Diesel vs. Gasoline Engine?

[burdell]

Originally Posted by Drover

If you just want an appliance to get you around, it's hard to argue against diesel. But when it comes to rip-snortin' fun, it's tough to be a high-revvin' petrol engine.

If ya want to go fast the finishing order at LeMans and other races the past few years say turbo-diesel's the way to go, may not have the ultimate redline but torque/HP in abundance.

[CHICAGOLAND92]

Wow you guys, thanks for all of the replys! I think I understand diesel a little better. I was always wondering why the RPM maxed out around 5.

Originally Posted by Drover

If you just want an appliance to get you around, it's hard to argue against diesel. But when it comes to rip-snortin' fun, it's tough to be a high-revvin' petrol engine.

That's my main concern. Whenever I think of diesels, I always think of semi's and how they take substantially longer to catch up with the rest of traffic. I mean I'm not gonna be racing and I know it won't be as bad on acceleration, but it's always good to give your engine a little push every now and then.

Originally Posted by BudinAk

Yes, the diesel has increased fuel economy, but...

Don't know about where you live, but here in Alaska diesel is exactly $1.00 per gallon more costly than unleaded gas. Basically this negates the advantage altogether of owning a diesel. (not to mention they are several thousand $$$ more costly to begin with) And make a heck of a lot more noise. Think I'll just stick with gas for now...

Bud

Yeah, that was another one of my concerns. Diesel around here is about the same as gasoline now, but I remember when gas was around $4, diesel was significantly higher (I also remember when I was little that diesel used to cost less than regular gasoline, what's up with that?). I guess to really see if it will make a difference, I'd have to do some of my own calculations.

Originally Posted by Omaha Rocks

Diesel engines fire on compression, as opposed to spark. They generally will have more torque, but less "snap". They normally get better mileage - though with the increased cost of diesel fuel, the savings are often negligible.

To be completely honest with you, if you're not at all familiar with diesels, I'd steer you away from them. I'm assuming your "user name" means you're from Chicago. Being in Chicago, you'll need to know how to operate a diesel in the winter - and that's a very different sort of thing. You need to run "blended" fuel or #1 fuel. You need to do specific things, or you WILL get stranded in the winter, with a diesel.

You assumed correctly . And yeah I'm from Chicago. I'm assuming you're familiar with our harsh winters haha. I think I read a post on here that diesels take longer to warm up in the winter.. About what's the difference between a gas engine and a diesel engine?



Once again thanks for all the help and replies guys.

[Drover]

Originally Posted by burdell

If ya want to go fast the finishing order at LeMans and other races the past few years say turbo-diesel's the way to go, may not have the ultimate redline but torque/HP in abundance.

Of course, diesels currently have huge displacement and airflow allowances versus otto-cycle powerplants in Le Mans right now, something the series is looking to even out in the coming seasons. In the meantime it's an apples-to-oranges comparison. Right now the only production diesel that comes even close to its petrol counterpart in performance is the BMW 335d -- and only if you match it up against the 328i instead of the 335i. And you'll have to be willing to shell out an extra 8 grand versus the 328i.

[EinsteinsGhost]

Originally Posted by CHICAGOLAND92

1. What are the main differences between a gasoline and diesel engine?
2. Also, the diesel engine is only rated at 215 hp. Will it be a slow SUV (sorry if this is a dumb question, I just don't get why the rating is so low)?
3. What are the benefits of owning a diesel besides the increased fuel econonmy, if any? What are the drawbacks?
4. Does anyone here own a Grand Cherokee CRD?

1. Primarily, in how they operate. Diesel engines are compression ignition, while gasoline engines use spark plugs. Diesels (almost always) are turbo charged, and take advantage of higher energy density in diesel versus gasoline. The disadvantage is that they don't rev as smoothly and as high as gasoline engines.
2. The ratings we speak of is the peak value. Diesels tend to produce most of their torque (typically) between 1500 and 3500 rpm (sometimes 4000 rpm), with peak torque arriving somewhere between 1500 rpm and 2000 rpm. This peak torque tends to be quite high, and as a result the engine has a lot more power in this range than does a gasoline engine. Past the peak, the torque drops continuously and as a result, the power curve doesn't rise as rapidly as it does in a higher revving gasoline engine. So, comparing peak power between diesel and gasoline engines can be deceiving. Although peak power may be low, the diesel engine will have near peak power over a broader range of engine speeds. In higher revving gasoline engines, however, power continues to rise and then drops past the peak.

As far as drivability is concerned, what matters most is engine response, transmission response and average power generated as the vehicle is driven. Gasoline engines will have greater performance advantage with all that peak power but only if we lived in a perfect world where one could drive at all times near peak power.

3. There're pros and cons both ways. I've never owned a diesel, and the only thing that would drive me towards it is that it could offer a step towards reducing our oil dependence, if we get far enough in the field of bio-fuels. They also tend to be better to towing (with all that torque at low end, there's more power available at low rpm).

4. Not me.

[sterlinggirl]

Originally Posted by CHICAGOLAND92

Diesel around here is about the same as gasoline now, but I remember when gas was around $4, diesel was significantly higher (I also remember when I was little that diesel used to cost less than regular gasoline, what's up with that?). I guess to really see if it will make a difference, I'd have to do some of my own calculations.

Diesel is a byproduct of gas refining, so you get a certain amount for every gallon of gas. The refineries can't change the ratio without a lot of trouble, so the prices of diesel and gas will fluctuate depending on which one is in shorter supply.

Over the last couple of years, diesel was in short supply because the economy was booming meaning that a lot of it was being used in construction, trucking, railroads, airplanes, etc. The push for ethanol meant that gas was diluted, so less diesel was available per gallon of gas used. The straw that broke the camel's back was China filling their SPR with refined diesel, which pushed the price up even further.

Now that the economy crashed, people are still buying gas for their cars, but diesel use has dropped considerably. Construction equipment is parked, trucking has slowed down, airlines have cut back on flights, and tons of people are changing out their oil furnaces for natural gas.

These days diesel is 10% cheaper than gas, and I'd expect it to keep dropping (in relation to gas) until the economy picks up again.

[Omaha Rocks]

Originally Posted by CHICAGOLAND92

You assumed correctly . And yeah I'm from Chicago. I'm assuming you're familiar with our harsh winters haha. I think I read a post on here that diesels take longer to warm up in the winter.. About what's the difference between a gas engine and a diesel engine?

I lived in Minnesota for nearly 20 years. I know about cold, harsh winters.

Your diesel engine will be fine after it has started in extreme cold. The problem is getting it to start. And for the most part, the warm-up time won't be significantly different than on a gas engine.

If you're going to drive, successfully, in the winter you MUST have good batteries and starter, you must run the right kind of fuel, and you must have the right oil. Otherwise, you're going to have problems.