Today I decided to turn my star wheel toward the engine for a little more low end and noticed a big difference. Has anyone noticed better or worse mpg's after turning their's?

 

I can honestly tell you that if you dont start driving harder, your mileage should be the same. My dad is VERY watchful of his fuel mileage. He gets 19-20mpg driving to and from work about every tank. I finally got him to turn his starwheel, and he really likes the low end increase in power(spools much faster), and he kinda likes the smoke from time to time too. Anyways, he hasnt noticed a worse or better increase/decrese in mileage. So it shouldnt affect your mileage at all other than the truck running a little better.

Eric

 

Unless you spend your time driving in very low rpms, (not recommended), you wont notice any difference at all.
The star wheel only affects fuel before boost is built. Basically the fist second or so accelerating on a green light.

Rich

 

No matter the mods your biggest affect on fuel loss is not controlling your RFG.
Right Foot Governor

 

This is true

all that the starwheel controls is the lower end boost on the first gear take off, I have tried it, and with the starwheel tighter, the fuel mileage is not that much better, infact with me i think its the inverse..

Rick

 

Well I turned it about 8 clicks toward the engine and it takes off better but no smoke, what does that mean?

 

Smoke is a product of one of two things, sometimes both:
1) Too much fuel
2) Not enough air.
Turning up the star wheel will only increase the initial puff of smoke if you get on it from a green light.
However, as the star wheel increases fuel prior to boost, the increased fuel will have the affect of spooling up the turbo faster.
Thus, the initial puff may be a little more prominant, but will not last long before the turbo kicks in.
I have moved my star wheel back an forth several times testing it. I found that there is a point where further turns really didnt make any difference at all.
Im guessing it has a lot to do altitude, exhuast pipe size (modifications) and air intake abilities.

Rich.

 

you will get better mileage with these engines if you've got them making some boost and some heat... there is a fine line where yes, if you bring the fuel in sooner without excessive smoke, you should get better mileage than if you've got it set up with the AFC ultra tight.

but the AFC controls pre-boost fuel in all gears... Air Fuel Control

 

I did some playing this year on our drive to Ontario with the 5er on. I found that if you can keep the boost 5psi or lower and the egt's below 800* you get the best mileage, now this was while towing. I have been palying around empty as well, and pretty much anything under 1900 rpm get' s the best mileage with my rig anyways. My starwheel is full forward and then back 3 turns as per the instructions that came with my afc spring kit.

 

AFC actually stands for Aneroid fuel control. Not sure if I spelled that right, but by my diesel school books that is what thy called it. As told many times before on this post it only controls fuel at no, and very little boost. You can adjust it with kits sold manty diffrent places, stock it controls 0-3psi fuel levels if my memory is working today. I have my truck with a #100 plate, boost turned up to 30psi and the thing screams. I get lots of smoke at any boost level pretty much, need to turn it down some. When I had it set right it would let just a tad smoke puff off the line and then turn to a slight haze through the mid range and clean out on top.

Also, yes your best milage should come at below 6psi, usually around 4-5 if you can run that boost levels and still be going fast enough to suit you.

BTW< great site here, hope I didn't come across too cocky with my first post, just wanted to jump right in and share.

George

 

Well after a week of testing (with a 8mm allen wrench and a brake spoon in my door pannel) and tweaking I gained 1 extra mpg. I went from a steady 14 higway and city to 15. Which is'nt all that great but I have the stock exhaust with a cat. That is my next project, at least 4" all the way. I have noticed my egt's are horrable when I drive under 55mph with my tranny locked out of o/d. I think that is why I'm not running a few mpg's higher.

 

good call, this is correct per Bosch