Cummins "secrets" on better fuel economy paper

[gumby79]

Originally Posted by cosmick

Drafting behind a semi is the best thing i ever tried for mpg. Just stay back enough to be safe. Do it away from urban areas.

Without proper reaction time you get this...


Smashed between truck cuse a nother driver decided to join your fun/drafting.
The .5-10% you save by drafting is not =to your life keep your 3-5sec intervals .
Most of the 100+car pile-ups were caused by following too close.

[Hersbird]

To be fair, that car between 2 trucks was no fault of the car, obviously the 2nd truck was the problem there. That truck wasn't going to stop if the car was or wasn't there. Also if you watch most videos showing big pile-ups, often the cars stop and control themselves fine, it's the trucks that come barreling up out of control, unable to stop that then involve those cars.

[gumby79]

If there wasn't room for the truck to stop? should the car have been in there? I have had trucks draft me 1-2sec with my 3-5 sec intervals . Then on a hill they'll pass me and draft the truck in front. Owner operator I'm guessing. Most trucks are going faster than I'm willing to burn fuel 70+mph. My $500 Insurance Deductible ROI is reason enough to not draft. Plus a much more relaxed mood begin able to see what's going on ahead to plan for hills and grades, traffic slowing a 1/4mi away.as well as driving in rear gun truck in Baghdad, IQ some times I run with a 300m /10sec. interval for comfort .
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Back on topic . Anyone else noticed a drop in cruse EGT on there Cummins after stepping up to synthetic oil? I'm seeing a 50-75°f reduction. And a significant reduction in turbo cool down idle time. Yes oilpan I cool my turbo. Its an antique 91 without water cooling. Before you rag me about my cooling practice. I've gotten 18 fill-ups at or above 25mpg in the last 3 summer months. Cool down time ws reduced from 1-5min to 5-30sec to reach 3-350EGT and the immediate shutdown is only resulting in a rise to 400EGT now as apposed to going to 5-600EGT I ve run expairaments.pulling a hevy grade @800 EGT 2mi past the summit last 1/2mi neutral costing stop aat 400 EGT kill it and the EGT was climb to 700°f and climbing that was as far as I was willing to cook/coak the oil in the bearings . This required turbo cooling is all but gone.

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Duse anyone have access to a BSFC for a late intercooled 1st gen I've only found a hp/tq map

[Fat Charlie]

Quentin Hapsburg: Do you gamble?

Lt. Frank Drebin: Every time I order out.

You take your life in your hands every time you get out of bed, and dispersing vehicles in combat conditions has nothing to do with traffic safety. Whenever my unit was up north we never had a problem getting crews to escort runs from Abu Ghraib to BIAP and back- there was a Burger King at BIAP. Sure, in retrospect it sounds crazy to run those roads just to get some burgers, but it was no riskier than any other time we got into our trucks.

With drafting, I'm already on the road at the same time and place as the trucks or buses. I'm not doing anything more or less unsafe than anyone else, I'm just the car who happens to be behind them. Better someone who's happy about it, someone happy to get the steadier speed and wind block than someone ranting about being stuck behind a truck and frantically looking for a way to shove his way into the line of cars passing it.

[slowmover]

"Drafting" means one cannot see far enough ahead to make the changes necessary to enable a safe and uneventful trip.

And, believe me, an empty 18-wheeler can scrub speed faster than one will envision.

To get back to the topic, make it about having loaded ones vehicle and/or towing a trailer fairly heavy for the vehicle, being to read the road surface ahead at highway speed is part of reducing steering inputs. Same in accounting for winds. One wants a fairly quick return to center with the steering AND as much space ahead to do it gently. Remaining lane-centered, dead-on, is the goal. Sane for coming down in speed well before an exit or construction (for which one has warning), and for the emergency slowing in the event of a wreck or ice, etc; as signalled by vehicles ahead.

In short, just as one cannot have too much fuel aboard, one cannot have too much space out ahead to both read and react to changes in conditions.

What gets hairy is the combination of adverse conditions. This is where bad habits kill people.

Drafting is a bad habit.

[Hersbird]

Although in theory, if you drafted at a space of say a foot, the lead wouldn't have the ability to slow fast enough to cause more then a mild bump between cars. The pictures of the really smashed cars come from one vehicle having time to come to a complete stop while the following car is back far enough, not paying attention, and traveling at full speed still. This is why I actually want the self driving cars and trucks, not so much around town but to make smooth flowing, drafting road trains on the highway. Maybe even with some kind of inflatable balloons between them to make a mechanical link.

[acparker]

It has been my experience that you can get a significant improvement in mileage by driving in the tip of the turbulence wake of a large truck or trailer. Get in close enough to just feel the buffeting. That usually gives a safe buffer, between 2 to not quite 3 seconds, on rural freeway, but just inside the rig's blind spot (with three trailer rigs I can sometimes see the side mirrors). Crosswinds shorten (alter the angle of) the wake, so it would be inadvisable to draft in those conditions. I don't drive closer than 2 seconds behind a semi rig, except in heavy, slower, urban traffic (because some idiot will always fill the gap).