What gives diesels their strong low-end torque characteristics?

[silverpig]

Originally posted by: nourdmrolNMT1
just remember you can put diesel in a gas car and it wont blow up but dont ever put gas in a diesel engine or else you might not be around for us to see you!

A dumbass here at work put gasoline into a diesel machine (I work on a golf course... it was a 3 cyl diesel utility vehicle). All that happened was the engine stopped. The mechanic was scared that the injectors were shot ($800 a piece x 2 injectors per cylinder x 3 cylinders = lotsa $$$), but luckily all that he had to do was a full fuel system flush. Started right back up as good as the day before.

 

[Cyberian]

Originally posted by: Zenmervolt

does the fact that diesels don't have a throttle also have anything to do with it?

Well, sort of. Since the incoming air is un-throttled (ie, non-restricted) the pumping efficiency of a diesel engine is always at its maximum. When a gasoline engine is at anything less than WOT the engine must work to force air in through a restricted opening (the throttle butterfly) which takes away some of the power. Since a diesel always has a free-flowing intake, its pumping losses are minimised. Remember, an engine is basically an air pump, the more efficiently air flows into and out of an engine the more power you will get if all other things are equal.

ZV

How does air reach the combustion chamber of a diesel engine?

 

[CocaCola5]

A diesel's combustion is better they don't have to rely on spark plugs which are not always perfect(poor timing or fire).

 

[mAdD INDIAN]

Can't diesel engines run on cooking oil (organic oil) as well ? Remember, there are farms that do 'grow' diesel oil as well.

About the throttle issue, if they don't have a butterfly, how do they control the 'throttle' via the gas pedal? What does the gas pedal do then???

Also, anyone ever read up on the Peugot RC concept sportcars? They have two cars, both exactly the same except for hte engines. One has a petrol, other the diesel. Both are equally fast on the race track. It proves that you can have a sports car that has good mileage.

Finally, you know what has more torque than a diesel engine? An electrical motor. Which makes me think that if we had the right gearing couldn't we use electrical engines? After all you can't multiply horsepower but you can multiply torque to your advantage!

 

[Ultima]

Originally posted by: mAdD INDIAN
Can't diesel engines run on cooking oil (organic oil) as well ? Remember, there are farms that do 'grow' diesel oil as well.

About the throttle issue, if they don't have a butterfly, how do they control the 'throttle' via the gas pedal? What does the gas pedal do then???

Also, anyone ever read up on the Peugot RC concept sportcars? They have two cars, both exactly the same except for hte engines. One has a petrol, other the diesel. Both are equally fast on the race track. It proves that you can have a sports car that has good mileage.

Finally, you know what has more torque than a diesel engine? An electrical motor. Which makes me think that if we had the right gearing couldn't we use electrical engines? After all you can't multiply horsepower but you can multiply torque to your advantage!

Hmm.. isn't it you can get torque from power by gearing (A type-R engine with the right gearing would make a lot of torque at the wheel, but would be revving quite high), but you can't get power from torque (No matter how you gear it 200hp is 200hp)?

 

[silverpig]

Originally posted by: mAdD INDIAN
Can't diesel engines run on cooking oil (organic oil) as well ? Remember, there are farms that do 'grow' diesel oil as well.

About the throttle issue, if they don't have a butterfly, how do they control the 'throttle' via the gas pedal? What does the gas pedal do then???

Also, anyone ever read up on the Peugot RC concept sportcars? They have two cars, both exactly the same except for hte engines. One has a petrol, other the diesel. Both are equally fast on the race track. It proves that you can have a sports car that has good mileage.

Finally, you know what has more torque than a diesel engine? An electrical motor. Which makes me think that if we had the right gearing couldn't we use electrical engines? After all you can't multiply horsepower but you can multiply torque to your advantage!

We do have them. There are about a million electrical trolley busses in Vancouver (they look exactly like regular diesels, except they have two prongs that stick up and ride on wires above the bus). Funny thing is there is only one gear. The motor keeps spinning faster and faster as the bus goes faster.

 

[Eli]

Originally posted by: mAdD INDIAN
Can't diesel engines run on cooking oil (organic oil) as well ? Remember, there are farms that do 'grow' diesel oil as well.

About the throttle issue, if they don't have a butterfly, how do they control the 'throttle' via the gas pedal? What does the gas pedal do then???

Also, anyone ever read up on the Peugot RC concept sportcars? They have two cars, both exactly the same except for hte engines. One has a petrol, other the diesel. Both are equally fast on the race track. It proves that you can have a sports car that has good mileage.

Finally, you know what has more torque than a diesel engine? An electrical motor. Which makes me think that if we had the right gearing couldn't we use electrical engines? After all you can't multiply horsepower but you can multiply torque to your advantage!

Yes, it's called biodiesel.

I believe instead of a throttle, the accelerator adjusts the ammount of fuel the injectors deliver...

I don't think there's such thing as an electric engine. We have electric cars. The problem is that those very large electric motors really suck down the juice, and our best power source is rechargable batteries.

To whoever was mentioning compression ratio.. the thing is.. that the stroke has a lot to do with the compression ratio.. the longer the stroke, the more air/fuel is drawn in.. and the harder it's compressed on the upstroke...

 

[Zenmervolt]

About the throttle issue, if they don't have a butterfly, how do they control the 'throttle' via the gas pedal? What does the gas pedal do then???

The "throttle" is controlled by altering the amount of fuel injected into the cylinder. The mixture in a diesel is not constant because it doesn't have to be since only the fuel (and not a fuel/air mix) is igniting. Modern diesels control throttle by electronically altering the amount of fuel delivered by the electronic injectors. Earlier diesels had mechanical injectors which used plungers to deliver the fuel, stepping on the throttle pedal actually increased the stroke of the plunger which meant more fuel was injected. There is no throttle butterfly anywhere in the intake system of a diesel.

ZV

 

[Cyberian]

I believe instead of a throttle, the accelerator adjusts the ammount of fuel the injectors deliver...

I think we still need air for combustion.

 

[Eli]

Originally posted by: Cyberian

I believe instead of a throttle, the accelerator adjusts the ammount of fuel the injectors deliver...

I think we still need air for combustion.

Yes. The engine draws in air.. and begins compression. By the time the fuel injectors activate, the air is highly compressed.. the moment the fuel is injected, it ignites.

Someone correct me if I'm wrong, or there are other methods.

 

[Zenmervolt]

Originally posted by: Eli

Originally posted by: Cyberian

I believe instead of a throttle, the accelerator adjusts the ammount of fuel the injectors deliver...

I think we still need air for combustion.

Yes. The engine draws in air.. and begins compression. By the time the fuel injectors activate, the air is highly compressed.. the moment the fuel is injected, it ignites.

Someone correct me if I'm wrong, or there are other methods.

You're correct Eli. Diesels are always taking in the maximum amount of air, only the amount of fuel that is injected into the cylinder is varried.

ZV

 

[mAdD INDIAN]

Thanks guys!

I think auto manufactueres should focus more on bio-diesel fuels...seems like the next logical step?

 

[Eli]

Originally posted by: mAdD INDIAN
Thanks guys!

I think auto manufactueres should focus more on bio-diesel fuels...seems like the next logical step?

Perhaps. There are even better fuels than biodiesel, though.. like alcohol, and hydrogen. Although it is a step in the right direction.

 

[Demon-Xanth]

Personally, I think the next logical step is alcohol. But that's just my opinion. As far as compression ratios go, 24:1 isn't uncommon (at least in n/a diesels)

This story is paraphrased from another forum:
At a Carlisle car show someone was letting cars run on a dynojet. It could measure 1200HP and 1200Lb/ft of torque. Some guy came up with a street truck (Cummins Ram) and pulled 760HP.The torque reading was buried just off idle but was estimated to be around 2000Lb/ft of torque. He was running both Nitrous and Propane injection along with 60PSI of boost.

And check out this bad boy.

 

[Eli]

Originally posted by: Demon-Xanth
Personally, I think the next logical step is alcohol. But that's just my opinion. As far as compression ratios go, 24:1 isn't uncommon (at least in n/a diesels)

This story is paraphrased from another forum:
At a Carlisle car show someone was letting cars run on a dynojet. It could measure 1200HP and 1200Lb/ft of torque. Some guy came up with a street truck (Cummins Ram) and pulled 760HP.The torque reading was buried just off idle but was estimated to be around 2000Lb/ft of torque. He was running both Nitrous and Propane injection along with 60PSI of boost.

And check out this bad boy.

If gasoline ever becomes over 2.50/gallon, it would be cheaper to run ethanol. Barring the initial expense of conversion, anyway.

 

[Triumph]

Actually, as far as energy content goes, conventional Diesel tops the list at somewhere around 130,000 BTU/gal, followed by gasoline at somewhere around 115,000 BTU's/gal. All the other fuels, biodiesels, ethanol, butane, natural gas, fall pretty far below that. When you compare all of the energy required to reformulate and refine those fuels, gasoline and diesel still come out on top. Right now, with the current technology and infrastructure, we're doing the best we can. Of course, this isn'te the be all and end all of fuel advancements. If you're talking about other things such as power requirements, less complicated designs, etc., well that's a whole 'nother ball game.

I'm just pointing out that alot of people forget the overall efficiency of fuels. A perfect example is the electric car: Look it has no emissions! (That's right, they come from the power plant!) Same goes for biodiesels and the like. Sure it comes from corn, and it burns pretty clean. But it takes land, fertilizers, heavy trucks, refineries, energy, etc to make corn into a combustible fuel.

Oh yeah, diesels are neat. I drove an 18 wheeler once. 9 gears, and a 2000 rpm redline. Wooohoooo!!!

 

[Demon-Xanth]

The only reason why I say alcohol is because of the ability to produce it, not just dig it up. Pertoleum fuels have the limitation of there only being so much of it, alcohol can be produced by growing and distilling. Might not be as easy, but we might have to go there eventually.

 

[Eli]

Originally posted by: Triumph
Actually, as far as energy content goes, conventional Diesel tops the list at somewhere around 130,000 BTU/gal, followed by gasoline at somewhere around 115,000 BTU's/gal. All the other fuels, biodiesels, ethanol, butane, natural gas, fall pretty far below that. When you compare all of the energy required to reformulate and refine those fuels, gasoline and diesel still come out on top. Right now, with the current technology and infrastructure, we're doing the best we can. Of course, this isn'te the be all and end all of fuel advancements. If you're talking about other things such as power requirements, less complicated designs, etc., well that's a whole 'nother ball game.

I'm just pointing out that alot of people forget the overall efficiency of fuels. A perfect example is the electric car: Look it has no emissions! (That's right, they come from the power plant!) Same goes for biodiesels and the like. Sure it comes from corn, and it burns pretty clean. But it takes land, fertilizers, heavy trucks, refineries, energy, etc to make corn into a combustible fuel.

Oh yeah, diesels are neat. I drove an 18 wheeler once. 9 gears, and a 2000 rpm redline. Wooohoooo!!!

Yeah, this is true.. Still though.. we can't keep using gasoline forever.

Why isn't there synthetic gasoline?.. We can make synthetic oil that is several orders of magnitude better than dino oils, so why can't we make better gasoline? If all gasoline was perfectly uniform, I bet you could use that to your advantage in emissions control...

 

[desertdweller]

The two main factors (besides cubic inches) are stroke and compression.

The compression on the Dodge Cummins, for example, is around 25 to 1 whereas most
gas engines are between 8 and 9 to 1.

The reason there is a disparity between torque and horsepower when compared to
a gasoline engine, is because of the lack of timing advance.

If you were to completely take out the timing advance in your gas engine, it would act alot
the same way as a diesel. The reason turbo diesels run better is two fold; increased cylinder
pressure and the resulting earlier burn of the charge in the cylinder. (it effectively advances the timing)

DD

 

[Triumph]

Well, the combustion process is a bit different than the lubrication process...

 

[Eli]

Originally posted by: Triumph
Well, the combustion process is a bit different than the lubrication process...

Yeah, but they're both made out of the same thing. If we can build one hydrocarbon chain molecule by molecule, we should be able to build any. eh?

 

[Triumph]

Originally posted by: Eli

Originally posted by: Triumph
Well, the combustion process is a bit different than the lubrication process...

Yeah, but they're both made out of the same thing. If we can build one hydrocarbon chain molecule by molecule, we should be able to build any. eh?

i dunno, i barely passed freshman chemistry

 

[PG]

Originally posted by: Demon-Xanth
Personally, I think the next logical step is alcohol. But that's just my opinion. As far as compression ratios go, 24:1 isn't uncommon (at least in n/a diesels)

This story is paraphrased from another forum:
At a Carlisle car show someone was letting cars run on a dynojet. It could measure 1200HP and 1200Lb/ft of torque. Some guy came up with a street truck (Cummins Ram) and pulled 760HP.The torque reading was buried just off idle but was estimated to be around 2000Lb/ft of torque. He was running both Nitrous and Propane injection along with 60PSI of boost.

And check out this bad boy.

Wow, great link. Here's a cut and paste from one page:

We want to drive the Sidewinder to the Bonneville Speed Trials, towing our racing gear, with great fuel economy. Then we want to put on the proper wheels and tires and go racing. And, we want to eclipse the current National Speed Record. The current record for a pickup with this displacement diesel engine is 159 miles per hour. Along the way we intend to tour, slalom, truck pull and drag race the Cummins. The Banks Sidewinder will be a capable demonstration platform for them all.

As icing on the cake, we also want to eclipse our own overall FIA World Pickup Speed Record that was set in the GMC Syclone project at 204 miles per hour. 210 miles per hour will do it nicely. Damn revolutionary goals for a light duty diesel but... those are the goals!

 

[LAUST]

They almost make it sound cool, but they still have to swap the tires at the track

The Diesels from ATS roll up on street tires and run 11 seconds @ 5800ft and thats a big 6900lb Crew cab 4x4