Ram 1500 diesel review

jus2shy wrote:

Hi Rob. Looking over the data again, the difference is that at 10mph, the Ecodiesel is already in the meat of its torque band given the transmission gearing. What you're seeing is that the power is the torque is falling off as the engine is being winded out. Figures are correct there assuming immediate lock-up (no torque converter slippage).

I wondered if that might be the case. It's not the data points that look weird, it's the shape of the curve. Basically there aren't enough intermediate data points to show it rising before it starts dropping.

The same thing is going on in the valleys with the EcoBoost. In reality there isn't a valley, rather there's a sudden dropoff when the truck upshifts. It might be useful if you could find a way to plot the curves that way, but I don't know how easy that would be with the spreadsheet plotter. As an alternative, more intermediate data points would achieve a better approximation.

jus2shy wrote:

Personally, given the wide operating ranges of these motors, I don't think we'll see much beyond a 9 or 10 speed. I worry that the future transmissions may spend too much time "hunting" but the theoretically smooth power delivery could be a good benefit as long as gear hunting is minimized.

The curves you have for the 8-speeds look pretty smooth to me. I tend to agree with your earlier statement that 8 is probably enough.

jus2shy wrote:

What would be the ultimate validation of this sheet is to see a tow test on some 3rd party website and have them drag race with trailers to see if the tale of the tape matches reality :).

I can speak from my recent experience. My old truck had a Hemi with a 5-speed. It had 2 overdrives so only 3 gears were useful for towing. When the engine got into its powerband (345 HP) it pulled like crazy, but due to the wide gear spacing, it spent a lot of time outside that powerband. My new truck has an EcoBoost which has only marginally more peak power (365HP), but it has a 6-speed with better gear spacing, and it's able to get into its powerband much more easily. The difference in towing is very noticeable.

-- Rob