Another one of my hobbies is modifying internal combustion engines to produce interesting and dramatic results, which is actually a lot more important to me than spudding, but spudding is growing on me.
Over the years I've made a few really cool things, like a turbocharged lawnmower, a lawnmower that could reach 40mph, etc.. and now this.
Anyway, yesterday I made an interesting contraption. It's a vapor carburetor- it vaporizes gasoline and then siphons off the vapor to be combusted in the engine in near-perfect stoichiometric ratio. The engine never sees any liquid gasoline as fuel, just the air on top of the gasoline. Through my initial tests, fuel consumption was decreased by about 30%, which is likely to be furthered once I install the new piston rings and adjust the valves.
I still need to install the intake heater, which should make the gasoline vaporize even easier.
Here is my prototype mounted onto a Briggs and Stratton model WI:
[youtube][/youtube]
The forum rules state that this section is for serious discussion of other hobbies, so hopefully this falls under that category. I apologize if it does not.
Posted: Sun Mar 13, 2011 7:44 pm
by Gun Freak
Wow... that is really... pretty smart. I don't know much about that stuff but it seems awesome. 8)
Posted: Sun Mar 13, 2011 8:29 pm
by Technician1002
Heated manifolds that are heated from the exhaust for fuel vaporization is quite common. The difficulty is heated air expands so the total mass of air/fuel that can be drawn is less. Fuel vapor further displaces air again limiting peak horsepower. The more common practice is to inject the fuel as a mist and finish vaporization in a hot cylinder and due to compression. With hot cylinder walls, the dilution of the lubricant is not a problem except in starting conditions. To compensate for un vaporized fuel in starting conditions, a rich starting mixture is used until the engine warms to normal operating temperature.
The efficiency gain from using vaporized fuel is only before the engine comes up to operating temperature.
Modern DEQ regulations limit the amount of unburned hydrocarbons that can be emitted. This is proof that most all the fuel is burned in normal operation and there is not 30% unburned fuel going out to the catalytic converter.
Higher efficiency has been reached by changing the valve timing from an Otto cycle to an Atkinson cycle. this reduction of drag on the throttle valve due to a low manifold vacuum, reduces the drag of pistons pulling against a vacuum. Toyota is using this in their hybrid engines. This greatly reduces loss at low and idle speeds.
Due to the large volume of fuel vapor, an easy to obtain source for the venturi, is the venturi ring used in Propane engines as they are designed from the ground up for efficient vapor operation. The venturi ring would work best for having proper mix over all load and speeds of the engine. All you need is a low pressure regulator to provide slight negative pressure on the fuel vapor.
Info on supplies are a google search away. I do recommend the venturi ring instead of a modified carburetor jet. They work much better.
Posted: Mon Mar 14, 2011 8:20 pm
by Jimmy K
Pretty much everything that could be altered on an engine to increase performance has been dome in some way shape or form... ICE's will probably go by the wayside in consumer products relatively soon with such advancements in electric motors and batteries anyway.
And regarding the reduction of the rate of fuel consumption that I got, it is indeed during the warm up period, as the limit of the reduction of the rate of fuel consumption approaches 0 after a looong time.
Posted: Tue Mar 15, 2011 11:20 am
by jrrdw
How is the acceleration? Have you given it a test of governor control from idle to wide open?
Posted: Tue Mar 15, 2011 3:59 pm
by Jimmy K
It throttled decently, as much as the old engine could allow. Oil was getting into the cylinder so I tore the engine down and am waiting for new piston rings. The engine's performance should be a little better after the rings are broken in.
Posted: Wed Mar 16, 2011 4:03 pm
by jrrdw
Jimmy K wrote:It throttled decently, as much as the old engine could allow. Oil was getting into the cylinder so I tore the engine down and am waiting for new piston rings. The engine's performance should be a little better after the rings are broken in.
Wiggle the valves while in the up posision to check the valve guides. It's surpriseing how much oil will get through the intake guide if it's worn and nobody ever see's it because the gas keeps the valley clean...