Just completed a trip from Oklahoma City to Pensacola FL and turned 17.0 mpg on regular 87 octane pure gas. Previous mileage has been 15.5 for years. The only difference is I installed a BBK 85mm TB before I left. I'm going to fill up with 93 octane on the trip back home and see what happens.

 

 

Bluejay, yes, the former 15.5 figure is based on pure gas.

 

Because the A/F ratio is a constant and controlled by the ecm, neither the intake or TB would have any effect on MPG.... most likely either environmental conditions induced more effective burn or better fuel blend (even if bought from the same gas station) would be the likely answer

 

We'll see what happens on the way back to Oklahoma on Sunday. Gonna drive straight through - 13.5 hours - on 93/91 octane gas.

 

Takes more data to back up a claim like that.

interested in more driving/miles and see the results!

 

The only "claim" I am making my friend, is what my average mpg computer is registering.

 

I'm with Patman on this. If you're comparing values you are seeing on the instrument panel in the Avg MPG window, then you are likely not seeing what you are actually getting. However, the fact that it is showing a higher average says something changed. I doubt the TB improved things though.

A more likely cause for the improvement would be a constant tailwind on your trip, or, as Bluejay suggested, some change in the gas blend.

- Jack

 

Well I will be head west this time, so maybe that will be a head wind? Mileage should drop if it is head wind drag.

 

I've been following this thread for some time, and I'll put my 2 cents in.

For all the years I've been driving, I notice this a lot. Reason being, is long distance highway driving will always yield better fuel mileage. Now, you noted that you got better fuel mileage. There could be a lot to do with that (assuming all weight stays the same, same traffic patterns, etc. In the order of most to least likeliness):

1. Use of cruise control and traffic conditions.
2. Most of the way was downhill.
3. Road conditions.
4. Wind direction.
5. Higher atmospheric pressure (n/a on S/C and T/C engines).
6. Better fuel.

For example: I work at two different places, about the same distance (within 4 tenths of mile). I will call them Work 1 and Work 2. Work 1 is all highway and is downhill most of the way. Work 2 is a mix bag of highway and city, and pretty level. To get home from Work 1, it is all highway and is then uphill. Work 2 is again, a mix bag of highway and city, mostly level.

Work 1 - ~20 mpg combined both ways
Work 2 - ~16 mpg combined both ways

One thing to note, road conditions. Most people don't pay much attention to the road surface. Believe it or not rough surfaced roads decrease fuel economy, versus smooth roads. So those concrete roads that these areas have will typically get the worse fuel mileage versus a smooth tarmac. Another thing to keep in mind.

I, like others, will be interested to see your return readings.

 

Just got back from Florida. I was able to average 20.1 mpg when I kept the speed between 55-60. This was during the first part of our trip near sea level. Later, during the middle part of the trip I accelerated to interstate speeds between 70-75 and the averaged dropped to 18. The final third of the trip was driven with no regard to trying to "nurse the throttle" and my truck returned to its normal 15.7 mpg.

 

Bottom line, the throttle body did nothing for you, as expected.

 

exactly, GLC!

 

Now, if you were to do some internal mods and get a corresponding tune, then the larger TB would have benefits. Does nothing for an engine with stock guts.