Exhaust gas afterburner??

[bschloop]

Has anyone tried running a seperate engine on the exhaust gas from the primary powerplant? I was thinking about finding a small engine and modifying it to run off of exhaust to work the alternator and power steering. my thought is to tap into the exhaust pipe before the cat but after the O2 sensor and run this to the carb of the small engine. then run the exhaust back to the cat. if anyone knows how large or small an engine I would need that would be helpfull.

[Piwoslaw]

5 stroke engine could increase FE by 5%-20%

[jamesqf]

You've got major problems with that idea, mainly that all the oxygen in the intake air should (in a perfect world) have been converted to CO2 in the original combustion. So you pipe that to the intake of a second engine, and the fuel you feed it won't burn.

[Frank Lee]

Sorry, but this is the first thing that came to mind:

Untitled Document

[bschloop]

Originally Posted by jamesqf

You've got major problems with that idea, mainly that all the oxygen in the intake air should (in a perfect world) have been converted to CO2 in the original combustion. So you pipe that to the intake of a second engine, and the fuel you feed it won't burn.

I was thinking more along the lines of exhaust + air not solely exhaust.

And yes it does seem a little Rube Goldbergish, but it seemed it might be better than trying to run the alternator off a turbo.

[Piwoslaw]

So maybe recycle some of the exhaust back into each cylinder? That's pretty much what EGR does. Daox has been playing around with increasing EGR.
Increasing EGR flow for better mileage

[bschloop]

well, the egr thing might be a better idea, I'm gonna try running an engine off the tailpipe emissions anyway, just out of curiosity. We'll just have to see what happens with that

[bschloop]

just tested my tailpipe emissions with a gas meter, and it turns out theres not even enough fuel in there to register. I also found out that at idle when warm my engine also puts out so little CO that it won't register. I used a Fire Dept. meter, that was just calibrated, so I know it's accurate. One more crazy idea debunked.

[comptiger5000]

Yep. Most modern cats clean up the exhaust really well once they get up to temp.

[jamesqf]

My favorite example of this is the (post WWII) turbo-compounded aircraft engine: Turbo-compound engine - Wikipedia, the free encyclopedia - an idea that died as soon as the engineers realized that the turbine would produce more power if they just eliminated the piston engine from the design :-)