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what kind of m.p.g. are you getting?

vaicase

vaicase

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morley michigan
i have a 1995 6.5 engine. ive had it since dec 09. now my m.p.g. are no better than 16.2. low as 13.6. total average has been around 15 . i use power service in the white bottle on all fillups. i had a 1997 2500 4wd in 2002 and it had 3.73 gears. it got from 22 summer to 17 winter fuel. i understand my 3500 has 4.10 gears. and at 70 mph its cranking almost 2400rpm. but thats a big difference. now is this ulsd the problem? thank you much
 
The USLD has less lubrication in it. I have 3.42's and i get about 19 ish empty highway. Boost is set a little high for the best fuel economy. Around my house and town i get a constant 16.
 
You are getting about what a 3500 truck with 4:10s gets, beefier frame on a 3500 plus gear = lower mpg , significantly lower than what you'd see with 3:73.

Do you have a longer wheel base now also ??? do you still have stock exhaust ?, do you have a cat on that truck ?

If yes to either could also be a more crushed turbo down-pipe , X-over, or more plugged cat.

The 97 had a GM-8 turbo and your 95 has GM-5 which is another difference as the GM-8 is more free flowing than GM-5.

Any boost enhancement features added ?

Miles on injectors ?

What kind of air filter ? 95 has flat panel, 97 should have had K-47 box with round freer flowing filter, also if the round had been replaced with aftermarket filter element that also would net some slight mpg gain.


What fan clutch is on it OEM or aftermarket ? some aftermarket fans come in earlier but don't disengage robbing power & upping mpg I had one of those for a while until shifting to one from Heath Diesel also swapping steel fan blade for composite one like Dmax truck has
95s also IIRC have snorkel in inner fender which is another restriction to intake of air, cut it out and replace flat filter with K-47 box off of a later model truck and use a Donnelson nano filter element from one of our Amsoil vendors here
 
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The cooling system was modded, what temp does it run at? if it has 180 degree t-stats you could gain maybe 2-3mpg by using 195 stats.

If you travel at 70mph a lot, look at getting taller tires to drop the RPMs when cruising. What size do you have now? 2" taller might drop you 200rpm.

Need to know stuff like TD mentioned, air box and what exhaust is on it?

Do you know what injection pump model is on it? Or better yet if you look at the PCM PROM and know the 4 letter code on it I could tell you something about the program and it may be holding you back. Later models advanced timing a lot more than the 94s. So if its stock that could get you another 2mpg from an improved timing curve. If its not stock thats good to know.
 
i am, running 245/75/16 tires. i took off the duals and put single tires on it. a couple of months ago. and it did not affect the mileage at all. go figure. the old tires were 215/85/16 same heght i beleive. i did not know about the themostat change. going from 180 to 195 would affect milage. it runs about 180 degrees a;ll the time. and the fan is loud. the pump i dont know how to check. as for the program. does anyone know how to check that out. it starts easy and runs real strong. the boost is about 4psi going down the road. and it maxes at 12 psi if i punch it then drops a little. i think thats when the wastegate opens. the exhaust is 3 into 4 just past the downpipe then 4 inch to the back. straight thru muffler. no cat. it runs a whole lot stroinger than my 97. this one is a reg cab. my 97 was ext cab longbox. also under the hood it has a kennedy diesel sticker , one more thing the airbox is stock. any little bit helps. thank you much...
 
The fan should not come on much, not until its over 200F, do you hear it often? That will take efficiency away. You can modify the clutch to engage later if its coming on too early. Sounds like you need 195 t-stats too.

The exhaust is good, but if you have the stock flat panel air box I would upgrade that soon. If the injectors are of unkown age and mileage they could drop you a mpg or two.

Here is a list I started, I will be updating it though. I have an update but need to proof read and get a mod to replace it in there, so probably be up on Monday. The list has the air filter box, and thermostat info, timing, injectors, ect... that can affect efficiency.
http://www.thetruckstop.us/forum/sh...ded-Mnx-amp-Mod-List-for-1994-and-1995-6.5TDs

Oh, and those tires are only appropriate for 3.73 gears or a dually used to pull massive loads through mountains, you should try 235/85/16 tires that are about 1.25" taller. Or taller if you get like 20" rims. Alloy wheels will also be a lot lighter than the stock steel ones, for less unsprung weight.

The list I made also covers additives, and I do not recommend PS for lubricity, unless they show some better results than has been tested in the past to be inadequate. I wouldnt use anything regularly with a detergent or anti-gel (unless its really really cold or you dont have winter fuel), but lube it every time.
 
You guys are sick off hearing this I know, but I went from 180 stats to 195 and got 3-4 mpg increase.
 
1998, K2500, 4L80E, 4:11 finals:

13-14 MPG average.

Combined mileage. Mostly short hops.

15-16 Mpg on a straight highway run.

Haven't gotten figures yet for towing, will after this summer....
 
buddy said:
The cooling system was modded, what temp does it run at? if it has 180 degree t-stats you could gain maybe 2-3mpg by using 195 stats.
Click to expand...

Burning oil said:
You guys are sick off hearing this I know, but I went from 180 stats to 195 and got 3-4 mpg increase.
Click to expand...

Seriously??? If thats the case, I am buying new tstats for the wifes 99 TOMORROW (damn stores are closed now!!!)
 
great white said:
1998, K2500, 4L80E, 4:11 finals:

13-14 MPG average.

Combined mileage. Mostly short hops.

15-16 Mpg on a straight highway run.

Haven't gotten figures yet for towing, will after this summer....
Click to expand...

Better find a tow truck that gets goood mileage:D. Sorry, just yanking your chain:)
 
my 97 got a hair under 14 when it was all stock except exhaust. after I modded it all up I wasnt able to get accurate mileage readings because the speedo was off, but it never seemed too bad until the last year or so. I thought the ULSD killed it. But between the lift, tires, lightbar, etc. I would have been surprised if I was pulling down 12.

So, stopped for fuel in my Sub today, it actually made me a little happy to throw $40 in it and see the gauge back up close to half. I haven't checked it since the first tank, I was getting over 14 around town in wintertime, with quite a bit of 4wd. I bet now I've got to be getting at least 17 highway with it. Having the huge tank makes it seem like the fuel lasts longer, the gauge doesn't drop as fast as a little tank does. Without actually figuring it out, it seems much much better than the dually was. It's nice to be able to drive past a gas station day after day and the gauge hardly moves.

I am some impressed to get probably 17 with a 17 year old 3/4 ton 4wd monster of a vehicle. Lots of newer trucks and SUVs not getting near that. My 02 Denali rarely saw 12. Once I get the 82 back on the road with the carb rebuilt, I'm hoping to get it up around 10 mpg, then I can feel like I'm doing as well as the newer 6.0 gassers.
 
I kinda wish I knew what my truck gets for mileage, I know when I had my 9.5 ft Kodiak camper on and towing a 2500 lb boat I was getting 15.9 mpg. Last time I check was maybe two years ago and calculated it out to 17.9 mpg. That may seem excessive but in Canada we use a bigger gallon so would have more btu's. anyone care to do the math to an American gallon. Our gallon is 4.54 liters. I believe the US gallon is 3.78 liters. On a side note I do intend on finding out soon what my mileage is now with the ATT. Ed
 
For the OP. Are you still getting winter blended fuels there? That alone will drop your MPG. Historically with a conservative tune I would see 17 in the summer and 15.5 in the winter.

Ed, as my ATT breaks in and has learned to get along with the PCM I've gone up from 15.5 winter blend to 17s. "Your results may vary."
I do know that I'm looking forward to the summer blends.
 
what is the difference between winter and summer fuel ??? real numbers? is it a different blend between the northeast. or midwest or where im at now in southwest kansas? because i went to michigan with a load of household stuff. small fridge, lots of books some tvs. probably a ton or so. with a topper. and i got 16.2 in ks. 14.5 in iowa. and15.8 when i filled in michigan. and empty on the way back i got 15.7 15.3. and 13.6 in kansas. about 2300rpm to 2500rpm,whats up with that? i fill at truck stops. now is that a bad thing? thank you much
 
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