'Trust'

iTrader: (24)

Ok so everybody knows the lower you keep your RPM's the better gas milage you get. But here is my question, would a person with 500HP/TQ at 3000 RPM's get better or worse gas milage than one with say 300HP/TQ to the wheels at an equal RPM. At first I thought they'd get the same or the 500 getting worse, but then I started thinking that maybe the one with 500 would get better, since obviously 500 would move a 3500lb car easier than 300 would meaning an easier load. It kind of makes sense to me but then again I can see how it could be the total opposite. Does HP or RPM denote MPG in these cars? And what about this, if a car makes 300HP/TQ to the wheels at 2k RPM's, does it get the same gas milage as one making the same power at 4K? Obviously I dont know the answers, but it was just a thought and I think I could do with stimulating some brain cells.

Ace$nyper

iTrader: (8)

It's a good theory but its all based on your mods and tune.

You can in theory be making more power and get better milage but a rowdy cam you'll never see the OEM milage somthing like a turbo i've seen a few cars *namely Hondas and Mistus* gain MPG and 50+ HP with a turbine swap and tuning.

So I guess it's fair to say yes and no just depends what is done.

WsSickLs6

takes more fuel to make more power, eh?

68ss_00ss_87_95

iTrader: (1)

with my sock hp 335@5500 i got 25mpg....when i got my sc and tuned it it was 440hp and still 25mpg....now i have larger injectors(i changed injectors for initial sc install too) and a diff cam and it went down to about 20mpg on highway...at around 1900rpm....i also heard before i got the cam an aftermarket cam would drop mpg (obviousley the more fuel added) so if i still had a stock cam and was pushin like 550 i would expect to be making close to 25 mpg....the wot is what seems to be the "most different" or has the largest difference...this is from my experience...it is true more power means easier to move but thats for acceleration....gearing is the key to mpg...if i had some 2.73's i bet id be doin a little better on the highway

Allergik2dyin

You'll see the biggest difference in gas mileage once you really get on the throttle because more fuel is needed. Otherwise, under normal driving conditions, there really isn't much of a change.

Starz T/A 17

iTrader: (6)

It all depends on the mods for example a 400 HP H/C T/A will get worse gas millage then a 400 HP turbod T/A b/c when not being raged out a turbocharger increases the engines efficiecy. So it all depends on mods and what kinda tune, too many unknown factors

fightinchunk

how big is the tank anyway? are premium fillups about 40 bucks for you guys?

Ell Ess Won

Just about. Gas is $2.45 here for REGULAR. Costs like $25 for 3/4 tank in my Camaro but I get 14mpg.

'Trust'

iTrader: (24)

Then explain why an LS1 gets better gas milage than a M3 that makes less power. Because the M3 has to push more air to make it due to the smaller motor, more air would require more fuel.

'Trust'

iTrader: (24)

I guess its a tough comparison though.

rgaynor85

well i just did headers and Y on my car and i went up like 1mpg i usually never get more than 17 and sometimes 16 but today i filled up for the 1st time sense my exahust and i hit 18.3 yay lol i guess it could be the driving conditions but all i know is im happy hehe

LittleSneak1

Trust is right it takes more air to make more power so it must give more fuel, my gto is a good example because it was carbureted, it had high performance heads and a cam and when you wanted more power you could change the jets and rods to allow more fuel in, in turn wasting more gas but giving you more power. Turbo cars can make more power and still use low gas because they dont always make maximum boost when driving around.

SladeX

It has a lot to do with the efficiency of the motor, even if you gain more hp and torque, the amount of fuel and air required to displace and thus move your vehicle remains unchanged.

Barring a change in the cam, even if you "free up more hp and torque" the air still being sucked in is still limited to 347 ci. What has changed is how efficiently it can take in that amount of air and how quickly it can remove it for the next charge.

Under normal cruising where load is limited to overcoming wind resistance and road friction, if anything mileage should go UP as less power is wasted when forcing the exhaust gasses out and taking in a fresh intake charge.

Where more fuel is used is when the load goes up, if rpm needs to climb quicker it CAN because the intake and exhaust charges go in and leave quicker.

Mods that will free up hp and torque will tend to increase mileage.

Mods that change how the engine works in order to make more power will decrease mileage.

RaNsOm

iTrader: (2)

gearing, hp, tune, weight....all factors in gas mileage. My gas mileage changed a little when I put the cam in, but then it stayed the same when I went from 3.42's to 4.30's partly because bigger cams are more effecient at more RPMs than the 3.42's were putting me at.