Stock MPG's vs. "Turned up" MPG's

[762frmafr]

I am looking for real world numbers. How many MPG's is everyone getting bone stock, vs. a "turned up" engine? It would be helpful to know how many miles are on the truck as well as a list of modifications. Also, 4x4 or 2wd and what kind of rear end gears and transmission is in the truck.

[cmann250]

It's been hashed out before, but since the search function blows here...

'89 D250 auto, therefore 3.07 gears since it's a non-O/D transmission.

Stock except for a rotated pin: 20.8 mpg once over 10 gallons putting around on county roads

2ng gen intercooler, HX35, 3200 rpm spring, fuel screw near run away, rotated pin, Cummins low pressure piston lift pump, 4" exhaust, and homemade intake (worth 110 hp all together): 19.2 mpg over 3100 miles and 162 gallons of fuel.

The 19.2 mpg figure includes a truck pull and hauling around a stock trailer to town and back, but 90% of those miles were at 70 mph on the interstate.

230k-270k miles on the truck.

[coolhand_luke]

93 D350 (d350 = 2x4 w350 = 4x4) dually, auto w/OD, extra cab LE. 330,000 miles. I drove it stock for a while and it averaged around 20 mpgs but it was a dog. I have turned up the fuel on the pump, 3200 rpm spring, bumped the pump 1/8", cut out the muffler, and installed an hx35. If I drive nice and easy, I will see around 20 mpgs. I have plans to do some tranny work like adding a after market converter and buying a new TPS. I also would like to ad a 4" straight exhaust and after market intercooler to lower exhaust temps. I need a better fuel pump as well because my stock one is crapping out. Oh, and top it off with a water/meth injection system and she should be running pretty. I think I could see high 20's. Adding power needs to be done correctly to see better fuel millage.

[762frmafr]

These are the kind of responses I hoped to see. Keep them coming.

[CumminsPower59]

1991 W350 SRW. NON-IC engine. 3.07 gears. 305/70 17 (34") Goodyear MT/R's.

With a sloppy 727, nearly stock pump, crappy K&N, stock everything else, w/mostly highway driving (55-65 mph): 14mpg.

With NV4500 conversion, moderatley turned up intercooled pump (184), stock 200k+ injectors, 2nd gen I/C, BHAF, DE 4" exhaust, GDS 60mm/14cm H1C, same driving: 21mpg. Note: I don't use 5th gear until 60mph+ can be maintained, i.e., Interstate.

[1992gen1_fan]

1992 W350 flat bed 3.54, 245/75-16 tires, weighs 8,850 lb empty (Turn up specs are in sig) Avg around 16 mpg with mostly town and dirt road driving . Highway only it'll get 18-19 fairly easy and have gotten 20.

With all completly stock there was'nt much difference. When I added the turbo and injectors mpg went down just a tad, maybe 1/2 mpg. After the pump adjustments it went up about 1 mpg from there.

[RCCUMMINS89]

The ONLY thing that has affected my fuel economy is timing and turbo.

[dunes450r]

90 w250 PODs, 727, 3.07s, 12cm hot side, 285/75/16s, 3200rpm spring about 15-16 mpg



90 w250 PODs, gutbag, 3.07s, 12cm hot side, 285/75/16s 3200rpm spring, HVLP lift pump about 17-18 mpg



90 w250 DAP 5x14s, gutbag, 3.07s, 12cm hot side, 285/75/16s 3200rpm spring, HVLP lift pump about 18.5-19.5 mpg

future testing should include a 60mm compressor upgrade and second gen intercooler

[JQmile]

The ONLY thing that has affected my fuel economy is timing and turbo.

x2....I can still get mid to low 20's at 70mph on mine.....47rh 3.07 gears 14mm and 5x25 injectors, 27deg timing, 62mm turbo

It's all speed and rpm. The 727 was really bad at higher speeds. OD helped a lot.

[simplysmn]

First gen cummin's swap dodge crewcab 4x4 6 in lift 37x16.5 Baja Ta tires 410 gear's mod's so far are fuel pin, 366 spring , hx35 12 wg housing stock injector's fuel screw turned in a couple turn's along with star wheel , On Average 17 mpg running around town not all stop n go and some freeway . as Long as I don't burry the skinny pedal it's all good but some times keeping it burried is fun and worst mpg has been about 14 running it like a dog .now before hx35 and 366 spring towing at 58 mph for 400 miles pulled down 16 mpg with ease .

[littleboy]

With fuel screw turned in to runaway 4x13 injectors and 4.10 gears i am getting 22 with a mixture of city and hiway at up to 75mph.

[willroach]

'89 with 727, i run almost 500 miles a week and i am averaging 20 MPG.

[Sutter1stgen]

S366,6x16s,a518, 3.07 gears, timing skipped a tooth, regular cab w250.
Back when I only had the 727 I could get 21mpg at 55 mph all day long.

Now with o/d I can get about 19-20 because of my setup.

[stoneagemaxx]

91 d250 reg cab intercooler covert 60mm htt stage 3 upgrade to the h1c w 18cm collar fuel turned way up 3800 rpm gov spring 47rh convert with medium shift kit 3.07 rear timing advanced 1 tooth and just below factory mark on the pump fuel pin ground starwheel down some smoke screw in a lil factory non i/c injectors for now never see less than 21 city usually 22-24 and 25-26 at 75

[stoneagemaxx]

well winter blend fuel has me down a little still 21mpg I also run power serve religiously