AmirGTR

Straight up.

Fuel economy is dictated by how much gas is fed to the engine. More gas goes in, worse mileage, more performance, and in most cases, more rpm too.

Imagine if a person who'll never get full no matter how much he eats. Would he eat more per day if he eats 1 meal a day or 3?

The only way he could possibly eat about the same in the same would be if his 3 meals are 1/3 of what he'd eat if he had 1. You can see where this metaphor is going.

If you really want to prove an engine operates on the same amount of gasoline at 1000rpm and 3000rpm you have to prove it gets fed 1/3 of what it gets fed per revolution at 3000rpm compared to 1000rpm.

I'm not saying it's impossible, ****, what do I know, you might even prove it.

As far as load goes...your 6th gear puts the most load on the engine. Never does your car feel as heavy as it does to your engine in 6th gear. Any kid with a bicycle knows this.

The reason SUVs get worse gas mileage, apart from their terrible aero, is because they're heavy and the engine has to rev higher for them to move. Ever tried pulling a trailer? Sure your car can get to the same speed in the same gear, but it's much harder for it. It might even stall. So you shift to a lower gear, rev up, and it'll pull it easier. The load is less but guess what happens to fuel economy? Yeah, that's why SUVs get shitty mileage. They usually have shorter gears to begin with.

The reason automatic f-bodies get worse mileage is because they have less and shorter gears. Automatics can get about the same gas mileage as manuals if they have the same number of gears with the same ratios and change gears early. Notice how all these hybrids are autos.

SS RRR

iTrader: (2)

You are mixing your line of logic between load and RPM and you forgot to reason why a Z06 with more power has close to the same mpg rating as a stock LT1 f-body. It's not because an auto has to rev "higher." It is because an auto has to use more throttle, burn more fuel, regardless of RPM to achieve the same work as a manual. The reason why SUV's, with smaller engines get about the same MPG rating as one of the same weight w/ a larger engine is because it is overweight and underpowered and has to use more fuel to accomplish the same amount of work.
Another perfect example is the difference between city and hwy MPG. While in stop and go traffic you are surely not using more rpm to get to your destination. If anyone says "it's because your engine is on longer..." needs to stab themself in the eye.

speed_demon24

iTrader: (6)

The Z06 is lighter, more aerodynamic and it has a more efficient engine. Not to mention a lightweight rotating assembly.

LSWHO

iTrader: (1)

I've already stated how to end this fight.

Somebody with a data logger and a map of their tune post up what I said.

It seems you are arguing to argue again.

94maro

on a full tank of gas all highway miles i got 200..and on the street idk..spend 20 buks for like 50-65 miles..**** ant cheap.. i also had the same question about this crap *** gas milage..lol

LSWHO

iTrader: (1)

Oh and I get 200 miles per tank too. Mostly city driving. Before I started modding my stock car with truck tires a bad O2 and 4/8 misfires I got 24/25 mpg on a 400 mile trip from chandler, az to san diego.

...oh wait. The taller truck tires wouldn't change my mileage... Non lock up stalls wouldn't either then I guess.

AmirGTR

No one needs to stab themself in the eye except someone who expects a car to get good gas mileage idling. You know what your MPG is at idle? 0mpg. Why? Load on the car? In neutral? I don't think so. It's because you're fueling the car to sustain 700rpm.

I get what you're saying about the automatic, and while I recognize the effect I don't believe it's the primary reason for the poor mileage.

If a car feeds more gas to the engine at a higher rpm there's no way it would have the same fuel economy over the same distance.

What do you have to say about the 6th gear having the most load while getting the best gas mileage? I'd like to hear it.

SS RRR

iTrader: (2)

Absolutely. All things mentioned decrease the amount of load on the engine which will let it accelerate with less effort. It all boils down to engine load.

SS RRR

iTrader: (2)

Driving in traffic has a lot more to do with acceleration and stopping than idling so I'm not sure what point it is you are trying to make. If you are saying poor mileage in city driving can be blamed on idling then you do need to stab yourself in the eye.
It depends on the terrain and speed when 6th gear has "the most load." Driving on a perfectly flat surface then sure, 6th gear is the best answer for the most efficiency. Keep the car in 6th over hills while trying to maintain the same speed and see what happens. You are making this far more complicated than it needs to be. The individual who stated to drive by vacuum instead of RPM gets it.

BTW... I never said anything about changing up a gear ratio and the engine using the same amount of fuel. Please re-read what I stated. Not for a second do I believe changing up a gear ratio will effect an engine by one claim in this thread of 8mpg.

AmirGTR

Um...
I'm not sure what your point is? What are you trying to say?

And yeah, idling in traffic does affect your mileage. You sit at stop lights one after the other, using gas that could have powered your car for say, 4 miles or so. Guess what? Your MPG goes down by 4 miles per gallon. If it was 22 it'll be 18. Fairly simple concept, I don't know why you keep denying it.

It'd use whatever amount of fuel is fed to it. I'm not making it complicated at man, your whole "load" theory is.

If you really wanna get super technical with it here's what you gotta think about: in a fuel injected car, the computer "decides" how much gas it'll inject. Your throttle input only suggests how much fuel to put in there.

Go figure that out and lemme know cause I'm curious myself; like, is it more efficient to drive at 5000rpm in first gear barely touching the throttle or drive 700rpm while flooring it in 6th gear? I'd love to know the answer to that.

Maybe you should try not going into 5th and 6th gear and see what happens.

If you got the same gas mileage then it's good news for me. My 10 bolt is almost done and I'd love to have it replaced with a 4.10 12 bolt.

05HD

You said: You are obviously wrong given that:

1. This is a conversation about average fuel economy
2. We are referencing road miles in the United States of America

If you beg to differ that these items are given, then you should not be posting here. You do not understand the question. If you agree that these items are a given, it is time to admit that you are just wasting bandwidth.

SS RRR

iTrader: (2)

My point is an engine works harder from start to finish when it has to stop and start repeatedly. More fuel is consumed. You are fixed on engine speed only which cannot be the only item to be taken into consideration.
Brilliant. Mind bogglingly brilliant.
As stated, I went from 3.73's to 4.56's and have done several trips around town and freeway. Mileage has not changed drastically. If your setup is optimal including gears/tires and has a spot on tune your mileage should not change drastically either.
Your reasoning regarding this doesn't make sense to any of what I've experienced therefore I have a hard time believing your RPM is everything about MPG theory.

LSWHO

iTrader: (1)

City driving is worse mileage because of acceleration. Stop and go is a lot of accelerating. It's not much to do with idle. Obviously idle will lower MPG, but i'd say it's pretty negligible seeing how you can idle for something like 45 minutes without burning a gallon of gas. That's A LOT of idle.


This is also why hybrids get better mileage in city than they do highway. They charge while decel/braking then they accelerate with generated battery power assistance or all electric motor as well.


I still don't get why you fools are arguing. Find the info I said and look at it.

The results will be plain as day.

LSWHO

iTrader: (1)

Do you not take into account the friction generated from higher RPM?

Simple fact is every car and every tune is different. It's so dependent on the total package NONE of you see it.

AmirGTR

I didn't say it's only rpm. I said it'll use as much fuel as you throw in it, simple as that. Tune the computer to stuff more fuel in there, it'll use more fuel. Tell the computer to put less, it'll use less. Nothing "mind boggling" here.

If I knew how the computer works I'd give you a definite answer but I know for sure RPM is a factor.

I do.

Simple fact is the tune, rpm, load, gear ratio, weight, aero, tire friction...all these contribute to the gas mileage. Anyone denying that needs to stab themself in the eye lol

LSWHO

iTrader: (1)

Nobodies denying that here, they already changed their story! Too bad we can see their old posts.

droccm98

i read these mpg things and they **** me off. for a few reasons, because it doesnt concern me, i could get 10 mpg, i love my car and love driving it haha, but more so, i have a v6, havent had my license for more than 6 months even, so im still drivin like i stole it, not as bad as first but bad.

bad enough to only get me about 100 to 140 miles a tank
someone teach me to drive calm

idformula

So by some peoples fuzzy logic, my 1967 army jeep that weighs 7k lbs and a 6 shooter with 5.88 gears should be in gallons to the mile instead of the 12mpg that I got intown/highway? It turns 3000rpms at 55mph btw.

Load does effect gas millage, plain and simple, in 6th at 60 on perfectly flat ground I barley have to tap on the gas to keep it there, which (carlos mencia voice) that means there's no load on the motor!
Load on the motor would be going up a hill in 6th, and guess what AmirGTR, your right about the pcm deciding how much fuel the motor gets, but when you have to floor it to get up the said hill, the pcm will dump more fuel in that scernairo than if you were to downshift into 5th to get up the hill.
Infact go to the parts store and buy a cheapo vaccum gauge and hook it up and drive around town through the various gears at various speeds, high vaccum means no load and no vaccum means full load, its not rocket science here guys.

AmirGTR

If you're 19 or younger, enjoy the madness while it lasts. I used to drive twice the speed limit at that age and never got caught. I was so damn focused man...lol

Now? I drive below the limit and I still get **** from the pigs. Why? No god damn focus. FML.

SS RRR

iTrader: (2)

What's mind boggling is you stating that throttle input is nothing more than a suggestion as to the amount of fuel to be used. Am I understanding this right?
I don't understand what you mean by load and weight? Cargo load and vehicle weight? Regardless, what you list all boils down to load on the engine. I thought this was understood. My fault for not specifying.
I don't for a second believe "friction from higher rpm" is enough to factor into the drastic MPG losses people have claimed. Your second statement is extremely true. If there is a loss of 8mpg after a gear swap on a stock car then there is something extremely wrong. Those with heads/cam combos with drastic MPG losses after installing gears either have a botched tune, are over cammed and do not have the correct wheel/tire combination or stab the gas everywhere they go. An engine operates most efficiently at torque peak. You want to drive economically then concentrate RPM on torque peak and as stated again, use a vacuum gauge.