Anyone want to explain engine specs?

[One Acre Farm]

Would love a fairly simple discussion explaining all the various specs one can read about engines. Basicaly, a crash course in bore/stroke, displacement, compression etc. Nothing too academic, but something I could use to compare one motor vs another. Any thoughts?

 

[RoyJackson]

Would love a fairly simple discussion explaining all the various specs one can read about engines. Basicaly, a crash course in bore/stroke, displacement, compression etc. Nothing too academic, but something I could use to compare one motor vs another. Any thoughts?

Just do a web search...whole bunch of layperson info on there.

 

[Dmace]

Here's some info on displacement, bore and stroke: Engine Specification | Truck Engines Specification Terms And Phrases Explained At engine-specifications.com

And if you really want to learn more about Diesel engines: HowStuffWorks "How Diesel Engines Work"

 

[McGeesEquip]

Would love a fairly simple discussion explaining all the various specs one can read about engines. Basicaly, a crash course in bore/stroke, displacement, compression etc. Nothing too academic, but something I could use to compare one motor vs another. Any thoughts?

When comparing the engine specs, also take notice of the engine RPM used to get the engine HP. The engine hp may be high, but is it due to being rated at a high engine RPM. Engines rated at a low engine RPM can have more reserved HP.

Sometimes the same engine will be used by one tractor source and rated at a given HP, and the same engine used by another tractor source and the HP rated differently because the engine RPM level.

 

[ModMech]

Horsepower is a mathematical calculation based on Tq available and the RPM at which the Tq measurement is made, nothing more.

Higher HP means you can accelerate faster (do more work).

Higher Tq means you can pull harder (move a bigger load).

Of course, assuming other factors are the same

Relatively longer stroke = more Tq, relatively larger bore = more HP (generally speaking).

Most "tractors" are diesels, so the compression ratio will be in the 15:1 to 23:1 range, lower for engines with "direct injection" or turbochargers and higher for those with Indirect Injection (pre-combustion chambers and glow plugs).

There are many different methods to measure "HP", if you are going to be using PTO driven impliments, PTO HP is the ONLY HP rating that matters. Unless there is a "Nebraska Test" rating, whatever numbers the manufacturer offers are wrong, generally way on the over-stated side.

An old farmer told me something that makes a LOT of sense, a "new" tractor will need about 2x the HP of a similarly sized "old" tractor to do the same job. Partially because the old models are HEAVY and can really pull and partially because of over-rating on the newer models.

 

[Ford tractor]

Compare PTO hp and drawbar hp. Take your pick based on what implements you will be using.


One other thing. Don't get too engrossed by the specs. As long as you have the power to do the tasks you need to get done -- how much HP over that amount is largely a lower order concern. It's much more important to your long term ownership to focus on the ergonomics of the machine. Do the controls fall under your hands? Is the seat comfortable when going over rough ground ? Can you easily look behind and below you (a very common position when doing about everything).