diesel vs. gasoline

[fasterbot]

hello -
i am hoping that somebody can give me a quick comparison of a diesel engine compared with a gasoline-burning engine.. i've been looking at trucks, and don't really know what the benefits/downfalls of a deisel engine are..

thanks!

[ivymike1031]

If I was getting a work truck, I'd almost certainly "go diesel." I can't think of a big advantage to gasoline engines for anything but high-acceleration applications, and even there they don't always win (but usually seem to).

[DMC12]

A Diesel engine (if built correctly) will last forever, get great gas mileage compared to an equivalent gas engine, and provide more torque. Look at 18 wheelers! Those engines go up to a milllion miles, and tow tons of cargo. Mercedes has the best Diesel engineers. Avoid early American Diesels... they didn't know what they were doing.

The only downfall of a Diesel is (at least in California) finding a gas station with Diesel. I like gas engines because you go anywhere, but with a Diesel, you have to get familiar with what stations offer it.

What trucks are you looking at?

[MBTN]

Also, diesel engines don't have spark plugs! However, they have very high compression ratios.

[DMC12]

Oh yeah! Good point I forgot that one... no spark plugs!

Also, here in California you don't have to get smog checks... ever!!! This is because Diesels don't produce the invisible gases that gas engines do.

Diesels are pretty cool... they just get bad raps from all the busses and burnt-out ones that people parade around that beltch out black smoke.

[fasterbot]

thanks for the info everyone!
i also just found this, incase anyone is interested: http://www.howstuffworks.com/diesel.htm

DMC12- I'm looking at old International Scouts, and have seen a few listed with diesel engines, that's why i was curious..

thanks again

[ivymike1031]

Originally posted by MBTN
However, they have very high compression ratios.

Um, are you saying that's a bad thing?

[DMC12]

Originally posted by fasterbot
I'm looking at old International Scouts, and have seen a few listed with diesel engines, that's why i was curious..

I know nothing about Scouts, but International does make some damn fine semi-truck engines. Good luck.

[MBTN]

No, I am saying that to explain why they don't need spark plugs. The heat from compression is enough to create combustion.

[Tines-Ballantines]

Hi everybody,

This is my first post here, so it won't be too long. Just to check out that it works Ok.

Concerning the Diesel / Gasoline comparison, there are lots of differences but it's also important to say that modern diesel car engines have little to do with those from the 80's or enven 90's, and they are not really comparable to truck engines.

Bye!

[ivymike1031]

oh yeah? What makes them so different from truck diesels?

[Tines-Ballantines]

Well, there are many differences in conception and technology.
For instance, the injection system is much more advanced and complicated. Truck engines are also much bigger for less power ratio.

* A truck engine such as the Ford F-250 / 350 will give you 185 kW for 7,3 litre = 25 kW/litre, and a torque of 881 N.m = 120 N.m/litre

Let's compare that to some diesel cars using different technologies:

Common-Rail technology, Injection pressure = 1350 / 1600 bar:

i) a little car like the Renault Clio 1,5 litre: 59 kW = 39 kW/litre and 185 N.m = 123 N.m/litre
ii) a sedan like the Laguna 1,9 litre: 89 kW = 47 kw/litre and 270 N.m = 142 N.m/litre

Unit injector technology, Injection pressure = 2000 / 2200 bar:
iii) VW Golf Tdi 1,9 litre: 110 kW = 58 kW/litre and 320 N.m = 168 N.m/litre

So you can see the difference in efficiency. They have less vibrations as well and are much less noisy (specially for the Common-Rail). Fuel consuption is very low.

[ivymike1031]

oh... I thought you were talking about real trucks, not pickups.

Common rail injection has just started being used on 6-8L truck engines in the last few years. Unit injection is used almost universally on semi trucks, and is used on some smaller vehicles. It's important to make a distinction between HEUI and mechanical unit injection, HEUI being the high-tech modern equipment (very competitive w/ common rail, if I'm not mistaken).

The biggest reason that truck diesels have a lower specific output is that they've got to last MUCH longer...

[enginerd]

Go with diesel. No tailgaters, cheap fuel, better gas mileage and more torque.