Oil & Fuel Diesel Tractor HP vs. ATV or Car

[Gary Fowler]

BTW; slowzuki I do understand the differences between HP and torque and I like many others tend to use the terms interchangeably. Like I said in my earlier post I over simplified it and I knew it wasn't completely accurate. But the basic math "priniciple" still remains the same whether your talking HP or torque. I don't mean to be nit-picky and if I'm wrong I'm wrong. Through gearing if you half the speed you are going to double the work available. That being said this is a great forum for getting and giving information.

What you are missing is the speed that the work is done. If a certain amount of work is done with a 1HP whatever, then a gear is installed that reduces the speed by half, twice the work can be done but a 1/2 the speed so the HP calculation doesn't change. You could keep gearing it down and picking up heavier loads but the same amount of work would end up being done in a specified time.

 

[Redneck in training]

Sorry to bring up this post again but Ive been searching for something like this for really long and just found it.
I have a Jeep Common Rail Diesel engine which produces 250 Nm at around 2000 RPM and 105 HP at 3800 RPM. will this engine face similar problems with respect to peak capacity ? I wanted ti use this to build my own tractor and can't figure out whether its okay to do that. I researched a lot of car engines and found this to be quite similar. Any insight will be great.

Tractor engines are in general derated to quite low specific power 20-30HP/liter. That is why they last forever even while running at full throttle. Another thing is tractor engines have flat torque curve. Automobile engine would produce at least twice the power for the same displacement. It doesn't mean that you can't use Jeep diesel for a tractor.

 

[Gary Fowler]

Yeah, uh, I've got a JD 5105 rated for 50hp and a MTD Yardman mower rated 20hp (gas briggs & stratton). The mower is decent for mowing, but there's no chance in (anywhere) it will do 40% of the work that my JD diesel tractor will do.

The drive system is part - HST in the mower vs. gear in the tractor - but HST CUT's can do fine. As unscientific as this sounds, there are differences in horses between different engines and purposes.

Now, if the Yardman had the gear system of a Ford 8N, then maybe it would do closer to 40% of what my JD does...

Lawnmower engines sure have a different rating system or some mfg. are outright lying. I had a JD 332 with diesel engine rated at 16 HP and pulled a 54" mower deck. It pulled and cut at the same speed as my 26 HP Craftsman so how does a 16 HP keep up with a 26 HP and don't say its because one is diesel and the other is gasoline so the torque is higher. The 322 model gasoline equivalent had 18 HP and would likely be the same in mowing ability (don't know this for sure since I never owned one but very likely ) Many of the older iron mowers were only rated at 12-14 HP but pulled 38-42" decks all day long in heavy grass at comparable speeds to todays mowers with double the HP.

 

[Redneck in training]

I too have read that article and it does make sense. However, in the frozen north the water would prove a liability were as a Stirling could use a much different working fluid.

First you run the engine in 4 stroke mode to thaw the water and then switch to 6 stroke. The water tank would have to be designed not to rupture when water freezes.

 

[Soundguy]

Lawnmower engines sure have a different rating system or some mfg. are outright lying. I had a JD 332 with diesel engine rated at 16 HP and pulled a 54" mower deck. It pulled and cut at the same speed as my 26 HP Craftsman so how does a 16 HP keep up with a 26 HP and don't say its because one is diesel and the other is gasoline so the torque is higher. The 322 model gasoline equivalent had 18 HP and would likely be the same in mowing ability (don't know this for sure since I never owned one but very likely ) Many of the older iron mowers were only rated at 12-14 HP but pulled 38-42" decks all day long in heavy grass at comparable speeds to todays mowers with double the HP.

yep. lawnmowers are rated at near max rpm before they explode and with no accy on them, and speacial fuel mix settings the consumer would never see. in the lab when it hits that mark right befor eexplosion then they can badge that lawnmower for 25 hp even though it's the sige of a 3l soda bottle.