Oil & Fuel Gas vs Diesel PTO HP

tinytractors · Mar 17, 2005

This may sound strange..., but is 24 PTO Hp the same for gas and diesel. My thoughts are that it is... but the amount of torque available at that HP differs between a diesel and a gas engine.... and that is what sustains the work being done (more with diesel)... or is this just a case of apples/oranges.

Thanks, Pete.

DmansPadge · Mar 17, 2005

You are correct. The horsepower might be the same but diesels have more torque than gasoline engines. Torque is turning force. Both gas and diesels have appropriate applications. But if I'm using a tractor... I want a DIESEL!

Egon · Mar 18, 2005

It may all depend torque/rpm and how the engine is designed.

Egon

Dargo · Mar 18, 2005

Yes, the torque makes a huge difference in available power. For example, when I was going to buy a zero turn radius mower, I looked at several 25hp gas models and a 21hp diesel model. I had each brought out to my property to try. In the same height thick grass, the 21hp diesel model would mow considerably better than the higher 25hp gas mowers would. In fact, there was a huge difference. After doing the actual side by side comparison in tall thick grass, it really proved to me that for mowers and tractors, torque is what you need. Not horse power. Based on actual results, I'd say that you would need a 30hp gas engine to do the work of a 21hp diesel engine. That's a huge difference! PTO output would be similar.

ericinmich · Mar 18, 2005

I’m going to agree with most/all of what has been said, but want to add my thoughts for a very specific situation.

If both a gas and diesel engine running the same RPM (ex. PTO speed 2600) and have 25 HP available, then both are putting out (at that speed) the same torque. After all, HP is just torque times RPM.

So, if you had a 25 HP load on the PTO, and that load never when up or down, then the engines would feel like the same power.

But, in the real world loads are always changing, and many times we are not running the engine at PTO speed. That is where the differences are easily seen. A diesel has a flatter (or even negative sloping) torque curve, and a gas engine has a positive sloping torque curve.

The bottom line is that in real world use, where you run the tractors engine at 25% to 100% PTO speed depending on the task, a diesel is much better suited for the job.

- Eric

WilliamBos · Mar 19, 2005

............but if you look at dyno sheets of a gas vs a diesel the torque will peak sooner and last for a longer rpm. ADVANTAGE DIESEL.

just my 2 cents.

Will

hudr · Mar 20, 2005

I have operated three different fuel types of tractors..gasoline, LP Gas and Diesel. The diesels just don't seem to "lug down" as much when put under load. They may hammer and smoke, but they keep right on pulling. I have had all three fuel types in the hay fields with similar HP ratings and the diesels just seem to get more done on less fuel and with less strain. I still use an old JD 720 LP (2 cylinder) from time to time, but if I really need a workhorse, I climb on one of the diesel tractors.
Just what I have noticed from my seat.

Hypernix · Mar 20, 2005

hudr,

Just curious, what is LP Gas? /forums/images/graemlins/blush.gif

Hypernix

KiotiJohn · Mar 21, 2005

</font><font color="blue" class="small">( Just curious, what is LP Gas? )</font>
Liquid propane. In the tank it's liquid, but comes out as a gas. Used for stoves, furnaces etc. John