Offshoreonly.com - Detnoation Problems

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Re: Detnoation Problems

Bearings not clearanced correctly? Who line honed the block? Oil flow problems? Did you loose oil pressure? Were the rod bolts new? Sounds more like an assembly issue. Those are what I would be looking at if your pistons are intact. Detonation will most certainly be seen on the piston and spark plug for that matter. Usually the spark plug fails too.

Re: Detnoation Problems

this was a new, GM crate motor, we could not pull rod and main caps because of warranty issues, which is why I do not know what the bearings looked like, other than the peices that were EVERYWHERE....

Re: Detnoation Problems

Quote:

Originally Posted by dean51267

Factory motors can have issues too, I still can't see how detonation would take out a main or rod bearing. You just got a motor built on a Monday morning or Friday afternoon....... :( Maybe your oil pump pick up fell off? What did the inside of your filter look like? If you had a bearing going bad there should be some pieces in the filter before the motor let go.

Re: Detnoation Problems

this has some fair picks

http://images.google.com/imgres?imgu...005-33,GGLD:en

Detonation explained
http://zhome.com/ZCMnL/PICS/detonation/detonation.html

some info I found
What evidence does detonation leave? What should the piston look like?

Absence of normal carbon deposits
Hole melted at side of piston dome and progressing behind top ring land
Broken spark plug ceramic at tip of plug or very white ceramic
Holes burnt into top of combustion chamber
Impact damage to piston dome

http://www.sacskyranch.com/deton.htm

http://www.hastingsmfg.com/Service%2...detonation.htm

What is detonation / knock?

Under normal conditions, the combusting air and fuel mixture inside the combustion chamber ignites in a controlled manner. The mixture is ignited by the spark, normally in the center of the cylinder, and a flame front moves from the spark towards the outside of the cylinder in a contolled burn. Detonation occurs when air and fuel that is ahead of the flame front ignites before the flame front arrives because it becomes overheated. Under these conditions, the combustion becomes uncontrolled and sporadic and often produces a pinging noise, or a "knock" noise when the conditions become worse.

So far, detonation sounds cool... why is it bad?

Detonation is definitely not cool. Detonation causes sudden pressure changes in the cylinder, and extreme temperature spikes that can be very damaging on engine pistons, rings, rods, gaskets, bearings, and even the cylinder heads. Even the best engine components cannot withstand severe detonation for more than a few seconds at a time. More severe detonation obviously leads to more severe forms of engine damage. If there is enough heat and pressure in the combustion chamber, detonation can begin to occur before the spark plug even fires, which would normally initiate the combustion. Under these circumstances, known as "pre-ignition", the piston may be travelling up towards a wave of compressed, exploding gas. These are the worst kinds of detonation conditions, and can bend con-rods and destroy pistons.

What causes detonation?

Detonation occurs when several conditions / factors inside the combustion chamber exist at the same time. Increased compression, high temperatures, lean fuel/air mixture, advanced ignition timing, and lower octane fuels are all factors that PROMOTE detonation conditions. The good news is that, because there are so many factors in play, you can always find a way to eliminate detonation if it exists.

Re: Detnoation Problems

spark plug detonation pick

http://images.google.com/imgres?imgu...LD:en%26sa%3DN

here are some picks of bearring failures

http://www.bobistheoilguy.com/bearin...aranalysis.htm

Re: Detnoation Problems

My Nitrous screw up,lean.

When I tore down the motor it didnt show any signs of detination in the top of the rod bearing.It showed a little crank flexing on the outer edges of the mains,but this was a 425hp shot on a 358ci engine.It also didnt push out the head gasket either :drink: It only showed 50% leak down on that hole

Re: Detnoation Problems