Does increased Power increase Efficiency?
 

Okay i have been thinking about this all day.

We will use semtex's car as a example.

Since he is putting down 330rwhp, while Driving at 65mph is his RPM lower than stock since it requires less power for him to maintain that speed?

Im a novice to the workings of the inside of the car but that is the theory that my brain came up with no idea if thats how it works.

Does the same ammount of gas get used to create all this power? If it does, doesnt that mean the engine is more efficient? then giving him better MPG?

Dude you bought a sports car. You already dont give a damn about MPG just by buying the car. And if your going to do performance mods to it you intend to drive it to its "potential" which in turn will give you very crappy MPG.

You want good gas go buy a smart car or a hybrid. You want an adrenilne rush its gona cost ya about 35K and lots of trips to the gas station.

RPM at speed is a factor of gearing, not power.

Agreed. But where I do think more power can result in greater efficiency is that for any given rate of acceleration, I don't have to use as much throttle now to achieve that acceleration rate as I used to. The trick, of course, is in whether or not one has the self-discipline to not use the additional power/acceleration that is now available. I personally do not. I don't really see the point of spending all that money to increase my car's power if I'm not going to use it. Indeed, what motivates me to mod my cars in the first place is that I always want more power. (It's a sickness, really. 'Quick enough' just isn't a concept that I can grasp.) If increasing fuel economy were my objective, I'd have traded in my Z for a Prius and started driving around like one of those annoying wanker hyper-milers. But, having said all that, I have noticed a slight improvement in my average mpg, by about 2 mpg. And I guess that makes sense, as there's no way I can drive the way I want to all of the time, due to traffic, weather, police presence, etc.

To produce the same amount of power the engine has to overcome less pumping losses due to the better flow of the aftermarket intake and exhaust. IF you can stay off of it you will get better mileage than stock.

ive tested my avarage per se in a 2 week period from filling up to about half a tank(during this "test" majority of driving i did was steet driving) i love hearing the sounds of the exhaust so under normal street driving driving i shift at about 4k
freeways i do the same i would say my average speed under normal conditions is 75mph but sometimes i had the urge to punch it i do a couple of redlines
i also tend to hold gear on 4th just to hear the exhaust and have "instant"burst if i want it

i hope those made sense

with that said after half a tank i filled it up until the pump clicks
look at my distance travelled and divided it with the # gallons
the bad news and its sad to say i averaged 15mpg(with the way i drive)
but the good news this is the same average that showed in the cars readout meter so it safe to say it is preety accurate :D

Umm...more power = more air/fuel.

Free breathing intakes can help increase the amount of air flowing into the engine. The MAF sensors pickup more air volume moving in and adjust by adding more fuel. Unless the ECU does NO adjusting at all (and the car leans out big time), adding performance parts like intakes and exhaust will reduce gas mileage at any RPM.

Think of it this way...the car is trying to maintain a certain air/fuel ratio. If you add more air, you need more fuel to maintain that ratio. This applies less at non WOT situations, but the idea is the same.

You may be pressing the gas pedal less, but you are using more fuel in those presses than you were before...In reality though. our cars are running a bit leaner, which I guess in theory means you are using less fuel. Trust me though, you are not going to get better gas mileage...

This is as much of a myth as turbo engines being more fuel efficient. They are less fuel efficient than their non turbo counterparts under WOT. The only reason why people say turbo CARS are more efficient is because you need a smaller engine to make the same power, so during the time when you are OFF boost, you are using a smaller engine and thus less gas. If you want to make 600hp from a 2L turbo you need as much air and fuel as a big NA block would.

Thats my theory.

calm down killer, i was only curious. I agree im happy with the milage i get currently. BUT this idea popped in my head and i wanted a answer to it.

after reading all responces it makes sence. so thank you all

We all have your sickness thats why we are all here ;p

Your theory does make sense to me

Some mods like headers and exhaust can increase effiecencey...but some work against it.

The amount of RPMs to go a certain speed do not change due to power increases.
The gear ratio's deterimine the RPMs at speed.

You might want to take some time to learn about the basics of how a car works..its really not that complicated.

I learn more and more from your guys educated posts. Infact i have learned more from this site since i joined then a while. i get basics but i coudlnt wrap my head around this one until i read the explantions

yeah...i totally understand. Once you dive into it...its a whole lotta fun..sometimes it takes a car like the 370z to get some people driven to figure it all out.