Quote:Thanks, that's a really good point. It wouldn't take much to make a heat riser stove for the header.

Found two more pics of the car from another participant today.



This shows the plexi glass grill blocks I used.



This is a view of the underside of the car with the choroplast belly pan. The slots cut into the back of it are to allow engine cooling air to escape.

I think that someone else has made this point before. You can get a much more 'consistant' performance from the carburettor if you can control the temperature of the air that is passing through it & it's very likely that the stock air filter housing with the vacuum controled hot air/cold air flapper valve is your best friend.

It has a thermo vacuum valve inside & when the air temp is below the pre set value, the valve sends vacuum to the servo & it shuts off the cold air inlet, allowing only heated air to be drawn in. If the temp rises above that pre set value, then it opens the flapper valve & admits cold air.
I believe [but don't quote me] that it is capable of maintaining a balance of hot & cold air to maintain a constant air temperature into the carb. If this is true, then you couldn't ask for more. The carb can then be tuned for optimum efficiency & it will maintain that efficiency for as long as the engine is running once it has warmed up a little.

As that well known drag racer, Smokey Unick often said, ... "bring your variables under control" Wise words to remember.

I see a target of 100 miles [160Km] per Imperial gallon [4.54609 Litres] as being within reach.

it would be very interesting to see what happens if u do take the extra hot air from over the exhaust manifold. why i say that is i have been wondering how u got such a good result. one explanation and i could be way off, is that because u run extra lean a/f mixture, constant flow carby can compete with sequential injection because the extra lean mixture condenses close to the inlet valve while it is closed for the rest of the cycle of each rev.

The idea is not to take "hot" air, but to take air at a constant temperature. Then you jet it lean within an inch of its life and be assured it won't vary as you are driving and drop even leaner and destroy the engine. In practical terms this means hotter than outside temperature so that you regulate the temp. Cooling the air is tricky.

There is another idea about super-atomising the gasoline via preheating and superheated air. But that has proven over the decades to be difficult to do. You can cruise OK but have almost no control over the mixture when accelerating.

also seems dangerous heating the fuel right up!

Quote:
Quote:Different words but same thought. Heated air will convert liquid fuel in the form of droplets into a gas much more quickly & efficiently than cold air ever will & as we now know, liquid fuel will not burn, only the gaseous form of it.
High manifold vacuum will also help here as the fuel droplets inside the manifold will boil at a much lower temperature at low pressures but this conversion from liquid to a gaseous state also sucks a lot of heat from the surrounding air inside the manifold, so heated air going in is a compensation for this.

This temperature drop when converting to a gas is a well known refrigeration principal known as 'latent heat of evaporation' & is the same principal that your evaporative room cooler works on.

Did you win? Interesting thread. Another way to get high compression ratios to work with standard fuel is to use water injection as it stops detonation. Something to consider if you are still looking for gains.

Thanks for asking, my B210 finished fourth overall at a new record of 77.04 mpg. It was far and away better than any of the older carbureted cars competing. Although I should have run in the historic class, I knew they were no competition my B210, so I decided to compete with the "big dogs" in the unlimited gas class. I was beaten by this white '89 Honda Civic HF [with the factory lean burn system] that was heavily modified and got 118 mpg!







The full results are on page 17, post #167.

Mike