Compression Question

I've been reading the posts about ignition systems helping to burn all the fuel, and someone recently asked about my maro's compression ratio. When I told him it was 11:1 or thereabouts he said that compression ratios that high almost don't need spark plugs to ignite the fuel due to the heat generated by the compression of the gases...his farm tractor is at 15:1 but it's running diesel, therefor the ignition system shouldn't really make a difference.

Makes some sense to me, but what do you guys think? I've got an MSD 6A ignition system with an accell distributor with that "fucking thing" on it, my shitty mileage is just because the way the engine is built, not because of fuel not burning completely, right?

ummm sounds good, the guy has a good point i have never thought of that..... i bet my 2.8's compression ratio ist too high cause everyting i do with the ignition system makes a huge difference. but isnt it not all about igniting all the gas ist it about consistency of the spark and the timing?

Don't know, I'm just a stupid CPA. That's why I asked.

Diesel engines and gas engines are 2 totaly different things. Diesel isnt vert combustable and its combustion is caused by compression. Gas is very combustable(the fumes moreless) and its energy is created by spark(ignition). He might have a point but in order to get complete combustion in each chamber you need a strong ignition. Timing and complete combustion are 2 very important keys to good gas mileage. Look at it this way... if your not burning all of the fuel as complete as possible in your chambers and it is blowing out your exhaust then you might as well have a small leak in your gas tank since your just spitting the gas right out.

the high compression used in diesle engines is a byproduct of the fuels combustion behavior. With a gasoline engine high compression will lead to the combustion of the air fuel mixture, we call this detonation. It is extremely damaging to an engine and is the force that blows drag racing engines to pieces. Gasoline engines need ignition systems regardless of compression, and actually operate in such a manner that the higher the compression, the more powerful ignition system is needed to light off the mixture. So whoever told you that your gasoline engine could do without an ignition system with a high enough compression has been around diesles for too long.

Thanks Iroc & Cuda. Its always nice to get a real answer after you've heard all the BS.

youre assuming my post isnt BS ;)

Would you be able to tell if some of your pistons are losing compression just by driving? Sometimes when i'm waiting at a light and the car is just idling, the pistons will be moving in harmony, but sometimes the harmony will be broking. Something like, HMMMMMMMMMMMMMdutddutHMMMMMMMMMMMM. It just bothers me. But u test the compression by buying the kit and hooking up to the spark plug, right?

youre assuming my post isnt BS ;)
WTF? Don't you start jerking my chain too! I already hear enough bs to not know the right answer when I hear it. Don't do it to me Iroc, PLEASE!!! YOU JUST CAN'T....

When I told him it was 11:1 or thereabouts he said that compression ratios that high almost don't need spark plugs to ignite the fuel due to the heat generated by the compression of the gases
In "theory" he is correct, but in theory only. In theory if the compression were high enough you wouldn't need fuel or an ignition source...just the heat of the air being compressed would cause the rapid expansion needed to rotate the engine.
The same theory has existed for decades in relation to jet engines, called a "pure ramjet", the only problem is that we don't have any metals that can withstand the heat and stresses that they would be subjected to during operation.

WTF? Don't you start jerking my chain too! I already hear enough bs to not know the right answer when I hear it. Don't do it to me Iroc, PLEASE!!! YOU JUST CAN'T....

Somebody needs some help and not from Iroc since he'll just mess with him.

hey morley, we have those jet engines, they are called scramjets ;)

and its a mod's perogitive to screw with members, im sure its in the job description somewhere.......

oh and link, i think your compression is fine, sounds like an intermittant misfire to me. check your plug boot connections, inspect your plug wires for damage, and check your distributor cap for carbon tracking.