double your gas mileage?

[dongalong]

In another 10 years or so, fuel will become a thing of the past.

THIS or similar will power our cars.

 

[viking1]

In another 10 years or so, fuel will become a thing of the past.

THIS or similar will power our cars.

10 years? Maybe when the oil really runs out. Not in our lifetimes. You don't think the shrunken heads will let anything like that happen do you?

 

[SteveHd]

In another ten years, electric cars might be practical.

 

[viking1]

In another ten years, electric cars might be practical.

If oil continues it's upward spiral in price, and advances in technology are able to negate the shortcomings of current electric cars. Not to mention the
price must come down. However, electric rates are going to climb as well.
We have a 4% hike that took effect as of today here. All in all electric rates are set to climb here by 25% over the next few years due to deregulation.
The average person cannot currenty get a return on an electric or hybrid vehicle due to the high cost. One would have to drive a lot of miles per year to get that money back in fuel costs.

 

[ClaireTalon]

The vast majority of "add on fuel saving devices" are a gimmick. Some of that stuff like special spark plugs or injectors may work. I doubt that it would even be enough to notice, though.

It generally helps to keep engine, drivetrain and tyres in a good condition; anything that helps squeezing moving the car as far as possible with as little energy as possible increases your mileage. Worn tires have a higher slip coefficient and hence move the car less than fresh tires with a lower slip coefficient. Same goes for using winter tires in summer: Thei higher mechanical grip demands more power to hold a certain speed.

Generally, I'd keep my hands off any special gizmos that announce great increases of your mileage through dubious scientific descriptions. There is no such thing that you can put into your tank, or tie to your fuel lines, that increases fuel efficiency. The only things that really help is care for the mechanic sides of your car, and an efficient driving style.

 

[Biggie77]

I would like to add a specific recommendation to Claire's general maintenance advise. On regular communter cars and trucks, change your transmission or transaxle fluid every 40,000 miles. I dated a girl that was overdue 12,000 miles on this. I had it flushed and changed and the mileage went from 25 mpg to about 28-30 mpg (overall average).

Also, electric cars are further along than many realize. Check out Toyota RAV4 EV - Wikipedia, the free encyclopedia .

 

[viking1]

I would like to add a specific recommendation to Claire's general maintenance advise. On regular communter cars and trucks, change your transmission or transaxle fluid every 40,000 miles. I dated a girl that was overdue 12,000 miles on this. I had it flushed and changed and the mileage went from 25 mpg to about 28-30 mpg (overall average).

Also, electric cars are further along than many realize. Check out Toyota RAV4 EV - Wikipedia, the free encyclopedia .

I change all the fluids regularly on my vehicles. Transmission, axles, transfer case, power steering, and coolant. I even flush the brake system with new fluid at least every two years, and usually every year. I clean the throttle body every year and fog the intake with sensor safe carbon cleaner. I use all synthetic fluids. Well, all except the brake fluid. The grade 5 silicon brake fluid isn't compatible with antilock brakes. I run injector cleaner through the fuel tank yearly as well. After working on cars, trucks and other equipment for over 25 years, I've learned maintenence does make a difference. I drove a '76 Chevy to the junk yard in '99. There wasn't much left of the body, but the engine and drive train was still okay.
The head nor the oil pan were ever removed on that engine.

 

[Rikter8]

Here's another way to think about it.

The ECM or "Engine control module" now commonly called the PCM "Powertrain control module" adjusts fuel consumption based on engine load. the PCM senses a percentage of load up of the transmission, and of the engine, and will adjust fuel mixture accordingly to the load.

Generally, yes, during a straight cruise, the engine isn't over much of a 12-15% load based on drag of the accessory drive, and transmission drag. (Hence you hearing "Ditch the clutch fan and go electric, because its a larger load on the engine, and takes more fuel.)

Aluminum engines have mostly made the way into cars, making gas consumption considerably better because of the shaved weight.
Hence, that's why the new LS7 500HP corvette can knock down 25+ MPG, because it doesnt have to work hard and it can lean out the mixture quite a bit during a steady cruise.

Now, If you've looked at new GM cars, you'll notice something that was on ther Mercedees Benz cars, called Displacement on Demand.
On a low engine load, the V8 engine quietly shuts off 4 cylinders to conserve fuel. When you need to pass, or based on road load, the other 4 cylinders kick in. Early "DOD" applications had some issues, but I havent heard of any lately. So there are technologies available, but it's making them affordable and integrating them into cars that everyone can afford.

When I talk larger displacement, Im speaking of conservative size, not crazy size like I use.
A mid-size car should easily be able to contain a small displacement V8, and Subcompact cars should be equipped with small displacment v6's.
I find absolutely zero use for 4 cylinder cars, unless they're running the tractor on the farm.
Here are a couple things I would recommend for anyone driving trucks, or cars with the old clutch style cooling fans.
1. ditch the clutch fan and go electric
2. Upsize the alternator for the fans, and for less load up of the alternator (Yes, this creates drag when you turn on all the electric accessories)
3. Use the AC less, and only use the Defroster to clear the windshield, then shut it off. (Your AC compressor runs when its on defrost)
4. Use Transmission coolers to keep things cool, and parts operating freely.
5. Think Aerodynamic
6. For us GM truck guys and girls, If your running a 4L80E, switch to a 4L65E-HD. You'll gain some quarter mile time, 80 wheel HP, and gas mileage behind that 6.0L.
But, that's just my .02.
C

Always? I/M/O the reverse is more likely to be true. I think an "overworked" engine would get better mileage. But I'm not an engineer so I don't really know.

Here's my thinking: Most of the time the engine isn't really working hard. A larger engine will have it easier, all other things being equal, but it consumes more fuel simply because it's larger. There's more air being drawn into larger cylinders and so more fuel goes in with that. At the times when the car is at a steady speed, say 40mph, either engine will be "loafing" but the larger one will be consuming more fuel. It's pumping more air/fuel through those larger cylinders. Even when both are idling, the larger engine will consume more fuel.

In the "real" world, it's a minor difference. Using the 95 Caprice mentioned previously, suppose we replace its engine with a 5.0 V8 TPI. [I specify "TPI" because the 5.7 "LT1" was also a tuned port induction design.] To keep all things equal a 150 lbs of deadweight would have to be added because the 5.7 is 150lbs heavier than the 5.0TPI. With those changes the improvement might be less than 1 mpg. Omit the "deadweight" and the improvement would be fractionally better.

The bigger factors are size and weight, anyway.Are there "unsynchronized" gearboxes being sold? I mean unsynchronized for gears above first. I thought such gearboxes fell out-of-favor before WW-II.:smile:

 

[JustAsking]

In another 10 years or so, fuel will become a thing of the past.

THIS or similar will power our cars.

This is a total fraud.

 

[SteveHd]

Rikter8, thank you for your detailed reply. Part of it went a over my head and I'm sure it did for other readers.

(Hence you hearing "Ditch the clutch fan and go electric, because its a larger load on the engine, and takes more fuel.)

I imagine the younger readers will wonder what a "clutch fan" is but I remember when most cars had them. I think that was sometimes called a centrifugal clutch. Worse yet, some cars had the fan directly driven w/o a clutch.

... On a low engine load, the V8 engine quietly shuts off 4 cylinders to conserve fuel. When you need to pass, or based on road load, the other 4 cylinders kick in. Early "DOD" applications had some issues, but I havent heard of any lately. So there are technologies available, but it's making them affordable and integrating them into cars that everyone can afford.

In my previous message, I didn't factor "Displacement on Demand" into my theory. If D-o-D is present, it changes everything.

Slightly changing the subject, you reminded me of Cadillac's "V8-6-4" debacle. In that design they inactivated cylinders by using a valve-lifter mechanism which stopped valves from opening/closing on up to 4 cylinders. The air trapped inside would get repeatedly compressed and expanded. The lifter mechanism proved to be the downfall. It had durability problems which became infamous. All V8-6-4s were recalled and those brought in were replaced with a conventional engine. That had to cost GM a bundle!

In today's EFI engines it's easy to shut off the injectors to selected cylinders. No action is needed to the valves.

 

[ClaireTalon]

<.> A mid-size car should easily be able to contain a small displacement V8, and Subcompact cars should be equipped with small displacment v6's. I find absolutely zero use for 4 cylinder cars, unless they're running the tractor on the farm. <.>

My significant other, Frank, drives an old-model Peugeot 505, which also has a 4-cylinder engine and handles quite well, runs smoothly and has a pretty good engine tractive force. The consumption is ranging between 18 and 20 mpg. There is use for 4-cylinder cars, and not only in the compact and subcompact sector.

<.> 5. Think Aerodynamic <.>

Repeat that a few times, one can't say it often enough!

 

[Rikter8]

My significant other, Frank, drives an old-model Peugeot 505, which also has a 4-cylinder engine and handles quite well, runs smoothly and has a pretty good engine tractive force. The consumption is ranging between 18 and 20 mpg. There is use for 4-cylinder cars, and not only in the compact and subcompact sector.
Repeat that a few times, one can't say it often enough!

True, The market is coming quite a ways with 4 poppers lately.
The Subaru WRX STI pumps out around 100hp per cylinder.

I shouldnt generalize, bites me in the butt every time!

The stuff I drove was like 2.0L and 2.2L 4 cylinders where they were zippy off the light, but just about had a heart attack at expressway speeds.

Aerodynamic Aerodynamic Aerodynamic.... Thats why I have a fiberglass hard tonneau on my truck as the wind doesnt get caught in the bed.
Incidentally...most peeps think that if you drop your tailgate down you'll get better gas mileage. I have to differ. I ran my truck without the coverand tailgate down at the track. It actually slowed my truck down at least a full second in the 1/4 mile. I'm guessing it's the large amount of vacuum being created behind the cab of the bed, VS just gliding off. (But im no air/fluid dynamics expert.)

I wrote a whole diddy earlier this morning on this thread, but either my connection or LPSG had bugs, and I lost the full page I posted.
GUess it was the boards way of tellin me to shut up.

 

[JustAsking]

Here is something interesting. My 1981 Honda Civic was rated at 44 mpg on the highway and I routinely achieved that gas mileage. I communed with that thing and put almost 200k miles on it. Why can't we just all buy 1981 Honda Civics?

 

[B_NineInchCock_160IQ]

Here is something interesting. My 1981 Honda Civic was rated at 44 mpg on the highway and I routinely achieved that gas mileage. I communed with that thing and put almost 200k miles on it. Why can't we just all buy 1981 Honda Civics?

Because they fell just barely shy of making enough of them so that every person in the world could have one. Maybe they'll hit that mark with the 2008 model.

 

[viking1]

Here is something interesting. My 1981 Honda Civic was rated at 44 mpg on the highway and I routinely achieved that gas mileage. I communed with that thing and put almost 200k miles on it. Why can't we just all buy 1981 Honda Civics?

I went to buy a small car like a Honda Civic Coupe, or a Scion. I could not fit comfortably in it. I could barely get my foot between the brake and center hump to get to the throttle. My head was right on the headliner. Instead I bought a compact pickup. It's four cylinder, and no it won't get 44 mpg. It does get 10 mpg better than my full size 4x4 pickup, which I still have. It cost less, has much more room, and had plenty of standard features. They don't want to make an afordable mid size car that gets decent mileage, but they can. An Accord or a Camry are a comfortable fit for me. They cost too much, and don't get much better milage then my little truck. When the car makers do their part, maybe the rest of us can do more. I don't drive enough to warrant the extra cost of a hybrid, and they don't do much out here in the mountains.

Rikter8's comments on tailgates are correct. It's been proven in tests that the tailgate down decreases mileage. I too, have a fiberglass tonneau cover. I am sure it helps, but has never been enough to measure by the odometer readings and hand calculated fuel consumption. At least, not on any pickup I have ever owned.

 

[ClaireTalon]

<.> Thats why I have a fiberglass hard tonneau on my truck as the wind doesnt get caught in the bed.
Incidentally...most peeps think that if you drop your tailgate down you'll get better gas mileage. I have to differ. I ran my truck without the coverand tailgate down at the track. It actually slowed my truck down at least a full second in the 1/4 mile. I'm guessing it's the large amount of vacuum being created behind the cab of the bed, VS just gliding off. (But im no air/fluid dynamics expert.) <.>

Well, that's trying to be more papal than the pope, if you keep your tailgate down. You may add another foot or ten to your mileage, but the risk of losing things and endangering the cars behind you would be too great.

However, it's interesting to see that the 4-cyl. (about 2L) Peugeot engine has about the same consumption as the 8-cyl. 4.2L engine of my Audi, around 18 - 20 mpg. However, the weight comes into the equation here, the Audi's unladen weight is nearly twice as much. The Mustang's consumption is (*BEEP*) I guess I would be killed if I told. You don't talk about it, just drive :wink:.

However, I have an interesting question, as we're talking about the effects of displacement dimensioning on gas mileage: What way do you want your displacement: Bore or stroke? LOL, I know that sounds sexist :wink:

 

[DC_DEEP]

However, I have an interesting question, as we're talking about the effects of displacement dimensioning on gas mileage: What way do you want your displacement: Bore or stroke? LOL, I know that sounds sexist :wink:

You are cruel, Claire. Pique my interest, willya?

I have more experience with the chemistry end of things, rather than the physics and engineering, but I'll give it a shot.

Given identical displacement, the engineers have already undoubtedly come up with an optimal efficiency range for bore-to-stroke ratio... it seems to me that increased bore/decreased stroke would be more beneficial than the converse. I would think the shorter stroke would divert less of the energy mechanically... I'm probably wrong.

 

[viking1]

I can answer the bore stroke ratio question. There is no one optimal answer.
It depends on the application. If you want to race, that is, run an engine at very high rpm, (formula one for example) a short stroke and large bore would be preferable. If you want max torque at low rpm (think commercial truck) then a long stroke and a smaller bore is better. Most car engines fall in between the two extremes.

I still think many car engines have to high of a prime operating range these days. Many make peak torque at 4000+ rpm. Pretty high for street use.
Diesel engines make peak torque at 1400-2000 rpm. Easy to keep them in the prime range resulting in greater efficiency. I guess that's why a Volkswagen Jetta with the diesel (177lbft torque at 1900rpm) can get 40+ mpg.

 

[B_big dirigible]

What way do you want your displacement: Bore or stroke?

Oddly enough, much 20th century IC engine development was skewed by certain European tax laws, which taxed bore but not stroke, leading to a definite trend toward prewar European engines with tiny cylinders but long, spindly strokes.

 

[Rikter8]

What way do you want your displacement: Bore or stroke? LOL, I know that sounds sexist :wink:

I like large bore, short stroke.
Lots of cubic Inches, with Lots of Rev capability.

Thats why the short deck 427 chevy was such a killer motor. It had the displacement to pull stumps if it wanted to, but the short stroke crank and rods that let it rev out to 5800 rpm (You can take them to 6200 but based on the camshaft installed, you'll probably stop making power at 6K)

I like hearing them rev out, with a holley 750cfm Double Pumper Mechanical secondary carb on top, and when those secondaries open....MMMMM time to cream thy shorts!
Ok..I must go. Need for speed.