[Red]

I've obviously confused quite a few people, so here is a new post to post questions/answers.

Quench is a term to describe the "meeting place" where your piston comes very close to touching the cylinder head. By closing this distance to a very small margin, you can increase compression in the engine while REDUCING it's tenacity to detonate.

Since at least two people believe it's all only theory and nobody is really using it, I provide the following:
<img src="www.abqimportscene.com/phpBB2/attach/red_1011306243_cc_quench.jpg" border=0>

This is a picture of a 100% fully stock cylinder head with some color -- the head off my 98 project engine. The two areas that I have highlighted in green are FACTORY quench pads. Hyundai, just like nearly every other car manufacturer in the WORLD, uses quench to give better fuel economy, make their cars able to use lesser-quality fuel while still running high compression AND without detonating badly.

Here is a diagram of how quench works in our BETA engines -- and basically every other engine that also uses quench:
<img src="www.abqimportscene.com/phpBB2/attach/red_1011306282_diag_quench.jpg" border=0>

When the piston comes to Top Dead Center of the engine, it comes very close to the cylinder head. In stock form, that distance is aroun 0.068 inches (68-thousandths). The factory tolerances are loose like this because you want to factor in carbon buildup, heat expansion and basically just "safety".

However, if you're building up your own super-engine and aren't going to feed it cruddy gas or have it tuned badly (ie it isn't going to have huge carbon deposits) then you can bring these clearances WAY down -- 0.035" has been suggested several places.

That means there is less gap between your piston and cylinder head than there is gap in your spark plug. That very tight tolerance forces the air to violently rush out of those quench pockets, which causes turbulence, which causes the gasoline to keep itself "saturated" in the air and as such burn more evenly.

This also forces all that 'explosion' to happen over a smaller surface area on your piston, resulting in slightly more power.

Questions and comments are welcome, but this is NOT a theoretical situation -- manufacturers have been using this stuff for years.

-Red-

 

[Red]

I can't edit my damn post to fix the links, so here are the pictures (in the order I posted them)

Stock cylinder head:
<img src="http://www.abqimportscene.com/phpBB2/attach/red_1011306243_cc_quench.jpg" border=0>

The diagram I drew up:
<img src="http://www.abqimportscene.com/phpBB2/attach/red_1011306282_diag_quench.jpg" border=0>


<hr width=60% noshade size=1 align=left>-Red-

 

[simp]

Ok, now I think I understand the basics here, but I'm not up to speed with the detonation thing.... As I understand it from your explanation properly designed quench areas can give you a better mixture of air and fuel, so you can go to a higher compression without the risk of the air/fuel mix detonating to soon. Correct????



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Simp...

 

[UFB]

Red,

What you have described is SQUISH - I think you should read my first reply to your post about this topic, I referred to it as squish - the same design that is lost when shortening con-rods!


<hr width=60% noshade size=1 align=left>Tiburon Turbo 350KW and 700NM AKA Black Monster

 

[HRD_Tiburon]

Quench, or squish area is typically the flat area on the top of the piston that's almost level with the top of the block deck. It must have a corresponding flat area on the deck surface of the head to qualify as quench.
If you look at a combustion chamber, you will usually see these flat areas, and they will have the volume of the actual combustion chamber between them. When the piston is compressing the mixture, as the piston nears the head, the flat areas on the head and piston come together and force the mixture from those areas to "squish" into the chamber, where the spark plug and burning mixture reside, so you achieve a more complete burn.
The quench area also runs cooler than the rest of the chamber / piston. These lower temperatures are where the "quench" comes from. When properly designed, the quench areas can have a tremendous effect on the quality of combustion, and allow higher compression ratios, and due to this they are considered "artificial octane".
With most wedge chamber motors as well as 4 valve motors with limited squish/quench area optimizing the piston to head clearance at TDC can prove very rewarding. Within the limits of what is typically seen on production motors, there is about 1% gain in output for every 6 thousandths of an inch (0.15 mm) reduction in piston to head face clearance made.

 

[Rudy H]

" nearly every other car manufacturer in the WORLD, uses quench to give better fuel economy, make their cars able to use lesser-quality fuel while still running high compression AND without detonating badly."

hehe you can almost point out that no domestics use it cause well number one their fuel economy sucks, running low compression and detonate over a period of time cause of crappy engines.

I m teasing.


<hr width=60% noshade size=1 align=left>1999 Hyundai Sonata GL V6
H7 Blue Eurolite
GLS Chrome Grill
Custom Intake/Header/Exhaust
55 shot Nitrous Express

--no longer with me--
1997 Hyundai Tiburon
Was a brave soul when combating the evil forces.

 

[UFB]

Some more info for those interested -

Take two cups of coffee - stand the next to eachother and then pour milk into the first cup - the mixture inside the cup goes a little milky and not all of the milk disolves into the coffee - even after 5 minutes.

Now take the second cup of coffee, and stir it, while stirring the coffee, pour the milk into the rotating coffee and you will see it turns completely milky almost immediately!

The first cup of coffee is what happens to your air/fuel mixture when your squish is removed (by shortening con-rods and using a head spacer to lower compression ratio's)

the second cup is what happens to your air/fuel mixture when lowering of the CR is done correctly by using a low CR piston or using a mechanical bond to build onto the combustion chamber.




<hr width=60% noshade size=1 align=left>Tiburon Turbo 350KW and 700NM AKA Black Monster

 

[Red]

This thread got a little attention over the weekend, nice to see

You can call it "squish" if you like, but the actual term is quench area. HRD explained it a little more technically, but for those who understood it he is correct.

<b>THIS</b> is a well-documented method of raising compression without comprimising the integrity of the combustion process.

There are some other more extreme/advanced methods that XLR8 was referring to earlier as "soft head theory" which takes quench to the next logical step -- making nearly the entire combustion chamber into a quench area. This is done with radically formed pistons which almost meet up with the cylinder head at TDC...

I don't think I could pull of a stunt quite that large (soft head) so I'm sticking with just quench pad optimization. My proposed 0.033" modification should yield a 5% or larger power bump, according to the physics rule in HRD's post. Quite honestly, I'm not expecting any additional power from it, just the ability to use 91-octane pump gas for slightly more boost (would like to run 18-20psi on pump gas with the E6K)

-Red-

 

[JAWS 021]

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Quite honestly, I'm not expecting any additional power from it, just the ability to use 91-octane pump gas for slightly more boost (would like to run 18-20psi on pump gas with the E6K)

-Red-
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
Ohhhhhhhhhhhhhh,... is that all???<img src=/images/forums/snitz/tongue.gif width=15 height=15 border=0>
Your krazy man,...
Yes i am jealous <img src=/images/forums/snitz/finger.gif width=33 height=15 border=0>

BTW,... hows the engine??? do you have a date set???


<hr width=60% noshade size=1 align=left>$hit happens...

 

[Red]

The engine is good, I just placed the LAST order with St. Charles Automotive for the crank sprocket (runs the timing belt), the washer behind it, the "flange" between the sprocket and the pulley, the big-ass bolt that holds that pulley and sprocket onto the crank end, there oilpan bolts (I broke two<img src=/images/forums/snitz/angry.gif width=15 height=15 border=0>) and 16 valve springs, retainers, spring seats and 32 retainer locks.

ARP has all the measurements for the head bolts and main studs, so I should have them all by next week.

I'd like to have the engine and ALL the hardware at the machine shop exactly two weeks from this Friday. I think I'm 100% on-schedule for it.

-Red-

 

[xlr8]

heh, Im not trying to be a choad here. The practice of running a decently small piston-head clearance is often a big problem when you are running forged pistons. Ive heard of numerous problems from the DSM owners using forged pistons and a .035" piston clearance. The main problem is pistons slapping on the head face when the engine is cold.

Alot of the good DSM engine builders are using a .045"-.060" clearance with forged slugs (especially JEs) on street motors. Again you need the extra clearance because of the expansion effects of the alloy used.

Rod stretch also limits how small the piston-head clearance can be run. Heh, although I'll bet those Crowers of Red's wont stretch much, same cant be said for stock items.

oh yah, there seems to be a little confusion on quench and squish. They are defn NOT the same thing. 'Squish' is the effect of turbulence created by the piston moving up in its compression stroke. 'Quench' is the cooling effect provided by creating contact areas which do not 'see' combustion and are therefore inherently cooler than the rest of the head/piston. The cooler parts 'quench' the heat of the inlet charge.

The confusion lies in the fact that the so-called 'quench pads' also add squish as in most cases one goes with the other but not necessarily.


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