Sweet Spot

[jersey250]

Hey all!! Just got a 250 on Saturday. Been in combustion engine trucks all my life first diesel. Been experimenting with rpms to see where I get the best mileage. Seems to be between 1700 and 1900 rpms. Anyone agree or disagree or have found a better spot. Have to relearn how to drive combustion all about keeping rpms low I understand that diesel is all about compression .

[Banshee34]

What year???? and Congrats!!!!!!!!

I find if I keep mine under 2k I'm good!

[66Bronco]

What you have discovered is the flat nature of a diesel's torque curve. Almost every production 4-stroke diesel produces their most efficient power in the 1600-1900 RPM range. They'll build HP to a certain extent on up to about 3300-3500 RPM, but peak torque doesn't change much.

[jersey250]

Hey guys thanks for the quick responses. Its a 2009 and thanks for the congrats. Don't know why I ever drove gas I'll never go back. Had her on interstate with cruise set. In that 1700 to 1900 rpm range I had mpg est in the 20's when I'd decrease speed thus rpms mpg would go down into teens same if I pushed her over 2000 rpms Its pretty cool figuring this stuff out.

[jersey250]

Hey do you guys have any recommendations on air intake systems?

[fairhaven]

I have an S&B CAI (oiled filter) and I like it very much. You will find that most use either the S&B or AFE.

[CountryAggie]

I've found that the 1700-1900 is the sweet spot on my truck also (which for me is probably a little slower speed because I have 3.73 rear end).

As far as tuning, check out the "General 6.4 Modifications" sticky.

[jersey250]

Thats where I will continue to experiment. Some guys have said they really don't even look at speedometer anymore just look at tac. Thank you all for getting back to me

[Joepalmer]

yep 1750rpm's is 65mph for me. 20+or- for winds here in south dakota, next biggest factor here is aerodynamics. i hope im not hijacking too far, but think its on track with the same intentions. Has anyone experimented with engine load % and economy?

*edit to clarify engine load %*

I have Spartan tuner that can track engine load. the "early lock" set up for me shift point is 1250rpms and lockup at 45mph. I just switched to the "late lock" same shift points until overdrive which is 55mph. lower load% but higher rpm to get up to speed. Most people floating around forums say early lock is better for mpg. we shall see.

[Arco3580]

I find that 1700 to 1800 with boost below 8 psi tend to provide the best MPG. I yield 19-19.5 HWY with my 3.55s depending on grade changes. Running the CAT DPF delete with a S&B CAI. Next upgrade is replacing the turbo back with a 4" exhaust. I am not expecting much better just cooler EG temps when pulling.