cat mpg opinions and advice

First things first is get rid of them oxycats under that truck, theres 2 of them on a KW and those are your biggest killers. If you get 5.8mpg running west over the rockies then dont complain, even with a 6NZ ecm i doubt you will see a big difference maybe 2-3 tenths increase, but the engine will run and pull much smoother.

MBN is not designed to be lugged to 1100rpm, neither is a 6NZ for that matter, i wouldnt lug anything that low EVER , the person telling you this needs to go back to truck driving school, 9.75mpg? Get real, not even pulling an empty trailer.

 

Catalytic converters in the mufflers that are on the truck, yours being a T6 they're probably vertical behind the sleeper. You will see a difference in fuel millage with a 6NZ ecm but dont think you are going to go from 5.8 to 7.5mpg, i would do a straight 550hp program, yank the mufflers, and drive the hell out of it.

 

Depends what turbo is on there now, get the part number off of it. Just get in touch with DDS he can re flash your ecm to a 6NZ file. Dont waste your time with PP and their overpriced junk.

 

24.5's are les fuel effiecient then 22.5's, tall rubber (in either size) is less effiecient then low profile rubber.

now that is considering the truck is setup properly for the tire size.


the gentalman who is saying he picked up fuel mileage from putting tall rubber on obviously had a truck that was not set up properly for the work he was doing because he was turning way too high of rpm's. his fix was to put tall rubber on lowering the RPM, if he would have swaped rear end gears to get the same rpm out of the low profile tires then he would have gotten even better fuel milage improvements. However you have to justify the cost of the upgrade and he may have already been due for tires.

 

I wish I could do that on every run. Loaded miles, but probably a 10k or less load.

Ken

 

Or bobtail and you just cleared it. Either that or that thing is way more off then 25%.

 

Never trust an on board computer for actual milage. Cat says my truck is averaging 6+ mpg yet my calculator shows that I am averaging under 4 mpg.

Oh and as 550 said. Don't run a c15 at less then 1400 rpm loaded. It won't pull it in top gear.

Reason why people get better economy at lower rpms is because they are going much slower thus there is alot less wind drag.