what is quench?

[Bandit72]

i hear you guys talking about quench and benefits of certain numbers...can someone please explain to me what this means.

thanks Ryan Olson

[chargerbr549]

A quench area is generally produced when you run a flat top type piston and you make it flush with the deck or called zero deck generally done by milling the block with a piston what is very close to the deck surface already and running a closed combustion chamber head, then running a .040" thick head gasket will achieve optimum quench, if it starts getting past .065" clearance between the piston and head surface they say that you lose that quench effect. It gives you a more efficent combustion chamber that is more resistant to detonation and more power.

[defiance]

My understanding is that quench creates turbulence, which somehow translates into a more powerful, less detonation-prone combustion.  Open chambered, no-quench combustion, however, somehow burns cleaner, so when emissions standards really started hitting hard, that's one of the first things that changed.

[Chryco Psycho]

when the piston gets that close to the head you will get turbulence as the air if forced towards the spark plug generally as the flame front ids coming the other way into the turbulence

[SeattleCharger]

 So, when you have maximum quench, your engine is burning the most gas, more gas is going in, thus you are quenching your engine's thirst for gas, and you get more power, and the milieage goes down to maybe 4 mpg.        JK, 

[Plumcrazy]

My understanding is that quench creates turbulence, which somehow translates into a more powerful, less detonation-prone combustion.  Open chambered, no-quench combustion, however, somehow burns cleaner, so when emissions standards really started hitting hard, that's one of the first things that changed.

It's the other way around.  The turbulance created by quench style heads promotes complete combustion.  Just about all emission era heads are quench type

[DC_1]

    And all this time I thought it was a Montreal stripper!

[Scatpack]

My understanding is that quench creates turbulence, which somehow translates into a more powerful, less detonation-prone combustion.  Open chambered, no-quench combustion, however, somehow burns cleaner, so when emissions standards really started hitting hard, that's one of the first things that changed.

It's the other way around.  The turbulance created by quench style heads promotes complete combustion.  Just about all emission era heads are quench type

If that is true then why do close chamber heads have better quench than open?Like 915's Vrs 906's?

[mally69]

ok so you guys are saying  that if i have 11.1 cr with open chambers and 11.1cr  with a closed chamber      the closed chambers will make more power 

[firefighter3931]

If that is true then why do close chamber heads have better quench than open?Like 915's Vrs 906's?

This can be a long and complicated discussion so i'll give the cliff note version. The open chamber heads have a .100 quench distance opposite the valves. The 915's are flat in that area, hence "closed". So, with a factory open chamber head, you have  .100 between the deck and the open part of the chamber...and that's not even accounting for the head gasket. With a closed chamber head and zero deck you have no clearance and the compressed head gasket creates the "quench zone". The felpro composite gaskets are .040 thick and are popular for this type of application.



As mentioned above, the idea is to push the air/fuel mix up towards the chamber to increase power by creating better combustion. Keeping the quench distance tight (.040-.060) accomplishes exactly that. With a loose quench build, fuel can ignite over the top of the piston....in the quench area opposite the chamber. This will reduce the potential power as opposed to having all the fuel burn in the chamber. The added bonus of quench type builds is that the chances of detonation are greatly reduced.



Ron

[SeattleCharger]

Firefighter, why is a reduced chance of combustion an added bonus of a quench type build?   
   I am new at this trying to understand this,  just getting confused a little.   Don't you want an increased chance of combustion?  Was that a typo?   When you say a quench type build, you mean a build that has lower quench area between top of piston at top of stroke and the head?   

[firefighter3931]

Firefighter, why is a reduced chance of combustion an added bonus of a quench type build?   
   

That is not the case : better combustion results from tight quench. The smaller distance squishes the mix towards the chamber.


Ron

[firefighter3931]

 Don't you want an increased chance of combustion?  Was that a typo?   When you say a quench type build, you mean a build that has lower quench area between top of piston at top of stroke and the head?   

Yes the better the combustion....the more power it will make. No that was not a typo...i said that detonation is reduced with a tight quench build...not combustion....go back and re-read what i wrote. 

On the quench question....yep, the closer the chamber is to the piston....the tighter the quench. 


Ron

[SeattleCharger]

 oh ya, oops, meant to say detonation, not combustion.  You are saying a quench build reduces chance of detonation?

I guess I am confused on what is detonation, applying to combustion.    the higher the detonation the more fuel is ignited? thus higher combustion? 
thanks firefighter,  sorry I questioned your typing   

[firefighter3931]

  I guess I am confused on what is detonation, applying to combustion.    the higher the detonation the more fuel is ignited? thus higher combustion? 

Detonation is commonly referred to as "pinging" or engine rattle. That is something you want to avoid because it will destroy your motor in no time....wasted bearings, fragged pistons, broken rings....

You don't want the fuel to self ignite....it needs to burn at the "right" time....too early is no good. Engine damage is the result.


Hey, no problem asking for clarification. It's all good and we're all here to help each other. 



Ron

[Chryco Psycho]

detonation is preburn due to heat like a diesel , it will ignite too soon & try to stop the piston from reaching TDC instead of burning when it will make the most power pushing the piston down th ehole AFTER TDC

[SeattleCharger]

You know how 10 to 1 compression and higher can cause pinging/dieseling with pump gas?   will a tight quench offset this?  a low quench 9 to one could actually knock more than a 10 to 1 quench built motor?   In other words,  with the piston going to the deck height with a .40 gasket, (optimum quench), can you get away with higher compression using  pump gas? 
thanks, Nate

[mally69]

my question is if you have lets say 11.1 with closed and 11.1 compression open chambers    how much hp would be lost  alot or just a small portion

[mally69]

 

[Chryco Psycho]

You know how 10 to 1 compression and higher can cause pinging/dieseling with pump gas?   will a tight quench offset this?  a low quench 9 to one could actually knock more than a 10 to 1 quench built motor?   In other words,  with the piston going to the deck height with a .40 gasket, (optimum quench), can you get away with higher compression using  pump gas? 
thanks, Nate

yes , you can get away with a bit more compression using the same fuel & the quench will stop the detonation