So here's another stupid question, the pinging can be heard, right? I think I've heard my truck do that periodically just after startup when I'm getting on the freeway. :steering:

 

Yep. The engine is cold and the air and fuel mixture is most likely falling out of suspension in the intake system and pooling on the floor of your manifold and cylinder walls. As the engine comes under load then this mixture can ignite.

Another reason for pinging or detonation is leaking rings as oil is not scraped off the cylinder walls as the engine ages. The oil mixture mixes with the air and remaining fuel, which lowers the octane values resulting in the engine detonating early.

Another reason as well might be carbon build up on the valves or piston tops, which results in hot spots on the top of the pistons and valves. This is much like having a loose cinder in the bottom of your gas grill when you turn it on and the mixture ignites before you get to hit the starter switch on the grill. A hot spot can cause this.

In the old days, we used to run a little water or transmission fluid down older motors which we knew had a lot of miles on them and were carboned up.

The water would convert to steam in the cylinder and would basically steam clean the piston tops and valves somewhat. Transmission fluid was used by some because of the detergent qualities it had. Its also really good for getting to know your neighbors as this results in a HUGE amount of white smoke being emitted from your exhaust system. Not something I would recommend for a modern engine or middle to upper class neighborhoods with covenents. :rofl:

"Mod your car, you'll like it."
:reddevil :reddevil :reddevil :reddevil

"I think we just hijacked this thread, Captain."
"Shields up!"


[Modified by wdo-mkr, 11:57 PM 2/19/2003]

 

Can you say "Free Radical",

Detonation is basically uncontrolled combustion, it happens when the conditions are right inside the combustion chamber. It can be caused by fuel quality, carbon, high compression, lack of proper cylinder head cooling or a combination of these things.

It has been addressed in the past by water or alcohol injection, or a higher quality fuel. Basically the water or alcohol injection is used to cool the incoming charge. As Paul stated it also scavenges the cylinders rather well.

Higher quality fuel elemenates some of the "Free Radicals" and slows the combustion flame speed because of the molecular make up of the fuel, more ring molecules.

Chevrolet visited the high cylinder head temps with the reverse flow cooling, good idea.

As far as the exhaust, some carbureated cars are going to be more affected by lowering the exhaust back pressure as this scavenges the cylinders, causing a low pressure zone which pulls incoming charge into the cylinders, it has the same type of affect on all cars, just carbed cars with the unsophisticated way that carbs meter fuel are more grossly affected.

Remember one thing, finely tuned cars are greatly affected by atmospheric variables. Here in Minnesota charge density can be hugely different. Tune your car to finely on a cool dry spring day and watch it destroy itself or lose a lot of power on a warm humid summer day.

Tony's .005 cents worth.

 

"Free Radical." Do I win something?

I think I have a headache.

 

:cool: :cool: !!! I'm assuming by this time you've already picked 'er up and put 'er to the test. Do you give the headers a :thumbs: ??

 

For the full report go here...
http://forums.corvetteforum.com/zero...427908#5427908