Ultra effecient combustion cars, under 1.5 litre, thoughts, pics, comments, designs, concepts Options

[pete-stevers]

Given todays economic climate, possible scaricity of fuel, and of course just the raw challenge of building a car with high mpg,
we should have a thread on cars of this nature, in production,prototypes,homebuilts, concepts and pictures.
( I wish i had the time and energy to build a car with a sub 1 litre engine, and maybe one day i will)

but lets keep it to combustion power, for now

[Dave_Darling]

Lean burn is no longer in favor because it produces more NOx than current standards allow.

Diesels are vastly popular in most of Europe in large part due to the fuel taxes; diesel fuel is taxed much less heavily than gasoline. In the UK, where the two are taxed a closer amount, gasoline cars are still more popular.

Small lightweight low-powered aerodynamic cars are the most efficient, in general. Ever been in a Geo Metro? Think about using one every day on your commute. And think about the late-chugging makeup-applying screaming-at-children soccer mom in her Expedition. (Or, conversely, the breakfast-eating still-shaving newspaper-reading man in his F150 King Kong Cab pickup.)

I really like my CRX, and it gets by far the most use out of any of the cars we have in my household. But it's definitely not for everyone...

Google "ford probe iv" to see a very aero-slick concept car that got good fuel economy. Wander over to http://www.aerocivic.com for a look at a serious home-brew aerodynamic Civic which is ugly as hell but quite functional. It would be interesting to see what could be done in that vein by someone who wasn't trying to do it as cheap as humanly possible... If we could lose the currently-standard ideas of what makes a car good-looking, we could have cars that got significantly better freeway mileage. But I still couldn't drive the Aero Civic on a daily basis.

Sandy's Sprite (pictured above) should be a hoot to drive, and get at least half-decent mileage. The aero won't be great, but a nice modern modestly-powered engine and light weight should help it get decent numbers.

...Oh, gearing! Can't forget gearing! For cruising steady-state you want the absolute tallest possible gearing you can get. (You can go too far with it, but you are unlikely to with any reasonably-available OEM gears.) One reason the current Vettes get 30 MPG on the freeway is because they can cruise at 60 MPH at something like 1500 RPM. If you had a smaller engine with the same gearing, you would have to use more throttle to maintain that but you'd get even better economy.

More research you can do: Google "throttle pumping loss" and "BFSC map" to get an idea of how efficient different throttle openings are. (Hint: About 75% open is generally better than almost closed.) For tons and tons of ideas, see http://www.ecomodder.com and look for the "master list of modifications" that save gas. Most of them are things we wouldn't choose to do for various reasons (aesthetics, convenience, etc.) but some of them are quite easy and not that obvious.

--DD

[EdwardBlume]

Lean burn is no longer in favor because it produces more NOx than current standards allow.

Diesels are vastly popular in most of Europe in large part due to the fuel taxes; diesel fuel is taxed much less heavily than gasoline. In the UK, where the two are taxed a closer amount, gasoline cars are still more popular.

Small lightweight low-powered aerodynamic cars are the most efficient, in general. Ever been in a Geo Metro? Think about using one every day on your commute. And think about the late-chugging makeup-applying screaming-at-children soccer mom in her Expedition. (Or, conversely, the breakfast-eating still-shaving newspaper-reading man in his F150 King Kong Cab pickup.)

I really like my CRX, and it gets by far the most use out of any of the cars we have in my household. But it's definitely not for everyone...

Google "ford probe iv" to see a very aero-slick concept car that got good fuel economy. Wander over to http://www.aerocivic.com for a look at a serious home-brew aerodynamic Civic which is ugly as hell but quite functional. It would be interesting to see what could be done in that vein by someone who wasn't trying to do it as cheap as humanly possible... If we could lose the currently-standard ideas of what makes a car good-looking, we could have cars that got significantly better freeway mileage. But I still couldn't drive the Aero Civic on a daily basis.

Sandy's Sprite (pictured above) should be a hoot to drive, and get at least half-decent mileage. The aero won't be great, but a nice modern modestly-powered engine and light weight should help it get decent numbers.

...Oh, gearing! Can't forget gearing! For cruising steady-state you want the absolute tallest possible gearing you can get. (You can go too far with it, but you are unlikely to with any reasonably-available OEM gears.) One reason the current Vettes get 30 MPG on the freeway is because they can cruise at 60 MPH at something like 1500 RPM. If you had a smaller engine with the same gearing, you would have to use more throttle to maintain that but you'd get even better economy.

More research you can do: Google "throttle pumping loss" and "BFSC map" to get an idea of how efficient different throttle openings are. (Hint: About 75% open is generally better than almost closed.) For tons and tons of ideas, see http://www.ecomodder.com and look for the "master list of modifications" that save gas. Most of them are things we wouldn't choose to do for various reasons (aesthetics, convenience, etc.) but some of them are quite easy and not that obvious.

--DD

Nice thesis there Dave.... thanks.

With the open throttle, I swear I got the best mileage out of my 993 in 6th doing 90-110 for long lengths of time... ie 280 between Cupertino and SF. I'm sure the lack of drag helped too...