Compression at which gasoline will ignite

[cody_e]

I know deisel engines use compression to ingite the fuel, I am wondering how much compression would it take to do the same with nomral gasoline?

[mazdatech177]

its the heat that ignites the fuel, compressing the air fule mixture heats it up rapidly and sometimes ignites it too early. there are so many variables to consider when talking about pre-ignition of fuel. so you could probably just look up the flash point of gasoline and get a good idea of how hot it has to be to ignite in the chamber.

Google is a wonderful thing...

[cody_e]

Originally Posted by mazdatech177

its the heat that ignites the fuel, compressing the air fule mixture heats it up rapidly and sometimes ignites it too early. there are so many variables to consider when talking about pre-ignition of fuel. so you could probably just look up the flash point of gasoline and get a good idea of how hot it has to be to ignite in the chamber.

Google is a wonderful thing...

Well as mentioned in this post: http://www.automotiveforums.com/vbul...d.php?t=512043

I want to vaporize the fuel before it hits the intake minfold. Now talking to my auto teacher, he says that especially in the summer you may have it ignite way before you want it to because the gas molecules can only expand so far before they ignite.

[beef_bourito]

the reason that it's worse in the summer is because the summer air is hotter. an increase in pressure will change the temperature, when you compress something it gets hotter. vaporizing the fuel will give you a more consistent, quicker, and better burn but probably won't do anything for knocking.

[cody_e]

Originally Posted by beef_bourito

the reason that it's worse in the summer is because the summer air is hotter. an increase in pressure will change the temperature, when you compress something it gets hotter. vaporizing the fuel will give you a more consistent, quicker, and better burn but probably won't do anything for knocking.

What do you mean for the knocking? This is essentially the same concept as natural gas except there's an added step. Yeah I know the summer air is hotter but I'm actually wondering how much of a difference it would make.

[beef_bourito]

it makes a big difference if you're running on the edge of knocking when it's cold outside. knocking is when the fuel burns before it is supposed to, it sounds like a knock in your engine, it's bad, kinda like taking a sledge hammer the the top of your engine.

Vaporizing the fuel helps fuel economy because it burns more completely, this gives you more power with the fuel you have so you don't need as much to do the same ammount of work. injectors already do this to a point, they have a high pressure pump pushing the fuel through a small nozzle, this makes the fuel into a mist. other things help like ethanol, it helps the fuel vaporize, and apparently acetone (paint thinner).

As for your original question, look on howstuffworks.com for how diesels work, this will give you an idea of the differences between a gasoline engine and a diesel engine. trying to apply a principle from a diesel to a gasoline is usually impossible without completely redesining the engine.

[curtis73]

It has nothing to do with compression. Its heat in minus heat out. Compression adds heat, but to say what compression is the starting point doesn't take into account the millions of other variables involved.

[cody_e]

I'll check that stuff out and mess around and try to build a pre-vaporization unit.

[LeSabre97mint]

Originally Posted by cody_e

I'll check that stuff out and mess around and try to build a pre-vaporization unit.

Cody

An after market for the Ford Model T was a vaporizer carb.

Here is a web site that you might be able to find some info about it: http://www.mtfca.com/



FYI

Dan

[jveik]

yeah compression prolly aint the only factor. My carbed 350 used to diesel a lot when i would shut it off until i fixed the timing. I know that engine couldnt have had more than 8:1 compression, its an emissions-era 350 for God's sake lol

[abaird]

Originally Posted by jveik

yeah compression prolly aint the only factor. My carbed 350 used to diesel a lot when i would shut it off until i fixed the timing. I know that engine couldnt have had more than 8:1 compression, its an emissions-era 350 for God's sake lol

When a gasoline engine diesels it isn't caused by compression it is caused by a hot spot in the cylinder(carbon deposit). If your idle is too high or maybe if timing is bad when you turn off the key the engine still turns drawing in fuel because carbs do that, and the hot spot in the cylinder ignites it.

FYI A diesel only compresses air(direct injection) When the piston moves up on the compression stroke, there is only air in the cylinder. Just before top dead center, fuel is injected into the compressed air and ignites.

As for this fuel vaporization, Cody, is your vehicle fuel injected?

[abaird]

Originally Posted by LeSabre97mint

Cody

An after market for the Ford Model T was a vaporizer carb.

Here is a web site that you might be able to find some info about it: http://www.mtfca.com/



FYI

Dan

Well if you think about it, when fuel air mix comes out of a carb it is just that, fuel air mix, the fuel is still very much a liquid and it is just sloshed around with some air as it heads down the intake runners to the cylinder. This is why the insides of cylinder heads(ports) are often rough to create a turbulance to mix this mixture better. So on a model T, I guess that anything that will mix this a little better would be a considerable upgrade.

If Cody could do something to increase this turbulance as the fuel air travels toward the cylinder maybe it would help, but REMEMBER not too many people can out engineer the factory not even the aftermarket.

[cody_e]

Originally Posted by abaird

As for this fuel vaporization, Cody, is your vehicle fuel injected?

Yes it is but I'll porbably experiement on a cheap, disposable engine. I made a thread there: http://www.devhardware.com/forums/sh...878#post501878 here about it and one at AF here: http://www.automotiveforums.com/vbul...d.php?t=512043

BTW, I'm not out engineering anybody. This technology has been around for a century, it's just been covered up by the oil industry.

[abaird]

http://www.get113to138mpg.com/FivsGenIV.htm
This has to be the cheesiest website I have ever seen. I hope no one has sent him any money. Don't get me wrong, I'm all for better gas mileage but this is a crock of shit. All car manufacturers have to comply with CAFE. Corporate Average Fuel Economy. So if there is some great way to get one hundred miles to the gallon, they would have done it. You don't see the government or oil companies stealing any hybrid cars.

[curtis73]

Good gosh. I wasn't going to say anything until now. There is no oil company conspiracy. The Pogue carburetor and its vaporization carb cousins are hoaxes. Just because it has a patent and someone said they drove a car 200 miles on one gallon of gas doesn't mean anything other than an ill-concieved publicity stunt to draw attention to a business.

The patent office was used as advertisement for years... still is. I can patent a new hair growth formula, but that doesn't mean it works.

Do a search for "pogue myth" and you'll turn up all you need. It has even been discussed at length here, but had you done a search you would have known that. Its a myth. The reason no one uses it is because it doesn't work, not because the oil companies squelched it.

Please do some more research before continuing talking about vaporization carbs. It will save us a very long argument.

http://www.mikebrownsolutions.com/fish3.htm
http://www.newmediaexplorer.org/sepp...in_england.htm

As you read up, you'll even see that there are huge discrepancies in the facts. Some reports place Pogue in a retirement home in his hometown of Winnipeg, Canada, where he had created the carb in 1935, while others place him in England creating the carb in 1890 before the carburetor itself was even invented. Some reports come from people who have visited Pogue in his retirement home last year, while others report that he died in 1975.