Instead of thinking lighter weight, you should be thinking "more aerodynamic".
Look, all wheels churn the air, and the more spokes a wheel has, and/or the less aerodynamic the spokes are shaped, the more they will resist being turned.
They act as fans literally, and everybody knows it takes horsepower to turn a fan.
Now multiply that fan by four, and you get an idea of what I'm saying here.
Getting the wheel up to speed is a small part of the total wasted fuel compared to the waste needed to sustain that speed over long periods of time.
For an example of this look at the optional wheels that come on the 50th Anniversary Edition vs this wheel pictured here.
Then also look at all the cars taken to Bonneville Salt Flats and compare those wheels.
See the similarity?
Forget the rims - any gain there would be unmeasureable. BUT - here are some things I've learned about getting mileage since I've had the TCH (about a year):
- The TCH doesn't just automatically get great mileage like magic. What it does is give you the OPPORTUNITY to get great mileage if you WANT to.
- You can't be in a hurry and get great mileage at the same time.
- You have to learn how the Hybrid Synergy Drive works, so that you can then learn how to drive the car for great mileage.
- Some specific things:
- Accelerate briskly up to the speed you want, then use just enough accelerator to maintain that speed.
- Take your foot off the pedal whenever possible-you'll be amazed how much you've just kept it on there in the past. This car is made to glide much easier.
- Maybe raise the pressure in the tires some. I hear 40 psi is good but makes for a hard ride.
- Keep under 70 mph on the hiway. 65 or less is even better.
- Remember - even when you don't do anything different at all, the mileage aint too shabby. 31 is the worst I ever got on any tank. But in Southwest Florida, I can spend a week or 2 going between Naples and Fort Myers and get 47 mpg. Most of the average time, I get 34 in SE Pennsylvania, with mixed driving types, and an incurable heavy foot.
Remove any cold air intake. If you let the engine ingest hot engine compartment air, it'll lean out the engine like a hot summer day. This saps power, but the MPG increases since you're using less fuel. Engines run richer with colder weather/air, since the air is denser.
Cold air = dense air = rich
Hot air = thin air = lean
It's an automatic adjustment in the ECU based on input from the intake air temperature sensor.
Some empirical data:
Cold air, 1GR 4.0L, 40psi front and rear: 58 deg F intake air, 16.7mpg avg
Hot air, 1GR 4.0L, 40psi front and rear: 102 deg F intake air, 20.6mpg avg
The ECU adjusts the air/fuel ratio to set factory tolerances.
Your engine does not run leaner or richer based on intake air temp, once it is up to running temperature.
Your so called empirical data is laughable because you forgot to figure in transmission and differential temperature, tire temperature, wind speed and direction...ect.
When the ECU is correcting for air/fuel ratio and the incoming air is cooler, it simply adjusts to a ratio that maintains the correct set ratio.
The benefit of a cold air intake is increased HP, because the engine can take in more air, and thus, more fuel, at the same rpm.
Given the exact same outside temp and load conditions, an engine will return slightly better fuel economy when it takes in colder air from the front side of the radiator.
AND....that's why factory engineers, with a Graduate Degree, have been designing cold air intakes for most late model automobiles and trucks.
If your silly idea held any merit at all, then all modern engines should be drawing intake air from inside a shroud, that is wrapped around the exhaust manifold. lol
When the ECU is correcting for air/fuel ratio and the incoming air is cooler, it simply adjusts to a ratio that maintains the correct set ratio.
The benefit of a cold air intake is increased HP, because the engine can take in more air, and thus, more fuel, at the same rpm.
And why is the engine using more fuel? Because the engineers know that colder air is denser, and intake temperature is figured into the fuel maps, hence why the increase in horsepower during the winter or on cold days. If the AFRs were static based on arbitrary values, we'd see serious reliability issues during temperature extremes such as those in the North during the winter and those in the Southwest deserts during the summer. The loss of power on hot summer days is directly related to the density of the air. The ECU is programmed with variable fuel maps dependent on intake air temperature (and other things, such as coolant temperature, engine load, VVT-i, etc.) because air density is based on that temperature, thus, if the intake air is hotter, the ECU will scale back the fuel because there is less air entering the cylinders at any given RPM in comparison to cold air. If the ECU did not reduce the amount of fuel, the engine would run quite rich and possibly fail emissions, in addition to wasting unnecessary fuel.
Engineers use cold air intakes to provide the best possible engine performance, not necessarily efficiency.
So, how about you remove your head from out of your *** and read up on fuel management on modern day electronic fuel injected engines?
There is such a thing as cold start enrichment.
There is also such a thing as engine enleanment during off-throttle operation.
So ... you pretty much proved my point. It doesn't take a genius to understand that in order for the engine to keep its set AFRs, more or less fuel must be used in relation to the density of the air and inputs from other sensors. Hot air is less dense, hence in order to maintain a stoich fuel mixture, less fuel is needed relative to colder air.
You guys are amazing. The poor slob just asked for some tips on getting better mileage, and you make it into an ego-busting, detail-quoting, blue-light-special shouting match that can't help any of us worth a darn.
Get your attention off yourselves and how much you think you know and take your tech arguments outside where you're not bothering the rest of us.
If you really think you are onto something, with the hot air intake producing better fuel economy, then the engineers who are working on the engine for the Prius, would probably like to hear from you.
They are not just trying to produce more HP, but better fuel management to get more out of a gallon of fuel.
It sure sounds like you've discovered the biggest secret to better fuel economy anyone has ever heard of.
If I were you, I would take your empirical data, and show it to them.
I'm sure they would be interested in learning something they have never seen before, in school, or in real world testing.
Why I'll bet they would say you were some sort of genius, for discovering such a great, and simple way, to get better fuel economy.
Everyone will forever be in your debt for sharing your empirical data with us.
lol
They are not just trying to produce more HP, but better fuel management to get more out of a gallon of fuel.
Baseless. You've not said one thing, or given one shred of evidence to counter me. The point of the Atkinson-cycle engine isn't to produce power; it is to raise the efficiency of the engine by delaying the closing of the intake valve, while also reducing the compression stroke and combining that engine with another power source.
Yes, the fuel management in a hybrid Toyota is very good. At part throttle, the engine runs lean to conserve fuel and provide just enough power to keep the car at speed. Off-throttle, the fuel injectors are shut off, and when possible, the hybrid system will also allow the engine to shut off completely.
But if you ever did comparisons between winter and summer MPG, you'd notice something interesting.
As for your "aero" post, the Camry Hybrid already carries a 0.27 coefficient of drag, which is quite good. I'd love to see you increase that with "aero wheels." lol! Like the engineers weren't in the wind tunnel testing a variety of designs.
Gee Jason, I sure am glad we all have you around to educate us about getting better fuel mileage by using hot air.
I'm sure that everyone will go out and tear their factory cold air intakes off, and reroute the incoming air from the hottest part of the engine compartment.
That way we can all get a 23.35% improvement.
Either that, or everyone should simply wait until the outside temp is above 100 degrees.
Hmm....hey wait a minute, maybe that's why your mileage is so much better in the summer, ya think?
Let's see, when the weather is above 100 degrees...the engine spends very little time getting up to temp..that would save gas...the transmission fluid would flow easier, and it would be easier to turn, so it would use less HP...and that would save gas...and the wheel bearing grease wouldn't be so stiff, so they would turn easier too...hmmm.....maybe your empirical data (lol) needs a little bit of tweaking.
Either that, or perhaps you might want to ask your mommy what the word empirical means.
On second thought, maybe you better not bother her, and go look it up yourself.
BTW Jason, we all love you here.
You have been a never ending source of amusement, and have managed to actually bring one engineer to tears of laughter.
And for that, I must thank you from the bottom of my heart.
It was good to see people with smiles on their faces after reading your posts.
Please keep up the good work, and when you discover another good way to increase gas mileage, let us know right away.
Everyone could use a good laugh now and then, even you.
Tips for getting more MPG!!
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