Starter Torque

[Egon]

It's gotta be the varying frictional coefficent of different metal chrystalline lattice form contact boundary layers subjected to thermodynamic pressure that make the difference Nomad. /forums/images/graemlins/tongue.gif

Egon

 

[mrcaptainbob]

Change youir name to SPEEDY! That's EXACTLY what I wuz gonna say! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gifBut ya beat me to it!

 

[bgott]

The 4 banger might have a starter that is starting to drag. Or it might be heavily carboned up, raising it's compression ratio. Or the timing could be over advanced. Or it could have been tested hot and the 6 banger was tested cold. Or it could have a dirty battery terminal. Lots of possible reasons. /forums/images/graemlins/smile.gif

 

[R_squared]

This post turned out to be a conundrum. I decided to post the starter curves because there was a lot of creative engineering going on. The curves were a practical viewpoint, but the test universe was limited - I ran out of personal vehicles to test. My neighbor has a 30 something Hp diesel Lamborghini tractor that I will try to ramp the next time I see him. All engines were tested cold. Some said that more specifications should be added to the engine and/or starter. That would have taken the fun out of the post. There really does not seem to be a clear cut generalization that can be made. The more you think about the frictional and electromechanical losses, the more sources you can come up with. The inrush current of the 4 cylinder diesel seems pretty high for a 4 cylinder engine, but the test universe is just too small to generalize on. I think that all we proved is that it was to close to call. Another thing this post proved is that there are a lot of good thinkers on this site. Some may be stinkers and drinkers to.

 

[nomad]

Yes, whenever Egon "drinks" he "stinks" and suddenly becomes a "good thinker" like he did above. See what he says above and try to smell the odor of his wisdom

 

[johnk]

Would the difference be more noticable if we were using a hand crank between the two?? Definitely would have to feel different with the increased compression in the diesel...Just thought I'd ask......................... /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

 

[Richard]

I've come to this thread late...but would it not be just as simple and reasonable to go back to say an old brand that had "dual" tractors? meaning, a diesel & gasser of the same model and simply compare their starters to see which is bigger?

 

[Soundguy]

Well.. speaking of that.. on the fords.. in the late 50's you could get the 8XX series in diesel or gas.. and that is why they switched over to 12v.. for the diesel engines. 6v didn't work so well due to the amount of copper the cables needed.. as it was.. the small gas jobs on 6v used 1/0 thick as your thumb cables.

Soundguy

 

[slowrev]

On the IH tractors the diesel starter is at least half again as long as the gas starter. Same model and just 1 CU inch difference displacement in the diesel and gas.

 

[Charlie_in_TX]

</font><font color="blue" class="small">( I've come to this thread late...but would it not be just as simple and reasonable to go back to say an old brand that had "dual" tractors? meaning, a diesel & gasser of the same model and simply compare their starters to see which is bigger? )</font>
Well that depends. If you are trying to answer the original question (without going back, it dealt with starter torque on a 30hp deisel vs a 6 cylinder jeep motor) then no. Comparing a 200 cu in deisel to a 200 cu in gas is not answering the question. I haven't seen anyone make the argument that a 25hp B&S is going to pull more current than a 25hp Kubota. That (or a 200 cu in gasser vs a 200 cu in diesel) is more of an apples to apples comparision on the face of it. It doesn't answer the original question.