Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Cummins "secrets" on better fuel economy paper

slowmover · 09-10-2016, 09:43 AM

Kenworth has one similar. I've recommended both several times over the years at this site.

Prominently, while vehicle spec has first place in understanding FE of a particular vehicle, comparisons to others (once past tech spec) is that

Climate
Terrain
Driver Skill

Are necessary

On RV forums, I searched for and found about one dozen comps to my truck and travel trailer. Same brand and motor. (Not otherwise as to spec). TT type had to be aerodynamic, all aluminum. Length from 27' to 35'. Weight from 7k lbs to 11k. Then, that the users making reports had to be in the South Central US. And travel speeds of 65-mph or less. Only then could I make an assumption that my FE of 14-16/mpg was normal.

Generally ignored are important considerations such as steering inputs per 100 miles. That KW and Cummins call them measurable should be a wake up. Especially with a 4WD and/or towing.

In another thread (and something I've brought up repeatedly) one needs a handle on solo mpg where the vehicle is loaded as if for towing AND is covering the same sort of climate/terrain AND at the same speed as if towing. Why? Because whether the testing was conducted in 1966 or today in 2016, the percentage FE drop is right at 40% given a speed of between 60-65/mph.

An aero trailer CAN be lower. Maybe trending towards 30%. Even lower is possible where the driver has route familiarity AND knows how to plan. I've done it with a UHaul no taller than the cab height topper on my truck bed. 25%. Twice, over the same route.

The KW and Cummins White Papers are aimed at revenue miles. Thus, in the final category of differences between drivers, a difference if almost one third is present. Same equipment, same load and same route.

This is the focus around here, in general. But I'd argue that much more attention to mechanical details is first. 40 will never be 30 if alignment on both vehicles isn't perfect. Same for brand drag on both. Same for book maintenance otherwise. Brand new vehicles aren't exempt from verification.

So, take your vehicle and load it to manufacturer maximum. Sand bags or whatnot. Learn to drive it well. Earn your stripes. This IS the design parameter, NOT solo driver.

Can't afford maxed air pressure tires, but load/pressure balanced. One cannot afford loss of handling traction, much less braking traction. Etc. A CAT Scale is an easy way to learn to load it. Look for differences cross-axle, as well. The heavier wheel position on the axle determines cold pressure setting.

I just came out of the main terminal shop. They worked me right in to correct the starboard toe alignment (off 1/16). They'd have laughed were my complaint about my AC being too warm. That's a preset interval check (PM, as it's known).

That my KW now tracks straight -- and tire ruin averted -- goes straight to the annual average mpg. I'm not having to scan the changing road surface as diligently. Won't jump around in the lane, now.

It applies to your air conditioned go kart. But you'll fix the AC first, right?

Load it to maximum and re-learn HOW to drive it. There's no real end to skill acquisition. It pays. There is no worthwhile education if done at the last moment. It's part of owning a piece of equipment to know how it operates under all conditions. Around here, we test.

09-10-2016, 09:43 AM	#6 (permalink)
slowmover Banned Join Date: Oct 2009 Location: Fort Worth, Texas Posts: 2,442 2004 CTD - '04 DODGE RAM 2500 SLT Team Cummins 90 day: 19.36 mpg (US) Thanks: 1,422 Thanked 737 Times in 557 Posts	Kenworth has one similar. I've recommended both several times over the years at this site. Prominently, while vehicle spec has first place in understanding FE of a particular vehicle, comparisons to others (once past tech spec) is that Climate Terrain Driver Skill Are necessary On RV forums, I searched for and found about one dozen comps to my truck and travel trailer. Same brand and motor. (Not otherwise as to spec). TT type had to be aerodynamic, all aluminum. Length from 27' to 35'. Weight from 7k lbs to 11k. Then, that the users making reports had to be in the South Central US. And travel speeds of 65-mph or less. Only then could I make an assumption that my FE of 14-16/mpg was normal. Generally ignored are important considerations such as steering inputs per 100 miles. That KW and Cummins call them measurable should be a wake up. Especially with a 4WD and/or towing. In another thread (and something I've brought up repeatedly) one needs a handle on solo mpg where the vehicle is loaded as if for towing AND is covering the same sort of climate/terrain AND at the same speed as if towing. Why? Because whether the testing was conducted in 1966 or today in 2016, the percentage FE drop is right at 40% given a speed of between 60-65/mph. An aero trailer CAN be lower. Maybe trending towards 30%. Even lower is possible where the driver has route familiarity AND knows how to plan. I've done it with a UHaul no taller than the cab height topper on my truck bed. 25%. Twice, over the same route. The KW and Cummins White Papers are aimed at revenue miles. Thus, in the final category of differences between drivers, a difference if almost one third is present. Same equipment, same load and same route. This is the focus around here, in general. But I'd argue that much more attention to mechanical details is first. 40 will never be 30 if alignment on both vehicles isn't perfect. Same for brand drag on both. Same for book maintenance otherwise. Brand new vehicles aren't exempt from verification. So, take your vehicle and load it to manufacturer maximum. Sand bags or whatnot. Learn to drive it well. Earn your stripes. This IS the design parameter, NOT solo driver. Can't afford maxed air pressure tires, but load/pressure balanced. One cannot afford loss of handling traction, much less braking traction. Etc. A CAT Scale is an easy way to learn to load it. Look for differences cross-axle, as well. The heavier wheel position on the axle determines cold pressure setting. I just came out of the main terminal shop. They worked me right in to correct the starboard toe alignment (off 1/16). They'd have laughed were my complaint about my AC being too warm. That's a preset interval check (PM, as it's known). That my KW now tracks straight -- and tire ruin averted -- goes straight to the annual average mpg. I'm not having to scan the changing road surface as diligently. Won't jump around in the lane, now. It applies to your air conditioned go kart. But you'll fix the AC first, right? Load it to maximum and re-learn HOW to drive it. There's no real end to skill acquisition. It pays. There is no worthwhile education if done at the last moment. It's part of owning a piece of equipment to know how it operates under all conditions. Around here, we test.