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Alcohol Lawn Mower

K

kevinthenerd

Platinum Member
Ok, you're probably thinking "this guy's nuts." Well, I am, so there's no need to repeat that.

I want to run my lawn mower on alcohol. My dad told me he did it once when he was younger, and I've seen online that many people have done it. Has anyone here done it? I hear that it's harder to start with the alcohol, but you start with a little bit of gas and add alcohol as the gas burns off.

How can I modify the carburator to allow the motor to start with 91% isopropyl alcohol?
 
is rubbing alcohol really that much cheaper than gas in terms of buying in gallons?
and i dont know where the hell u can buy gallons of rubbing alcohol
 
LOL...

You really want to run your mower on alcohol, huh?

Expect less power, unless you shave the head to increase compression.

And most mowers do not have replacable jets, so you will never get it exactly right without replacing the whole carb.
 
Originally posted by: Imdmn04
is rubbing alcohol really that much cheaper than gas in terms of buying in gallons?
and i dont know where the hell u can buy gallons of rubbing alcohol
Click to expand...

It's not the price. It's the performance I want. And no, I'm not going to use this motor for mowing lawns.
 
Originally posted by: kevinthenerd
Originally posted by: Imdmn04
is rubbing alcohol really that much cheaper than gas in terms of buying in gallons?
and i dont know where the hell u can buy gallons of rubbing alcohol
Click to expand...

It's not the price. It's the performance I want. And no, I'm not going to use this motor for mowing lawns.
Click to expand...
Alcohol, by itself, does NOT increase power.

Alcohol contains considerably less energy than gasoline. You have to modify the engine in other ways to get the powah.
 
i think that alchohol is more expensive, at lest when you buy it at longs. be careful or else your friends will start calling you stubby.
 
Originally posted by: Eli
Originally posted by: kevinthenerd
Originally posted by: Imdmn04
is rubbing alcohol really that much cheaper than gas in terms of buying in gallons?
and i dont know where the hell u can buy gallons of rubbing alcohol
Click to expand...

It's not the price. It's the performance I want. And no, I'm not going to use this motor for mowing lawns.
Click to expand...
Alcohol, by itself, does NOT increase power.

Alcohol contains considerably less energy than gasoline. You have to modify the engine in other ways to get the powah.
Click to expand...

No, you're right. Alcohol alone doesn't increase power. It does, however, burn with greater efficiency and at a lower temperature, allowing me to run it with other factors increased and still remain within a safe temperature range. For example, I could use forced-induction or run the mower at higher RPM's.

 
Originally posted by: kevinthenerd
Originally posted by: Eli
Originally posted by: kevinthenerd
Originally posted by: Imdmn04
is rubbing alcohol really that much cheaper than gas in terms of buying in gallons?
and i dont know where the hell u can buy gallons of rubbing alcohol
Click to expand...

It's not the price. It's the performance I want. And no, I'm not going to use this motor for mowing lawns.
Click to expand...
Alcohol, by itself, does NOT increase power.

Alcohol contains considerably less energy than gasoline. You have to modify the engine in other ways to get the powah.
Click to expand...

No, you're right. Alcohol alone doesn't increase power. It does, however, burn with greater efficiency and at a lower temperature, allowing me to run it with other factors increased and still remain within a safe temperature range. For example, I could use forced-induction or run the mower at higher RPM's.
Click to expand...
The biggest thing you can do is up the compression.

You will not be able to run the mower at higher RPMs on alcohol. The limiting factors regarding RPM(assuming the carburetor can flow well enough) are valve spring tension and connecting rod strength.

The stock valves/springs will float at about 5500RPM. Even at that realitivly modest speed, the connecting rod will end up in pieces on the outside of the engine if you run it at that speed for very long, especially under load.
 
Originally posted by: Eli
Originally posted by: kevinthenerd
Originally posted by: Eli
Originally posted by: kevinthenerd
Originally posted by: Imdmn04
is rubbing alcohol really that much cheaper than gas in terms of buying in gallons?
and i dont know where the hell u can buy gallons of rubbing alcohol
Click to expand...

It's not the price. It's the performance I want. And no, I'm not going to use this motor for mowing lawns.
Click to expand...
Alcohol, by itself, does NOT increase power.

Alcohol contains considerably less energy than gasoline. You have to modify the engine in other ways to get the powah.
Click to expand...

No, you're right. Alcohol alone doesn't increase power. It does, however, burn with greater efficiency and at a lower temperature, allowing me to run it with other factors increased and still remain within a safe temperature range. For example, I could use forced-induction or run the mower at higher RPM's.
Click to expand...
The biggest thing you can do is up the compression.

You will not be able to run the mower at higher RPMs on alcohol. The limiting factors regarding RPM(assuming the carburetor can flow well enough) are valve spring tension and connecting rod strength.

The stock valves/springs will float at about 5500RPM. Even at that realitivly modest speed, the connecting rod will end up in pieces on the outside of the engine if you run it at that speed for very long, especially under load.
Click to expand...

It's relatively easy to beef the valve springs (for someone with mechanical experience, at least), and the motor won't be under tremendous torque. I want it to run a huge fan/propeller. Had this been a 4-stroke, I'd worry about the connecting rod on the exhaust stroke.

My application is very similar to a hovercraft, only backwards.
 
Originally posted by: kevinthenerd
Originally posted by: Eli
Originally posted by: kevinthenerd
Originally posted by: Eli
Originally posted by: kevinthenerd
Originally posted by: Imdmn04
is rubbing alcohol really that much cheaper than gas in terms of buying in gallons?
and i dont know where the hell u can buy gallons of rubbing alcohol
Click to expand...

It's not the price. It's the performance I want. And no, I'm not going to use this motor for mowing lawns.
Click to expand...
Alcohol, by itself, does NOT increase power.

Alcohol contains considerably less energy than gasoline. You have to modify the engine in other ways to get the powah.
Click to expand...

No, you're right. Alcohol alone doesn't increase power. It does, however, burn with greater efficiency and at a lower temperature, allowing me to run it with other factors increased and still remain within a safe temperature range. For example, I could use forced-induction or run the mower at higher RPM's.
Click to expand...
The biggest thing you can do is up the compression.

You will not be able to run the mower at higher RPMs on alcohol. The limiting factors regarding RPM(assuming the carburetor can flow well enough) are valve spring tension and connecting rod strength.

The stock valves/springs will float at about 5500RPM. Even at that realitivly modest speed, the connecting rod will end up in pieces on the outside of the engine if you run it at that speed for very long, especially under load.
Click to expand...

It's relatively easy to beef the valve springs (for someone with mechanical experience, at least), and the motor won't be under tremendous torque. I want it to run a huge fan/propeller. Had this been a 4-stroke, I'd worry about the connecting rod on the exhaust stroke.

My application is very similar to a hovercraft, only backwards.
Click to expand...
😕

All modern lawnmower engines are 4-stroke.

How do you plan on beefing up the valve springs? Just buy an aftermarket set?
 
I'm sure you can find pure methanol or E85 fuel(85% ethanol/25% gas) rather than using rubbing alcohol. To use alcohol in a carbureted engine with a carburetor designed for gasoline, you'll have to change out the carburetor jet. If you can't find a drop in replacement jet, you will have to figure out the right diamater and machine one yourself. Running time per volume of fuel is about halved on alcohol.
 
It is rather simple to do, remove and disassemble carb, remove main jet, drill jet two to three drill #'s larger, reassemble carb.
Remove cylinder head, shave .050 of surface, reassemble with new head gasket, remove idle mixture screw, carefully grind .030 of the tip, reassemble, adjust idle mixture screw 3.5 turns out from bottom.
Prime the carb with gas, start engine, if the engine starts then immediately dies, unscrew mixture screw one additional turn.
Once warmed up at idle, accelerate the engine to full speed, if it sputters (lean condition), disassemble carb and drill jet one drill # larger, continue this process until full speed enrichment is correct.
 
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