Turbo diesels...

[Turbo6Smackdown]

How does the octane requirement work in turbo diesel cars? When you turn the boost up, what do you do about the fuel?

 

[forcefed3.8's]

Diesel don't rely on octane. Diesels run on cylinder pressure and heat, rather than a spark. Diesels make power with fuel rather than air. The side effect of the fuel is smoke and heat, you need the air, boost, to cool things down, and make a more complete burn. Extra fuel makes more boost, with no other changes. The smoke means power to a point. If you could use the same amount of fuel, but add more air to clean up the smoke, then it would make more power, as the fuel would be burned more completely. My Duramax made around 21psi stock, and now 32psi with more fuel with no wastegate mods. It smokes like crazy, and EGT's are very high.

 

[TURBO 6]

Diesels require Cetane. The higher the cetane number the more power the engine can make.

 

[joe_schindler]

How does the octane requirement work in turbo diesel cars? When you turn the boost up, what do you do about the fuel?

Diesel works differently. While diesel has a very low Octane value (25 to 30); it contains more energy (about 10% more BTU). The CN number is more of a rating of how fast you go from ignition to combustion.

A diesel engine works very similarly to a gasoline engine; in that fuel is burned with oxygen to create power to spin the flywheel. Not all diesel engines are supercharged; and wouldn’t survive if they were. The diesels that are built for supercharging (turbocharged) are simply designed to take the additional stress. They still have a limit.

You might notice that most of the new diesel cars and trucks don’t smoke much.

 

[Dabigguy]

Wouldn't it make sense to tune the truck where it burns all of the fuel that is blowing out of the exhaust which equals more power for the same amount of fuel consumed?

Why do the heavy hitters smoke?

 

[Turbo6Smackdown]

I see. So could I turn up the boost on say, a disel rabbit? When I go to the pump, I don't normally see choices of desiel fuel... why is that?

 

[forcefed3.8's]

Wouldn't it make sense to tune the truck where it burns all of the fuel that is blowing out of the exhaust which equals more power for the same amount of fuel consumed?

Why do the heavy hitters smoke?

If you could cram more air in, it would make more power, but adding the fuel itself makes power too. Bank's Duramax doesn't smoke, but he is running alot of nitrous.
Turning up the boost won't really make too much more power without more fuel. Air isn't the primary power maker. It is just needed to complete the combustion process. Gas engines work off air, diesels work off fuel.

 

[BOOSTBROTHER]

Diesels need 2 things to make power fuel and air, the more you and the power you get. The more power you make the more heat it makes.
EGT HEAT KILLS DIESEL!
you can run most diesels all day long working them HARD and not hurt them as-long-as you don't get them HOT.

 

[joe_schindler]

Wouldn't it make sense to tune the truck where it burns all of the fuel that is blowing out of the exhaust which equals more power for the same amount of fuel consumed?

Yes; that’s what the new “clean” diesels do.

Why do the heavy hitters smoke?

What’s a little smoke when you’re looking for big power?

I see. So could I turn up the boost on say, a disel rabbit?

You could; but unless you can add more fuel to the greater amount of air; you won’t make any more power.

When I go to the pump, I don't normally see choices of desiel fuel... why is that?

Because the CN is standardized by country/region; you don’t get a choice.

If you could cram more air in, it would make more power, but adding the fuel itself makes power too. Bank's Duramax doesn't smoke, but he is running alot of nitrous.

Only the efficient burning of fuel will make power. Adding fuel that won’t get burned; or unneeded air (oxygen) won’t make more power.

Turning up the boost won't really make too much more power without more fuel. Air isn't the primary power maker. It is just needed to complete the combustion process. Gas engines work off air, diesels work off fuel.

Both engines work by the combustion of fuel with oxygen. It’s the ignition source that is different.

Diesels need 2 things to make power fuel and air, the more you and the power you get. The more power you make the more heat it makes.
EGT HEAT KILLS DIESEL!
you can run most diesels all day long working them HARD and not hurt them as-long-as you don't get them HOT.

Well; hummm. There will be additional heat generated as a byproduct of generating additional power; but if properly designed and tuned; the EGT will not be higher at increased load or power levels.

There is no free lunch here. At some point; even a diesel engine will break.

 

[Turbo6Smackdown]

If you could cram more air in, it would make more power, but adding the fuel itself makes power too. Bank's Duramax doesn't smoke, but he is running alot of nitrous.
Turning up the boost won't really make too much more power without more fuel. Air isn't the primary power maker. It is just needed to complete the combustion process. Gas engines work off air, diesels work off fuel.

So are you telling me that when the maf starts to see more incoming air, it doesn't tell the ecm to give more fuel??? I'm lost...
Both engines work off of fuel AND air, or they wouldn't have an air filter and a gas tank... What I'm trying to figure out is, there HAS to be an computer controlled adjustment of fuel, as more/less air is being pushed thru... Is that computer NOT not adjusting fuel for air? When more air is starting to get sucked thru that maf, doesn't more fuel get added regardless?

 

[forcefed3.8's]

You control power and rpm's in a gas engine by regulating air (throttle blade). In a diesel, there is no throttle blade, you just add fuel, the air comes from rpms and/ or boost. The roll of air and fuel are almost reversed. A gas engine could not be run with an open intake manifold, and adding fuel to control rpms. Adding more boost won't add more fuel. The amount of fuel is controlled by injector pulse in the computer program. The computer won't give more fuel because it sees more air. The purpose of a mas on a diesel is to add fuel in proportion to airflow to make complete clean combustion. The computer won't go beyond if it sees more air, because it isn't lean, it is oxygen rich, which has no negative effects. If you have ever seen an old mechanical 12 valve Cummins, they smoke alot, even when driving normal. They have no air metering capabilities.
If you are adding more fuel and getting black smoke, it is burned fuel. Adding a bigger turbo will clean it up, meaning more efficient combustion, which is more power. White smoke is unburnt fuel. The smokiest tune isn't always the most powerful, but will most likely run hotter. I have a 100hp program that smokes more than a 150hp program.


In a diesel, the fuel is making the power. The air is needed to make complete efficient combustion. Without excess fuel, more air will do little to nothing.

 

[joe_schindler]

So are you telling me that when the maf starts to see more incoming air, it doesn't tell the ecm to give more fuel??? I'm lost...

Most (except very new) diesels don’t have a MAF or ECM.

Both engines work off of fuel AND air, or they wouldn't have an air filter and a gas tank... What I'm trying to figure out is, there HAS to be an computer controlled adjustment of fuel, as more/less air is being pushed thru... Is that computer NOT not adjusting fuel for air? When more air is starting to get sucked thru that maf, doesn't more fuel get added regardless?

Neither gas nor diesel needs a MAF or ECM. The coolest diesel I ever saw was a diesel jack-hammer. Just had a fuel tank and a big filter element.

You control power and rpm's in a gas engine by regulating air (throttle blade). In a diesel, there is no throttle blade, you just add fuel, the air comes from rpms and/ or boost. The roll of air and fuel are almost reversed. A gas engine could not be run with an open intake manifold, and adding fuel to control rpms.

Gas engines only have this for carburetion. They will run fine with a well designed drip system and no manifold and no carburetor.

Adding more boost won't add more fuel. The amount of fuel is controlled by injector pulse in the computer program. The computer won't give more fuel because it sees more air. The purpose of a mas on a diesel is to add fuel in proportion to airflow to make complete clean combustion. The computer won't go beyond if it sees more air, because it isn't lean, it is oxygen rich, which has no negative effects. If you have ever seen an old mechanical 12 valve Cummins, they smoke alot, even when driving normal. They have no air metering capabilities.
If you are adding more fuel and getting black smoke, it is burned fuel. Adding a bigger turbo will clean it up, meaning more efficient combustion, which is more power. White smoke is unburnt fuel. The smokiest tune isn't always the most powerful, but will most likely run hotter. I have a 100hp program that smokes more than a 150hp program.
In a diesel, the fuel is making the power. The air is needed to make complete efficient combustion. Without excess fuel, more air will do little to nothing.

I think the confusion begins with not every gasoline engine is a 3.8 SFI Turbo Buick engine; and not every diesel is electronically controlled either.

 

[Turbo6Smackdown]

Oh. So what do you do to a turbo diesel car, to make it go faster?

 

[forcefed3.8's]

Computer programming and injectors. Opening up the exhaust and intake makes a difference too.

 

[joe_schindler]

Oh. So what do you do to a turbo diesel car, to make it go faster?

Push the accelerator pedal down a little more.

 

[turbofabricator]

Diesels make AMAZING power when fueled and boosted. Tractor pullers run more than 250 (two hundred and fifty) psi boost. A local drag racer runs 90+ psi boost on his Cummins and is one of the fastest in the nation. Tube chassis truck is in the works. Last time I talked with him (3-4months ago) he had driven it down his street. (here's his street driven diesel)Google Image Result for http://image.dieselpowermag.com/f/features/dodge/9107015+pinline_medium/0707dp_01_z+dodge_dakota+side_view.jpg I really want to stay away from them, becasue if you even open the hood to just check the oil, you are DIRTY!!!!! and smell like jet fuel. (I get enough of THAT at work!)
Here is what happens when you over boost a Diesel: Tractor Pulling Insane Engine Blow Up! Engine Flies out of the Tractor! - Video
YouTube - Tractor pulling - Blown engine
YouTube - Internatinal Harvister Blow Up

 

[forcefed3.8's]

Diesel rules!