Fuel Economy - manual transmission

[Woodie]

That's great in theory,

Not theory, it was theory when BMW came up with it 30 years ago, but it's well proven now. That's why EVERYONE uses it for improved mileage.

but in real life, the air/fuel mix is constantly changing because you let in more air before the fuel gets there and vice versa.

It is constantly changing, but within milliseconds and within a small range, it stays pretty close to 14/1, that's the whole point of computer controlled fuel injection.

The difference in pulse width of the FI between "light" on the throttle and "heavy" is orders of magnitude, not the maybe 2x in RPM between a low gear and a high one.

And the difference in airflow is also orders of magnitude different.

[~tc~]

Airflow doesn't matter - this discussion is only about the amount of fuel used.

...and engines are more tuned to maximize the efficiency of the catalytic converter than for stoichiometric efficiency. Almost all manufacturers run a bit rich in closed loop, and considerably rich in open loop. Purchase and install a wideband O2 sensor, and you will see for yourself.

[SamirD]

Of course they're using the only gas allowed, and no way does E10 make a difference worth mentioning in a modern car. Older cars sometimes have a substantial drop in mileage, but if you can show repeatable results of more than 1 mpg change, I'd be completely flabbergasted. Ethanol has 30% less energy, the 10% mix has 3% less energy, 3% is less than 1 mpg. There are also some actual improvements in efficiency available from ethanol which most modern cars take advantage of, offsetting a smidgen of that.

I'm no fan of E10, I think it's government meddling and trying to wave a majik wand to make a problem go away, but to claim it makes a huge difference in mileage is disingenuous. They do owe me for a new weedwacker and leaf blower, E10 killed them dead, along with 100's of millions of others.

Most of my cars are older, so I see a pretty significant difference with using an ethanol blend. But I remember seeing in the Kizashi manual where ethanol blends were fine, so I guess I won't have to worry as much.

How did the ethanol kill your power tools? I know the rubber lines can deteriorate quicker, but was it that bad for them?

[SamirD]

Let me add that this was on 10% ethanol fuel.
Regardless of accuracy from my small sample, a few things are clear from my observations and that of others with 6 speed manuals:

- The 6 speed Kizashi can easily go over 30 MPG on the highway even with the 18 inch wheels.
- The EPA figures underestimate the Kizashi's hwy MPG (they rate it at 29 MPG for models with 18 inch wheels).
- The observed MPGs from owners here show that CVT fuel economy and manual transmission fuel economy are more similar than what the EPA figures show.

I think this is rather important to note because the auto industry is trumpeting CVTs as the most efficient transmission for internal combustion engines. While they are known to be more efficient than tradition autos, the evidence that they are better than manuals is not very convincing. I consistently see EPA figures that show CVTs getting better fuel economy than their manual versions, but owner data shows otherwise in various makes and models.
My point here is that manuals have yet to be trumped by CVTs in terms of real world efficiency. Traditionally, it was known that manuals offered better fuel economy than geared automatics. This was verified both statistically and empirically. Now, CVTs have higher numbers on paper, but many owners are observing efficiency nearly equivalent to manuals.

It's good to see some real world data that backs up what didn't exactly make sense about EPA numbers. Even with the same gear ratios (or the infinitely adjustable nature of cvts), an automatic can never be as efficient as a manual where the driver makes the decision of the best gear ratio for fuel economy.

[SamirD]

In 13 months after 28 tanks I am averaging 21.3 MPG, with a overall average speed of 21.5 mph. So I am not sure whether to blame the car or the slow city driving around here.

Even though I have the CVT, I'd say it's definitely the city driving. You can only get so much efficiency <45mph. In my experience, it's after that speed that you get any really good mileage.

[SamirD]

Airflow doesn't matter - this discussion is only about the amount of fuel used.

...and engines are more tuned to maximize the efficiency of the catalytic converter than for stoichiometric efficiency. Almost all manufacturers run a bit rich in closed loop, and considerably rich in open loop. Purchase and install a wideband O2 sensor, and you will see for yourself.

But since air is a component of the mixture, you can't completely disregard it.

Yes, the efficiency is dependent on the programmed ratios, but you still get gains from freeing up the restrictions via an intake and exhaust, so the air still has something to do with it.

[Woodie]

How did the ethanol kill your power tools?

Things that sit over the winter seem to have problems, the water in the ethanol turns to gum inside the carburetor. Don't know if it's the combination of ethanol and 2 stroke oil, or if the tiny ones just have tinier passages to gum up, I've never had a problem with my lawn mower.

My nephew works in a small engine shop and when I asked him about it he just giggled. Since 2010 carburetor rebuilds on small engines like that have skyrocketed, they rarely survive three winters. So, rather than spend $80 every three years for a new one, or $50 to get the carb rebuilt and still have a half worn out tool, I decided to go rechargeable. Probably going to find out that the batteries last three seasons and I'm in the same boat.

Once again, your Federal government F's up something which had worked fine for years.

[~tc~]

How did the ethanol kill your power tools?

Things that sit over the winter seem to have problems, the water in the ethanol turns to gum inside the carburetor. Don't know if it's the combination of ethanol and 2 stroke oil, or if the tiny ones just have tinier passages to gum up, I've never had a problem with my lawn mower.

My nephew works in a small engine shop and when I asked him about it he just giggled. Since 2010 carburetor rebuilds on small engines like that have skyrocketed, they rarely survive three winters. So, rather than spend $80 every three years for a new one, or $50 to get the carb rebuilt and still have a half worn out tool, I decided to go rechargeable. Probably going to find out that the batteries last three seasons and I'm in the same boat.

Once again, your Federal government F's up something which had worked fine for years.

Sta-bil

[SamirD]

How did the ethanol kill your power tools?

Things that sit over the winter seem to have problems, the water in the ethanol turns to gum inside the carburetor. Don't know if it's the combination of ethanol and 2 stroke oil, or if the tiny ones just have tinier passages to gum up, I've never had a problem with my lawn mower.

My nephew works in a small engine shop and when I asked him about it he just giggled. Since 2010 carburetor rebuilds on small engines like that have skyrocketed, they rarely survive three winters. So, rather than spend $80 every three years for a new one, or $50 to get the carb rebuilt and still have a half worn out tool, I decided to go rechargeable. Probably going to find out that the batteries last three seasons and I'm in the same boat.

Once again, your Federal government F's up something which had worked fine for years.

I knew about the water in Ethanol being an issue during storage, but didn't know about the gelling. Makes me worried about some of my cars that haven't been started in a while.

[~tc~]

How did the ethanol kill your power tools?

Things that sit over the winter seem to have problems, the water in the ethanol turns to gum inside the carburetor. Don't know if it's the combination of ethanol and 2 stroke oil, or if the tiny ones just have tinier passages to gum up, I've never had a problem with my lawn mower.

My nephew works in a small engine shop and when I asked him about it he just giggled. Since 2010 carburetor rebuilds on small engines like that have skyrocketed, they rarely survive three winters. So, rather than spend $80 every three years for a new one, or $50 to get the carb rebuilt and still have a half worn out tool, I decided to go rechargeable. Probably going to find out that the batteries last three seasons and I'm in the same boat.

Once again, your Federal government F's up something which had worked fine for years.

I knew about the water in Ethanol being an issue during storage, but didn't know about the gelling. Makes me worried about some of my cars that haven't been started in a while.

Sta-bil - seriously, you don't know about this?


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