Any news on gas engine CUTS?

[SPYDERLK]

Lots of good thinking if you only can get past the sloppy comparisons so you can make sense of it. ... A revved engine is only at full throttle if it is carrying a full rated load. A non loaded engine running at it rated rpm is in a High Idle mode, putting out only enuf power to spin. The Corvette blew up at very low load - similar to hi idle. Something was wrong with it.

Forklifts never go for extended periods under hi load condition.

 

[GManBart]

Dang, I wonder why they put such oversized engines in them? Really they could just put a 5hp Briggs and Stratton in and be done with it. I mean since it takes no effort to do all that.

Nobody said anything like "it takes no effort to do all that." It's just a simple fact that fork truck engines don't get set at rated power and left there for hours on end, much less have the ability to take shock through the driveline the way a tractor engine does like when using a tiller or rotary mower.

I simply can't understand why people are so confused by this. Tractor engines are made the way they are, and cost what they do, because that's what's required to have an engine that will provide the power, reliability, and durability we expect from them. Tractors aren't cars or fork trucks or gensets, or any of the other things people want to use as comparisons, so the demands placed upon them are different.

 

[Loadstar]

Nobody said anything like "it takes no effort to do all that." It's just a simple fact that fork truck engines don't get set at rated power and left there for hours on end, much less have the ability to take shock through the driveline the way a tractor engine does like when using a tiller or rotary mower.

I simply can't understand why people are so confused by this. Tractor engines are made the way they are, and cost what they do, because that's what's required to have an engine that will provide the power, reliability, and durability we expect from them. Tractors aren't cars or fork trucks or gensets, or any of the other things people want to use as comparisons, so the demands placed upon them are different.

-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.

 

[buickanddeere]

Hint: My post said "SCUT/CUT". I know full well where they are and where they aren't ... that's kind of the point of THE LAST 44 PAGES!

We are saying the spark ignition engine will make inroads into the CUT and other light and medium duty equipment . Where Tier V emissions and where diesel costs more than gasoline or LP.
Kubota for example has a whole line of spark ignition engines. High compression DI engines in light highway applications are crowding the Tier IV diesel out. With mileage per btu near to or equal to diesel. Small Injected gas engines in lawn equipment and off-road vehicles provide diesel mileage where a diesel is not practical. The engines are out there now. Tier V emissions and when diesel prices rise again will push the spark ignition farther into the current light diesel market.

 

[buickanddeere]

We're talking about tractors, not fork lifts....sheesh.

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?

 

[Hinomotoman]

No one has mentioned compression ratios. If you tried to put 23/1 compression on a gasoline engine, it would be disasterous.

Eugene

 

[buickanddeere]

You're making my point. The engine in a fork truck is lighter, and cheaper because it can be lighter and cheaper and still not fail. That wouldn't be the case if you put that engine in a tractor. It would have to be heavier, and more expensive to survive. I was pointing out that a modern tractor engine of the same horsepower is (in this case) 50% bigger...there's a reason for that. The manufacturers aren't arbitrarily making the engine any larger or more expensive than necessary.

Short version....tractor duty cycles are harder than fork truck duty cycles and that changes engine requirements. For whatever reason, folks are trying to use fork truck engines as some sort of comparison they think is valid, but it's clearly apples-to-oranges.

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.

 

[buickanddeere]

No one has mentioned compression ratios. If you tried to put 23/1 compression on a gasoline engine, it would be disasterous.

Eugene

Please tell use how or why that is a valid line of reasoning and pertinent to the conversation . Btw the DI gas in Mrs B&D's ride runs just fine at 11.6 to 1 on 87 octane.
The "high" compression ratio is all about increasing thermal efficiency on the power stroke . When throttled the compression ratio maybe as low as 4 to 1 when cruising. This is where a throttled spark ignition beats a diesel's thermal efficiency at part load.
Have you ever seen throttle blades outside the first stator blades on a stationary gas turbine engine ? They are there to improve part load thermal efficiency.
Why do you think higher compression is better? Are you aware of how the basic Otto cycle Brayton design operates . It's all about effective pressure under the curve on the power stroke vs the average pressure in the compression stroke. The engine works by heating and thus increasing combustion chamber pressure after the compression stroke. The delta T and thus the delta P is lower when the combustion chamber is hotter rather than cooler. A high compression ratio has already used power stroke energy to dump more heat into the combustion chamber with high compression vs low compression .why do you think intercoolers are used on reciprocating diesel and on gas turbines between the compressor stage and combustion chamber ? To improve thermal efficiency , reduce max combustion temps and increase max possible full rated power.

 

[hutchman]

This is where a throttled spark ignition beats a diesel's thermal efficiency at part load.

I hate to bring up auto comparisons again but I can't let a comment like that stand ... there is NO straight gasser (and I'm even including those stupid little SMART cars) that can best the highway MPG of my 2002 VW Jetta TDI. Heck, I don't think there is one that can beat my 2006 TDI either so I'm tired of you spouting off how much more efficient the gasser is when it simply isn't so. If there was something out there (that wasn't as big as a pregnant roller skate) in a gasoline engine that efficient as you say I'd be driving it. I used to drive 1 1/2 hours one way to work ... I know what I'm talking about. It pains me I'm not driving an American car but cents per mile is what is important to me and I'm rolling in the vehicle that has that capability ... 13yrs old now and will still break 50MPG on highway ... speeding and AC blasting.

 

[hutchman]

I hate to bring up auto comparisons again but I can't let a comment like that stand ... there is NO straight gasser (and I'm even including those stupid little SMART cars) that can best the highway MPG of my 2002 VW Jetta TDI. Heck, I don't think there is one that can beat my 2006 TDI either so I'm tired of you spouting off how much more efficient the gasser is when it simply isn't so. If there was something out there (that wasn't as big as a pregnant roller skate) in a gasoline engine that efficient as you say I'd be driving it. I used to drive 1 1/2 hours one way to work ... I know what I'm talking about. It pains me I'm not driving an American car but cents per mile is what is important to me and I'm rolling in the vehicle that has that capability ... 13yrs old now and will still break 50MPG on highway ... speeding and AC blasting.

.... and before you try to call me a liar again like the last time we had this conversation maybe you need to spend some time reading here:

60 MPG / 900 Mile Club / 1000 Mile Club - TDIClub Forums

... because it's not just me and it's not some fluke!