zero turns to maintain the township's sports fields because they last so long, and power through grass when its thick.

Last year I worked for a golf course on grounds crew and we bought a new Ferris diesel Z-turn and got rid of our old Toro gas Z-turn for the same reasons. I no longer work there but I still talk with my old boss and he says that they cut the same areas with the Ferris in half the time they did with the Toro (same deck size just different engines)

I used the Ferris briefly before I stopped working at the golf course last year to mow an area of 7"+ grass that we only cut every month or so (time saving purposes) and the difference was amazing. The Toro barely had enough power to move while cutting the grass but the Ferris just plowed right through it, didn't even slow down.

fireman9
05-04-2011, 11:35 AM
I just bought a used Hustler diesel and sold my Scag Wildcat ! The hustler has a 60" cut and 27 hp Shibaura diesel the Scag had 30 hp Kohler and 61"...
I was a little worried about cut issues with the XR7 deck because the Scag did cut nicely but it HASN'T BEEN an ISSUE. The XR7 cuts nice and at full speed too. I've cut massive amounts of grass that would have stalled the Kohler dead in its tracks even at a crawling ground speed with the diesel and it doesn't slow down... All things considered the diesel Kicks A$$ in the power & torque department. Plus I've mowed the first half of my route this past week and I've only used a half of a tank of diesel fuel as compared to emptying both the tanks on the Scag. I've mowed this route for the past two years with that gas eating pig and it's always sucked both tanks dry! I simply can't believe I have only used about half of one out of the two tanks of fuel on this machine. WOW! Looking forward to see how many hours both tanks can go for...

P.S---- I also own a FERRIS IS3100 and love it for the ride, It has the 26 HP Kawa, I knew it would be a little underpowered in the thick stuff, but thats not what I bought it for...flying over rough soccer fields it's great!

32vld
05-04-2011, 01:42 PM
I disagree with that, lots of people are buying diesel mowers who aren't just farmers with fuel barrels.

My uncle who is the Highway Superintendent for a town up in MA just bought several diesel JD zero turns to maintain the township's sports fields because they last so long, and power through grass when its thick.

Last year I worked for a golf course on grounds crew and we bought a new Ferris diesel Z-turn and got rid of our old Toro gas Z-turn for the same reasons. I no longer work there but I still talk with my old boss and he says that they cut the same areas with the Ferris in half the time they did with the Toro (same deck size just different engines)

I used the Ferris briefly before I stopped working at the golf course last year to mow an area of 7"+ grass that we only cut every month or so (time saving purposes) and the difference was amazing. The Toro barely had enough power to move while cutting the grass but the Ferris just plowed right through it, didn't even slow down.

Are you comparing apples to oranges?

What was the HP of the old Toro?

What is the HP of the new Ferris?

vinny_a
05-04-2011, 01:55 PM
Are you comparing apples to oranges?

What was the HP of the old Toro?

What is the HP of the new Ferris?

The old Toro (only a few years old) had the 27hp Kohler in it if I remember correctly. The Ferris has the 33 hp CAT diesel in it, so 6 hp difference which is significant but the Toro wouldn't even come close to cutting it. The area was on a very gentle slope so you could only cut going downhill, you had to turn off the blades and go back up the hill to cut another path because the Toro just couldn't handle it. The Ferris on the other hand had plenty of power going back up the hill. For what we used it for the Toro was a joke.

pugs
05-04-2011, 02:45 PM
The old Toro (only a few years old) had the 27hp Kohler in it if I remember correctly. The Ferris has the 33 hp CAT diesel in it, so 6 hp difference which is significant but the Toro wouldn't even come close to cutting it. The area was on a very gentle slope so you could only cut going downhill, you had to turn off the blades and go back up the hill to cut another path because the Toro just couldn't handle it. The Ferris on the other hand had plenty of power going back up the hill. For what we used it for the Toro was a joke.

You are comparing a ~750cc gas engine to a 1500cc diesel.

ClassicLawnCareInc
05-04-2011, 03:39 PM
If cost isn't an issue as the 1st post said there is no reason to not buy the diesel what so ever. I have 7 mowers, 2 gas and 5 diesel and the diesel wins hands down in ever dept. It has more torque, cuts thicker grass better, gets better mpg and is smoother. The only posible downside would be the fact that the diesel engine weighs about 150 lbs more, and i know as some people have said " on a wet lawn that makes a difference" I disagree. If your cutting a wet lawn any zero turn is going to leave ruts. And the diesel isnt more headahce or maintenance. It goes longer between oil changes and never breaks down for me personally. I have 3 john Deere 997 diesels, 2 Hustler diesels and two Wright brand gas stand ons. My oldest diesel has 1300 hrs on it my oldest gas engine has 1300 hours on it and Ive spent a good amount of money on repairs for the gas engine, and none on the diesel.

SouthSide Cutter
05-04-2011, 09:00 PM
If cost isn't an issue as the 1st post said there is no reason to not buy the diesel what so ever. I have 7 mowers, 2 gas and 5 diesel and the diesel wins hands down in ever dept. It has more torque, cuts thicker grass better, gets better mpg and is smoother. The only posible downside would be the fact that the diesel engine weighs about 150 lbs more, and i know as some people have said " on a wet lawn that makes a difference" I disagree. If your cutting a wet lawn any zero turn is going to leave ruts. And the diesel isnt more headahce or maintenance. It goes longer between oil changes and never breaks down for me personally. I have 3 john Deere 997 diesels, 2 Hustler diesels and two Wright brand gas stand ons. My oldest diesel has 1300 hrs on it my oldest gas engine has 1300 hours on it and Ive spent a good amount of money on repairs for the gas engine, and none on the diesel.

Got some friends one bought a 997 and the other bought a TT. And the 997 ruts worse than the TT. And my TT ruts worse than my TC, I just think the diesels are over kill for most lawns.

4 seasons lawn&land
05-04-2011, 09:14 PM
I would consider a diesel on a 72". Nothing smaller. Even the 72 would be border line/on the fence. Some of those smaller diesels out there actually cant compete with the big 30+ hp gassers. No experience to back that up, just what I have heard.

ClassicLawnCareInc
05-05-2011, 11:00 AM
One could argue that the diesel is over kill, I personally always say its better to have some extra or reserve power than to run at max all the time.

On the smaller diesels like my 2 hustlers it has 25 hp and it does a great job for small lawns. It has plenty of power, its a smaller machine and cuts better than my gas mowers.

blowerman
05-05-2011, 03:10 PM
I would consider a diesel on a 72". Nothing smaller. Even the 72 would be border line/on the fence. Some of those smaller diesels out there actually cant compete with the big 30+ hp gassers. No experience to back that up, just what I have heard.

Odd to give an opinion if you don't have experience... To say "Some of those smaller diesels out there actually cant compete with the big 30+ hp gassers."
While some might be true, my own experience we added a 25hp kubota diesel in a TT and have found our fuel usage savings of over 1 gal. per hour and power is equal if not better than our 30hp. + gas motors.

Minus the weight issue, the change over to diesel is well worth it!
That's my opinion with field data to back up my reasons!

Mark Oomkes
05-05-2011, 03:42 PM
I am looking to buy a new mower and leaning toward a diesel (Ferris IS2500). But a small engine guy told me that he preferred a big gas engine to diesel engine because of torque. He said it was his experience that a gas engine could maintain blade speed better in thicker grass and he attributed that to the amount of torque the engine could produce. I had always understood that a diesel motor produced more torque over a gas engine, but he went on to say that was true only when you got into the higher horse powers (65hp and higher).

The other issue with a gas engine I wonder about is ethanol. The higher ethanol blends (E15, E20 etc..) are coming in the not to distant future and conventional gasoline will be harder and harder to find. I have been hearing the service guys (and recently EPA) telling me how hard ethanol blended fuel is on small engines. I don;t want to buy a machine that wont have an easily available and compatible fuel supply in 5 or 6 years.

Take costs out of the discussion and what are the advantages or disadvantages of either engine type.
Is there a cut difference?
Does a diesel "pull" better and keep on cutting on hills or rough terrain better than a gas engine or vice versa.
Does anyone know how the engine manufacturers are planning on dealing with the ethanol levels? Will fuel injection engines help resolve the problems ethanol causes in small engines?

First off, find a new small engine guy. I wouldn't let this guy work on a tricycle. What an idiot.

If money isn't an object, go with the diesel, you'll be thrilled that you did.

Can't answer the ethanol questions.

I would consider a diesel on a 72". Nothing smaller. Even the 72 would be border line/on the fence. Some of those smaller diesels out there actually cant compete with the big 30+ hp gassers. No experience to back that up, just what I have heard.

Have you ever run a 72"?

Or a diesel?

Can't compete? On fuel usage, true enough, you'll be going through gas much quicker on a 30+ HP gas than a diesel. And be able to cut more grass, and taller\thicker.

As an aside, you might either want to listen to other people or just stop listening.

Odd to give an opinion if you don't have experience... To say "Some of those smaller diesels out there actually cant compete with the big 30+ hp gassers."
While some might be true, my own experience we added a 25hp kubota diesel in a TT and have found our fuel usage savings of over 1 gal. per hour and power is equal if not better than our 30hp. + gas motors.

Minus the weight issue, the change over to diesel is well worth it!
That's my opinion with field data to back up my reasons!

P-shaw, field data? My brother's uncle's cousin's sister's niece's nephew's grandma said gas was better.

I can't give actual gallons, but close. First Lazer we bought was a liquid cooled. On a long day or a lot of grass, we'd have to switch tanks sometime in the afternoon and use about half the second tank. Got an air-cooled for a demo once and ran out before noon on the first tank. The diesels I have now (Daihatsu crap) will run one tank dry a couple times a year. Barely.

If I could get diesels on my WB's I would.

Normal maintenance is no different than a gasser. Long term--on my Daihatsu's--I was screwed. They are crap, which explains why Exmark doesn't use them anymore. Still wouldn't keep me from buying another diesel Z.

gbparn
05-05-2011, 06:05 PM
I didn't say he was MY small engine guy. It was a small engine shop I came across in my travels trying to find a dealer who has a Ferris 2500 on the floor.

Concensus here is that a bigger gas engine does not outperform a diesel engine and the torque comment is bovine scat.

Someone in this thread mentioned they had a fuel injected gas engines? Which brands are using fuel injection? Will the fuel injection reduce some of the fuel issues that are caused by ethanol?
Are the engines in commercial mowers big enough that they really aren't having much issue with ethanol. Or is it the trimmers, saws and older boat motors the ones having the ethanol problems.

I have a JD 737 and have had problems with the 24hp Kawi on it. JD service tells me that some of the engine issues that mower is having are related to ethanol. I think its also related to bad design too.

4 seasons lawn&land
05-05-2011, 07:29 PM
Odd to give an opinion if you don't have experience... To say "Some of those smaller diesels out there actually cant compete with the big 30+ hp gassers."
While some might be true, my own experience we added a 25hp kubota diesel in a TT and have found our fuel usage savings of over 1 gal. per hour and power is equal if not better than our 30hp. + gas motors.

Minus the weight issue, the change over to diesel is well worth it!
That's my opinion with field data to back up my reasons!

uh that would be the reason for the second sentence. Can you read?

Mark Oomkes
05-05-2011, 09:12 PM
uh that would be the reason for the second sentence. Can you read?

No, but he can hear.

TWerner
05-09-2011, 09:34 AM
Huge Diesel Fan here. Even if it were just because they sound so much cooler when you first start them up.

The biggest plus for the diesel's isn't so much that it makes more torque, but that their torque curve is much flatter. If you always run your gas engine at full throttle and never lose any RPM's, then the diesel won't benefit you much from a power point of view, but it will save you a LOT of gas. Partly because they burn less at WOT, but also because you won't have to run WOT all the time. You'll have plenty of power at 70%.

If you're running more than 30 gallons of gas through your mower a week, and a diesel will take 15 gallons, how long does it take for a more durable engine that's saving you $250 a month in gas to pay for itself? Probably not long in Florida, but might be a while in Vermont with the shorter mowing season.

Todd

bamaturf
05-09-2011, 09:56 PM
i run gas & diesel. 25 kaw over 1 gal per hour likes gas
26 efi kohler 1 gal per hour
26 kubota diesel .63 gal per hour 9.5 gal into 15 hrs
bx 26 kubota tractor .52 gal per hr 3.4 gal into 6.5 hrs
this tractor was a rental for sat , moving topsoil & digging up stumps, has the
same 26 hp diesel as my zd326. amazed at the fuel mileage. most of the time
we run off road diesel @ 20 cents a gal cheaper than regular diesel

DLCS
05-09-2011, 10:15 PM
I have gassers and I have a diesel. My diesel is a JD 997 w/72" deck. The 997 burns 1/4-1/3 a gallon per hour. I had a 850a with a 72" before the 997 and the 31hp Kawasaki burned almost 2 gallons per hour. The extra cost of the diesel will pay for itself quickly with todays gas and fuel prices. I don't see how you guys who run these big block gassers can justify them over long term with todays fuel prices. Diesel is a better option today. I need to replace my 757's next year, i'm hoping Deere comes out with a smaller diesel in a small frame ztr, you listening Deere? BTW, i didn't buy a diesel for horsepower or torque. I bought it for fuel savings and longitivity.

KINGMADE
05-10-2011, 02:24 AM
Sounds like your small engine guy does not like to work on diesels. Diesel motor will out torque the gas one all day.

luckylawnboy
05-17-2011, 02:00 PM
I ran a ferris with the 3 cylinder 31 0r 33hp cat diesel is 5100. It was a useless piece of crap. Blade tip speed would drop just from from driving the machine. When cutting it would only mow at half speed if that in heavy grass. I loved the ride but the machine was way under powered. It needs a turbo in my opinion. I would like to try the Dixie Chopper or Bad boy as they use a 4 cylinder cat engine. I just dont understand why they are not putting turbos on these small diesel engines?

My z 970 with 37 hp gets 1.8gph but it cuts twice as fast as that ferris plus I paying a guy twice the labor if I buy a diesel. Dixie Chopper had a turbo Diesel that was 50hp but that mower was out dated.

Mark Oomkes
05-17-2011, 03:02 PM
I ran a ferris with the 3 cylinder 31 0r 33hp cat diesel is 5100. It was a useless piece of crap. Blade tip speed would drop just from from driving the machine. When cutting it would only mow at half speed if that in heavy grass. I loved the ride but the machine was way under powered. It needs a turbo in my opinion. I would like to try the Dixie Chopper or Bad boy as they use a 4 cylinder cat engine. I just dont understand why they are not putting turbos on these small diesel engines?

My z 970 with 37 hp gets 1.8gph but it cuts twice as fast as that ferris plus I paying a guy twice the labor if I buy a diesel. Dixie Chopper had a turbo Diesel that was 50hp but that mower was out dated.

They do, Kubota has a couple models in Toros that have turbos.

IIRC, that is the same model Ferris I demoed and it had plenty of power as well as the great ride. Just didn't like the cut quality.

Tall Rider
05-17-2011, 03:21 PM
Ok to add another monkey in the barrel right now lets throw another problem into the mix. Right now where I live diesel is $4.39 a gallon. Now couple that to the added cost of the machine and is having the diesel ZTR really more efficient or better right now in todays market? I take into consideration what type of use these machines would work in, heavy commercial or industrial and all I here about on here is how cheap that area of work is going for now. Normally in better times with cheaper fuel prices this is how these other company's could afford to bid these larger properties so cheap. Right now I don't see any added benefit of the diesel and the weight of one around here would rut something fierce. Does anyone know what a 2011 Toro 590D in a 60" or 72" goes for now? I remember they were close to 17K or 18K before and no one around here knows anything about Daihatsu engines. Anyone run one?

Mark Oomkes
05-17-2011, 03:37 PM
Ok to add another monkey in the barrel right now lets throw another problem into the mix. Right now where I live diesel is $4.39 a gallon. Now couple that to the added cost of the machine and is having the diesel ZTR really more efficient or better right now in todays market? I take into consideration what type of use these machines would work in, heavy commercial or industrial and all I here about on here is how cheap that area of work is going for now. Normally in better times with cheaper fuel prices this is how these other company's could afford to bid these larger properties so cheap. Right now I don't see any added benefit of the diesel and the weight of one around here would rut something fierce. Does anyone know what a 2011 Toro 590D in a 60" or 72" goes for now? I remember they were close to 17K or 18K before and no one around here knows anything about Daihatsu engines. Anyone run one?

Doesn't matter, run from the Daihatsu's as fast and as far as you can. They are the biggest POS engine's I have ever had the displeasure and expense of owning.

Worse than a Ford 6.0, and I have 3 of those.

Guaranteed within 1500 hours they will need a rebuild. Either the head will crack or oil consumption will be through the roof.

There's a reason Exmark stopped using these boat anchors and bit the bullet and are using Kubotas now.

TLS
05-17-2011, 03:50 PM
The biggest issue with diesel power is weight. This is true in light trucks, and in ZTR's.

A Kohler V-Twin weighs in just under 100lbs dry.

A.... (lets use Kubota) 3cyl 1L Diesel is over 200lbs dry. Now add 3 more quarts of oil, a radiator, hoses, fans, and coolant.

Adding 2-300lbs to a 1300lb ZTR is a BIG deal.

Especially when we have some rather excellent air cooled V-Twins these days.

This Kubota Diesel is 25hp and ~45lb/ft of torque. You can get a gas powered V-Twin that will blow it's doors off when it comes to power and RPM maintaining torque.

ZTR quality continues to improve, but for the most part, a ZTR is pretty worn out after 3K hours, no sense putting a 10K hour engine on a 3Khr ZTR. Especially when the diesel is adding thousands to the MSRP.

I'd love to have a little 1L diesel that's TURBO'd to keep torque up and maintain RPM's better. Don't know why manufactures dont explore this a little further.

TWerner
05-17-2011, 04:30 PM
I'd love to have a little 1L diesel that's TURBO'd to keep torque up and maintain RPM's better. Don't know why manufactures dont explore this a little further.

Cost! A small turbo would add more cost than a few extra cc's of displacement.

You make a lot of good points on weight, and on the engine outliving the frame. My experience with diesel engines is in tractors, and weight is not an issue there. In fact, my Kubota was a bit light.

I don't have enough info to crunch the numbers, but if a diesel uses 65% of the GPH, what is the fuel savings/season for a busy LCO. I'd think there would be much bigger savings on LCO's that manage huge properties where you put a lot of hours on the machine, and wouldn't spend a lot of hours carting a heavier mower around.

Fuel savings would seem to be the biggest benefit to a diesel. Plus they sound better than a gas engine LOL

Mark Oomkes
05-17-2011, 04:36 PM
Toro already has a 4WS and a Z with the Kubota turbo diesel. 32 or 33 HP something like that.

As for longevity, yes I figured that into it as well, but I think (if Daihatsu's weren't crap) that it would have paid off for me, and we don't mow as much as a lot of members.

Also, I wouldn't compare the weight of an air-cooled to a diesel, in fact, based on my experiences, I would never buy an air-cooled mower if a L\C is available, strictly due to fuel usage.

TLS
05-17-2011, 04:43 PM
I used L/C'd on several occasions over the past 30 years, and each time I had issues with coolant leaks, water pump leaking, hoses, etc.

As a blanket statement, unless a L/C'd version offered something an A/C'd didn't, I'd stick with A/C'd.

For instance, back in 2001, you couldn't get a ZTR with more than 25hp. Lazer offered the L/C'd Kawi and it was 27hp....I bought it for the 2hp....sold it for the complexity and leaks.

Mark Oomkes
05-17-2011, 04:48 PM
Interesting, we have very few problems with leaks. Or water pumps. Or hoses.

Been using L\C mowers since '79 when we bought our first Toro Groundsmaster 72 with a 19 HP Continental. Sold that one with over 4,000 hours on it, had over 6,000 last I heard. The other 2 we had both had over 4,000 before our first major engine problem. Otherwise normal tuneups and oil changes. Never had a water pump on those.

2 Toro 455D's, 1 Toro 4000D, a Howard Price 1260, Toro 3000-D, Exmark Lazer all had L\C since then. Coolant and leaks were never a major problem on any of them. Hard to say the cooling system was even a minor problem on any of them.

hackitdown
05-17-2011, 04:56 PM
Interesting, we have very few problems with leaks. Or water pumps. Or hoses.

Been using L\C mowers since '79 when we bought our first Toro Groundsmaster 72 with a 19 HP Continental. Sold that one with over 4,000 hours on it, had over 6,000 last I heard. The other 2 we had both had over 4,000 before our first major engine problem. Otherwise normal tuneups and oil changes. Never had a water pump on those.

2 Toro 455D's, 1 Toro 4000D, a Howard Price 1260, Toro 3000-D, Exmark Lazer all had L\C since then. Coolant and leaks were never a major problem on any of them. Hard to say the cooling system was even a minor problem on any of them.

Kawasaki L/Cs?

Cummins343
05-17-2011, 05:02 PM
All my mowers are kawasaki gas's with the highest one being 23hp. I also have a 72" Grasshopper ZTR with a 35hp Diesel. LOVE THAT MOWER! I've cut commercial accounts with it, accounts that would ultimately ruin a gas motor lol. I love that diesel. Doesn't burn as much fuel as a gas either imo.

gbparn
05-18-2011, 01:39 AM
Are there standard rpms the gas and diesel motor shafts turn? I understand the gas shaft turns at 3600 and the diesel turns at 2400. Some sort of industry standard for gas and diesels. If this isn't the case, I will keep looking for a mechanic.

TLS
05-18-2011, 05:05 AM
There are diesels that turn all different RPM's.

ZTR wise, I've seen 3000 and I've seen 3800.

heather lawn sp
05-18-2011, 07:25 AM
2 997's 2500 hours, 72 inch & 60 inch
Kubota GF 1800 500 hours
John Deere 757 800 hours, 60 inch
John Deere F725 2nd engine (chassis 2500 hours)
John Deere M655 2nd engine (chassis 2100 hours), 54 inch
Diesel consumption 189 litres (50 US gallons) a week
Gasoline consumption 200 litres (53 US gallons) a week


The 9's pull about 400 hours a year the 757 & 655 pull about 250 per year.

The little 18hp Kubota will keep up with the re-engined 25hp L/C Kawi F725, both 54"

TWerner
05-18-2011, 08:03 AM
2 997's 2500 hours, 72 inch & 60 inch
Kubota GF 1800 500 hours
John Deere 757 800 hours, 60 inch
John Deere F725 2nd engine (chassis 2500 hours)
John Deere M655 2nd engine (chassis 2100 hours), 54 inch
Diesel consumption 189 litres (50 US gallons) a week
Gasoline consumption 200 litres (53 US gallons) a week


The 9's pull about 400 hours a year the 757 & 655 pull about 250 per year.

The little 18hp Kubota will keep up with the re-engined 25hp L/C Kawi F725, both 54"

400/250 is 1.6. So if I read that correctly, your 3 diesels are running 60% more hours total, but burning 6% less gallons of fuel than your 3 gas mowers? That comes to almost exactly 41% less fuel burned.

I assumed the diesel and gas mowers were the same size and mow at the same speed. It's more than a 41% savings if the diesels cut more per hour.

Using $3.50/gallon to be conservative, and 50 gallons/week on gasoline, that's $175/week on gasoline versus $105/week on diesel. Buying ag diesel might make the savings a bit more, say $75, but even so, if you only save $25 a week on a mower running 400 hours a year, it will take a while for a diesel to pay for itself.

For a better analysis, I'd need the hours per week per mower.
Then I can plug in the numbers to show how much you save per hour on fuel. Again, I am assuming your diesels and the gas mowers cut the same area per hour.

Mark Oomkes
05-18-2011, 08:06 AM
Kawasaki L/Cs?

In what? :confused:

hackitdown
05-18-2011, 08:28 AM
In what? :confused:

Your lawn mowers.

heather lawn sp
05-18-2011, 08:33 AM
400/250 is 1.6. So if I read that correctly, your 3 diesels are running 60% more hours total, but burning 6% less gallons of fuel than your 3 gas mowers? That comes to almost exactly 41% less fuel burned.

I assumed the diesel and gas mowers were the same size and mow at the same speed. It's more than a 41% savings if the diesels cut more per hour.

Using $3.50/gallon to be conservative, and 50 gallons/week on gasoline, that's $175/week on gasoline versus $105/week on diesel. Buying ag diesel might make the savings a bit more, say $75, but even so, if you only save $25 a week on a mower running 400 hours a year, it will take a while for a diesel to pay for itself.

For a better analysis, I'd need the hours per week per mower.
Then I can plug in the numbers to show how much you save per hour on fuel. Again, I am assuming your diesels and the gas mowers cut the same area per hour.

The argument for area isn't completely relavent, The big diesel mowers are open terrain mowers, the smaller gas mowers are hill climbing & close quarter trimmers.

I'm working in litres here but the ratio's will be the same. Yes we are using marked diesel in the mowers.

Gas $1.205, 2621 litres 2010
marked diesel $0.9765

Season for mowing is 25 weeks

Excluding the small out front mowers as only auxilliary mowers, They will only burn a couple of gallons a week as back up's and specialty mowers, (steep hill work with 4x4, power sweeping, aerating).

Each 9 goes out with a Z gas. unit 1 72" and 54". unit 2 60" and 60". The 9's of course are slightly faster. I've got the gas at 4.22 L/hr about 1.1 US gallon /hr.

$5.06/hr 54 & 60 inch

Still working up diesel numbers

Mark Oomkes
05-18-2011, 08:33 AM
Your lawn mowers.

The Lazer had one.

The others were diesels. I don't think Kaw makes a gasser big enough to run those mowers. Or a fuel tank.

hackitdown
05-18-2011, 08:38 AM
400/250 is 1.6. So if I read that correctly, your 3 diesels are running 60% more hours total, but burning 6% less gallons of fuel than your 3 gas mowers? That comes to almost exactly 41% less fuel burned.

I assumed the diesel and gas mowers were the same size and mow at the same speed. It's more than a 41% savings if the diesels cut more per hour.

Using $3.50/gallon to be conservative, and 50 gallons/week on gasoline, that's $175/week on gasoline versus $105/week on diesel. Buying ag diesel might make the savings a bit more, say $75, but even so, if you only save $25 a week on a mower running 400 hours a year, it will take a while for a diesel to pay for itself.

For a better analysis, I'd need the hours per week per mower.
Then I can plug in the numbers to show how much you save per hour on fuel. Again, I am assuming your diesels and the gas mowers cut the same area per hour.

I tend to agree, the savings on fuel is small. I average 350 hrs each per year on two mowers. Based on a 40% reduction on my fuel consumption, I would save about $400 per year (per mower) on fuel by switching to diesel. So unless a diesel mower is more productive, and saves on labor costs, I don't think I can justify the up front expense of a diesel.

All things being equal (other than the engine), how much more does a diesel upgrade cost on a mower?

hackitdown
05-18-2011, 08:41 AM
The Lazer had one.

The others were diesels. I don't think Kaw makes a gasser big enough to run those mowers. Or a fuel tank.

Got it. I think the guy with the leaks was talking about a Kawi L/C engine.

Mark Oomkes
05-18-2011, 09:08 AM
Got it. I think the guy with the leaks was talking about a Kawi L/C engine.

I understood it to mean any and all L\C engines.

heather lawn sp
05-18-2011, 09:17 AM
I tend to agree, the savings on fuel is small. I average 350 hrs each per year on two mowers. Based on a 40% reduction on my fuel consumption, I would save about $400 per year (per mower) on fuel by switching to diesel. So unless a diesel mower is more productive, and saves on labor costs, I don't think I can justify the up front expense of a diesel.

All things being equal (other than the engine), how much more does a diesel upgrade cost on a mower?
Being rude and countering your question with a question, how big a mower?

Kubota ZD221 $10,368
Kubota ZG222 $7,754

. . . TW's assumption was for 3 mowers should be 2 out fronts are only auxilliary, and check his assumptions are with/without the marked diesel price.The 9's are 72 inch and 60 inch, 132 inches total. The gas are 54 & 60 inch 114 inches total. The 9's have 15% more forward speed. Statistically speaking 33% more area per hour. Last computation done was diesel at .9 gallon per hour.

So 33% more area
81% fuel cost
& 81 % fuel consumption

diesel over gas up to 2 x productivity

I'll verify 2010 marked diesel fuel consumption

heather lawn sp
05-18-2011, 10:27 AM
Being rude and countering your question with a question, how big a mower?

Kubota ZD221 $10,368
Kubota ZG222 $7,754

. . . TW's assumption was for 3 mowers should be 2 out fronts are only auxilliary, and check his assumptions are with/without the marked diesel price.The 9's are 72 inch and 60 inch, 132 inches total. The gas are 54 & 60 inch 114 inches total. The 9's have 15% more forward speed. Statistically speaking 33% more area per hour. Last computation done was diesel at .9 gallon per hour.

So 33% more area
81% fuel cost
& 81 % fuel consumption

diesel over gas up to 2 x productivity

I'll verify 2010 marked diesel fuel consumption

I lied

diesel fuel consumption was 4.72 L/hr or 1.24 US gallon per hour


So
33% more area
81% fuel cost
112% fuel consumption

fuel cost and consumption virtually cancel out (90%), same cost per hour leaving 33% more area per hour. Bear in mind the 997 cost about twice as much as the ZG 221. ($7,000 spread over 7 year of life)

997 $4.61/hr
665/757 $5.085/hr
The test becomes:

Can you save $1,000 or more a year in fuel to pay for the mower?

Our $3700 diesel bill would increase by $1,233 for gas

For us this works

One further wrinkle, note both our older gas engines were swapped out at around 2000 hours, the diesels are still around at 2500 hours

Question: Does anybody have the gas consumption of 72 inch Z-turn mower?

TWerner
05-18-2011, 11:33 AM
I lied

diesel fuel consumption was 4.72 L/hr or 1.24 US gallon per hour


So
33% more area
81% fuel cost
112% fuel consumption



Sorry for the errors. I did state my assumptions and say I needed more information.

I'm a little confused. You put 112% on fuel consumption, but previously said you were burning more gallons of gas in less hours than you were diesel. How did you come up with 112% fuel consumption? Was the gallons per week wrong? If not, then:

400hours/25weeks is 16hrs/week/mower->32 hours/week total 50gallons/32hours is about 1.6gph
250hours/25weeks is 10hrs/week/mower->20hours/week total. 53gallons/20hours is 2.65gph

Again, I get about 40% less gph.

Given the diesels are bigger and still moving faster, a diesel on a smaller deck mower might save even more GPH. I think $4 fuel savings/hour of mowing is a lot. Even $2/hour is enough to make the diesel pay for itself quickly if you mow large properties. If your mower runs 15 hours a week and rides on a trailer the rest of the time, diesel doesn't make much sense because you'll pay more to haul the extra weight.

hackitdown
05-18-2011, 02:32 PM
Kubota ZD221 $10,368
Kubota ZG222 $7,754

Ok, it sounds like the cost to upgrade to a diesel on a 54" mower is $2,600. If I can save $400 per year on fuel (I am running 52" mowers...close enough comparison for me), the break even point is 6.5 years at my 350 hrs per year, or at about 2300 hrs.

I have to think that a gas mower with 2300 hrs is at or past the end of it's engine life. Assuming a diesel will go a lot more hours, then the payoff is really big after the break-even point. A gas engine swap is a couple of thousand dollars, and presumably the diesel will just keep running.

Or am I missing something?

TWerner
05-18-2011, 02:44 PM
We need to clarify the GPH with Heather Lawn SP.

If the burn rate is 40% less, or a gallon less per hour on a 72" mower, then you save about $4/hour. That's the price of a gallon a gas plus the lower cost of a gallon of ag diesel. If you pay more for diesel, figure you'd save about $3.5/hour.

So $1200 to 1400/year in gas. Probably a bit less on a 52/54" mower, but still significant.

I'm not clear on the numbers from yet.
Sorry,
Todd

hackitdown
05-18-2011, 03:00 PM
We need to clarify the GPH with Heather Lawn SP.

If the burn rate is 40% less, or a gallon less per hour on a 72" mower, then you save about $4/hour. That's the price of a gallon a gas plus the lower cost of a gallon of ag diesel. If you pay more for diesel, figure you'd save about $3.5/hour.

So $1200 to 1400/year in gas. Probably a bit less on a 52/54" mower, but still significant.

I'm not clear on the numbers from yet.
Sorry,
Todd

I think it would be less on the smaller 52/54" mowers, since I'm only burning 1 gph of gas. Factoring in the higher cost of diesel, and the assumed 40% lower consumption, I would save about $1.15 per hour.

I will be mowing more hours this year (and in the future I hope), so the break-even date could be sooner. And if a diesel is somehow more productive, saving labor $$. As someone said, more hours, and bigger mowers make the best case for diesel.

Are they cheaper to maintain?

TWerner
05-18-2011, 03:23 PM
Hard to make it pay if you only burn one gallon an hour. Are they cheaper to maintain?

My tractor's diesel wasn't cheaper to maintain, it was the same as a gas engine. Filters and oil. I can't think of many other costs. It did get an oz of marvel mystery oil in every tank of fuel, but that's like scooby snacks for the dogs and cost a few bucks a year.

I'm curious, before that 2000hr mark where you buy a new gas engine, how much do you spend on engine maintanence? I've had to rebuild a carburetor because I left old gas in all winter, but other than that, I don't know what engine costs there are for you guys running gas mowers hundreds of hours a year.

Todd

hackitdown
05-18-2011, 03:35 PM
Hard to make it pay if you only burn one gallon an hour.

My tractor's diesel wasn't cheaper to maintain, it was the same as a gas engine. Filters and oil. I can't think of many other costs. It did get an oz of marvel mystery oil in every tank of fuel, but that's like scooby snacks for the dogs and cost a few bucks a year.

I'm curious, before that 2000hr mark where you buy a new gas engine, how much do you spend on engine maintanence? I've had to rebuild a carburetor because I left old gas in all winter, but other than that, I don't know what engine costs there are for you guys running gas mowers hundreds of hours a year.

Todd

Not too much really, oil and oil filter once per month, air filters twice a year, spark plugs here and there. I replaced a coil once.

heather lawn sp
05-18-2011, 03:38 PM
Sorry for the errors. I did state my assumptions and say I needed more information.

I'm a little confused. You put 112% on fuel consumption, but previously said you were burning more gallons of gas in less hours than you were diesel. How did you come up with 112% fuel consumption? Was the gallons per week wrong? If not, then:

400hours/25weeks is 16hrs/week/mower->32 hours/week total 50gallons/32hours is about 1.6gph
250hours/25weeks is 10hrs/week/mower->20hours/week total. 53gallons/20hours is 2.65gph

Again, I get about 40% less gph.

Given the diesels are bigger and still moving faster, a diesel on a smaller deck mower might save even more GPH. I think $4 fuel savings/hour of mowing is a lot. Even $2/hour is enough to make the diesel pay for itself quickly if you mow large properties. If your mower runs 15 hours a week and rides on a trailer the rest of the time, diesel doesn't make much sense because you'll pay more to haul the extra weight.

We have a large variance in fuel consumption. We can increase consumption 10 and 40% if it is a heavy growth week, such as this spring or if the trimming is falling back. In the middle of a dry summer consumption can fall. The deck loading can drink through more fuel than the mower speed. When trimming time is high in spring, the diesels get less time. In August trim time is minimal and productivity and diesel consumption surges ahead.
The numbers I used are season long, 3779.28 litres of marked diesel and 800 hours. We can mow 25 acres per day per unit, is that a lot?

The Kubota dealership voiced an opinion that gas to diesel of same horsepower might be 30% difference in consumption. Add to that $1.205 gas to $0.9765 diesel, cost per hour could be significant.

marked diesel 0.7 litre @.9765= $0.683
gas 1.0 litre @1.205= $1.205

There's your double factor

hackitdown
05-18-2011, 03:46 PM
We have a large variance in fuel consumption. We can increase consumption 10 and 40% if it is a heavy growth week, such as this spring or if the trimming is falling back. In the middle of a dry summer consumption can fall. The deck loading can drink through more fuel than the mower speed. When trimming time is high in spring, the diesels get less time. In August trim time is minimal and productivity and diesel consumption surges ahead.
The numbers I used are season long, 3779.28 litres of marked diesel and 800 hours. We can mow 25 acres per day per unit, is that a lot?

The Kubota dealership voiced an opinion that gas to diesel of same horsepower might be 30% difference in consumption. Add to that $1.205 gas to $0.9765 diesel, cost per hour could be significant.

marked diesel 0.7 litre @.9765= $0.683
gas 1.0 litre @1.205= $1.205

There's your double factor

Diesel is cheaper in Canada?

heather lawn sp
05-18-2011, 03:54 PM
We have a large variance in fuel consumption. We can increase consumption 10 and 40% if it is a heavy growth week, such as this spring or if the trimming is falling back. In the middle of a dry summer consumption can fall. The deck loading can drink through more fuel than the mower speed. When trimming time is high in spring, the diesels get less time. In August trim time is minimal and productivity and diesel consumption surges ahead.
The numbers I used are season long, 3779.28 litres of marked diesel and 800 hours. We can mow 25 acres per day per unit, is that a lot?

The Kubota dealership voiced an opinion that gas to diesel of same horsepower might be 30% difference in consumption. Add to that $1.205 gas to $0.9765 diesel, cost per hour could be significant.

marked diesel 0.7 litre @.9765= $0.683 3779.28 litres and 800 hours 4.72 L/hr
gas 1.0 litre @1.205= $1.205 2621 litres and 621 hours 4.22 l/hr

There's your double factor
or close to it

heather lawn sp
05-18-2011, 03:58 PM
Diesel is cheaper in Canada?

seriously cheaper

$1.205 /litre gas
$0.9765/litre marked/dyed/coloured diesel

Ridin' Green
05-18-2011, 03:58 PM
Diesel is cheaper in Canada?

They are refering to off road deisel, which has a different color dye added to it to signify that it wasn't taxed, but it's otherwise the same fuel.

OR deisel is cheaper than gasoline almost everywhere.

You don't want to ever get caught running OR deisel on the road in your truck though. That's one steep fine!

heather lawn sp
05-18-2011, 04:07 PM
Ok, it sounds like the cost to upgrade to a diesel on a 54" mower is $2,600. If I can save $400 per year on fuel (I am running 52" mowers...close enough comparison for me), the break even point is 6.5 years at my 350 hrs per year, or at about 2300 hrs.

I have to think that a gas mower with 2300 hrs is at or past the end of it's engine life. Assuming a diesel will go a lot more hours, then the payoff is really big after the break-even point. A gas engine swap is a couple of thousand dollars, and presumably the diesel will just keep running.

Or am I missing something?

you're on the right track

TWerner
05-18-2011, 04:31 PM
Diesel is cheaper in Canada?

off road or farm or agricultural diesel isn't taxed like the stuff at the gas station. they add red dye to it so if you get stopped at a weigh station and they dipstick your tank, you get fined. not an issue for a mower.

I have trouble making the numbers work for you if you only burn a gallon or so an hour. I'd check that number, but there's more to it than just that.

You'll also want to look into whether or not there's a place near you where could buy the offroad fuel and what they price it at for a small quantity.

Figure your time to get there and back, the price of gas you burn getting the diesel fuel ....

I love diesel, but hard to make a case for it saving you money if your mower is that efficient where you're mowing.

heather lawn sp
05-18-2011, 05:57 PM
Interesting observation made:
if gas engine is $2,000 plus to replace @ 2000 hours then that would make the cost of the mowers, in this example The Kubota ZD &ZG the same at 2500 hours $7,700 plus $2000 engine and install versus $10,370 for the ZD.Yes newer engine in the gas mower at 2500 hours but diesel saving @ $1.78/hour or $4,400 for diesel ZD221 @ 2500 hours.

So gas mower better residual value by three quarter of an engine life ($1500)
but diesel cheaper operation by $4,400 fuel savings. In line with the $400 a year suggested earlier.

(one of the engine swaps was found at a surplus centre for $975, a John Deere engine in a crate. As suggested the other engine was $2,160 with taxes)

geminibuddy
05-20-2011, 10:37 AM
If looking- remember there is a weight difference- my Kubota ZD60 cuts like crazeee and it does have more torque and sips fuel. The only downside is that if I were mowing small yards I would have trouble with the size/weight of it (#1300lb machine only)- But as for "knocking it down" I mow 3 acre lot of bermuda in 1.5 hours including edging/trimming/blowing that I have seen other mower take 2-3 hours and bogging. Mine is a great piece of equipment. One decision for me is the dealer/service is less than 2 miles away and I have access to diesel also.

heather lawn sp
05-20-2011, 10:40 AM
If looking- remember there is a weight difference- my Kubota ZD60 cuts like crazeee and it does have more torque and sips fuel. The only downside is that if I were mowing small yards I would have trouble with the size/weight of it (#1300lb machine only)- But as for "knocking it down" I mow 3 acre lot of bermuda in 1.5 hours including edging/trimming/blowing that I have seen other mower take 2-3 hours and bogging. Mine is a great piece of equipment. One decision for me is the dealer/service is less than 2 miles away and I have access to diesel also.

Exactly

We cut 50 schools a week with Z Turns. It's not a 'small time' machine. You have to pile on the hours to make it pay for the extra cost of the diesel engine over the gas engine.

TLS
05-20-2011, 01:55 PM
The only downside is that if I were mowing small yards I would have trouble with the size/weight of it (#1300lb machine only)

The ZD326 is a 1700lb machine!

Considering most gas 60" class ZTR's are 12xxlb machines, that is a LOT of extra weight. Not something you really want to be using on residential lots.

heather lawn sp
05-20-2011, 04:46 PM
The ZD326 is a 1700lb machine!

Considering most gas 60" class ZTR's are 12xxlb machines, that is a LOT of extra weight. Not something you really want to be using on residential lots.

. . . and the JD 997 is 1900 lbs

TLS
05-21-2011, 08:32 AM
The 60" 997 is 1774lbs

hackitdown
05-21-2011, 10:02 AM
The ZD326 is a 1700lb machine!

Considering most gas 60" class ZTR's are 12xxlb machines, that is a LOT of extra weight. Not something you really want to be using on residential lots.

We mostly cut residential...but the lots are large. 30K sq/ft lawns are not unusual. A small lawn around here is still over 10K sq ft (actual lawn area). The minimum lot size in my town is 2 acres.

The weight issue would concern me in the spring, when the ground is soft after the thaw and spring rain.

heather lawn sp
05-21-2011, 04:47 PM
. . . and the JD 997 is 1900 lbs

well . . . fuelled and 72"