Will Tier 4 lead to gas tractors again?

[buickanddeere]

Think of the crankshaft as a lever being pressed on by the connecting rod. The further the rod is pushing away from the crank centerline, the greater the leverage or torque. Short stroke high rpm diesel equals poor performance.

View attachment 479061

Attached is a perfect diesel cycle. Piston reaches top dead center and heat is added (fuel injected) keeping cylinder pressure high until mid stroke. The result is lots of leverage but a controlled burn. In basic terms, heat added at a constant pressure. The Otto cycle (gasoline engine) has heat added at a constant volume (TDC) and that peak pressure drops as the piston goes down. The result is lower torque, and to make up for it add cycles (higher engine speed). It's a simplification but for comparison, a Ford Ecoboost 3.5 has 365 HP and 420 ft lb while the 6.7 Powerstroke has 420 HP and 925 ft lb. both are direct injection. Max power at 5,000 vs 2,800. Remembering the old days and our gas tractors (maybe not so old as we still have 4 gassers around the place) they don't really get down and grunt when we hit a hard pull. They die. Most of our diesels really bear down and pull through.

Not so. Per cubic inch even the old carburated gas farm tractor engines mad more power and torque than the natural aspirated diesel . Check the Nebraska tests if you don't believe me.
With the same cam , same cylinder head , same compression and same displacement engine . The small bore/long stroke engine makes the same power as the short stroke/large bore engine .

 

[buickanddeere]

late to this...
We don't have small fuel efficient diesels because the big three don't make small fuel efficient diesels. They also have problems bringing affiliate diesels to the US because diesels are contrary to big ags position on ethanol. The EPA enforces that political position with anti diesel regulation.
We don't have great bio diesel from algae or other secondary waste sources because diesel doesn't have a great lobby in congress like corn does. Bio could solve several problems all at once: One of the best sources for algae is sewage waste runoff ponds. Turn human waste into bio, since we seem to be pretty good at creating more humans and waste this seems beneficial on many levels.
We don't have electric tractors or good cars for that matter, because Battery technology just isn't there yet. Electric motors however are awesome 100% torque at 1 RPM. Infinitely flat powerband up to the motors physical limitations. When someone comes up with a battery, neigh an energy storage mechanism, to power electric motors for a realistic run time, then well have something.

We don't have batteries yet because there is now way to increase energy density of batteries. If there was something better than lead acid, NiMH, alkaline and lithium to operate at room temperature and atmospheric pressure .
There is a set amount of ions in a pound of lead or lithium and that is it . No different really than there is 115,000btu in a gallon of gasoline .
Unless the Almighty adds some new elements to the periodic table. It's time for people to wake up and understand battery energy density is not going to increase.

 

[buickanddeere]

The determining factor is the length of time it takes the fuel to burn. Diesel fuel takes longer to burn hence lower rps. There are ways to cheat like a pre combustion camber.

Actually not . It is the short durection cam timing and the small valves from a small bore/long stroke design that choke off high rpm power due to the engine not being able to empty and fill the combustion chambers .

 

[vsteel]

We don't have batteries yet because there is now way to increase energy density of batteries. If there was something better than lead acid, NiMH, alkaline and lithium to operate at room temperature and atmospheric pressure .
There is a set amount of ions in a pound of lead or lithium and that is it . No different really than there is 115,000btu in a gallon of gasoline .
Unless the Almighty adds some new elements to the periodic table. It's time for people to wake up and understand battery energy density is not going to increase.

I remember talking to a PHD material engineer that worked on batteries and she said batteries do get better, just in small amounts. She said if they can get a 3% better in a year, it has been a good year.

There are much better energy storage devices than we use now, but there are other problems with them like size, or materials used or some other limiting factor.

 

[vsteel]

late to this...
We don't have small fuel efficient diesels because the big three don't make small fuel efficient diesels. They also have problems bringing affiliate diesels to the US because diesels are contrary to big ags position on ethanol. The EPA enforces that political position with anti diesel regulation.

The problems with bringing in diesels to the US are two fold.

First, to go through all of the government tests is a huge cost. A company needs to know they are going to sell a ton of vehicles or they are not going to recoup the initial investment to get it approved for sale in the US.

Second, diesels made in other countries have different emissions standards so are designed differently. US standards care about Nitrogen Oxides (NOx) and Particulate Matter (PM), while the EU worries about Carbon Dioxide (CO2) and Carbon Monoxide (CO). Basically European regulators are focused on fuel efficiency and American regulators are focused on smog and health impacts of air pollution.

 

[adventure bob]

"Second, diesels made in other countries have different emissions standards so are designed differently. US standards care about Nitrogen Oxides (NOx) and Particulate Matter (PM), while the EU worries about Carbon Dioxide (CO2) and Carbon Monoxide (CO). Basically European regulators are focused on fuel efficiency and American regulators are focused on smog and health impacts of air pollution"
I might buy your different environmental focus argument if there were data to support it. VW, MB, BMW, FC all have brought diesels to America with the same emissions control systems they run in Europe. Yes they had to go through very expensive EPA type certifications for those, the point is that they passed with the same systems they're running in Europe. Now if were talking about underdeveloped producers in third world countries like Tata, Lada Sun or some of those, your right; no way a Tata diesel is going to pass an EPA type certification. However the Big three aren't likely to go looking to those companies for engines. They're looking to their subsidiaries and partners in Europe and Japan. The same Bluetec benz here is the same Bluetec benz in Germany.

 

[RalphVa]

"Tier 4" in my VW Jetta TDI is leading me back to a gas engined car. Plan to pick up a Mazda3 next week.

Many new gas cars get 40 mpg just like my TDI and not soot burnoff problems like on the TDI (e.g. false "check engine" lights and boost alarms, due to sensor).

The Mazda3 I test drove seemed to perform as well as the TDI does. Not quite the torque, but it goes pretty much the way I need it to.

There are NO stick shift diesel cars with the demise of the VW TDIs. Been driving stick shift diesels for 40 years.

Ralph

 

[truckdiagnostics]

Actually not . It is the short direction cam timing and the small valves from a small bore/long stroke design that choke off high rpm power due to the engine not being able to empty and fill the combustion chambers .

Agree and the reason it is two short is because the fuel takes longer to burn than gas. You can cut the time needed down for scavenging(which is what I believe you are talking about) by adding a turbo on a diesel or making exhaust valves bigger or adding exhaust valves. They also use a pre-combustion chamber which helps. At the higher rpms you just do not have the time to get the fuel to burn complete enough in the time given, before the exhasut valve has to open. Slow the diesel down get your road speed by adding more gears now your getting somewhere. It would be interesting if you could get a CVT transmission to hold up behind a diesel, that would get you the needed gearing to run low speed high torque diesel in automotive application.

 

[buickanddeere]

I remember talking to a PHD material engineer that worked on batteries and she said batteries do get better, just in small amounts. She said if they can get a 3% better in a year, it has been a good year.

There are much better energy storage devices than we use now, but there are other problems with them like size, or materials used or some other limiting factor.

Cost, reliability, lifespan, toxicity, flammability.
Batteries have a hard limit in capacity just as does a gallon of gasoline . A battery is somewhat similar to a sponge soaked with water, most of the energy/water can be poured in and squeezed out of the sponge. However the battery like the sponge can not have all the energy/water removed.

 

[buickanddeere]

Agree and the reason it is two short is because the fuel takes longer to burn than gas.
No discernible difference.


You can cut the time needed down for scavenging(which is what I believe you are talking about) by adding a turbo on a diesel

No

or making exhaust valves bigger or adding exhaust valves.

Yes


They also use a pre-combustion chamber which helps.

only for starting a diesel with low compression pressure due to having a long duraction cam to allow improved volumetric efficiency at "high rpm" for high rpm power.

At the higher rpms you just do not have the time to get the fuel to burn complete enough in the time given, before the exhaust valve has to open.

No

Slow the diesel down get your road speed by adding more gears now your getting somewhere. It would be interesting if you could get a CVT transmission to hold up behind a diesel, that would get you the needed gearing to run low speed high torque diesel in automotive application.

There is "too slow" of rpms. Lowers combustion chamber temperatures .
CVT wastes power due to friction losses. Best compromise is the 6,7,8 or 9 speed auto transmissions with a lockup torque converter.