Engine/Transmission (1994 - 1998) AFC, Valet Switch, and Fuel Economy

[Cooker]

I am wondering if anyone has any personal experience with different AFC housing positions and fuel mileage. I think Ted J. was the one who suggested that moving the AFC housing fully forward will have a negative imact on fuel economy. Does anyone have any real world numbers on this? Is the loss so small it is hardly noticable?



It seems to me like a Valet switch, if on, would increase fuel economy. Am I correct in thinking this? Has anyone run a tank with the valet on as compared to off and compared the MPG's between the two?



Thanks,

Ryan

 

[mikel]

When I got my truck it was totally stock. It got 19-20mpg on the highway making the trip that I drive every day, set on cruise.



I then added a #4 plate, moved the AFC all the way forward, added an AFC spring kit and GSK. I currently get 19-20mpg on the highway using cruise. From what I have seen from owning three different diesel rams (2 24valves and 1 12 valve), if you don't change the way you drive you won't change your mileage by modifying the engine.



I don't have a valet switch, so I can't help with the 2nd part of your question.



Later,

Mike

 

[Rams-n-Hogs]

Depending on how I drive, I usually get between 18-22. My truck did that stock, and it still does it, even with 370's and a #10. I have not noticed a difference in MPG using valet mode or not. My last unloaded trip from Md to Il, I got 22. 5 twice. On the way there, I drove in valet mode. On the way back, I left the valet off. I noticed no difference in mileage, as long as I kept my foot out of it. I actually think my mileage has gone up slightly since the mods, but I don't keep actual logs. I just figure it by hand at every fill-up. My AFC is full forward, along with everything else.



Jim

 

[San Felipe Bob]

My findings

Ok here ya go .

In valet mode i get about 15 to 20 lbs of boost max.

normal driving moderate 1/2 to 3/4 throttle nets about 10 psi.

In go go mode (no valet) She pumps out 36 psi. yeee haaaa

I went one step further and installed an indicator light that signals at 7 psi. I used to call this economy mode.

The light only comes on if in valet mode.

When the valet (go-go mode) is off the indicator light does not work.



Any way here's the finding's... .

Set -up.

3k gsk , Banks plate full forward, afc totally loose,gov. arm adj,14cm wastegated,15. 5 timing, non egr, no kitty,afe filter.

about 350 hp?



I have driven mixed hwy /city and kept it below 7 psi.

I get the same mileage in valet mode driving it hard peddle to the metal.

The engine seems happiest and best milage when driven at 10 or 12 psi.

So I just bring the boost up to 10 or 12 untill I reach crusing speed at 70 mph

So this tells me keeping the boost down on my combination of bombs only manages to be no fun to drive.



I have found it's most enjoyable to drive in Go-Go mode and just go easy on the go peddle.

End up getting the same milege and it keeps the grin going. ''



However the mileage goes down the tubes when driven hard without the valet on . Full booost with enough black smoke to make the EPA cry. . Yeeee Haaaa

So if you just can't controll your right foot a Valet switch might be for you.

Valet mode is just that "VALET".

Use it in the snow ,use it when someone else needs to drive,

Use it to save a worn out trans,

P. S. Valet switches are fun too.

Take off in valet mode WFO... .

Then at about 50 or 60 keeping it WFO turn the valet off and hang on!



SFB

 

[Rams-n-Hogs]

P. S. Valet switches are fun too.

Take off in valet mode WFO... .

Then at about 50 or 60 keeping it WFO turn the valet off and hang on! - SFB

WOOOOOHOOOOO, I'm gonna have to give that a try. Oo. Oo. Oo.



Jim

 

[Berrigan]

When you guys are talking about a valet switch on a 12 valve, how is it installed?



I have a #11 full forward, afc 3/4 forward.

Its kinda smokey on acceleration but great low end power.



My valet switch opens a 12 volt solenoid valve that bleeds a small amount of the boost signal to the afc.



The afc sees less boost than the engine is getting and holds back the fuel. Less power and zero smoke.



MPG change is about 1/2 mpg less with the switch set to power, and I agree with you that thats because I am using the power. If a accelerate at the same rate with less pedal pressure the mpgs are the same.

Bill

 

[Rams-n-Hogs]

Bill,



That sounds like the same setup I have.



Jim

 

[JoshPeters]

Where do you guys get this set up? Every once in a while, my dad wants to borrow my truck... and well... . he drives like a grandpa... (which he's not... at least yet... ) The last time, he got in my truck and roasted the tires leaving the driveway, he got on it like he would his truck... . A Valet switch would be nice... .





Josh

 

[Cooker]

Thanks for the info, it is exactly what I was looking for



I thought the AFC movement would yield negligible results for MPG's, but I would have imagined the valet would have had an impact. I was obviously wrong, it shows I still have a ton to learn about the P Pump.



I guess I will probably still end up with a valet, but only for driving in snowy conditions because it can even get a little squirly in the rain I can't imagine it in the snow.



As always I appreciate the info. Thanks again.

 

[1dslram]

I have the Variable Valet and can take off at WOT in Valet and switch to Variable then Full power and watch the eyes on the guy in the right seat. Its like having two afterburners.



As for milage I get the best in valet because of the cutback in fueling, I use it mostly to reduce smoke here in So. Cal.

Bruce

 

[WadePatton]

MPG

A given truck at a given speed (highway cruising) is going to burn the same amount of fuel whether it is in KILL mode or SLEEP mode. Only under acceleration is extra fuel going to be consumed. IOW to get big MPG, keep the boost down while getting up to speed and keep your speed down too.



My mileage seems to get better with BOMB's, but not during the "test it out" phase.



So, where do I learn more about this VALET doomahickey? I'm spicing up Dad's 12v and he likes it more tame than I do.

 

[vssman]

To be honest, the biggest impact in fuel economy I've seen was when I 'upgraded' my tires from the stock 245/75 Goodyears to 255/85 Kelly MSR's. Everything else hasn't changed (much) what I get unless I drive it hard.

 

[Rams-n-Hogs]

Wade,



Piers has them, and so do a few other people. I got mine from Turbomaster. Mine is nothing more than an electrically operated vacuum switch that is installed on the back of the AFC housing. The boost line hooks to it, and when the switch is turned on, it turns the boost down to the AFC. When I dynoed in Aug, I did one run with it on, just out of curiosity. It cost me over 100 hp, and almost 300 ft/lbs of torque.



Jim

 

[1dslram]

It cost me over 100 hp, and almost 300 ft/lbs of torque.



That is the reason I developed the Variable Valet. With it the AFC does get the signal but at a slower adjustable rate. You get the HP back but at a slower rate reducing smoke, EGT's and fuel consuption. Crusing is not a problem the problem is when you step on it with a heavy load or on a hill and the AFC increases fuel too soon and that increases smoke, EGT's and fuel is wasted, slowing the boost signal to the AFC allows the turbo to spool thus you burn the fuel reducing smoke, EGT's and reduce fuel consuption.



The heavyier the right foot the greater the difference. I am in the over 60 crowd and drive my truck like I stole it, but that is how I drive all the time.



Bruce

Soon to have twins

The brat needs another 100 HP