when I was creating another thread it brought this idea into my head. everyone seems to say drive like a grandma nice and easy will get you the best gas mileage. with what I have seen I almost don't believe it and my theory almost seems t ogo against it so figured I would get your ideas.

with both my cars I usually shift right at 2500-3000rpms either way so that isn't much of a variable but how much throttle is. in my mazda I'm slightly noise limited anymore as to how much throttle I can give it but it still has followed the same trend. my honda I have almost always gotten better mileage when I give it moer gas when taking off as long as I keep the shift points the same. if I drove it like mad and shifted at 5000rpms I'm sure it would change things by quite a bit but I try to keep the shifts just like normal just using moer throttle to get to cruising.

now I don't have any hard proof I admit but it almost seems as though it would work out. when you give the car more throttle like this sure your using more fuel per rotation of teh engine, but you should be also making more power for a given amount of fuel. brake specific fuel consumption should be better. this also in turn with being able to get up to cruising speed a lot faster.

this does make sense doesn't it?

 

It definately makes sense, just like you might get better MPG @ 60mph rather than 50 or 70...

 

Its not so much accelerating like a grandma, but maintaining your momentum and not using the brakes. If you let off the throttle after seeing that you need to slow down and coast down slower, minimizing the use of the brakes, you WILL get better MPG. If you keep on the throttle until you have to aggressively use the brakes, you will KILL your MPG.

I have a Dodge 1500 Quad Cab truck with 20s on it and a 4.7 that gets 18 mpg in daily stop and go driving.

 

I can easily understand that. on and off the brakes with constant speed changes easily will kill mileage. I've just heard from many people even seem to say that best way to get mpg is nice and easy on the acceleration also.

 

Graph it, and see what happens.

I would say create two graphs, and note the behaviour of the curves.

Plot MPG vs. RPM
Plot Power vs. RPM

The objective here is to maximize MPG.

We know that there is internal friction in the moving parts of the vehicle, and we know that momentum helps replace some of the force required to propel a vehicle.

So there is a trade off, you need more power to get off the line than you do to keep the vehicle moving. The objective is to to maintain speed with the lowest rpm and highest gear, to be the most efficiennt MPG.

And if you incorporate power into it, you want the most power with the least amount of fuel. So lets say you produce 1 hp for 1mL of fuel. Well its not a linear graph, it would change at different RPMs due to road conditions and engine type. So you are looking for a POWER to FUEL ratio that is as BIG as possible. BIG power divided by LITTLE fuel, equals Big number (greater than 1).

The problem is determining where to shift.

I havent done multivariable calculus yet, but it could probably be used to solve this.

But if you maximize power, and mpg, you can come up with an RPM range, and if you dont exceed that you should be saving as much gas as possible.

So if you plot those two curves on the same graph, there is a point where they will start to decline relative to your independant variable, the RPM. So this will give you a max point and u should try to keep below that RPM.

You have to be creative with the graphing though, the MPG graph will have to be exploded to see scale.

 

right now both my stick based cars are um... well... lets just say I'm driving a corsica right now and they don't come in a stick so giving the car more throttle would cause my shift points to be later which would negate what I'm refering to.
either way accelerating at 25%throttle or 75% throttle you would need to shift at the same point either way. that's at least what I do with my honda. give it around 70-80% throttle but yet still try to shift by 2500rpms.
cruising rpm would be the same no matter what throttle you would use to accerlate with.

 

Interesting aspect. I usually take things to the extreme when looking for answers to seemingly hard to answer questions. We know that driving in the highest gear possible gives the best mpg. So if we are so easy on the throttle that we "never" get to high gear then our mpg sucks. My conclusion; get your @$$ in high gear as quickly as possible..

 

you mean you arent getting good enough mpg with that briggs and stratton under the hood..

If you take off like a dumptruck you actually burn more gas.. you want to accelerate slow but not too slow, shift at lower rpms, keep the TCC locked

Also you want to do as much "coasting as possible" coasting=free gas mileage, calculate red lights and just coast to them and by the time you get there its green sorta thing.. no speeding up just to stop sort of stuff

 

are you sure about that accelerate slow part though? engines commonly run more efficient under high load since the throttle blade presents less of a pumping loss. I mean sure you are using more fuel per rpm but since you should be using it more efficient you should be generating more power per rpm also. that and you would get up to cruising speed that much quicker.

though as far as auto's go you very well could be right though as if you put more pedal into it that just means it's going to shift that much later.

and rotary motors don't get the greatest gas mileage for their size but I'm not driving that or my honda right now. I'm at least driving american but hardly a respectable one. 91 corsica

 

hey its winter im driving a 91 cultass beater.. not like slow slow, but not fast, you know what I mean just gradually, faster than grandma drives but not as fast as a pissed off teenager

 

Everything you are talking about is engine specific.

An american v8, or most american engines for that matter, will deliver most of their power down low. The imports (asian) tend to rev a bit higher before they get any power in. The euro cars, just try to balance it with alot of fancy engineering.

So you are correct in saying what youre saying, but accelerating slowly usually yields better mileage. Refer to the graph that i was telling you about. You can visually determine which RPM will give you the most power and least gasmileage. Thats where you should shift.

The graph ofcourse will be very hard to make, i suggest if you do alot of long distance trips, calculate it on those in your 1:1 gear. Get a flow meter. Go slow about 1000 rpm for about 20 mins, record your mileage, and how much fuel you flowed. Then 2000 rpm, then 3000 rpm, as high as you want. You can go shorter intervals for the higher RPM if you want but it wont be as accurate.

Get a dyno done to the highest RPM you measured your results to and plot the graph. Maybe you dont wanna put that much money into making a graph, but were jus saying hypothetically.

As well, i totally agree with the coasting thing. The bigger your car, the better this works. Generally, following the speed limit will get you more MPG than goin 20 over. Ive found this out on a 1200km round trip.

My dad used to be a courier driver on commision, so fuel played a HUGE part in his job. We drive a 1996 Chev Lumina van with a 3.4L aod FWD . He did atleast 700 kms a day for this job, sometimes up to 1000. He usually used up 3/4 of a tank per day. But he found if he coasted as much as possible it helped.

On the gas for 3 seconds, off for 2
on for 3, off for 2, etc...

He found he nearly doubled his gas mileage per tank. You need to be on the highway, and be over the limit to see results for this method. Because in my van, the TC lockup was engaged, and when you lifted to coast, it would disengage, so when you went on the gas for 3 seconds, it would actually rev much higher, and by the time it locked up, it was time to lift again. So it wasnt effective on the speed limit.

 

rpms or cruising. aren't related to what I'm refering to here online170. shift points aren't really realated either. well if your driving a stick at least. I know a lot of this goes out the window with an auto unless it is a manual shift body.

 

I've noticed a lot of the same things as rx7speed, accelerate slow or fast(reasonably) but shift at the same rpm and get very similar mileage.

Ever race at NYIRP?

 

no, just been to lancaster once

 

There is a "happy medium" someplace, but it changes with conditions.
Too hard on the pedal, and the mechanical losses ( gears, tire heat, etc. ) go way up.
Not enough, and you hang low gears too long. ( time is a factor )
Anytime there is braking, that's directly throwing away the energy from the gas you already paid for and burnt.
My truck, for instance, on level road I'm best off with an easy accel.
Up a long hill, I'm better off standing on it, taking the 2 GPM ( not MPG anymore ) for a short bit, and being able to get off the gas, rather than a "reasonable" accel at 2 MPG the whole way.
It almost always takes a disproportionate less amount of fuel to maintain than to accelerate, at all, so the sooner you can get closer to just maintaining, the better off you should be. The "instant" MPG displays available in many new cars, and most of the DIY-ALDL stuff is a big help in this regard.
Of course, it could be just me.

 

I have.

Here's what to keep in mind, the lower your RPMS are, the longer you give the fuel used in each power stroke of the engine to work. That generates efficiency. More throttle with earlier shift points yeilds better mileage that lighter throttle and higher shift points (Given the same rate of acceleration.) The difference is gonna depend on almost every variable related to the car, tires, gearing, aero, bore and stroke, camshaft, etc.

All this talk about winter rats, you guys should feel like your in Cadillacs, I'm driving a 92 Escort wagon, with more rust than metal, 195k miles, and 1.9 liters of pure excitement. (Dissapointment, actually.)

 

Ever seen a white 82 sport coupe with black primer front fenders and a black primer front bumper? It probably was running around 13.0-12.7.

 

Engine more efficient at WOT? Here we go again. . .

Think about a couple of things:

What happens to the A/F ratio when you increase the load on the engine (such as accelerating quicker than Granny)?

Ever heard of "skip shift"?

 

it goes rich I know. and what happens when you accelerate like a grandma? your in the pedal for a lot longer.

 

We need to plot fuel consumption against rate of acceleration. But to get any real data, its gonna require equipment most of us do not have.

327???? - I wasn't there much this year, and never with the Camaro.

 

hey i resent that, my winter car is a 96 corisca and i think its an ok car. its no camaro but its dependable and the 3100 will eat some rice while im at it. i would rather have a 60 degree v6 any day over one of those whiney vtec concoctions. you avatar even says "honda sucks". well let me just say i only own GM cars, and will only own american cars. my corsica has 129 K on it, and still runs great, i dont know why people regard them so poorly. it gets good gas millage, and the ride isnt too bad. its not a road handling car, but it wasn't built for that. it was built to be cheap transportation. they do a good job of that. i also had a 91, that car had 170K on it when i sold it, it still ran good but the body has rotted out. as far as i know its still on the road, doesnt look pretty anymore that for sure but it still runs. all i know is that no one can even talk to me about an import. i want nothing to do with them. i would rather drive a corsica than a toyota, simply becuase i am a patriotic american and that all that to it.

 

"Longer". Not "a lot longer".

 

Two ways I can think of, off hand.
1. Anything with a MPG readout, or that can calc it from a log.
2. A known measured quantity of fuel, like a 1 quart can, along with pump and plumbing
to run off that, instead of the tank, and a "measured mile" through the type of driving one wishes to do.
Not that tough, but more work than I care to do.

 

one factor to consider:

"The power required to overcome the aerodynamic drag is given by:


Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power.

It should be emphasized here that the drag equation is an approximation, and does not necessarily give a close approximation in every instance. Thus one should be careful when making assumptions using these equations."

 

Or, more time/work than most of use would like to go through...

MPG readouts would work pretty good, if they are accurate. I don't know what goes into their calculation, I would imagine its injector pulse width, injector co-efficient, fuel pressure, rpm, and mph. If the car has it built in cool, if not, thats gonna take some work. Doing scans with the right tool could work, but thats a lot of work.

 

They work off of the MAP sensor. Keeping a constant MAP reading will yield better gas mileage.
What really kills gas mileage is lugging the engine. To the engine it is the same as pulling a trailer loaded down. Keeping the RPMs up will increase MPG. The Asian markets have figured this out. Most of the Asian cars I have driven on the highway at 70 MPH have a tach reading of ~3000 rpm and the get relatively good gas mileage for the CI of the engine.
I have a 67 pickup that has T56 six speed with the .62 overdrive sixth gear. Having a 350 and cruising at 70 mph with the rpms at 2200 RPM the MPG goes down severely. But if i leave it in 5 ( 1:1) at 70 mph with the rpms 3100 RPM the MPG go up. This is the same stretch of road going to and from work.

 

reason why I regard this corsica so badly is in 100k miles this has had more problems then any other car I have owned. it cost just as much to fix as my imports. gas mileage isn't great even for a 4 cylinder. all in all this car just seems to be very cheaply made and has been nothing but problems. I can understand cheap transportation and that is what this car was designed for but that doesn't mean it has to be made cheap. Though I can understand your support the US but anymore those boundries seem to blur with foreign made domestics and domestic made imports. With that I would prefer not to support something cheap like the corsica I own but I don't have a lot of choice in that matter right now.



@57 when accelerating faster to get up to cruise speed quicker (even if it isn't that much shorter) enough to make up the difference of the lower a/f ratio used though. I honestly don't know and have seen things done that say both ways. I do remember way back in a road & track they had an article that showed heavier acceleration worked for better mpg. I have also know though that common thought seems to say lighter acceleration would give better mpg though I haven't seen test that way and it would be nice.

 

Have a look at the charts in this paper:
http://www.adlabs.com/library/HEV/SA...ght_Trucks.pdf
For the particular 5.4L engine tested it had its highest efficiency around 2200 RPM and 330 Nm torque. Hybrid cars gets good MPG because when the engine operates at all, it runs in this sweet spot (that seems to be 2/3rds of max torque and a little less than half of max rpm, for that engine). It also corresponds with what Online170 said about his dad's findings about the rather special coasting technique he used.

 

lets see with 129K on the clock this is what has been fixed on this car. my father inlaw owned the car before me so im well aware of the history of this car. just note my car has the 3100 v6, a much better running engine than the 2.2 that you have. it manages 27 highway and will still smoke the tires
items replaced:
1. water pump
2. fuel tank (salt damage)
3. exhuast (salt damage)
4. trans side cover (correded through, salt- winter)
5. evap line (salt damage)
6. parking brake inop (salt damage)
7.1 set of plugs in 129K miles of driving
8. 1 set of wires
9. brakes and tire normally worn while driving
this is this car's service history as far as i know. my father-in owned the car from almost new. he loved it, i dont mind it either.yes the interior is somewhat lacking but i still find them to be a reliable car. this car has original engine and trans without a doubt. it runs well and doesnt leak oil at all. this car has also been driven in the buffalo area for 10+ winters and the salt is very hard on cars and some (if not all) of these repairs are going to be needed no matter what brand of car it is.

now lets get on to my camaro. its a 1989 camaro with a 305 tbi. it has over 165K on the clock. original engine and trans as far as i know. its not terribly quick for a camaro but it is dependable, handles like a dream, looks great, and delivers fair gas millage, even by 2007 standards. it also makes a cool sound through a 3" exhaust and headers. its a great car and i will have it for many years to come. im going to do a 350 swap, not becuase the 305 is shot but because i want more power. it doesnt leak anything, it has been spared salt so it has no rust.

both of these cars are built well for their intended roles. i like both of them for their intended purpose. i also dont think you even own a third gen camaro and im not entirely sure why you are on this forum. are you here to start silly arguements? we are here becuase we enjoy AMERICAN made performance cars, not imports. i dont think too many people on this forum care about imports. you avatar says it all. wankles are ok but we are here to talk about to talk about third gen fbodys. im sorry i got into the corsica thing but i dont like people bashing on my chevies period. i get defensive. so unless your talking about swapping a wankel into a third gen(that would be highly custom) i dont think anyone really cares about them here.

 

For the question as posed, doesn't really need to be accurate, just consistant.
Whether the result is in MPG, or acre-feet per furlong, or something else, either it uses more fuel, or less fuel, over a given distance, so *anything* that will give a number over distance, and is repeatable, will answer the question.

I'm not aware of a MPG readout in a ThirdGen, though there are mods to many of the ECM DIY stuff that will yield a number that could be used. The ALDL stock doesn't have anything in it that can be used for this, so either invent a way to consistantly measure the fuel used over a short distance, or do it over, and over again, for at least a full tank. ( Not me !! )
The calc isn't that tough, if the data is available. You need the injector flow rate, and duty cycle over time, and the average MPH over the same period.

 

They don't use MAP, but keeping the LOWEST map will yield better MPG, that's true.
( constant is easy. Glue the loud pedal to the floor, and keep a constant MAP at 100 kPa )

Close.
Keeping the engine in it's most efficient range, whatever that is, will always yeild better MPG. Lugging is not efficient.
It's probably not higher RPM in most ThirdGencases, but it could be. The imports work better the way they do, because they've deliberately built the systems to run smaller mills, and keep them near peak more of the time. As a result, they have no reserve. Good mileage, but poor passing, moderate acceleration, and a 7K RPM red line stock.
Somehow, a rice-burner whine in a Camaro just doesn't seem "right."
Even so, GM has learned. Look at the new stuff. Underpowered engines, but high stall converters to make up for poor launch, and lock-up to make up for the high stall in cruise, lots of gears to keep the RPM in the zone. Just enough power available, but no more.
Run the combination as close to peak as much of the time as possible, and it works.

 

please don't take everything so personally just because my views differ from yours. as to why I'm here it's because I have owned a 71 camaro, my friend owned a 91 camaro, my other friend owned an 87 firebird. seems simple enough to me as to why I would be here. what one owns doesn't equate to what they do or do not like. I'm also here because I like cars. import or domestic doesn't matter to me as I just like cars. I still have yet to see this owning a thirdgen requirement that seems to be implied by many newer members.

I'm not here to start fights either. I made one comment about the corsica that started you making a huge reply to it. if anything I'm not trying to start the fight about the corsica if I was here to just troll and start fights I would say soemthign like chevy suck, not the 91 corsica sucks. but as you even said, this site is to talk about thirdgen fbodies so why are we even talkign about the corsica? BTW smoking the tires isn't a sign of power, just a sign of no traction. with your thirdgen I don't even know why your bringing that up as I never said anythign about thirdgens or for that matter even GM products just that one line about the corsica I drive isn't very grand.

this thread wasn't designed around the rotary motor. if it was chances are I would of taken it somewhere else but from my understanding the way you drive effecting gas mileage is applicable to all cars and since generally I respect and get along with most of the members of this site I came here with the question. As far as others caring about the rotary I would say in the six years I have been here many questions have been asked about it or the rx7 in general so it seems some do care about it. Honestly that comment even stands with many imports I would say also. wouldn't you want to know your enemy or would you rather just blindly shoot in the dark not knowing anything?

Why are you making as though I'm sitting here trying to push imports and my rx7 on people in this thread? I brought my rx7 up what twice before this? all that said is that it doesn't get teh g reast gas mileage and the other is that I seem to get better gas mileage when driving with higher rate of acceleration. same thing with my honda that it seems to do better with a higher rate of acceleration. Being that those are the cars I own it is only me bringing my experience to this thread. the experience would of been the same if I said my thirdgen gets better gas mileage under heavier acceleration, but since I don't own a thirdgen I can't say that. does that mean I should leave my experiences out even though it relates to the thread at hand and this thread is able to be applied to a thirdgen either way. I wouldn't think so. If I was here preaching about imports being so great and wonderfull I could at least understand but I'm not. in honestly in this thread I wasn't even saying much of anything import related your the one who brought this up and started to turn this into an import vs domestic thread and yet at the same time question me as to if I am only here to start arguements.

as far as the corsica I partly own in under 100k miles the car has gone through head gasket, warped head, stuck brake calipers (the floating caliper design sucks), leaks coolant, leaks oil, motor and tranny mounts shot, plastic easily breakable on the interior, carpet fades too readily, speedometer is very weird and laggy, fuel gauge is messed up as the sender I bet needs replace, no temp gauge, transmission could prolly be adjusted/rebuilt and more. these are at least some of my complaints and problems with the car and there are even more which in my opinion is not so great for a car this young. this also isn't my first experience with the corsica either which wasn't so great either.

My avatar has nothing to do with honda in general sucks. it is more related to my 76 accord and some of it's problems and how it's a little weird cars. if your curious look up CVCC. In a nutshell 3 valves a cylinder, 3bbl carb that feeds two different a/f ratios to two different combustion chambers per cylinder. good idea when it works not so fun when it doesn't. in general I don't think honda sucks, just a lot of honda owners who are blindly loyal, and think them and their cars are perfect.

so now that we have this out of the way I hope can get off you getting this thread off topic I hope we can get to the question at hand.

 

well i say that no matter if im driving my third gen 305 camaro, my 3100 corisca, or my 4.3L vortec blazer they all get the best millage when driven in a sane manner. it seems the harder you push it the more gas it burns. the cruise control works in both my corisca and my camaro and i use it in both vehicles. get the car up to speed and push the button on the turn stalk. car stays at a steady rpm and car maintains proper speed with just the right amount of throttle. my camaro gets very good highway millage for a v8 powered car. it gets in the mid-twenties on the expressway. city millage is fair but not really good.
my corsica gets incredible millage. i still dont understand why you have so much trouble with that car, i have owned 2 of them. yes they are lackluster but they have always got me where i needed(dependably) to go 6 months out of the year. i would also agree that the 2.2L's weakness is the the head gaskets, they are known to fail. they are a bi-metal engine, cast iron block aluminum head. they expand and contract at different rates and over time ruin the head gasket.
anyways i got defensive becuase i felt that you might not really have an interest in third gens, i wasnt sure. i thought that most people that came to this forum owned third gens. usually when i am here that is what i discuss. my 1989 camaro RS with a 305 tbi and everything i do with my car, right now im planning a swap for a 350 tbi. i have a used engine that im going to rebuild and install in my car, and then i would like to get it painted. my car is in good shape but the paint is crappy, has its fair share of scratches and imperfections but the sheet metal is as solid as new. it has never seen a winter. that car is my baby, my cosrica is just a cheapy little car i run in the winter, but it does what it needs to do and does it well. its a sacrifice to the "camaro gods", lol. it goes to **** so my camaro can live a long healthy life.