Gas engine and Diesel of same specs.Pull the same.

I don't completely agree with the comments about displacement.

When you apply boost to diesels you are in a sense increasing the displacement. So while at 0 gauged psi, you might have more displacement in a BBC, when you spool that turbo up to 15psi or more you are doubling the displacement so now your comparing a 7.4 BBC to a 11.6 CTD.

It sounds really obvious and I'm sure a lot of people understand that but I just wanted to out it in writing so we are all clear. Many people jeep going back to the whole there's no replacement for displacement argument but it all seriousness the CTD is pushing out more exhaust gas than the larger gas competition so therefore it has more displacement.

All the peak up numbers and tq numbers were made at peak boost or max displacement.

4x4ord wrote:

wilber1 wrote:
The big difference between these engines when it comes to low RPM torque is the turbo charger. There are turbocharged, direct injection gas engines available in production cars that are a match for the latest DM,PS or Cummins when it comes to low RPM torque per liter of displacement and blow them away when it comes to peak HP. Fuel economy and durability may be a different story however.

Although I agree with you to a point, when your talking car engines I'd still take the diesel.

546 lb ft and 381 HP 3.0 liter 45 mpg diesel

" It's interesting to note the rapid fuel consumption dropaway with the extra weight - the similarly sized BMW M550d xDrive Touring returns consumption of 6.4 litres/100 kilometres (44.1 mpg imp) and CO2 emissions of 169 g/km, while the heavier BMW X5 M50d returns 7.5 litres/100 kilometres (37.7 mpg imp) "

Don't forget they are reporting Impg. So in a slightly heavier vehicle, it's not much over 30USmpg in the SUV. And thats if it hits the rating.

4x4ord wrote:

wilber1 wrote:
The big difference between these engines when it comes to low RPM torque is the turbo charger. There are turbocharged, direct injection gas engines available in production cars that are a match for the latest DM,PS or Cummins when it comes to low RPM torque per liter of displacement and blow them away when it comes to peak HP. Fuel economy and durability may be a different story however.

Although I agree with you to a point, when your talking car engines I'd still take the diesel.

546 lb ft and 381 HP 3.0 liter 45 mpg diesel

So would I but I doubt we will see that engine in North America.

wilber1 wrote:
The big difference between these engines when it comes to low RPM torque is the turbo charger. There are turbocharged, direct injection gas engines available in production cars that are a match for the latest DM,PS or Cummins when it comes to low RPM torque per liter of displacement and blow them away when it comes to peak HP. Fuel economy and durability may be a different story however.

Although I agree with you to a point, when your talking car engines I'd still take the diesel.

546 lb ft and 381 HP 3.0 liter 45 mpg diesel

The big difference between these engines when it comes to low RPM torque is the turbo charger. There are turbocharged, direct injection gas engines available in production cars that are a match for the latest DM,PS or Cummins when it comes to low RPM torque per liter of displacement and blow them away when it comes to peak HP. Fuel economy and durability may be a different story however.

Hybridhunter wrote:

Golden_HVAC wrote:
I was going up a grade near Mammoth Mountain, I guess 6% or a little steaper on highway 395. I was driving a Country COach with a 8.3L diesel, and my buddy was driving a Elite with a 10.4L Cat engine, both with over 600 foot pounds of torque. The other friend had a 454 GMC motorhome, outran both of us, and was at the campground gate 15 minutes before us, checking all of us in before we got there.

Those gas engines can make some power when required. The limiting factor with a diesel is most do not make as much torque as the RPM goes over 2,900, and really drops off once the govoner is reached.

Cummins are slow turning engines for a reason, the pistons weight is twice as much, rotating mass is much higher than the gas engine that is larger displacement, but making nearly as much toque, and more overall horsepower.

Change it a couple of years, to the 800 foot pound torque specs, and the diesels finally wake up.

Fred.

Well Sorta.... 800ft/lbs at 2500 rpms puts the same power to the wheels as 400 ft/lbs at 5000 rpms. Usually for about $10K less, I might add.....

800 lb ft @ 2500 rpm does put the same power to the wheels as 400 lb ft @ 5000 rpm but when the load requires 3000 lb ft of torque on the axle to make it up the hill the gasoline engine might not be able to find a very favorable gear to pull in. It would likely take a 10 speed 400 hp gasoline power train to compete with a 6 speed 400 HP diesel, although even 6 speed to 6 speed a hill could be found somewhere that favors the gasoline unit.

Golden_HVAC wrote:
I was going up a grade near Mammoth Mountain, I guess 6% or a little steaper on highway 395. I was driving a Country COach with a 8.3L diesel, and my buddy was driving a Elite with a 10.4L Cat engine, both with over 600 foot pounds of torque. The other friend had a 454 GMC motorhome, outran both of us, and was at the campground gate 15 minutes before us, checking all of us in before we got there.

Those gas engines can make some power when required. The limiting factor with a diesel is most do not make as much torque as the RPM goes over 2,900, and really drops off once the govoner is reached.

Cummins are slow turning engines for a reason, the pistons weight is twice as much, rotating mass is much higher than the gas engine that is larger displacement, but making nearly as much toque, and more overall horsepower.

Change it a couple of years, to the 800 foot pound torque specs, and the diesels finally wake up.

Fred.

Well Sorta.... 800ft/lbs at 2500 rpms puts the same power to the wheels as 400 ft/lbs at 5000 rpms. Usually for about $10K less, I might add.....

Golden_HVAC wrote:
I was going up a grade near Mammoth Mountain, I guess 6% or a little steaper on highway 395. I was driving a Country COach with a 8.3L diesel, and my buddy was driving a Elite with a 10.4L Cat engine, both with over 600 foot pounds of torque. The other friend had a 454 GMC motorhome, outran both of us, and was at the campground gate 15 minutes before us, checking all of us in before we got there.

Those gas engines can make some power when required. The limiting factor with a diesel is most do not make as much torque as the RPM goes over 2,900, and really drops off once the govoner is reached.

Cummins are slow turning engines for a reason, the pistons weight is twice as much, rotating mass is much higher than the gas engine that is larger displacement, but making nearly as much toque, and more overall horsepower.

Change it a couple of years, to the 800 foot pound torque specs, and the diesels finally wake up.

Fred.

I bet the power to weight ratio was in favor of the GMC 454 Motorhome.

I was going up a grade near Mammoth Mountain, I guess 6% or a little steaper on highway 395. I was driving a Country COach with a 8.3L diesel, and my buddy was driving a Elite with a 10.4L Cat engine, both with over 600 foot pounds of torque. The other friend had a 454 GMC motorhome, outran both of us, and was at the campground gate 15 minutes before us, checking all of us in before we got there.

Those gas engines can make some power when required. The limiting factor with a diesel is most do not make as much torque as the RPM goes over 2,900, and really drops off once the govoner is reached.

Cummins are slow turning engines for a reason, the pistons weight is twice as much, rotating mass is much higher than the gas engine that is larger displacement, but making nearly as much toque, and more overall horsepower.

Change it a couple of years, to the 800 foot pound torque specs, and the diesels finally wake up.

Fred.

Just think of what can be done with an 8.3 tho! It's always been about the potential to me. Craig