Diesel vs Petrol performance???

alledgedly....hmmmm;-)

I cant remember the last time i drove a petrol vehicle - do they still make them?

Go to a dealership that sells a 4WD which has a modern turbocharged, intercooled common-rail diesel. Examples may be a Jeep Grand Cherokee 3.0 CRD, Merc ML300, BMW X5 3.0d... as well as the Hyundai Terracan CRDi.

My 2.7 CRD keeps up with V8's up the hills without even thinking about it. My mate has a slightly worked Disco V8 and mine will even overtake his - with similar trailer weights on.

The best thing? I get 8.0L/100km and gets 18!

If you disregard perifial add-ons, eg, turbo's etc, and compare power,torque, thermal efficiency, whatever you want to call the act of burning fuel in a given volume, gram for gram, cc for cc, oz for oz, petrol will deliver a bigger bang than diesel every time. BUT, it'sthe nature of the torque band that is defining compared to the petrol engine. The diesel will deliver a high-torque figure, but only for a very narrow rpm band in it's range. The petrol engine will deliver a more explosive torque rise over a much broader rpm range and at a higher rpm bracket too.

If you are running a 4.2D, like me you are running old technology.

To be fair, get a petrol engine with a carby on it for comparison.

If you want to compare a recent injected petrol with diesel, try a more common stage 1 or even the newer stage 2 common rail turbo diesel. These are getting 40kw/litre, about the same as petrol, and a lot more torque.

Bosch are suggesting that witht eh new 50ppm diesel and stage 3 common rail injection, the new diesels will be up to 80kw/litre. Same as a 4.5l V8 or 6 cylinder petrol 4wd putting out 300 kw plus. VWs 5 litre diesel has 230kw and 750nm of torque. That's only stage 2. Of course, VW don't use common rail injection for the new diesels, they have a rocker off the cam to each injector to a little pump to generate pressure.

I have a simplistic view on this (I'm a 3.0 TD user - 118 kW)..... life needs to be simpler !
Litre for litre................
Engines with more KW have more power (petrol or diesel) - KW is power.
Engines with more torque have more torque - not necessarily more power (see the KW for that).
ALL of the KW in a diesel is easily on tap - comes in at medium revs.
MOST of the rated power in a petrol motor is on tap, BUT you have to get right up to the tacho red line ! Do you want to do that consistently ?
Advantages of hi-tech diesel ? Economy overall (unless you pay too much for that option) - greater range per litre - less gear changing.
Disadvantages of hi tech diesel ? Less power, on the rare occasions that you may need those high levels.

torque is pulling power
grunt is horsepower...nothing beats grunt!....(not entirely true but, consider torque as being a by-product of grunt)

What's the need for speed? A standard diesel will still do the speed limit, how fast do you need to go? Buy a 4wd for 4wding, buy a sports car for dragging people off at the lights if your testosterone levels are still teenage.

Guys Can someone set him straight????? Diesel VS Petrol. The same conversation is held all around australia. I guess it started back when diesels had no electronics and the petrols did, that ment alot of keen 4wdrivers required a vehicle that would not run away from a leaking tap. Today in europe diesel is the way of the future, more torque better economy and now more perfomance. (In some european cars). However petrol motors are getting alot better than they used to be with Variable Valve Timing etc. However according to manufacturers a turbo diesel is a better vehicle for touring and towing. (Toyota website press release) I just bought a CRD Hilux and love it heaps of power and torque at the right rev range 1400rpm to 3600rpm, the v6 does not kicj into 3600rpm in manual form that is. Therefore the diesels rev range is more responsive than the petrol, the way i would describe a petrol is that it has acceleration power but not true raw power down low. You can crawl through things in a diesel that a petrol motor would'nt dream off with out your foot on the accelerator. Go the diesel and the end of the day car companies are investing in diesel technology as the way of the future.

My 72kw diesel will match my 135kw V8 on the hills. Ultimately the V8 is quicker afterall as it does have more power and torque but there is not much in it - maybe you have a dud diesel. The clue to a diesel is not so much its actual torque output because ultimately it may or may not be better than a petrol but its flat torque curve - as a general statement diesels develop torque low down and it remains fairly consistent across the rev range where a petrol normally starts low and builds up to peak at about 1/2 - 2/3 of the rev range then drops off - there are always exceptions of course.

My diesel experience is don't bother with the traffic light drags but give them a run for their money on the highway.

Garry

I sometimes travel with a couple of blokes with petrol 4WD's and tow off road vans that weigh about the same as my camper. We all get to where we are going at the same time, and all carry the same amount of fuel, but when it comes time to fill up I can take up to 25lt less for the same distance. Now you work that out over a 8-10,000 k trip.

Touring speed can vary between 95 - 100 on the highway, and can enjoy the trip with not trying to keep up with the traffic.

I can remember having to change down my petrol powered Rangie a few years back trying to keep up with a diesel powered Landcruiser in a head wind. New diesels are great and will do all a petrol one will with greater economy.

Obviously for the show of a V8Diesel you aren't getting the skin off any custard.

I have loved diesel Rover, Citroen, VW Passat and Peugeot overseas on unlimited roads in the medium to high 100 kph - I mean 150+ up to 170 to stages where we Aussies look in the mirror or look to roadblocks ahead. Love to get a 3 litre Merc actually in a road car.

Interesting responses, it always causes an argument or two. I find some diesel afficiando's get very worked up if you even hint that petrol motors have torque too.

The 'petrols are useless' pub arguments baffle me. I generally reply that if the 4.2 diesel has so much more torque than a petrol why does it struggle on even moderate hills and if a trailer is hooked up, well you have a real battle on your hands then. I would have thought a long hill would be the perfect test for comparing 'pulling power'. Can anyone tell me why a long, steady hill wouldn't be a good indicator of a vehicles real world torque output? My 4.5 will putt up climbs in low range quite nicely and does long hill climbs on the bitumen with ease at the speed limit.

I own a petrol and a diesel so the debate doesn't really bother me either way, but the heated discussion it creates intrigues me. I never argued that petrols are better, just that they do pretty bloody well too IMHO. I do love the low down grunt of the V8 oiler, but I reckon that large modern petrol 4x4's have fairly broad spread of practical, usable power too just quietly.

Anyway, thanks for the responses, I'm off to nurse my hangover.........uuuurrrrghhhh

Hi again

Torque = work
Force times distance (eg. bang times crank rad.) shifter nut!

Power = work divided by time

Hp is a figment of James Watts imagination, he had to sell he's steam engine!

An engine (motor) petrol, diesel, electric produce torque only

It's the time that produces power (RPM) m = minutes

thats why a 4.5l petrol can have more power than a diesel 4.5l engine, it will rev higher.

the main reason petrol engines can not produce as must torque as a diesel engine is, that the bang is all over around 1/4 of the rev. as a diesel will last a lot longer around 1/2 a rev.

it's all easy it's just maths

I can go on for ever but i wont

Regards

Richard

ps I will stand to be corrected

Some people are on some serious drugs , The only reason you would own a diesel , is for economy and to travel to areas that dont sell petrol or gas. To say that it has more torque is bull bleep , they have diffrent torque , I has peek torque m one has a longer torque line ,

To make comment that my diesel keeps up with V'8 , you are on serious drugs and need to seek help quick.

To think your City driven diesels will last to a Mill kms , you are on drugs . If you live in the country and do long trips , yes you will get great km's . City driven diesels are lucky to do 300,000 to 400, 000 kms .

Then after all has been said and done , go re build it and spend your 10 k if your lucky and go straight to the pub to brag about your fuel savings

torque is multiplied by gearing (300nm in 1st gear is 300 x 3 = 900nm x diff ratio of 3.75=900 x 3.75 = 3375nm !!! at wheels.)
power is NOT multiplied so 150 kw is 150 kw in every gear (- losses)

A petrol with 300nm at 3000rpm is as powerful as a diesel with 600nm at 1500rpm (with a gear selected to match).

Thats why diesel engines have have high torque but low power(they cant make good torque in the higher revs)

petrols just have more power.

I’m not going to pick any sides other than give my own experiences.

I’m intrigued about all the diesel “torque” as many times I have followed diesels into churned beach sand scenarios only to find they start slowing down in clouds of black smoke and eventually stop. I’ve always wondered about the so called massive diesel torque as my efi V8 easily drives around them as it has heaps of torque and HP at the stab of the pedal. The diesels just don’t seem to have that instant rev capability to get you back up to the required speed etc.

Many a time I have also had the scenario where it was necessary to give the engine a quick stab to climb up a sand washout etc and the diesel if front or behind wouldn’t make it as its rpm’s instantly dropped etc.

I’ve stopped and watched various vehicles negotiate long stretches of churned sand etc and it always seems to be the big diesels that make the hardest job of it as they don’t seem to be able to get instant rpm. They seem to start off fine but then slowly die and bog. I’ve snatched many diesel Cruiser and Nissans out of sand so I’ve never been able to understand this “massive torque” issue.

Fuel consumption is their forte but again if I sit on 110kph I get 12.5L/100 so this is also a non an issue for me. Granted if I hitched up a large van etc then the tide would turn.

There’s case for both but for me there’s no substitute for a healthy petrol V8.

I can idle up a steep hill in low range first doing about 600-800 rpm in my 4.2 diesel gq patrol. I haven't ever tried this in a petrol but i imagaine it would be hard to do this in a petrol without wheelspin.
Barnesy