Combustion chamber slot what the....?

[min301]

Re: Combustion chamber slot what the....?

Nice.... ;D

[CTX-SLPR]

Re: Combustion chamber slot what the....?

I'm pretty sure that was The Silver Buick with the 455 heads off of his Centurion. Buick pistons have a "nipple" in the middle of them that no one has ever explained to me atleast.

Don't some pistons have "flame slots" in them?

[Eric68]

Re: Combustion chamber slot what the....?

You know, I don't think this slot idea is about making more turbulence in the chamber. For one they are talking about the "quench area". Take a look at this pic and look at the quench area, see how the aluminum is showing on the edges of where the cylinder walls are.


Now look at this pic, that has a groove through the quench area, see how you can't see anymore aluminum around the edges.


Basically it's the old line of gun powder to the explosive trick. Basically by creating that groove your giving the flame in the combustion chamber a bigger route into the quench areas, thus allowing the fuel that is trapped in there to ignite easier.

So I guess if you want to know it you should do it or not, go pull a head and see if you have any clean spots. ;)

The top pic shows an oiling problem. Hope they fixed that before the grooving.

If you want more turbulence in a chamber just tighten the quench up. When everything is cold you measure the quench but when the engine is heated up and running at RPM the quench is NOT what it measured cold. It is common to see an imprint of the quench pad on the top of the piston. I saw it at .033" (measured cold) in my SBC so how could you possibly create more turbulence with a groove than "complete evacuation" due to "near contact" ? Grooves are not a fuse, the spark plug is the fuse. There should be no significant fuel in the quench area to light off at TDC with a fuse anyway.

Kieth Black put a nice article on quench in his catalog. He explains that when quench is set cold less than .060" (the tighter without heavy contact the greater the effect) you create a significant amount of turbulence and cooling effect on hot spots. When you set quench cold greater than .120" you get normal combustion across the entire chamber and there is no quench effect. When you are in the middle, between .060 and .120", the "quench area" is susceptible to abnormal combustion (detonation) even worse than a full open chamber. Looks to me like the grooves fall into that dreaded .060 - .120" depth

PS> I once had a ring seal issue and the edges of my pistons were clean as a whistle much like the top picture.

[min301]

Re: Combustion chamber slot what the....?

Thank you.

[VWMMP]

Re: Combustion chamber slot what the....?

Someone on speedtalk did some testing. Here are the results.

http://www.revsearch.com/grooves/grooves.html

[TC]

Re: Combustion chamber slot what the....?

So there are things to be gained from the grooves. ;)

[dieselgeek]

Re: Combustion chamber slot what the....?

Apparently they don't do lots at WOT, but from the original link I get the impression it's an attempt to improve performance at part throttle, or on stationary engines, etc.

Min301, not every attempt to improve performance, is meant for race engines...

[min301]

Re: Combustion chamber slot what the....?

What? It's not??? ;D

[TheSilverBuick]

Re: Combustion chamber slot what the....?

I posted some pic's of some cylinder heads that look like that, but it was a general "This looks funny" post, and the engine had only about 200 miles on it so the rings hadn't been seated yet plus was running extra rich.