optimal MPG mods

[K15 Blazer]

When I bought my truck I got almost 20mpg on the highway, now im getting 14....
So this thread is for the do's and dont's of optimal MPG on the HWY

Things that changed from stock:
offset wheels
K&N filter
delete catt.converter
Delete intake box (open tube from fender to filter pan)
mud flaps
2" lift
front air dam delete
much thicker engine oil
a VERY low temperature thermostat
plastic engine fan

Now... most of this did improve HP... but running the engine temp too cold, and letting it gulp in more air and removing the air dam were probably the worst for hwy mpg... since then i have installed a vacuum gauge, rebuilt the EGR sytem and put a good 195* thermostat back in.
and a TBI spacer is in the plans too

What have you done on your truck to make it a better highway runner that helped or hurt the MPG?

 

[Big D]

running much thicker oil isnt going to help your Miles Per gallon.

How do you get away with deleted cats in land of Prius Hippys?

 

[Blue95]

Why thicker oil?

 

[thz71]

As said above why thinker oil? The air damn made no difference. Letting the engine have more air helps mpg not hurts it. I'm guessing you went up in tire size?

 

[poncho62]

Things that changed from stock:
offset wheels...Bigger tires too?...mileage will suffer
K&N filter...negligible
delete catt.convO2 sensor now calls for rich mode
Delete intake box (open tube from fender to filter pan)
mud flaps...more wind resistance
2" lift...again, more wind resistance
front air dam delete...more air gets under truck causing more wind resistance
much thicker engine oil....harder to turn engine
a VERY low temperature thermostatsame
plastic engine fan.....fan cant coast at speed like a clutch fan

 

[K15 Blazer]

Its a "diesel" on paper

I need to run thicker oil because 5w30 dropped the oil psi to ZERO at a idle... im amazed I didn't get valve clatter. so its kinda an insurance measure

 

[twomanymontes]

Things that changed from stock:
offset wheels...Bigger tires too?...mileage will suffer
K&N filter...negligible
delete catt.convO2 sensor now calls for rich mode
Delete intake box (open tube from fender to filter pan)
mud flaps...more wind resistance
2" lift...again, more wind resistance
front air dam delete...more air gets under truck causing more wind resistance
much thicker engine oil....harder to turn engine
a VERY low temperature thermostatsame
plastic engine fan.....fan cant coast at speed like a clutch fan

This is all true. And a low thermostat will not allow the engine to get to proper temp [also if the computer is still hooked up, it won't stay in closed loop] and will cause it to run richer, using more fuel.

 

[Blue95]

As said above why thinker oil? The air damn made no difference. Letting the engine have more air helps mpg not hurts it. I'm guessing you went up in tire size?

Wrong, air dam is a big difference, less air going under the truck the better the MPG, less turbulent, why do you think the newer Ford's have a main one then one that hangs even lower in the center and back some?

 

[thz71]

Wrong, air dam is a big difference, less air going under the truck the better the MPG, less turbulent, why do you think the newer Ford's have a main one then one that hangs even lower in the center and back some?

Lmao alright

 

[SwampHound]

Wrong, air dam is a big difference, less air going under the truck the better the MPG, less turbulent, why do you think the newer Ford's have a main one then one that hangs even lower in the center and back some?

The science behind it is true, but on our pigs, I've never seen it make difference.