Supercharger MPG decrease?

[Flyinrazrback]

Quick question for you guys, I just got my magnuson installed and tuned by AED. Runs hard! My question is, before adding the supercharger on the highway at 65mph and 2000 rpms (3.73 gears) I was getting about 22-23mpg cruising. Now, with the supercharger installed cruising down the highway I am only seeing 15mpg at 65mph/2000rpms. Is this normal drop off for a forced induction setup? I am hoping that the fuel flow calibration is just jacked up and I am still getting decent mileage on the highway.

 

[Torchy]

I experienced the same thing on a customer of mine's car.

 

[Vert]

I know they have to tune a FI with more fuel so you will see a decrease, but my mpg increased by 1.8 mpg after a few days of driving.

 

[Aaron@JPCRacing]

Well you do have to spin the supercharger which does take energy so yes some mpg drop would be the norm.

 

[Tron84]

Seems like a pretty drastic drop.
I still get around 26mpg highway cruising making about 700hp

 

[JerryC]

I didn't lose any mpg after my Roush was installed. I had Justin tune mine to drive like stock, stock shift points and stock throttle sensitivity.
Later when I got another tune that is more like a normal performance tune and it did drop about 2 mpg in city driving. Going by the built in mpg meter I don't see any change in hwy mpg from stock.

 

[Vert]

I get 16.2 city and if I grandpa it on the highway i can get up to 24.

 

[bmyles]

I get 25 now I got 28 before the blower. Highway

 

[Flyinrazrback]

I get 25 now I got 28 before the blower. Highway

What gear ratio?

 

[SID297]

Have you hand calculated a tank yet? My bet is on the computer being off.

 

[DSG2003Mach1]

Have you hand calculated a tank yet? My bet is on the computer being off.

this

and what do the widebands say your AF is when cruising like that? If you're pig rich at cruise it should be obvious

 

[pickles]

I get 25 now I got 28 before the blower. Highway

same here. i got 3.73's

 

[Flyinrazrback]

I will check the AFRs tomorrow during cruise. The only thing I can think of is either the fuel computer is off or the fact that the magnuson has a bypass valve on it where it shuts off at low throttle settings and the engine is just turning it with more drag. Not for sure on that as I am not sure exactly how the bypass valve works on it.

 

[bmyles]

3.55

 

[blackbeast12]

I got 18mpg before the s/c with mt-82 and 3:31's, now s/c tremec and 4:10 13mpg around town!

 

[Coyote'13]

Have you hand calculated a tank yet? My bet is on the computer being off.

+1, mine was off by about 5 mpg vs what the computer calculated

 

[mhyjek]

Blower type, tune, gear ratio, transmission have and of course how it's driven will dictate mpg. I have Paxton setup Lund tuned had mt 82 with 3.31 now tremec 2.66 gearset with 4.10 gears. Before with mt82 car would average 16 city 21 highway then I got the tremec and a new tune cal for better drive ability now the car gets 18.5 city and 26 highway. Calculated by hand the computer states About 1 higher on average in my setup. AED/Shaun is an awesome tuner I would datalog and see what he says maybe vacuum leak or strategy error. He will get it straightened out.

 

[numbnutz]

My Paxton AED tuned gets 12-13 city according to the computer. What gets me is when I fill up it only shows 191 miles to the tank. Does that seem right?

 

[Scott8583]

Not sure what mine was before, but sat I had the cruise set at 74 and was getting 23 mph on the highway w/ 3.55 gears

 

[gimmie11s]

This whole thread is meaningless if the numbers are not hand calculated.

Come on.