2004 Kenworth T600
Cat C-15 435hp bridge
EF 13spd Trans mod # RTLO16913A
3.55 rear ends mod # DSP40

Average 5.2-5.8 depends on load, generally drive 65-70. Haul reefer trailer normally @72-78k lbs.
At 65mph my rpms are a hair above 1400.

Im wanting any advice on getting better fuel mileage.
My options that ive found are these:
(would like any and all input on these)
1. new muffler from pittsburg power.
2. wire harness for fuel to trick ecm about fuel temp
3. air tabs
4. change rear ends to different gear ratio to lower rpms at 65ish.
5. jetstar hydrogen injection from dynamic fuel systems
6. add trailer skirt to my reefer trailer
7. add full fairings to my truck (only has fairings halfway to end of tanks)
8. a newer higher performace turbo
or
9. buy a solar powered truck.....

what does the wire harness for the turbo do for you exactly?
does it only give better turbo response and a smoke screen?

so these are the options i know about, i would apreciate any and all opinions and knowledge on any of these. what might help, what will help.
Thanks

I wish I could get that with my C-15... I've averaging 4.7 to 5.0

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well tomorrow im gonna go get the serial number off it and make 100% sure its a bridge, really interested in what a few members are saying about cat motors and things to do with them, hopefully i have a few options

I wouldn't spend the money on the air tabs or a hydrogen system. From what I hear the air tabs pretty much just give ya a little bit more visibility in the rain. I would go after a reprogrammed ECM or a Bully Dog system to take care of the ECM. All the aero stuff (fairings and skirts) will help, but it all comes down to your right foot.

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'06 379 Pete with a MXS C-15 550 with heavy haul program, 200gph FASS, high flow mufflers, fuel and boost harnesses, shimmed fuel pump, Bully Dog downloader, Spinner II bypass filter, Schaeffer's synthetics in all boxes, and a 18 speed tranny. Leased to Schneider on their Choice program.

hey Morph, good question. I hope to learn more about that here, also.

Switch to a taller tire. You must be running low pro 22.5's.

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My Wagon Ain't Saggin'!!!

yep, low pro 22.5 and i went out and checked engine and it is a mbn.

[quote=pullingtrucker;1088822]I wouldn't spend the money on the air tabs or a hydrogen system. From what I hear the air tabs pretty much just give ya a little bit more visibility in the rain. I would go after a reprogrammed ECM or a Bully Dog system to take care of the ECM. All the aero stuff (fairings and skirts) will help, but it all comes down to your right foot.[/quote]


what pulling trucker said. Watch alot of guys take off like they are in a drag race.
Also, what happens when you limit speed to 65 mph?

not me, i think i piss a lot of people off cause i take my time gettin up to speed. when i run 65mph i get upper five like 5.7-5.8mpg. and i dont mind drivin that speed, but no way will i stay sane if i drive 55 from michigan to cali. so if i could figure out exactly what i can do to this truck/motor ill stick with the 65mph, but would love to see 6.2-7mpg. ive been doing readin here about the fuel temp harnes and the boost harnes, and a different ecm still a bit lost on that though. fuel temp harness seems simple, not sure if i would need the boost harness, not clear on what it does exactly.

as per the different ecm if i got one, is that something i would need to get programmed by cat? would i need to change my turbo or anything else?

thanks for the input so far.

I drive a 2000 Freightliner Century w/ a C 15 rerated to 500hp. I ran most of the summer getting upper 9's (9.75) for mpg. My loads are light (about 12K) and I generally drive the I 5 corridor between Seattle Wa and Yreka CA. The things that helped me get the mileage up to that level were:

1. Upgrading the motor from 435 to 500 hp.
2. Centramatic wheel balancers.
3. Air Tabs.
4. Keeping the trl as close as possible to the cab.
5. Drive the speed limit (really it's legal!)

The key to good fuel economy from a cat is to keep the rpm's low. The engine will pull just fine at 1100 rpm. Upping the hp will help keep you in a higher gear (therefor lower rpm) for more of your drive time. If you cruise at 65 then think about changing the rears to a lower ratio so that at 65 mph the engine runs at 1100 rpm.

Vibration is an energy waster. Dynamic wheel balancers work well because tires are always picking up stones and becoming a little unbalanced because of it.

I got about a 4% increase in mpg from installing air tabs on my tractor. They cost me about 200$ for the set to do the tractor. Cheap for the gain.

Keeping the trl close to the cab helps. When ever I am empty the fifth wheel is all the way forward. If I have the time I will adjust the 5th wheel position to put the steers at 12.5K when under load. (this is legal in the states I normally run in).

Getting to high mpg performance takes an attitude. It's not about running slow (though that helps), it's about having an active desire to keep improving the number. It is one of the few addictions that is also profitable.

Good luck!
Ken