--- When will gas self ignite?? --- Temp?

[dremd]

DATA! YES!


I know this is against the spirit of the discussion, but why not just go Diesel? You can run lots more compression then!

[basslover911]

So why cant diesels run gasoline instead?!

I mean they can start in colder climates much better because of the lower flash point of gasoline, and they can burn and work much cooler and waste less energy in the form of heat... ??

Sure, they can just drop the compression a bit I suppose, but wouldnt gas be better for lets say colder climates and just not running so hot...?

[CobraBall]

Auto-ignition of gasoline occurs at 280C/536F. <http://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html>

The starter motor and batteries for an engine with a 100:1 compression ratio would be HUGE.

A top fuel dragster/funny car engine estimated H.P. is somewhere above 8000. The stresses on pistons, connecting rods, crankshaft, bearings, cylinder walls limit the life of the engine at wide open throttle to no more than 5-6 seconds.

IMHO a gasoline engine with 100:1 compression ratio would last somewhere between a few minutes and one hour if you could get it started.

[basslover911]

An let me get this straight, would the engine need to run hotter or cooler at 100:1 compression to ignite whatever fuel it is you are using?

[some_other_dave]

Also note that self-ignition would happen when the temperature in the chamber got high enough, which isn't necessarily when you want it to happen. Spark-ignition happens before TDC, which (absent any combustion) would be the point of highest pressure. You do that so the mixture has time to burn while the piston is still in a position in its stroke to turn that into motive power.

Frankly, I'm not sure exactly how older diesels deal with that. I know that a lot of the more modern ones inject directly into the combustion chamber, and that is how they regulate when ignition starts.

Gasoline injected into a diesel motor might burn too quickly???

-soD

[bgd73]

for a fuel that disspiates easily in air? Compression ratios are kept low, demanding a timed spark, to get the most out of it. IE a 9:1 dump truck with a gas engine has more towing ability than a 11:1 gas engine in the same truck. the fuel is way to fast to let it smack around like an inline four does with it...or inline 6.You would get the compression, and then need 35000 rpms to make up for the shear speed of loss, like a bad engine that doesn't want to run efficently...