View Full Version : Hp ratings on diesel engine?
11-09-2002, 01:03 PM
I use a pair of diesel bladerunner mowers and I am extremly happy with them! Yesterday a dealer wanted me to try out a zd28 kubota rated a 28hp. It is a pretty nice machine I do not like all the gadgets and it is similar to the zd21 but overall pretty nice. My question is were are they getting this hp rating because it bogged a lot in the heavy leaves? Now I am not only saying that it was underpowered but I have also test drove exmark and encore with the 27hp briggs diesel and they to were very underpowered especially with a 72" deck. Now on the other side I have also test drove a dixie chopper with the 23.8hp engine that they call 26hp and it seemed decent or atleast it had more power than the briggs. I have a 27hp and a 32hp bladerunner and they both have lots of reserve power. So is the hp rating a sticker or do manufactures of these engines just rate them diffrently when they market them to the mower manufacture, or is it the mower manufacture that rates the power such as I beleve is the case for dixie? Or is there just that much diffrence in the diffrent brands of diesel engines?
I know it's a lot to digest but just currious as to what gives!
Maybe some of the manufactures of these mowers could explain the ratings.
11-09-2002, 02:40 PM
I am going to keep an eye on this post. I hope there is a lot of explanation on this subject!
11-09-2002, 06:20 PM
I do not know how all the manufactures rate there horsepower but I do know that some are rated in kw and sae ratings.
11-09-2002, 06:50 PM
What only us missouri boys going to comment on this post:D
11-09-2002, 11:18 PM
You asked, "So is the hp rating a sticker or do manufactures of these engines just rate them diffrently when they market them to the mower manufacture, or is it the mower manufacture that rates the power such as I beleve is the case for dixie? Or is there just that much diffrence in the diffrent brands of diesel engines?" The answer is, "all of the above, but not always at the same time."
On the Kubota ZD21, Model: D782-E
Displacement: 0.778 liter
Engine Family: 1K BXL 778 KCB
Code number: 1G009-0000
Engine Serial Number: 1E6163
Engine output as stated on the engine data plate that is attached to the engine: 14.4 KW. This converts to 19.2 horsepower, using the approximate formula of 1KW power output equals 1.333 HP. The advertised output of 21 horsepower is stated in my owner's manual as a "manufacturer's estimate." That estimate may relate to factory testing at 3600 RPM without any engine accessories. As installed in the ZD-21 the engine is governed to operate at 3200 RPM. Another possibility is that the engine puts out a true 19.2 horsepower at 3600 RPM and that the 21 horsepower data is advertising hype. The latter is my guess. Kubota has excellent engineering facilities and it is hardly necessary to estimate the power of their engines.
As one moves from consumer grade equipment to commercial grade, power ratings tend to become more realistic. Some engines are rated at 3600 RPM but then governed to a maximum of 3200 RPM or less for hydrostatic transmission durability and long engine life. It is tempting for a manufacturer to quote the 3600 RPM power output even though the engine power at 3200 RPM is much less. The ZD28, my opinion, has a more realistic power rating than the ZD21. The reason is that the ZD28 has a much larger displacement engine in relation to the claimed power output. Other thoughts are welcome.
11-11-2002, 06:54 PM
Hey shawn what are you doing driving a kubota?:D Just kidding!
Marvinlee is correct in what he is saying however there are some other factors as well! You mentioned the Briggs diesel on the Encore or Exmark vs. the Yanmar used on the Dixie. Here is a quick breakdown of the two engines the Briggs is 950cc rated a 27hp at 3600 rpm. The Yanmar is 1006cc rated at 23.8hp at 3600rpm. I do not remember the torque diffrence between the two but the yanmar has more torque due to the cc diffrence between the two. Another example is the lombardini 27hp that you bought recently it is 1028cc engine. Know another couple of things to consider on your bladerunner is the engine has a roller OHC in it which will free up hp! Also the tandem drive on the hydralics runs more effecient again giving you more available hp to the mower deck!
When shopping for a diesel always remember to look at the torque of the engine rather than the hp. Alot of people get hung up on 50hp or more but really never look at the torque of the engine which is what you need to cut grass! A good example is this we had a rotary engine that we prototyped for awhile. It put out 105hp but only had 38ft.lbs of torqe! Guess what! It was super fast running down the street but when you wanted to mow it was like driving a v-8 race car that had lost six cylinders!
I hope this sheeds some light to your question, there are also other factors that give more hp to the machine that I really can't go into detail on!
11-11-2002, 07:56 PM
I have the "26" hp. Yanmar on a 60" DC. This is my understanding about the difference in the plate on the engine and the rating that DC uses. DC wanted more hp than the Yanmar was rated so they turned up the fuel. If I understand this right that gives the engine more rpm's and hp. While my mower was still under warranty they did an "upgrade" and installed an electric fuel pump and some other things to make this all work. They also increased the rpm's if they were lower than 3725 - 3750. The reason for the new pump was because they said that the engine was not getting the proper amount of fuel by gravity feed.
Here is a rundown of HP and Torque values of various ZTR engine choices...
27....LC....Daih....44 N/A Diesel
31....LC....Daih....54.6 Turbo Diesel
As Kubota and Yanmar don't seem comfortable with posting their Torque values, I don't have them listed.
It's not just torque, its where this torque is AT in the powerband.
That 31hp Diahatsu Turbo Diesel is a real......"hoss" (hey I said it!) :D
Just wish Exmark would implement it into their lineup.
11-15-2002, 01:29 PM
Your yanmar engine on your chopper was not gravity feed on the fuel pump! It has a mechanical fuel pump on it from yanmar. The reason for the electric pump was for the guys that would run that engine out of fuel, it took forever to get it primed again. Most of the time when you did finally get it primed to start your starter was shot from all of the grinding. The solution was the electric fuel pump. On the yanmar 3tne74 engines that we tried there was no increase in hp with the electric fuel pump! As far as making the rpm of the engine faster that was just a governor adjustment just like you would have on a gas engine. The rating that you have on your engine plate is the true diesel hp rating on the yanmar engine the briggs is an automotive rating. The two rating are very much diffrent but both can be accurate if you are comparing apples for apples!
11-15-2002, 08:23 PM
I have been thinking about getting the Kubota ZD21 with the 60" deck because price wise its cheaper than any other diesel 60" on the market. I was worried it wouldnt have enough power due to only 21hp....I figure my 16vanguard is enough for me on my 48" hydro walk behind im not sure on the tq. with that does it compare ?
11-16-2002, 04:18 PM
What brands of diesel engines have you used on your machines?
11-16-2002, 04:48 PM
99% of all engine manufacters rate there hp. at the flywheel.. this is true for any engines, be it automotive, large truck, or lawnmowers. they rate the hp. with no accessorys on them. as a general rule (this is a broad statement and does not apply to all) the true hp. of any engine is somewhere around 18 to25% less than advertised. this means a 25 hp engine wil put out somewhere around 18.75 to 20.50 to the ground (or drive wheels)
11-18-2002, 06:33 PM
We have prototyped virtually every diesel engine on the market!
01-17-2003, 08:45 PM
These mowers are the HP that they are advertised. No gimmik or they wouldnt say it was. If they say its 27hp its 27 why anything else! end of story.
01-21-2003, 02:44 PM
Then why does the 23hp yanmar have more power than the 27hp briggs, or the 27hp lombardini have more power than the kubota 28hp?
01-21-2003, 03:15 PM
Its the way the power is put to the ground just how a Ford powerstroke with less HP than a chevy duramax can out pull it with a equal load but a Chevy duramax could smoke a ford powerstroke in a drag race without a load. Its all how that power is put to the deck and wheels.
01-27-2003, 07:41 PM
Very well put BUNTON GUY!:)
The fact is it is a combination of things that make one vehicle stonger than another, wether it be trucks or mowers.
01-27-2003, 08:14 PM
most diesel engines vs. gas engines have a greater torque at the same hp. level. Torque is where it is at, but you have to look for that number buried in the engine papers.
My favorite numbers game is the new KAW 29 hp engine. it has the same displacement, but with new electronics and computers, it makes 2 more horse. did the torque go up? if not, no real gain in mower power.
02-05-2003, 04:45 PM
Very interesting post! I would be currious to know what the torque ratings are for the briggs, kubota, yanmar and lombordini engines are!
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