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Bull
09-18-2005, 11:40 AM
Does anyone have any information about a Toro ztr coming out soon with a 23 hp Kubota diesel? I would like to know as much as possible about this unit. Thanks

South Florida Lawns
09-18-2005, 03:54 PM
they should know some specs and maybe have a brochure. The Toro website doesn't show this mower yet so you might have to wait a while.

John Gamba
09-18-2005, 08:44 PM
they should know some specs and maybe have a brochure. The Toro website doesn't show this mower yet so you might have to wait a while.


It will probably be the XS.

John

Bull
09-19-2005, 02:58 AM
My dealer said that he will have one in October. They always set up a booth at the fair and said that he will show it there. He does not have any info on it however at this time. It is supposed to be a three cylinder which my understanding is you can get the same amount of work out of a smaller horsepower engine if it is a diesel as with a larger gas engine.

WREBELMACHINE
09-25-2005, 10:28 PM
not enough power in my opinion!

Texas Mower Parts
09-25-2005, 11:12 PM
It's a 25 Kubota diesel, just like the new 06' Exmark.

mowtech
09-26-2005, 12:01 PM
not enough power in my opinion!

If you have an interest in moving to diesel engines from gas my word of advice is to demo the diesel machines before discounting the lack of horsepower. There are several reasons for this.

First, diesel engines are generally rated more conservatively than gasoline engines. Instead of the horsepower look at and compare the engine’s displacement and you will see this.

Second, diesel engines normally run lean, this means that whenever it is overloaded it can actually increase torque by adding additional fuel. A gasoline engine cannot. Because of this, diesel engines will out lug a gas engine allowing you the operator time to adjust to overloads while a gasoline engine will generally stall. This means you want more and more horsepower on your gas machines to overcome this stalling. Diesel engines can be sized closer to the required load because they are harder to stall.

It will take at least a 30 horsepower gasoline engine to perform as well as a 23 horsepower diesel engine.

fool32696
09-26-2005, 12:45 PM
I agree with mowtec. Personally I'd take a 23hp diesel over a 30hp gasser any day of the week. The diesels run more efficiently (use less fuel). They are generally built much stronger (to handle the high compression ratio) and this leads to very long engine life. I've heard of Kubotas run into the 10000hr range in tractors. Also you can run off road diesel in them which I think runs about 50cents a gallon cheaper than on road diesel. Everyone here mowing with gassers is paying road taxes for cutting grass. As far as power goes, cutting grass is all about torque and that is what diesels do best. I would be willing to bet that the 23hp diesel makes more torque than the 30hp gas. It wouldn't surprise me if it made A LOT MORE TORQUE than the gas motor. The only bad things about a diesel are up front costs and heavy weight.

MBDiagMan
09-26-2005, 01:20 PM
Diesels make their torque at lower rpm. Horsepower is calculated as a function of torque and RPM withe RPM having an exponential effect on the HP rating.

The long and short of this is that a 26HP diesel makes MORE torque than a 26HP gas engine.

Have a great day,
Doc

mowtech
09-26-2005, 02:59 PM
Diesels make their torque at lower rpm. Horsepower is calculated as a function of torque and RPM withe RPM having an exponential effect on the HP rating.

The long and short of this is that a 26HP diesel makes MORE torque than a 26HP gas engine.

Have a great day,
Doc

Careful, Horsepower = Torque*RPM/5252. This shows a linear relationship between rpm and hp, not exponential!

When discussing diesel engines versus gas, make sure you don’t confuse the automotive application of engines to equipment such as mowers. In a mowing application the engines run at constant speed (you don’t push on the gas pedal for more power). Today on mowers, engine speeds between gas and diesel are comparable. At the same speed an engine with the same horsepower produces the same torque per the formula. On the other hand, a diesel that runs slower than a gasoline engine rated at the same horsepower would have to produce more torque to deliver the same horsepower, again per the formula. When we talk about torque in the fixed speed application; however, we generally are talking about “pull down torque”. A fixed speed engine slows down under load. This is because it can only produce so much horsepower so when it is asked to deliver more it can only slow down to compensate. Again this is per the formula. This is called droop. In a diesel as it droops under load the torque actually rises while a gasoline engine the torque remains flat. This torque rise will allow the diesel to lug longer and not stall. This is the performance advantage the diesel has in mowing applications and yes, the peak "pull down torque" under load of a 26 hp diesel is greater than a 26 hp gas engine and that greater diesel peak torque is at a lower speed.

Envy Lawn Service
09-26-2005, 09:15 PM
mowtech,

I sure welcome you here for your help in explaining diesel power v/s gas power.
I've been trying to "hammer-in" the advantages of diesels to these guys, but just haven't been able to put it the way you do.


Anyways, yeah, it's a 25hp Kubota powered Toro.
'Bout time Toro/Exmark hooked up with Kubota.

WREBELMACHINE
09-27-2005, 12:15 AM
Mowtech

I am probably the last guy you would need to explain diesel vs. gas. I have been converting to diesel for the last 3 years. I currently run a 27hp a 32hp and a 34hp diesel. and I still have my gas units that are being replaced. What I meant was if it is a kubota 23hp it is lacking in power compared to some of the other diesel engines that I have demoed.

Envy Lawn Service
09-27-2005, 12:37 AM
It's a 25hp and the answer is NO.
Even the 21hp Kubota's are strong... and the 22hp MaxTorque is WOW!
If the Kubota is a sales sucess for them, I bet they step up to the 28hp BOW-WOW!

TClawn
09-27-2005, 01:57 AM
Is kubota coming out with a two cylinder vertical shaft diesel? I heard something about it, but nothing certain. if they are not, I wish somebody would make one. I would love to have all diesel mowers, but the weight and having to depend on a dealer to fix the engine if it breaks down are the things that are holding me back.

Envy Lawn Service
09-27-2005, 02:14 AM
TC,

Yanmar makes that engine and has for a while.
Pretty much the same weight as a V-Twin gas.

Diesels are really not that extremely heavy like everyone says.
Check weights on Grasshopper mid-mount diesels against gas.
Then check diesel engine MFG weight charts.

You will find some of the mower MFG are responsible for the extreme extra weight.
Poor engineering... addition of counter-balance weights... ect.

grass disaster
09-27-2005, 02:23 AM
why would you buy a toro with a kubota motor... that doesn't say much about their product.

you don't see a kubota with a toro motor in it do you?


i think i'd just go and buy a kubota

Tonyr
09-27-2005, 02:27 AM
I had gas engines in my last 3 mowers, at the time I thought nothing could be better than my last, 28hp Kohler EFI.....

Until I bought my J.D 997, 31 hp diesel yanmar engine, this will hum away quietly, not die down as easy, so smooth, quiet, cheaper to run...

after experiencing the torque factor a diesel has over a gas, I sure would hate to go back to gas, I don't know why more people don't run diesel ZTR's.....


Then look at Hustler, 34hp CAT....now we are talking serious engines! :cool2:


ok, so they are a bit bigger.....it that really so bad?

TClawn
09-27-2005, 03:00 AM
TC,

Yanmar makes that engine and has for a while.
Pretty much the same weight as a V-Twin gas.

Diesels are really not that extremely heavy like everyone says.
Check weights on Grasshopper mid-mount diesels against gas.
Then check diesel engine MFG weight charts.

You will find some of the mower MFG are responsible for the extreme extra weight.
Poor engineering... addition of counter-balance weights... ect.

then why doesn't EVERY mfg have an air cooled compact Z with a diesel engine? I would buy it.

mowtech
09-27-2005, 08:33 PM
then why doesn't EVERY mfg have an air cooled compact Z with a diesel engine? I would buy it.

The Yanmar vertical shaft engine produces less than 19 horsepower, it is water cooled not air cooled, has an aluminum block, vibrates, and is very noisy, thats why.

mowtech
09-27-2005, 08:39 PM
why would you buy a toro with a kubota motor... that doesn't say much about their product.

you don't see a kubota with a toro motor in it do you?


i think i'd just go and buy a kubota


Perhaps it's because Kubota builds excellent diesel engines--that's what they are good at and most of the mower manufacturers know that. There are a lot of companies that focus on building very good mowers--many probably better than Kubota, but do not build engines.

mowtech
09-27-2005, 09:01 PM
Mowtech

I am probably the last guy you would need to explain diesel vs. gas. I have been converting to diesel for the last 3 years. I currently run a 27hp a 32hp and a 34hp diesel. and I still have my gas units that are being replaced. What I meant was if it is a kubota 23hp it is lacking in power compared to some of the other diesel engines that I have demoed.

Didn't mean to offend anyone. If you want more power go for it. It's just that diesels are relatively new to most in the landscape business (including the manufacturers) and I just want to make sure everyone understands the performance differences because many do not. If someone likes the power they have say with a 27 hp Kohler and they're interested in going to diesel, they won't need to spend the extra money for a 27 hp diesel or more to be happy--a 23 hp may suit them fine, but then again maybe not. Anyway, I'd hate to see any of you not go to diesel because of the cost of a larger one or buy too large of one and waste money on what you may not need. Diesels are not necessarily for everyone and I'm not trying to sell them, my purpose is to inform so hopefully everyone at least who reads these posts will consider the possibilities and make an intelligent decision. Anyway my advice is to demo before you decide, most will be surprised at the differences.

palm boy
09-27-2005, 10:41 PM
a 23 or 25 diesel is plenty hp for majority of lco's. I have a 23 mitsubishi diesel in a Ransomes front runner w/ 60"deck and it is plenty of power for the thick st augustine and bahia grass here.

Tonyr
09-27-2005, 10:56 PM
I can say one thing....sceptical at 1st, the 31hp yanmar in my J.D 997 has so much more grunt than the 28hp efi gas kohler ever could dream of....I never thought there could be such a large difference.

Diesel is clearly my choice from now on!

Only downside is liquid cooled engines take a little more checking, radiators and screens need to be kept clean, but once you get into habit it is ok.

Engine size....very rarely do I drop revs, but rather have too much than not enough, I from my experience in my work type wouldn't go under 30hp, but I do heavy work...

Bay de Noc Lawn Car
09-28-2005, 07:39 PM
The Kubota diesels are great. I have a 1989 718d grasshopper that runs a 61in. deck nicely. It has almost as much power as my 2002 725 grasshopper - Kubota gasser. :)

TLS
10-01-2005, 03:09 PM
I cant believe that Exmark/Toro has chosen a 25hp class engine.

The 27hp Diahatsu was adequate for the 60", but very underpowered for the 72".

Why on earth did they go LESS? A 28 or 30 for the 60" and a 34hp for the 72's is far better suited.

I had a Yanmar 22hp on my JD Front runners. Talk about gutless. When the going got tough, the smoke show started, and I simply had to slow down.

I'll have to demo one though and see for myself. I want MORE power, not LESS!

WREBELMACHINE
10-01-2005, 07:35 PM
TLS is right the kubota 25 hp is underpowered! I have demoed the zd28 and is was very lacking in power. Now it might have been not set up correctly but it definetly was lagging behind my 27hp lombardini and it is way behing my 32hp lombardini and 34hp dihatsu! I was told today by a exmark rep that they went with the kubota because it cost less than a dahatsu 27! I bet the price of the mower did not go down! Kubota makes a good engine but I wonder how long she will live when you have it in the governor constantly!

mowtech
10-02-2005, 09:46 AM
I cant believe that Exmark/Toro has chosen a 25hp class engine.

The 27hp Diahatsu was adequate for the 60", but very underpowered for the 72".

Why on earth did they go LESS? A 28 or 30 for the 60" and a 34hp for the 72's is far better suited.

I had a Yanmar 22hp on my JD Front runners. Talk about gutless. When the going got tough, the smoke show started, and I simply had to slow down.

I'll have to demo one though and see for myself. I want MORE power, not LESS!

A 27 horsepower diesel should have plenty of power for a 72-inch deck as I've stated before in many other posts, it should way out perform at 27 horse gas. I know that there were a number of Diahatsu diesels that were built with the injection timing off which can make a huge difference in their power output. Unfortunately as far as I know this was never recognized by Briggs and many of these engines were never checked for this. I believe this is why units with this engine often are considered underpowered--too bad.

Another thing when comparing engine power, keep in mind that engine manufacturers can be somewhat creative in how they rate the engine. So unfortunately you are not always comparing apples to apples. If power is your concern, I'd highly recommend you demo,

TLS
10-02-2005, 09:59 AM
mowtech,

Here is a thought for you to ponder.....

Just a few years ago, 60" ZTR's were equipped with 20hp Kohler twins.

Now they're equipped with 28hp EFI Kohlers.

To some 20hp was pleanty.

To me 28hp isn't enough.

Before you say what hp will and will not have pleanty of power, consider each operators need for power.

A 25hp Kubota Diesel engine simply isn't enough to properly power a 72" deck.

I'd like to see the power/torque charts for the Diahatsu and the Kubota. If the Kubota looks better than the Diahatsu, I'll change my tone.

WREBELMACHINE
10-02-2005, 08:44 PM
Another thing to look at would be the cid displacement between the kubota and the dihatsu!

ALarsh
10-05-2005, 12:15 AM
I know that there were a number of Diahatsu diesels that were built with the injection timing off which can make a huge difference in their power output. Unfortunately as far as I know this was never recognized by Briggs and many of these engines were never checked for this. I believe this is why units with this engine often are considered underpowered--too bad.

Do you know what diahatsu models this problem occured on? Should I be concerned if I am looking at buying a 2004-2005 diahatsu model?

Grass Man
10-05-2005, 12:46 AM
.... So far just a rumor :rolleyes:.


Does anyone have any information about a Toro ztr coming out soon with a 23 hp Kubota diesel? I would like to know as much as possible about this unit. Thanks

mowtech
10-05-2005, 02:43 PM
mowtech,

Here is a thought for you to ponder.....

Just a few years ago, 60" ZTR's were equipped with 20hp Kohler twins.

Now they're equipped with 28hp EFI Kohlers.

To some 20hp was pleanty.

To me 28hp isn't enough.

Before you say what hp will and will not have pleanty of power, consider each operators need for power.

A 25hp Kubota Diesel engine simply isn't enough to properly power a 72" deck.

I'd like to see the power/torque charts for the Diahatsu and the Kubota. If the Kubota looks better than the Diahatsu, I'll change my tone.


TLS,

I didn’t mean to be so presumptuous to tell you how much power you need. You obviously have to determine that yourself based on your conditions and what kind of performance you want. I understand the trend to more horsepower. Today decks have higher capacity and everyone wants to mow faster. My point is not to argue about how much is enough for you. I just would like everyone to understand the differences between gasoline engines and diesel engines so that you can make an intelligent choice. When it comes to performance they are not the same. A 28 horsepower diesel should easily out mow a 28 hp EFI. So just because the 28 EFI was not enough power for you doesn’t automatically mean a 28 horsepower diesel will not be enough power.

One thing to keep in mind with engines is that not all manufacturers rate their engines in the same way. Manufacturers of gasoline engines tend to be very liberal in their ratings. Diesel engine manufacturers tend to be more conservative. That plus the lugging ability of the diesel makes direct comparison between gas and diesel very difficult. Displacement can be a better way to compare engines, but you must also look at the actual speed the engine is running in your application. You get more horsepower out of the same engine if you run it faster. When I compare engines I try to look at power curves created by independent testing. I believe the Kubota in question is the Kubota 902D. At 3600 rpm this engine puts out just over 25 horsepower. As I recall the Daihatsu puts out something slightly less than 26 horsepower. So in reality there isn’t a huge difference. I don’t remember what the 28 hp EFI puts out, but I’m almost positive it’s less than 25 hp. Look at the displacements: 28 EFI=724cc, Daihatsu=952cc, Kubota=898cc. Anyway, I’m not saying that a 25 horse diesel engine makes sense with a 72 inch deck or even that a 27 horsepower diesel is enough for you. But what I am saying is don’t always take horsepower at face value. DEMO DEMO DEMO

TLS
10-05-2005, 02:51 PM
mowtech,

I understand what your telling me. And I'm fairly well versed in engines both gasoline and diesel.

All I'm trying to figure out is that for some reason, Exmark is blazing the trail nicely on their gasoline engines, but taking steps backward in their diesel development. With the current price of fuels, you would think they'd be the opposite.

Personally I'd like to see a nice little compact diesel with a turbo. Sip fuel when the going is easy, yet able to muscle through the nasty stuff with 50+ lb/ft of torque.

All this in a compact frame (ie. standard Lazer specs) and under 1500lbs.

mowtech
10-05-2005, 02:54 PM
Do you know what diahatsu models this problem occured on? Should I be concerned if I am looking at buying a 2004-2005 diahatsu model?

I know specifically of several cases where readjusting the timing solved the so called lack of power on these machines, but I don't know the extent of the problem or whether anything has been done about it. If you buy one it should be somewhat obvious--if the machine seems gutless verses a beast. If the machine seems underpowered for any reason I would have a diesel mechanic look at it and check the injection timing. This is easy to do and easy to fix.

mowtech
10-05-2005, 03:05 PM
mowtech,

I understand what your telling me. And I'm fairly well versed in engines both gasoline and diesel.

All I'm trying to figure out is that for some reason, Exmark is blazing the trail nicely on their gasoline engines, but taking steps backward in their diesel development. With the current price of fuels, you would think they'd be the opposite.

Personally I'd like to see a nice little compact diesel with a turbo. Sip fuel when the going is easy, yet able to muscle through the nasty stuff with 50+ lb/ft of torque.

All this in a compact frame (ie. standard Lazer specs) and under 1500lbs.

I agree--I think the ideal machine would consist of the most accepted frame and tire sizes (standard Lazer) with as much diesel hp you can pack in there. Most diesel machines today are too big and too heavy. However, I think you will be seeing more and more diesel options from everyone. It will be interesting to see what they are.

TLS
10-05-2005, 03:09 PM
I agree--I think the ideal machine would consist of the most accepted frame and tire sizes (standard Lazer)

Personally, I'd like to see a switch to 15" front casters and 26" rear tires.....Only get rid of the space fore and aft of the deck. Make the tires hug the deck real close. The new XP and XS are so stretched out. There is no need for this.

John Gamba
10-05-2005, 03:12 PM
The new XP and XS are so stretched out. There is no need for this.


Tommy
They ride better and are better balanced.

John

mowtech
10-05-2005, 03:24 PM
I think John is right, with the heavier engines the deck needs to be forward to counterbalance the extra weight.

TLS
10-05-2005, 03:49 PM
I realize this, however....my LC Kawi is on the heavy side, and I still was able to remove a weight block from the front. It's not stretched out.

Ride is better mainly due to the 26" tires. If they added the 15" fronts, you'd see an even better ride.

Dependable Mowing
10-05-2005, 05:17 PM
According to Toro's website, it is a 23 hp Kubota Diesel, w/ either 52" or 60" decks, which makes me think it's in the regular Lazer frame and not the XS/XP frame.

Dependable Mowing
10-05-2005, 05:31 PM
Also, the 25 hp Kubota Diesel that will be on the new exmarks should be more than enough to power those machines from my experience. A large horse farm that we mow has an older Kubota outfront 4wd with the same engine and a 60 in deck. It will go through really thick wet grass with very little to no bog, and that's also pushing 4wd and a shaft gearbox. It cut's like crap, but that's due to the old stamped deck design, not the engine. With the newer deck designs, the engine should have it easier I would think. I think Exmark is making a wise decision going to Kubota engines. The horse farms around KY use mostly Kubota mowers from what I can tell, with a lot of them being run all day and every day.

TLS
10-05-2005, 05:34 PM
Cut a 72" swath of 8" of thick growth down to 4", going uphill, at 8-10 mph, at ~19,000'/m blade speed with hight lift blades. The 42 lb/ft of torque Kubota will choke.

John Gamba
10-05-2005, 06:07 PM
Cut a 72" swath of 8" of thick growth down to 4", going uphill, at 8-10 mph, at ~19,000'/m blade speed with hight lift blades. The 42 lb/ft of torque Kubota will choke.


A Friend that has a 2001 26Hp FI said, when he tried the 31 60" going up a hill that he has with his mower it would bog a little, i said what did the XS do? He said he pushed on the levers and it popped a wheelie :p



Tommy try one please ;) You will never talk Liquid again :waving:

John

TLS
10-05-2005, 06:10 PM
John,

I DID demo both a 60" and 72" XS.

I was VERY happy with the performance (could always use more speed), but didn't like the fact that it's a 1500lb A/C ZTR. Plus, though the power of the Briggs impressed me, the sound did not. And, from what I hear, they are thirsty!

John Gamba
10-05-2005, 07:38 PM
John,

I DID demo both a 60" and 72" XS.

I was VERY happy with the performance (could always use more speed), but didn't like the fact that it's a 1500lb A/C ZTR. Plus, though the power of the Briggs impressed me, the sound did not. And, from what I hear, they are thirsty!

Cost offset???? Isn't that what the diesel heads say???????????

jtkplc
10-22-2005, 04:47 PM
Here is a link they listed in Turf Magazine. It talks about the new 23HP Kubota Diesel that will be on the Toro Z Master.

http://www.toro.com/professional/lce/whats_new/index.htm

TLS
10-23-2005, 10:34 AM
I saw that link the other day as well.

23hp??? :help:

They're claiming it's able to power through conditions that would strain a gas engine.

So I'm gonna take a guess as this is what they will use in the eXmark's as well.

Definately NOT going down to a 23hp.

Seems this is the effect of the engineering teams feeling the fuel price hike of Katrina, and downsizing engines to squeak better economy out of them.

Definately NOT the same engineers that worked on the XS.

KUBOTADAN
10-24-2005, 09:33 AM
I run two Kubota diesels. Can't beat them as far as engine performance.
I don't like Kubota's deck design, doesn't cut as good as some mowers.
I am looking at Hustler's 34 hp Cat . 70ft torque at 1800rpm. Engine will last
forever. But it's $16000. That price I will be the only operator.

mowtech
10-26-2005, 02:36 PM
I saw that link the other day as well.

23hp??? :help:

They're claiming it's able to power through conditions that would strain a gas engine.

So I'm gonna take a guess as this is what they will use in the eXmark's as well.

Definately NOT going down to a 23hp.

Seems this is the effect of the engineering teams feeling the fuel price hike of Katrina, and downsizing engines to squeak better economy out of them.

Definately NOT the same engineers that worked on the XS.


One final word on horsepower. Name plate ratings on Gas engines are normally what is called gross horsepower. That is what the engine will produce without a muffler, without an air-cleaner and without any accessories such as an alternator. Diesel engines tend to be labeled by their net horsepower, that is what they actually put out the PTO. This can make a huge difference. Let's compare the new Kohler 30 horsepower gas engine versus this Kubota D902 23 hp diesel engine. Displacement: Kubota, 898cc; Kohler, ~735cc. Maximum shaft output torque (Net): Kubota, 45 ft-lbs; Kohler, 38 ft-lbs. Which engine do you think actually puts out more shaft power and will have the best performance in the grass? Me thinks the Kubota.

TLS
10-26-2005, 02:40 PM
Where are you getting your Kohler specs from?......

Specs for the CH750 and CV750 models:
Power @ 3600 rpm
Maximum 30hp / 22.4 kW
Recommended 25.5hp / 19.0 kW
Displacement 45 cu. in / 747 cc
Bore 3.3 in. / 83 mm
Stroke 2.7 in. / 69 mm
Peak Torque CV750: 47.1 lbs.ft. (63.8 Nm) at 2600 RPM
CH750: 47.5 lbs.ft. (64.4 Nm) at 2400 RPM
Compression Ratio 9:4:1
Dry Weight 105 lbs. / 47 kg
Oil Capacity w/filter 2 US quarts / 1.9 liters
Dimensions (L x W x H) CH750 W/ heavy-duty air cleaner: 14.0” x 17.7” x 27.8”
CV750 W/ heavy-duty air cleaner: 20.5” x 17.7” x 22.5”

mowtech
10-26-2005, 03:01 PM
Where are you getting your Kohler specs from?......

Specs for the CH750 and CV750 models:
Power @ 3600 rpm
Maximum 30hp / 22.4 kW
Recommended 25.5hp / 19.0 kW
Displacement 45 cu. in / 747 cc
Bore 3.3 in. / 83 mm
Stroke 2.7 in. / 69 mm
Peak Torque CV750: 47.1 lbs.ft. (63.8 Nm) at 2600 RPM
CH750: 47.5 lbs.ft. (64.4 Nm) at 2400 RPM
Compression Ratio 9:4:1
Dry Weight 105 lbs. / 47 kg
Oil Capacity w/filter 2 US quarts / 1.9 liters
Dimensions (L x W x H) CH750 W/ heavy-duty air cleaner: 14.0” x 17.7” x 27.8”
CV750 W/ heavy-duty air cleaner: 20.5” x 17.7” x 22.5”


Couldn't remember the exact displacement. But the outputs in their specs for torque and horsepower as you are showing are GROSS outputs, not actual in the machine NET outputs. They are also showing wide open throttle data versus governed. My data is for machine configured engines with air-cleaner and muffler with governed output from actual engine dyno testing by an independent lab. This is how engines should be compared--as actually used. The differences are not unusual, they are typical of gas engines.

TLS
10-26-2005, 03:07 PM
I just discovered that they DON'T put this engine on the 72"ers. While it may be adequate for their 52" machine, the 60" will still be marginal at best.

Almost confusing....take a look at this chart supplied by TORO.....Interestingly enough it's comparing a 30hp gas to this 23hp Kubota.

http://www.toro.com/professional/lce/whats_new/images/chart.gif

jtkplc
10-26-2005, 03:14 PM
I just discovered that they DON'T put this engine on the 72"ers. While it may be adequate for their 52" machine, the 60" will still be marginal at best.

Almost confusing....take a look at this chart supplied by TORO.....Interestingly enough it's comparing a 30hp gas to this 23hp Kubota.

http://www.toro.com/professional/lce/whats_new/images/chart.gif

we need mowtech to explain the graph and tell us why the diesel is best, cuz i still don't quite understand.

mowtech
10-26-2005, 03:32 PM
Yes, I've seen this, that's why I tried to make the same comparison. Horsepower is tricky as in the past engine manufacturers have used different rating methods for labeling their engine horsepowers. So you are not always comparing apples to apples which obviously can be misleading and confusing. There is actually a class action law suit currently going on against small gas engine manufactures related to this horsepower labeling. Because of this, in the future we will see more consistent ratings across all manufactures which will make everyone's life easier when making engine selections. But in the meantime, consider that relative to horsepower ratings, diesels are generally rated on NET outputs while gas engines are rated on GROSS outputs which in general overstates what they really provide to cut the grass.

TLS
10-26-2005, 03:34 PM
Explain this.....

Kubota
http://www.kubotaengine.com/curves/gifs/D905.gif

mowtech
10-26-2005, 04:21 PM
Okay, the Kubota curves are wide open throttle curves. This is what the engine produces when used in a variable speed application such as a truck. Left side of the graph is the engine throttle pulled back to low idle while the right side shows the throttle opened all the way to maximum speed. The Kubota curves, for that matter those of most Japanese diesel manufacturers are quite accurate except that Japanese diesel fuel has slightly lower energy content than US fuels so they are slightly under what the engine will produce in the USA. Kubota is providing both NET and GROSS ratings on the graph. The INT means intermittent--they don't want you running the engine at full output all the time. The Toro curves shown are governed curves, particularly governed torque curves. This is how an engine is used in a mower. The graph shows the engine performance at the high idle setting where you generally run it while mowing. Right side of the graph shows the output under no load--at no load the output torque is zero and engine is running at its top speed. Torque is produced as load is applied. As you move to the left on the graph the output torque corresponds to the load--the further left you move on the graph the greater the load on the engine and the more it droops under load. What Toro is showing is that the Kubota puts out more torque than the 30 hp gas engine without saying that the Kubota produces more hp because then you would be getting into the horsepower rating question which is confusing (I think!)

I admit I have a bias to diesels because I've worked with them a lot over the years, but I am not trying to sell anyone on diesels. I've posted enough on the advantages and disadvantages. Only you can decide what is right for your operation. Only you can decide if the diesel is worth the added out of pocket cost. Only you can decide how much hp you need. My point only is to be careful when comparing hp, especially between diesel and gas engines. When it comes to price and things like fuel consumption and weight, if you compare a 30 hp gas engine to a 30 hp diesel to make your decision, you will not be comparing the right engines.