Ram 1500 diesel review

bimbert84 wrote:

Great work! But although the general story is what I'd expect, some of the data points seem incorrect. For example, the EcoDiesel is in 1st gear at 0mph and 15mph. HP is rising, which is right, but torque-at-the-wheels is dropping, which isn't. There's also strange behavior with the (theoretical) EcoBoost at 40mph, but you don't have any source data for that one. I'd suggest just removing it. Would you mind double-checking the other calculations? There's tremendous value in these graphs, and I think it'd be worthwhile to make sure they're correct.

-- Rob

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).

The source data for the ecoboost is from the previous spreadsheet, I just cut and pasted the results onto this one to overlay the difference in power/torque delivery. Also, some people say the HEMI will be beaten by the ecoboost etc... just trying to give some comparison and contrast between the different types of engines. What you're seeing at the ecoboost is what the power delivery would be given the 6-spd transmission versus the ability for both the HEMI and Ecodiesel to stay in the optimum power range thanks to the ZF 8-spd transmission employed by RAM. So the Ford's Ecoboost is forced to leave it's optimum power range and suffer a little bit before it gets back into its optimum operating range. I can now understand why Ford and GM are partners in developing 9/10 speed transmissions. You see far more abrupt interruptions in power and torque delivery in the 6-speed versus the 8-speed. This is also why there was a huge marked improvement from 4-spd transmissions to 6-spd units. That was really fascinating for me. 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.

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 :).