Hybridhunter wrote:
wilber1 wrote:
Hybridhunter wrote:
Even the tiny base V6's are making 150Hp by 2500rpm. That is sufficient to tow most 1/2 ton towable trailers. Is it really a big deal to run at 2500 rpm vs 1900? Really? And the diesel is at "full throttle", and "high rpm"just as much, it just happens to have a narrower rpm range than a typical gas engine.
Well, try running 2500 rpm in OD.
If you read the whole thread, you would have seen where I posted that towing either of 2 trailers that I tow (very tall 3800#, or a Rockwood too type at 6000# curb), I cruise in 5th, (technically OD) at 2200-2400 rpm from 65 to 70mph. A good wind puts me in 4th at 2800@65. Smooth as butter, and 4000rpm from redline. (No typo).
Climbing in my truck is done at higher rpm, up to 4500, where the horsepower is 240hp, same as the ED at max rpm. At that point, if I was to use all 300hp, I can drop a gear, or drive along side the ecodiesel, with him pulling 3600rpm. Big deal, $4000 more to save 900rpms? Not for me.... Think about that for a second, same hp, only 900rpm more....
Heck, my last bike cruised at 5000rpm, it didn't make me want to run out and buy a diesel, my sled cruises at 7000+...
Let's use your example.
Truck A: 150 HP @ 1900 RPM
Truck B: 150 HP @ 2500 RPM
Gear both so they are turning 1900 RPM in OD at 65 MPH. Pretty normal gearing.
Truck A can tow at 65 MPH in OD and only have to gear down for bigger hills. Truck B will have to gear down for almost every hill, either that or it will have to run 85 MPH for its engine to make the same HP in OD as Truck A does at 65 MPH. Kind of self defeating considering how much more power and fuel it will take to run at 85.
An apples to apples comparison. The 650 and 800 6.7 Cummins both put out 350 HP peak at the same RPM but the 800 makes 20% more power at 1600 RPM. Which truck will have to shift down more often when cruising at highway speeds?
I have an Audi which uses the same 8 speed as these trucks. Cruising at a constant speed in 8th and shifting down enough to raise the rpm by 600 has me hunting between 6th and 7th.
The Pentastar puts out more peak HP than the ED and with 8 gears I am not surprised it can pull 2 tons at 70 MPH and climb hills well. But in what gear compared to the ED?
No matter what you drive, more rpm equals more noise, more wear and more fuel.
