Why are basically all 4wds diesel? All i know about diesel engines is that they seem to blow a *** load of smoke!!!

Torque!

how man?

is diesel still resonably cheap? is it negood for ya engine.

Ive been told LPG aint...cause it doesnt lubricate the engine?

diesel engines produce way more torque than petrol. this is why most trucks, busses and 4wds use this. they need the torque for being able to get moving under load or up/over big arse rocks and shit. you cant really ask is deisel any good for ya engine coz they are made for diesel and are completely diferent to petrol set ups. however if you try putting diesel into your commo it probably aint going to be a good thing. then again, it is a commo! LOL, you might even pick up a few kw's!

im almost out of my current tank...
ill try it and get bak 2 u how it went

In europe now though dont a lot of their cars have diesel engines or petrol diesel engines or something.

Yeah the diesel setup is different

eg they dont use spark plugs they use glow plugs, diesel combusts under compression (if I recall rightly)

I've even heard of some instances (unverified validity I'll admit) where tractors have been run on cream (dunno how!?) instead of diesel. lol


But yes diesel engines produce MUCH more torque than a petrol engine. And there are some sizes of diesel engine that you just wont see in a petrol equivlent. EG, my mates dad's 6wd landcruiser has a 4 (or 4.5) litre 4 cylinder. 50kW, but the torque is something massive like 700+Nm

when i was about 10 my mum put a full tank of diesel into the family commo wagon. was funny, especially when i thought the guy at the service station was drinking the diesel through a giant straw.. childish ignorance... i miss it so

...they sound like shit too...

Parked next to a brand new Merc four wheel drive one day and the guy started it up... sounded like a mini-truck.... not appealing for a merc. :roll:

Many of you probably already know this, but some don't, looking at their posts. So here goes:

In a petrol engine, the petrol/air mix is compressed to about one ninth of it's original volume and ignited by the spark plug. In theory, the mix instantaneously combusts, greatly increasing the cylinder pressure and forcing the piston down, and making the wheels go around. In practise, the combustion does take time but that is out of the scope of my explanation...

In a diesel engine, the air is compressed by a factor of between 17 and 22, MUCH higher than the petrol engine. When the piston reaches top dead centre on the compression stroke, diesel is injected into the combustion chamber. (Note that in some diesel engines the fuel is injected into the intake tract and it is an air/fuel mix that enters the chamber)

Now, compressing a gas increases the temperature. In the case of a diesel engine, the temperature at 17:1 to 22:1 compression is high enough for the fuel to spontaneously ignite, increasing the pressure above the piston, making the wheels go around. The actual ignition of diesel is a relatively slow process and instead of there being an "instant" combustion, the fuel burns slowly. This is the primary reason why diesels don't rev as much as petrols.

In Europe, diesel is much cheaper than petrol. The increased cost of the initial purchase is more than offset by the fuel savings. Also, modern high speed diesel engines are very, very efficient in changing the chemical energy in the fuel into kinetic energy to make the wheels go around (ie: they make more miles per gallon!). I was in the UK and I hired a Peugeot 206 2 litre turbo intercooled diesel. How does 600 MILES to a 50 litre tank sound?

Last statement, petrol engines are about 8% efficient in turning chemical energy into kinetic energy. A stationary, two stroke industrial diesel can approach 50% efficiency.

there was a peugeot that ran from melb to rockhampton on a 45L tank. cant remember the details exactly, but it was a world record, 3 adults in the car. it was one of the new direct ingection thingymabobs. all i really remember was it was desiel.

for tho that dont know rocky is bout 750km north of brisbane so its a fair f#cking way.

and it still had heaps in the tank when it got here.


Tim

im almost out of my current tank...
ill try it and get bak 2 u how it went

I hope you are being funny :shock:

yah i was redav...im not that silly man!

You DID buy a commo tho dan ;) hahaha :p

yas killbilly n i cry myself 2 sleep everynight!

You'll be back soon though ;) and all will be forgiven!

Because a diesel can run a much higher compression ratio comared to a petrol. 17:1 comared to about 10:1 for a petrol engine. This results in higher thermal effeciencies. In other words a Diesel engine is better able to convert the heat from the combustion process to mechanical energy. If your in the buisness of transportation and making money then diesel is the prefferred and in most cases only option for trucks, buses, ships and industrial machinery. But wait I hear you ask. Why isnt diesels used in cabs or light aeroplanes. Well in cabs smoothness and performance are also considerations. diesels are not as powerful for a given size and not as smooth as petrol. Gas is also the prefferred choice for cabs as it is relatively cheap and has a minor performance penalty. In Europe the majority of cabs are diesel as petrol is rather expensive. In light airplanes diesel engines are only just starting to become popular. The problem has always been power to weight. A diesel engine does not deliver as much power to for its weight compared to an Avgas or petrol engine engine. Not an issue for a truck or ship but very impotant for an airplane where weight is an important consideration.

Nigel