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View Full Version : Fuel Consumption gas vs. diesel


ace56320
06-29-2006, 11:47 AM
I am considering switching form kohler's ch745 27hp engine to kubota's d902 25hp diesel, if I can save some money. Can any tell me what the gph ratings are on these engines?:confused:

mowtech
06-29-2006, 03:37 PM
At maximum horsepower output--

Kohler CH745 27hp will burn approximately 2.2 gph
Kubota D902 25hp will burn approximately 1.7 gph

Of course in normal mowing conditions both would burn considerably less with an increased fuel efficiency advantage to the Kubota engine.

TURF DOCTOR
06-29-2006, 03:43 PM
The cost over a diesiel to gas is high diesiel's run longer is it worth it seems breathing the diesiel fumes all day would give you a headache.

ProStreetCamaro
06-29-2006, 03:53 PM
What I really want to know is why does these small engines burn so much fuel? My 350 hp camaro SS gets 31 mpg but a my 23hp kawi burns 1 1/2 gallons per hour? Something doesnt seem right here. I understand that my camaro isnt maintaining a 3,600 rpm engine speed but the smaller engines shouldnt burn so much fuel.

probe1957
06-29-2006, 04:59 PM
What I really want to know is why does these small engines burn so much fuel? My 350 hp camaro SS gets 31 mpg but a my 23hp kawi burns 1 1/2 gallons per hour? Something doesnt seem right here. I understand that my camaro isnt maintaining a 3,600 rpm engine speed but the smaller engines shouldnt burn so much fuel.

I think that's a good question. I suspect it has to do with the power to weight ratio, but I have no idea.

ALarsh
06-29-2006, 06:26 PM
Why are my numbers giving me 1.05 Gal/hour on a 27HP Kohler air cooled?

I filled up the Z full & a 6 gallon tank at 250.7 HRS.

Now I just filled up again, the Z and the 6 gallon tank again and it was 18.349 gallons.

Now I have 268.1 HRS on the Z.

If i'm doing my math right, that means I used the Kohler for 17.4 HRS on 18.349 gallons which gives me 1.05 gal/hr???

What am I doing wrong?

mowtech
06-29-2006, 07:24 PM
Why are my numbers giving me 1.05 Gal/hour on a 27HP Kohler air cooled?

I filled up the Z full & a 6 gallon tank at 250.7 HRS.

Now I just filled up again, the Z and the 6 gallon tank again and it was 18.349 gallons.

Now I have 268.1 HRS on the Z.

If i'm doing my math right, that means I used the Kohler for 17.4 HRS on 18.349 gallons which gives me 1.05 gal/hr???

What am I doing wrong?


Probably nothing. Around 1 gallon per hour is a fairly typical average consumption rate for a Z mower. ProStreetCamaro's number of 1-1/2 gph seems high unless he is mowing in heavy conditions with a lot of hills. My number for the 27 hp of 2.2 gph is if the engine ran continuously at maximum horsepower. No one runs anywhere near maximum horsepower all the time.

ProStreetCamaro
06-29-2006, 09:49 PM
Probably nothing. Around 1 gallon per hour is a fairly typical average consumption rate for a Z mower. ProStreetCamaro's number of 1-1/2 gph seems high unless he is mowing in heavy conditions with a lot of hills. My number for the 27 hp of 2.2 gph is if the engine ran continuously at maximum horsepower. No one runs anywhere near maximum horsepower all the time.


I am giveing an average. This 23 kawi sucks fuel down worse than anything I have ever owned. Its between 1 1/4 to 1 1/2 gallons per hour which is high IMO.

kc2006
06-29-2006, 09:54 PM
when I had the 27hp kohler with the triton exmark for the month it was using almost 2 gallons an hour, right around 1.75-1.8 gallons an hour.

28efi is using a hair under 1 gph, about .8-.85 I love it.

mowerman90
06-29-2006, 11:21 PM
I switched from a 27/52 Super Z to a 28EFI/60 Super Z this year. I never measured the difference but it seems/feels like the 28EFI uses half of the fuel that the 27 did. I'm soooooooo glad I got the 28EFI.

dcondon
06-29-2006, 11:28 PM
Our 23 kawi is very hard in gas. If you run it more them 8 hrs you have to fill up both tanks. Now, our Kohler will go a day and a half without needing fuel. I would not go to a diesel for two reasons. One, Diesel fuel has been in the past few months more money here. The second reason is because the diesel moter is going to way out last the unit. JMO

slicksilverado01
06-29-2006, 11:32 PM
my ventrac with the vanguard 31hp turbo diesel burns a hair less then a gallon an hour. that is under normal mowing conditons. under loads it burn a bit more. plus the fumes arent so bad. but the black smoke is cool.:cool2:

the oil filter cost more then gas. plus I use off road diesel at $2.30 a gallon and I have a tank at home (300gallon) and on my trailer (30gallons) I am saving hundreds of dollars a month on fuel costs.

TLS
06-29-2006, 11:56 PM
when I had the 27hp kohler with the triton exmark for the month it was using almost 2 gallons an hour, right around 1.75-1.8 gallons an hour.

28efi is using a hair under 1 gph, about .8-.85 I love it.

WOW! I fill up tomorrow. I don't think mine is that good.

hosejockey2002
06-30-2006, 12:19 AM
My 350 hp camaro SS gets 31 mpg but a my 23hp kawi burns 1 1/2 gallons per hour?

Your 350 hp Camaro SS most certainly does not get 31 mpg when your foot is on the floor and you are using all 350 hp. The fuel consumption for the Kawi is probably at full throttle. I would bet your Camaro may get 31 mpg at 45 mph in high gear, on level ground or down hill. Either that, or you're just good at fish stories or bad at math....:dizzy:

green acres lawns
06-30-2006, 01:11 AM
my ventrac with the vanguard 31hp turbo diesel burns a hair less then a gallon an hour. that is under normal mowing conditons. under loads it burn a bit more. plus the fumes arent so bad. but the black smoke is cool.:cool2:

the oil filter cost more then gas. plus I use off road diesel at $2.30 a gallon and I have a tank at home (300gallon) and on my trailer (30gallons) I am saving hundreds of dollars a month on fuel costs.
My 72" Sabretooth tiger also has the vanguard 31 hp turbo diesel, and it burns about .8 gph under normal mowing conditions. It has a 10 gallon tank and I can run all day on a little over 6 gallons. I mow a 59 acre school system, so its not unusual to mow 4 to 5 hours non stop. We mowed and trimmed 33 acres in 12 hours last Saturday. My girl friend trims while I mow, then I grab a trimmer and help her finish. This school has 2 large playgrounds, 2 ball diamonds, 1 soccer field, a football stadium, open fields, islands, ditches, and lots of trees+ chain link fences to trim around. No spraying allowed.

mowtech
06-30-2006, 10:47 AM
I am giveing an average. This 23 kawi sucks fuel down worse than anything I have ever owned. Its between 1 1/4 to 1 1/2 gallons per hour which is high IMO.


Could be. I do not have dyno test results for this engine.

mowtech
06-30-2006, 11:12 AM
Your 350 hp Camaro SS most certainly does not get 31 mpg when your foot is on the floor and you are using all 350 hp. The fuel consumption for the Kawi is probably at full throttle. I would bet your Camaro may get 31 mpg at 45 mph in high gear, on level ground or down hill. Either that, or you're just good at fish stories or bad at math....:dizzy:


I agree. Which Camaro engine is he referring to? 350 horsepower? I would have to assume that is an older Camaro, perhaps 1970. But then, if that is the case, I would be surprised to learn that he gets 30 mpg. My recollection is that these cars got somewhere around 12 mpg. These engines were built back in the days when there where no mpg requirements for the manufacturers and certainly no pollution control. These engines used big Holley four barrel carbs that really sucked the gas. Anyway, if he is referring to a more modern version of the Camaro (I donít recall that they make a 350 hp engine anymore. I know they build an aluminum block V8 350 cubic inch engine that puts out maybe 305 hp.) But I donít claim to be any kind of expert on Camaros so pardon me if I am wrong. Anyway, these newer engines utilize state of the art electronic port fuel injected systems with sophisticated fuel management that result in high efficiency and improved mileage. To get 30 mpg I would have to believe this is what he would have to have, but 30 mpg still seems quite high. Anyway, this type of fuel system is part of the reason you seem to burn less fuel in your vehicle versus Z mower. (At 55mph and 30 mph you would be burning about 1.8 gallons per hour.) Now most of your two cylinder engines on your Z mowers are still carbureted. This does make the engine quite a bit less fuel efficient than todayís automotive engines. Note that Kohler does offer a 28 hp EFI engine with port injection that is considerably more efficient than other engines as mentioned in another post, but it has just not been popular enough for others to follow suit and for them to offer more models. Too bad. Now, besides this fact is how much of the power you are actually using. In an automobile cruising down the freeway at 55 mph you are actually using very little of that available horsepower. At 55 mph your engine is probably spinning at around 2 grand with maximum hp maybe up at 7 grand. This puts you somewhere quite a bit under 100 horsepower just to cruise. I donít have the curves to know exactly how much hp. All that extra horsepower is only used when you jamb on the foot pedal and are trying to accelerate as fast as possible. Now with your Z mower you are most likely using at least 50 per cent of the horsepower all the time in light conditions but, most likely more with heavier conditions. So the efficiency differences of the engines and the amount of horsepower actually being used should explain the difference in fuel consumption.

nmurph
06-30-2006, 01:29 PM
it had to be a typo..no one on here would ever exagerate!!!!!!! he must have meant 13 mpg....the max stock hp for a recent vintage camaro was 335hp. they were rated at 31 mpg highway with the 6 sp manual. that was because they were turning about 1400 rpm. romp on the thottle very much and they would return the same mpg as those late '60's/early '70's camaros, 12-13 mpg.

Randy J
06-30-2006, 02:01 PM
At maximum horsepower output--

Kohler CH745 27hp will burn approximately 2.2 gph
Kubota D902 25hp will burn approximately 1.7 gph

Of course in normal mowing conditions both would burn considerably less with an increased fuel efficiency advantage to the Kubota engine.


I would think mowing thick tall grass would give a large advantage to the diesel also, as thanks to the torque they should handle such situations better.

kc2006
06-30-2006, 06:44 PM
A good way to compair a car engine being used the same way a mower engine is being used is to look at nascar. Constantly at the peak rpm and peak hp going around that track. Thats how we're basicly running our mowers. I dont watch nascar so I have no clue what kind of mileage they get, maybe 4mpg (a couple of laps per gallon)? And they can do how many laps per hour? Laps per hours=gallons per hour :D Thats just a simple easy way to look at it.

topsites
06-30-2006, 06:52 PM
What I really want to know is why does these small engines burn so much fuel? My 350 hp camaro SS gets 31 mpg but a my 23hp kawi burns 1 1/2 gallons per hour? Something doesnt seem right here. I understand that my camaro isnt maintaining a 3,600 rpm engine speed but the smaller engines shouldnt burn so much fuel.

Carburetion.

I KNOW your camaro ain't carb'ed, cauz if it were, you'd be seeing 14-17mpg city, 20-odd hiway.
That you see 31 is wild too, most I ever saw in my T-bird was 28 but I guess that's close enough, still that was ALL highway.

TLS
06-30-2006, 11:59 PM
I got 1.23 g/hr last week and I just checked tonite and I got 1.45 g/hr.

This is full tilt mowing. Working it HARD.

My figures are full tank hours (8-10hrs), and are filled at the same station to the same amount in the tanks. In other words....Its pretty accurate.

I'll have to check during a "normal" growth week or a week in July/Aug when the grass is thinner.

jt13speed
07-11-2006, 11:30 PM
Does anybody have any figures for any X series John deere's? I have an X475 with 23hp kawasaki and i average about 4-4.5 hours on a 6.5 gallon tank. I also mow with an X595 diesel with 62inch deck and can mow for alittle over 5 hours on that with a tank of diesel.

Now a friend of mine is claiming that the guy who mows his lawn burns a tank of gas in about 1.4 hours...its an X485 25hp EFI. Is there any circumstance that is even possible? Apparently he mows at full 8.5 mph the whole time full throttle from the time he starts the engine to when it shuts off.

I have a 54inch deck and the 485 has a 62inch would that make to much of a difference to the fuel usage. I think there must be either a miscommunication or something SERIOUSLY wrong with that tractor. Feedback would be great thanks.