CajunCC

That's how people make silly amounts of power with a turbo diesel. You can run up the boost to ridiculous levels without worrying about detonation. You're really only limited by the amount of fuel you can get into the motor.

hammertime

iTrader: (1)

You guys need to realize that power production in these cases are optimized around the boost. You wouldn't expect an 8.5:1 LSx motor that was built to take 20lbs of boost to run well naturally aspirated, would you?

Diesels are only limited by how much air is available to burn the fuel you can inject. Turbos and higher boost add much more air, which can then burn much more fuel to create more power. The only limit as I understand it is the resuolting exhaust gas temperatures.

You are thinking through the process from the wrong angle. Since the throttle controls the amount of fuel metered, not air, the only way boost pressure would drop is if less fuel were being burned.

You close the throttle, less fuel is burned, less hot gas is available to maintain turbine speeds and therefore, boost drops.

Hal StClair

iTrader: (3)

Diesels have been running engine controls for emissions for years. From MAF sensors to cats, egr's, soot traps and fuel vapor returns they run most of the same controls we find in our gas motors. Although diesels are usually lower rpm runners, not all diesels are created equal. VW's have 4600+ rpm red lines. Model airplane engines are actually diesel and they really buzz.
And as far as performance is concerned, I know of a 1.9ltr VW Golf TDI that runs mid 13 second quarters in a totally stock bodied street only car and still pulls 35+ mpg.
When the new low sulfer diesel gets into full production next year we should see a lot of new oil burners here.
I love my C6, but I've put 55,000 miles on a 2005 Golf TDI and averaged 42+ mpgs over the last year in it.Nice at $3.00 per gal for fuel.

kossuth

iTrader: (12)

Yeah that's correct somewhat but remember this. It takes approx 21 parts of air to burn 1 part of diesel fuel. In a gasoline engine it only take approx 14 parts of air to 1 part of gasoline. Diesel engines can only build as much boost as the exhaust gasses will allow and you need fuel to do that. You can put a turbo on a non turbo engine and not mess with the injection pump or injectors at all and it will run ok. The engine will only build as much boost as the fuel will allow. Black smoke is unburned diesel passing out the exhaust which is also creates boost but it isn't effient boost. Also alot of unburnt diesel (aka black smoke) will raise your EGT's in a big hurry. The 7.3 fords and the 6.2 GM's were never turbo charged from the get go. Ever follow a old 7.3 diesel pulling a heavy load up a steep hill? It blows alot of black smoke doesn't it. All adding the turbo charger does is basically take those expanding gasses from the burnt diesel fuel and spin the turbo forcing more air into the motor bringing the air fuel ratio much closer to 21:1 which is where it should be anyways. No black smoke = effient power. Black smoke = somebody trying to get everything they can out of it. Why anybody would build a non turbocharged diesel is beyond me.

Cliff notes: better mileage on the older diesels from the addition of a turbo is due to the inability of the engine to draw in enough air naturally aspirated to bring the air/fuel ratio to 21:1

kossuth

iTrader: (12)

I'm going off of old school diesel knowledge being I've worked on diesel tractors and such. The way it is metered is the injectors are under pressure from the injection pump. Think of an injection pump as a yard sprinkler. Each cylinder receives a pressure shot from the injection pump at a predetermined time kinda like a yard sprinkler. At a predetermined pressure the injector will open (usually around 1500 psi or something like) "warning if you ever mess with the injectors on a diesel and try to bleed them to get the engine to start be extremely careful. Diesel fuel spraying at this pressure can actually KILL YOU so be extremely careful" Because a diesel can't detonate from a lack of fuel basically it would just be underpowered if it doesn't have enough fuel. That's why there isn't really a metering system in place like you would recognise on a gasoline motor. Only metering taking place is basically the duration of the shot of fuel into the chamber from the injection pump and injector. How the injection pump does this exactly I'm uncertain. Everytime we had a problem with the injection pump on one of our tractors we just took the pump to a shop or ordered a rebuilt unit. Wasn't cost or time effective for us to dink around with something we didn't have the tools or experience to mess with. But you have to time it just like you would time a distributor basically. My dad has a 99 Dodge Ram with a Cummins diesel in it and I've worked on it alittle with him but it is alittle different animal. It's a 24V ISB motor, I call it a hybred old school diesel. It uses a injection pump and old school injectors but the injection pump is computer controlled. The ECM determines the duration of the shot into the combustion chamber and so on from a IAT, TPS, ECT, and MAP sensor. This is why the programmers work the way they do. They basically alter the fueling tables in the ECM like they do in a modern fuel injected gasoline engine. The 89-98 Dodge diesels were basically old school and worked the same as every other diesel for the last 50 years or so. The newer Dodge diesels from my understanding use what you guys were refering to earlier as the common fuel rail setup. I'm not at all familar with it in practice but I have a decent idea of how it works.

DAPSUPRSLO

iTrader: (14)

I currently have an 02 f250 with a 7.3litre turbo powerstroke and am very curious to why this motor is considered not to respond as well to the power programmers and chips as that of the 6.0litre power stroke, 5.9 cummins 24v, and 6.6litre duramax. Can someone actually explain the differences to me? I'd imagine it's something to do with the fuel delivery system of each particular application and the variable vein turbo's on the duramax and 6.0 litres.

kossuth

iTrader: (12)

The only thing I can think of is there is some sorta restriction in the injection pump somewhere that can't be overcome but that is only a guess. The injection pump might be non computer controlled too and the only thing the computer controls is the wastegate on the turbo or vice versa. These are only blind guesses though

DAPSUPRSLO

iTrader: (14)

Yeah, possible. I asked the question over on a diesel forum as well, interested to see what kind of responses I get!

Venkman

iTrader: (4)

The government is actually not helpting make things easier.

Just picked mine up last friday. It gets almost 50mpg on the highway and can run off 100% biodiesel off the showroom floor.

The government has now made it illegal for sale in 2007 and the manufacturer must go back to the drawing board for 2007 thanks to the new emission standards.

Cutting off our nose to spite our face.

blackz93

iTrader: (2)

LOL!!


I never said I was unaware of the fact that the turbo is what makes the power! I was just wondering how good they are for power N/A.

kossuth

iTrader: (12)

Run like dog ****

kossuth

iTrader: (12)

While we are talking about the difference between diesels and gasoline engines I found this on the internet. It isn't very exciting but it gives you an idea of how some of the older diesels were setup. He is running a 1950 something Farmall 400 diesel. Basically it starts on gasoline and switches over to diesel. Won't start on diesel because the engine doesn't have glowplugs or an intake charge heater. We used to have one of those damned things. I hated it LOL. There was a pressure relief valve in each cylinder bank in the cylinder head that basically lowered the compression from 18:1 to 8:1 when you were starting it on gasoline. We had one and it was kinda a neat tractor but cylinder head would always crack so we got rid of it. http://www.chatstractors.com/Video/F...une_6_2005.wmv

bichin95redta

In BROAD, GENERAL TERMS, it's mostly about compression. Diesels are also called "auto-ignition" engines, in that they run such high C/R's, that alone is enough to "set-off" the air/fuel mixture.

Again, in BROAD, GENERAL TERMS, diesel engines have to be built more strongly than a gasoline, spark-ignition engine, and are usually heavier. Remember back during the fuel crisis of the mid '70's when GM tried "converting" SI blocks to diesels by using higher CR's and funky heads? They were a dismal failure, as they weren't purpose-built diesel engines from the get-go.

Compressing air to super-high temperatures, and then injecting atomized fuel into that super-hot air, is a good way to make large amounts of power. This is exactly how a jet engine works, although via rotary, instead of reciprocating means. Jet engines burn a fuel that isn't much different than kerosene or diesel fuel.

blackz93

iTrader: (2)

So, how do you crank up the HP on one of these things (off-road dump truck) or is it computer contolled? 1998 Mack.

kossuth

iTrader: (12)

There is a good chance it is computer controlled, but I could be wrong. I'd check with your diesel mechanic. It is basically the same running gear as a 18 wheeler. In the 18 wheeler world depending on the transport company they can tune the engine down or turn it up. I know Swift transportation has their trucks governed at 65 or 70 mph and that is all the faster it will go. Some freelance drivers have their trucks intentionally turned down because they find it's hard to keep the truck at a posted speed limit on the interstate. Some of those guys just flat fly (for a 80,000 lb truck anyways) on the road IE 80-90 mph. I'd ask your mechanic and possibly a few others. I bet there is a ton of things that are possible that we aren't aware of.

blackz93

iTrader: (2)

True.

ANYTHING to help get that 100,000 pounds up the hills!

kdogc5

iTrader: (2)

Is Gm Comming Out With A Vin Diesel????? Or What Is The Vin On Your Diesel.....

Spdmini

You want to make as much boost as it will take. Mess w/ the wastegate... either wire it open or closed I cannot recall b.c Im far too drunk.

blackz93

iTrader: (2)

These trucks have no wastegates. They digest as much boost as the turbo will make!

kossuth

iTrader: (12)

Add as much fuel as the injector pump can. Not sure how feasible that is but hey boost = fuel and boost = power so therefore we can conclude that fuel = power LOL.