Forced Induction & MPG!

[SRT8U]

Just thought I would post my thoughts and experiences on this. While I have only had my car up and running w/ the Vortech for a few days and I am still running the Vortech (super rich) Canned tune, I have gained an avg of 1-2 MPG in my daily drive which is an all stop and go 30-60 MPH commute. Pre-Supercharger I was averaging 14-15 MPG in city Driving, if I really tried I could avg 15.5. Since the install I have been averaging 16-17 MPG driving the same route. Most people assume that when you add forced induction you will automatically lower your mileage due to more power, larger injectors etc etc. However, because you are making more power it takes less effort to get to speed or to maintain the same speed when compared to a stock engine. On our Mustang Supercharger kits where we include our own BMCP Tune customers have been gaining significant MPG as well as power. This seems to be the case so for on the Hemi as well, even with the stock Vortech Tune. I am by no means suggesting a S/C as a fuel mileage mod or saying that this will always be the case, highly modified cars like Lisa's stang certainly don't get awesome mileage. However, for most stock/bolt on type vehicles that add forced induction a mileage increase of some sort is just icing on the cake to me! How are you other Vorteched cars doing with mileage?

In a normal week I go through a tank of gas in 5 days of my daily commute. I am on Day 3 of this tank and still have almost 3/4 of a tank left wohoo!

[Columbo]

You Wrote:

"Most people assume that when you add forced induction you will automatically lower your mileage due to more power, larger injectors etc etc. However, because you are making more power it takes less effort to get to speed or to maintain the same speed when compared to a stock engine."

My question:

When you say "it take less effort" are you saying the supercharger makes the engine more efficient, so that the amount of energy (gas) it takes to move the car is decreased? If so how does it achieve that?

Since the weight of the car, and the rolling resistance remains constant, the amount of force it takes to move the car will be constant as well, so the only way to decrease the amount of energy (gas) it takes to produce that force is to make the engine more efficient. I understand how superchargers make more power...more air + more gas = bigger explosion, but I don't see how they can increase efficiency?

My theory is that the increase in efficiency is coming from the tune. I know the Vortech tunes are rich at WOT, but what about just cruising around? Could it be that the part throttle maps are running "leaner, but still safe" then the stock tune? How about the timing at part throttle? Maybe the tuners at Vortech have changed the timing at part throttle which results in more power being produced for the same amount of gas being burnt?

Am I making sense? I've owned and messed around with F.I. cars (turbo and supercharged) for years and while I completely understand how boost increases power I can't seem to wrap my brain around why it increases efficency as well...which I have experienced on all my cars.

[Hemi31]

What he means is you don't have to step on the gas as much to maintain the same speed.......
Chris my car has been seeing 22-23 on open roads which is about 1 mpg better than when it was stock.

[Columbo]

Yeah, but is that because it's producing more power, or because it's more efficient? I can understand that a more powerfull engine needs less pressure on the gas peddle to make it go the same speed, but how does that increase efficiency?

[BAMF]

I think you're thinking too hard.

[CHARGERTREV]

Yeah, but is that because it's producing more power, or because it's more efficient? I can understand that a more powerfull engine needs less pressure on the gas peddle to make it go the same speed, but how does that increase efficiency?

Yea....well E= MC2....now what...I just went there....chill dude MY head hurts from thinking about what you said.

[ChagaRT]

Because everyone knows when your driving you have to push down on the pedal, now when you push on that pedal it shows on your RPM's. More effiecent car (Supercharger with tune) has 2k RPM with barely on the pedal. We will say going 80 (Freeway crusing). Now with a stock engine it takes half the pedal to reach 80 and your at 3k RPM. Im making up the numbers btw, lets not make that a new topic

All this means less power used to achieve same distance.

[Columbo]

Sorry guys...sometimes I get all cross-eyed from thinking too hard

I'll just enjoy the mileage and the power and not think about the why.

[BAMF]

Sorry guys...sometimes I get all cross-eyed from thinking too hard

I'll just enjoy the mileage and the power and not think about the why.

It's just that, to me, whether it's the efficiency or the power helping MPGs, it sounds like nearly equivalent ways of stating the same idea. Sounded like you had it understood, you just didn't know it cuz you'd gone cross-eyed.