Quench Article

[m79ded]

Hi All

Merry X-mas to all and a Happy new year coming, Please stay safe all.

I came across this video talking about quench and was intrigued by what Matt had to say. It's actually the opposite of what I have been doing and many of us Mopar guys as well.

Tight Quench has been promoted as a deterrent of detonation but here I find 2nd guessing myself. I wonder if we have been doing it wrong, I went through alot of effort to get my quench to .035

In the article he talks about putting 5 to 7 degree slope to make it a "SOFT CHAMBER"



Thanks

 

[Dajkzo]

A lot depends on the shape of the chamber and piston. The concept behind "quench" is based on forcing the intake charge back into the flame front which lowers the temp and prevents pre-ignition (ping/knock). The Gen III hemi has a tapered quench in the cylinder head, but it's not the same design as a wedge (B/RB).

The guy uses the term "detonation" when I think he is talking about pre-ignition. If/when a detonation occurs, it only happens once because it tends to be catastrophic!! It's not a fast burn, it's an explosion and the pressure spike is enormous. So I question his semantics.

 

[Ranger16]

The guy uses the term "detonation" when I think he is talking about pre-ignition. If/when a detonation occurs, it only happens once because it tends to be catastrophic!!

I think you have it backwards, Pre-ignition is catastrophic, but engines can lve with detonation for a long time.

http://www.contactmagazine.com/Issue54/EngineBasics.html
"An engine can live with detonation occurring for considerable periods of time, relatively speaking. There are no engines that will live for any period of time when pre-ignition occurs."

 

[steve340]

Good video thanks for posting.
If you are racing and have high compression ratio I would do it after seeing this.
For lower street compression ratio "might" not be a major factor.

 

[Dajkzo]

I think you have it backwards, Pre-ignition is catastrophic, but engines can lve with detonation for a long time.

http://www.contactmagazine.com/Issue54/EngineBasics.html
"An engine can live with detonation occurring for considerable periods of time, relatively speaking. There are no engines that will live for any period of time when pre-ignition occurs."

Ah, now I see why the automotive folks use the terms that way. The small (but destructive) shock wave is from outside the flame (the spark). I found some articles where pre-ignition is described as what I see in a high speed event. The shock wave is supersonic and the entire charge detonates so quickly.... well, we know what it looks like So the auto engineers call it pre-ignition when under the right conditions we get one large "bang". Other times we call something like this https://en.wikipedia.org/wiki/Texas_City_disaster a detonation.