Why do diesel's last longer then a gasser????

[DarylB]

EGR is one of the only ways to get the NOX emissions down to a reasonable level. They even use EGR cooler to lower the temp of the inert gas further.

The soot levels of modern diesels are pretty low. As far as I know, all the current new diesels call for low ash oil and using anything else will clog the DPF in short order.

I've got a diesel myself, even if it isn't a truck. It uses far less fuel than the competitors gas engines and it's a Kubota, so it should be running for a long time.

Slick ride. Lots of those things down in my area, but I've never seen a Kubota. Mostly Polaris rangers, Yamaha Grizzlys, Kawasaki mules.

My truck has EGR but no DPF (2006 engine, 2007 chassis). The oil turns black in a week with the EGR. After 5k miles on the old non-egr truck the oil would still be brown. As soon as I can afford an ECM Tune, the EGR valve will cease to exist (operate).

 

[Peacock]

Slick ride. Lots of those things down in my area, but I've never seen a Kubota. Mostly Polaris rangers, Yamaha Grizzlys, Kawasaki mules.

My truck has EGR but no DPF (2006 engine, 2007 chassis). The oil turns black in a week with the EGR. After 5k miles on the old non-egr truck the oil would still be brown. As soon as I can afford an ECM Tune, the EGR valve will cease to exist (operate).

Try to find some low ash oil if you can. It seems to help.

 

[spacemule]

I'll buy the 5k and dual pumps, but not 6500rpms... Stock internals? I dont think so Tim.

My thoughts exactly.

Have you ever noticed that diesels sound like they're spinning much faster at a given rpm than a gas engine? I suppose that's because they run much longer strokes to get the greater compression ratios necessary and therefore the piston speed is faster at a given rpm than a gas motor. Probably why they take so much more power to crank as well.

 

[DarylB]

Try to find some low ash oil if you can. It seems to help.

Running Shell Rotella, not sure if it was low ash or not. (i'm due for the 2nd oil change anyway). As one guy put it - I dont like my engine eating its on poo, which is basically what an EGR does.

 

[DarylB]

My thoughts exactly.

Have you ever noticed that diesels sound like they're spinning much faster at a given rpm than a gas engine? I suppose that's because they run much longer strokes to get the greater compression ratios necessary and therefore the piston speed is faster at a given rpm than a gas motor. Probably why they take so much more power to crank as well.

Yep. The high compression is what makes em harder to crank. It is a "compression ignition" engine ya know

 

[spacemule]

Yep. The high compression is what makes em harder to crank. It is a "compression ignition" engine ya know

Yeah, but I think that's only part of it. Consider the extra leverage against the crank from equal amount of downward force on the piston because of the longer stroke. Given equal compression pressures, the diesel would still be harder to crank.

 

[wood4heat]

Like a fuel heater? Ford used these on the old 7.3 and 6.9. Only used for cold start. I guess the Big 3 never had a reason for a high revving diesel, so they never tried it.

Most diesels have no reason to rev high. They produce so much torque at low rpm that they don't need to rev high. Most pullers only run so much rpm to build as much energy before releasing the clutch. I've got friends that tractor pull with a small block Deere and they leave the line a good 2,000 rpm more than the run during the pull.

I realize it's not practical to run a diesel at high rpms I'm just curious about the technical aspects of doing it. Sounds like Honda played with the idea so I wondered where they wound up with it and how they got there. You already learned me something about what limits rpm, I thought it was just piston speed.

 

[spacemule]

You already learned me something about what limits rpm, I thought it was just piston speed.

I'm talking out my ass here, as most of you know, but seems to me if piston speed were the only limiting factor, it would be easy to overcome. You could achieve the much higher compression ratios with a shorter stroke by using a very small chamber area above the piston.

 

[wood4heat]

I'm talking out my ass here, as most of you know, but seems to me if piston speed were the only limiting factor, it would be easy to overcome. You could achieve the much higher compression ratios with a shorter stroke by using a very small chamber area above the piston.

But as you pointed out in a previous post the longer stroke gives more leverage on the crank. This is part of where they get all the torque. Then again if we're pushing the rpm limits we'll probably throw some torque out the window anyway.

Anyone know what sort of rpm a volkswagon Jetta TDI turns?

 

[Peacock]

I'm talking out my ass here, as most of you know, but seems to me if piston speed were the only limiting factor, it would be easy to overcome. You could achieve the much higher compression ratios with a shorter stroke by using a very small chamber area above the piston.

The head is flat. The valves generally protrude into the bore. Usually the piston is a bit under deck height. The combustion chamber is usually in the piston itself. This style of piston is called 'mexican hat'. They have a point in the middle that lines up with the injector in order to properly distribute the fuel throughout the piston.

 

[woodchuck361]

stroke has nothing to do with the compression ratio. (
You can have long strokes with low or high compression and you can have short strokes with low or high compression.
Compression is determined by how small a space the fuel mixture is squeezed into.
The length usually determines the amount of torque. longer stroke engines usually produce more torque and are slow to rev up./lower max rpm due to more rotating mass. while short stroke motors produce more h.p. and are fast to rev. up

There are many variables and some exception but for the most part this holds true.

 

[dpcutter]

Diesel engines also last longer then gasoline engines because the fuel acts as a lubricant. During cold starts, there is always some blow-by, in a gas engine, this is a solvent not a lube and will damage engine parts if excessive amounts enter into the engine. On a diesel, blow-by is a concern, but the diesel fuel itself is a lubricant, unlike gasoline, which is a solvent.

 

[DarylB]

Anyone know what sort of rpm a volkswagon Jetta TDI turns?

Here's some specs on the 1.9 (1998 model). They phased this motor out in 2006 due to emissions. I think the new engine is 126hp and more torque
Horsepower:
90 bhp @ 4000 rpm (~147 bhp @3500 rpm)

Torque:
149 lb/ft @ 1900 rpm (~311 lb/ft @2200 rpm)

4 grand isn't out of the question, it's a smaller engine. Bigger cubes generally mean less RPM's (in a diesel)

 

[TDunk]

Well i'll tell ya what DarylB. Go onto Woodruffdiesel.com. You'll see a blue reg. cab long bed dodge on there (not sure what links to click) But i know for a fact that truck will turn 6500 rpm, believe it or not.

 

[Frank Boyer]

Look for a bunch of new diesel cars and light trucks in the next few years. Ford has a 1/2 ton pickup, Honda a car or two, Toyota a pickup etc, etc.

 

[55chevyparts]

As far as the 1.9 TDI, red line on tach is 4600 and I haven't found any reason to push it above 4000. The reason I have it is for the mileage, average about 50 per gallon. With a 5-speed it turns about 2000 at 60mph and 2600 at 70.

 

[DarylB]

Well i'll tell ya what DarylB. Go onto Woodruffdiesel.com. You'll see a blue reg. cab long bed dodge on there (not sure what links to click) But i know for a fact that truck will turn 6500 rpm, believe it or not.

But with the stock bottom end and stock internals?:deadhorse: I doubt it. That was your original post said. Most hopped up trucks at least run a stud kit to keep the head from blowing off due to the abnormally high boost pressures. Even wastedgated turbos are going to crank out a lot of boost @6500rpms

 

[TDunk]

But with the stock bottom end and stock internals?:deadhorse: I doubt it. That was your original post said. Most hopped up trucks at least run a stud kit to keep the head from blowing off due to the abnormally high boost pressures. Even wastedgated turbos are going to crank out a lot of boost @6500rpms

I said the engine block and internals were stock, nothing about the head. I know that Dan and Luke said that the rotating assm. was stock. It had all been balanced and the pistons lightened (not sure if they lightened the crank and rods or not) And i think the mains were studded,diff. caps, and something was modified for the oil pick-up. Now the head on the other hand, yeah that's pretty wicked. The turbo on it is so big that they had to custom make an exhaust manifold to get it away from the block. I'll try and post some pics. of it if i can find them.

 

[SWI Don]

Around 6000 rpm is what I have been told is about the max rpm for med sized diesels (7-9L) used in tractor pulling. I'm not saying that some guys aren't running faster but diesel can only support a flame front that is only so fast. To run those kind of rpms it requires lots of custom parts to have them hold together for long.

Don

 

[Jumper]

Look for a bunch of new diesel cars and light trucks in the next few years. Ford has a 1/2 ton pickup, Honda a car or two, Toyota a pickup etc, etc.

How bout a Dodge Dakota with the 3.2 Mercedes diesel they put in the Grand Cherokee. I'd buy one tomorrow.