which engine is really better, deisel or gasoline and why and also which engine last longer?

Question

i own a BMW X5 gasoline, with the way the gaz prize is going there's no releif in site, so i was thinking maybe i can switch to deisel in the other hand people are saying deisel cost too much to maintain and the difference at the pump is not significant

Answer 1

Dear Fueler-

Neither engine is better than the other. They both serve a purpose. However one is more efficent than the other, and that would be the Diesel Engine.

Lets do a little Basic Automotve Education, shall we??

The Gasoline Engine which just about everyone is familiar with is called a Spark Fired Internal Combustion Engine. This means the Air/Fuel mixture is introduced in a mixed state, then compressed and ignited by an ignition source such as a Spark Plug. As the gasses burn they force the piston down in the cylinder and that energy is then converted by a connecting rod and a cranshaft for delivery to your wheels.

Gasoline engines have one major fault. They are extremely in-efficent at creating the necessary energy to move your vehicle. Contrary to popular opinion, even the most efficent Gasoline engine only allows you to utilize 20% of its total energy. Pretty sad eh? Well that is the truth.

But its how we get that 20% that makes the difference. An Engine's output power, (which is the part we use for cars and trucks), is very small. The other 80% is waste energy we call heat. That heat is removed from the engine through radiators, intercoolers, and fans.

But here is what is more frustrating with a gasoline engine. It does not use all of its available fuel. So that 20% is at the cost of unburned or partly burned fuel being exhausted out the tail pipe. That is the reason for all of the emission control equipment on your car.

OK, now its time to switch modes, and head for the hills here.

Diesel engines work in much the same way that a gasoline engine does. The difference is they are compression fired rather than fired by a Spark Plug, now hold up, I will get to the Glow Plugs here in a minute, so lets not jump ahead.

The Diesel engine pulls air only into its cylinders. No fuel is mixed as it enters as in the Gasoline engine. The piston compresses the air until it is superheated by its own compression. At the last possible moment a fuel injector introduces the Diesel Fuel into that superheated air. The mixture now detonates and forces the piston down in the cylinder. This detonation is the knocking sound that all Diesel engines produce as a part of their normal operation.

Now here is the kicker. The Diesel engine has 30% its power available to you, at a lower temprature than the gasoline engine. However, the cost is acceleration and engine RPM. Diesels turn over at a slower rate of speed, so we make up for that loss through gearing. What you gain is Torque. That is why industrial equipment use these engines.

Diesel Engines also burn 90% to 98% of their fuel. There is so little fuel left in the exhaust gasses that the only materials being exhausted are the soot from the combustion process, CO2, and NOx. Unfortunately, that is the price for burning fossil fuels.

But, what you gain, is a power increase that is more efficent because it used all of its available fuel, and only exhausted true waste products. Not something that requires EGR Valves, (Exhaust Gas Recirculation), and Catalytic Converters, Cold Air Injectors, and all of that other junk.

Diesels can be more expensive to maintain, but they also tend to last twice as long as their gasoline couterparts, which is another reason 1,000,000 miles on a Big Rig is nothing. Their engines are normally not rebuilt until that rig has another million on top of that.

On the industrial equipment, (Caterpillars, Bull Dozers, and other construction equipment, they measure their operations in hours not miles. Besides, how do you measure miles in a Cat? I think you need to measure Tons of Earth!

I hope that clears up a few myths for you. Good Luck!

Answer 2

Tekkaman saber that is an outstanding job of explaining internal combustion engine operation for dummies. You know what you are talking about. One myth that I think you planned to put to rest and apparently forgot was the use of diesel glow plugs. I have observed more than a few of these self proclaimed experts that think the engine is fired by the glow plug all the time-like a super hot spark plug. Glow plugs are simply an aid for cold starts and are not used once the engine warms.

Answer 3

Tekkaman Saber.......you are awesome, and i could not have put this answer better myself (literally)

its so unfair the treatment diesels get, as a diesel mechanic, sometimes it makes me outright mad that people don't understand the awesomeness of a diesel engine, they are more powerfull and can be just as fast(I've seen it people) as a gas engine, with WAY less emissions and MUCH more durability.

i applaud you re efforts

Answer 4

diesel cars now days are just as good if not better than petrol yes diesel lasts longer yes they are more costly to repair but if you buy a good diesel you won't have a lot of repairs to do they are more expensive to maintain but you get more kilometers out of your tank than you do with a petrol so that and the price difference at the pumps says it all. you could buy a bio-ethanol car much cheaper than but petrol and diesel.

http://en.wikipedia.org/wiki/Bioethanol

Answer 5

Either way, I would suggest looking into either biodiesel or ethonal to mix in with your fossil fuel.

Answer 6

If you want to burn less gas, get a smaller, more efficient vehicle.

Answer 7

DIESEL!!

heres why...