Re-geared and free-spinned the 3500 4x4 diesel

[slowmover]

Originally Posted by skyking

I scored some of the lightest wheels around, the stock alloys off the 2011 4th generation Ram. The same Michelins on those alloys is 61 pounds, for a total reduction of 92 pounds of rotating mass. I will report the results.

I've looked at latest factory six spoke alloys to increase size to 18" and per wheel weight rating. Rear axle can handle more than 6k, and those would bring me to 6700# per tire & wheel rating. I haven't checked all compatibility issues or weight. From 17" stock and 3042# rating, to 18" and 3680# rating. This has to do with potential increases to travel trailer tongue weight load.

Frankly, outside of having trans gears and axle gears Microblued, standing start and other acceleration issues are almost impenetrable past engine parameters.

[skyking]

you can get about 6% with either the 17's or 18's at 295 width, in the Michelin Defender LTX M/S.
I wish they made a taller, narrow tire for us. A 265/80 would be a fabulous tire, reducing RPM by 6% would show up for guys like you with the long term logging.

[skyking]

320 miles today, all but 40 of it freeway @ 60 MPH. I had a ladder over the tailgate but I propped it up so it was horizontal at least.
24.27 MPG
This is the new baseline.
When I got the truck it was stuck at about 19, regearing it got to 22, and the slightly higher OD ratio and new cam got it to here.
Now I will try the airdam. I got the app torque going and that provides a very nice instant MPG and average that was closer than the overhead.
Slowmover, if you don't have torque and a bluetooth OBDII transmitter in your truck I suggest you try it.
Of particular note was percentage of load. One can look at that, at the instant MPG, and draw some conclusions from there. If you did that we could compare notes.

[gumby79]

Is there a coalition between%load ,EGT,and throttle position? What kind of EGT's are you seeing, flat , mild hill ,and grade?
For me at 60-65 400° is the brake point from on power to compression breaking ,the point I go to neutral. IMHO the EGT is the diesel version of a Vacuum gage for gas. The lower the temp to hold speed the better economy your going to get.

[skyking]

That was a problem. When I ran the torque app on the OBD splitter, it froze the smarty touch. That is my EGT instrument.

[gumby79]

Did the smart going dumb ( quiet) change the tune? IIRC you have a very mild tune for cam compensation.

[skyking]

It is not tuning on the fly. Any changes take a few minutes and key cycles to flash the ECM.

[slowmover]

Originally Posted by skyking

. . I got the app torque going and that provides a very nice instant MPG and average that was closer than the overhead.
Slowmover, if you don't have torque and a bluetooth OBDII transmitter in your truck I suggest you try it.
Of particular note was percentage of load. One can look at that, at the instant MPG, and draw some conclusions from there. If you did that we could compare notes.

I look forward to so doing. Am travelling almost full time now, one to two months at a time. And will follow your lead. I'm much in favor of having our trucks (and others comparable in model spec) to try and draw deductions about work versus longevity versus reliability and against economy.

300-miles at 60-mph on cruise is easy (when these questions are considered important), and I think we can learn to distinguish climate and terrain differences. Truck spec is obvious, and cruise control at a given speed eliminates driver problems.

[skyking]

I'm running with two strikes against me, taller so more frontal area, and the short bed does not help either. I get some back with the taller gears, but my conclusion so far with the two trucks is: It is all about aerodynamic drag. Speed is not my friend, as the CD is so high.
I notice you talk about 57~58 MPH and I think even that little bit makes a difference. These engines are quite miserly, but when pushing a brick you can only do so much.

[slowmover]

You may remember my comments in re speed choice on my FE thread. I think I characterized 58/9-mph as the "fast" economy speed (GPS correction). 60-mph was where one really starts to see a decline. 58-62 is a good range for highway work. This past month it has been where I've travelled. Speed limiter and radar proximity device. Maintaining space is the safety key, and I may go several 400-450/mile days without passing anyone.

Higher than 62 and one is mixing with big trucks. At the speed limit one is trapped by four wheelers. In each, lane changing (steering) and brake plus acceleration events become more commonplace. So it's not just air resistance.

Lower than 63-mph is best. Peripheral vision is fantastic, and stress is low by comparison to 65 and higher. And travel time isn't really affected on 300-mile trips (record engine hours versus miles). Trip planning to control number of stops and their length is how time is saved (safety is two hours or 100-miles to stretch; and an hour break after 4-hours driving. Combine with meal and fuel stop).

Details apply after that, so that advantages of 58-62/mph multiply. And they do.

I start from the assumption that braking and handling for a pickup teach limits from 55-65/mph. Rollover chances greatly increase. So, use what works in this speed range. One may not have the best gear choice for a speed in that range. But a little higher or lower to use Direct or Overdrive given conditions is how I see to place myself. FE second to that.