Any news on gas engine CUTS?

[SPYDERLK]

Again a "tractor" is too broad a brush. Somebody out ploughing 1000acres fulling an average of 180HP from 200HP engine from sunrise to sun set daily. That is a HD service diesel application .
Mr Retired out on his rural estate putting around on his CUT or SCUT "tractor "is not operating at full rated rpms from sunrise to sun set at full power for 1000hrs per season.
Mr Retired light and medium duty service is hauling a bucket of dirt to a flower bed, pulling a lawn sprayer , lawn roller , going to get the mail, carrying a bail of hay to the horse, cleaning stables . Cold starts to move snow is better with a spark ignition too.
Mr Retired will be hard pressed to put 100hrs a year on the CUT or SCUT . How much fuel savings is there going to be ? Zero.

Then again Mr Retired may run his HST tractor at full load for extended periods snow throwing or mowing or tilling. Its quite easy with infinite ground speed control.

 

[SPYDERLK]

engine RPM stress is totally different than crankshaft load. You need to account for the difference.

Yes, but no you dont have to account for the difference if you are at the rated working rpm of the engine. % full load then becomes the only variable.

 

[SPYDERLK]

Simple fact, light-duty engines like what we see in cars and light trucks can be damaged while operating within their RPM/load limits. Heavy-duty cycle engines normally can't hurt themselves even with an idiot operator....wide open throttle, in any gear, and they won't be damaged. That's the difference.



QUOTE]

Yep wide open throttle with an engine that is restricted by a mechanical device that is designed to keep the RPM from going into the danger zone where it will come apart. But yet I have seen many fail over the years just as I have seen gas engines fail!

By the way I am not sure when they started installing rev limiters on vettes but my 86 didn't have one and if it did it was way up past the indicated red line as I never found it and I am not the type that babies anything.
As for running sustained at a higher RPM for extended periods I have done that also! I honestly drove what would be about a 2 hour drive at the speed limit with nothing left but first gear in my Firebird after blowing the tranny at a back street race in the city! New tranny the next weekend and the engine never skipped a beat and Its still going strong today.

Not wide open throttle. High idle, whether governor or operator limited. An engine will reach top rated speed at very low "throttle" if it is only lightly loaded. Running long term, at rated rpm and full sustainable load is where diesels are superior. Categorically, they can be worked harder.

 

[DarkBlack]

Sigh.. So what's the "rated working rpm" of the Vette engine?

 

[SPYDERLK]

Ill guess 10% below redline.

 

[DK35vince]

You are saying that there is no turbo lag? We all know that can't be true

Believe whatever you want.
Meanwhile I will continue to run the turbo diesels every day with no notice lag.

 

[GManBart]

-Starting and stoping loaded is harder on an engine than a fixed continuos load in the power band.
(we probably agree on that)

-engines of any petroleum based fuel can run in their optimum power band they were designed for, for a long time.
(we probably agree on that)

-gas engines of years ago withstood the test of time. They were built much stronger then. Some probably stronger than a present diesel of similar hp. So not a great comparison for modern gas or diesel.
(we probably agree on that)

With that said I don't think a gas engine would be a total bust in cuts maybe not the best move but many have no interest in modern emissions diesels they are forced due to lack of options. A gas engine with today's ignition and fuel injection in a tractor would work. Yes some components would have to be beefed up. I don't foresee manufacturers spending money on R+D and production changes for this though. I have gas and diesel trucks and tractors. If I could switch my older gas ford to a multiport injected distributorless engine tomorrow I would because it's industry proven tough. Diesel tractors do their job and do it well I have no argument there.

Yep, pretty much agree with all of that.

 

[GManBart]

Uncle Putz out puttering around with his CUT, SCUT, off road ATV and lawn equipment . Has a similar duty cycle to a forklift.
A diesel is built for and works best at continuous full rated rpm and full load. Moving into the post 2007 emissions era with particulate filters. Particulate diesels do not fare as well idling, start-stop duty and putting around at part load at low rpm .anybody remember the tendency idling diesels to wet stack?

Sure, but not all folks putter around with the CUT or SCUT, so manufacturers have to build them to be on the heavy/strong/durable side if they want to avoid failures and warranty claims. Modern diesels are also a lot better about wet stacking than older designs.

As I've said all along, a manufacturer could make a DI gasser engine for SCUTs and CUTs that would work fine, but it likely wouldn't increase their sales at all, so it would be wasted development money on their part. Sure, they would be able to offer a somewhat less expensive option to customers (the exact amount is open to debate), but those same folks would be buying a tractor either way in most cases. I just can't see that making any business sense to them, and it's almost certainly why they aren't offered now.

 

[GManBart]

Again a "tractor" is too broad a brush. Somebody out ploughing 1000acres fulling an average of 180HP from 200HP engine from sunrise to sun set daily. That is a HD service diesel application .
Mr Retired out on his rural estate putting around on his CUT or SCUT "tractor "is not operating at full rated rpms from sunrise to sun set at full power for 1000hrs per season.
Mr Retired light and medium duty service is hauling a bucket of dirt to a flower bed, pulling a lawn sprayer , lawn roller , going to get the mail, carrying a bail of hay to the horse, cleaning stables . Cold starts to move snow is better with a spark ignition too.
Mr Retired will be hard pressed to put 100hrs a year on the CUT or SCUT . How much fuel savings is there going to be ? Zero.

The average SCUT/CUT owner seems to put about 200 hours per year on their machines, but saying it's mostly just light or medium duty is simply a guess on your part. Many of those folks use their machines to till food plots, rough cut fields with mowers, etc, and those are extended hours at PTO speed. That means the engine has to be built to withstand that for many thousands of hours...that puts them into a heavy duty-cycle. I'm not sure why you even reference large Ag machines that make 200hp....you don't think those are built even more heavily than the engines that currently go in SCUTs and CUTs? Seriously?

The fact that some folks never use their tractors at PTO speed for hours on end doesn't mean the machines don't need to be built to withstand that duty cycle.

 

[GManBart]

No, I made my point, but you missed it. Back to the OP's original post questioning a gasser in a tractor vs a diesel, for the same price a company could sell you a tractor with a much larger CC gas engine, that would make the same power at a low RPM as the smaller diesel. They don't do it because the gasser uses more fuel, the gas is more unstable and flammable. It's not because it can't survive. It could if it were also governed to 3k rpm's.

You're not "getting it" at all.

The main reason to offer a gasser option in tractors would be to lower the cost of the engine in the machine. If they keep the price the same and build the engine bigger it would be a dumb move on their part. Same purchase cost, higher fuel costs, and no increase in durability.....I don't see that as a successful business model. :confused2: