Squish Band

[walt]

Would someone please tell me what a Squish Band or Squish Band head is? Somehow I missed that while I was away from modeling.
Thanx

[CharlesF]

Hi

It's a band around the head with VERY close spacing between that area and the piston top at TDC. The actual combustion area is a bowl in the centre of the head

The idea is that as the piston approaches TDC the gas there (around the sides) is rapidly accelerated towards the centre, causing a great deal of turbulence and thus good fuel/air mixing.

[walt]

Thanx for the info, Charles. I'm getting the picture now and will look at some of my heads to see which might be squish band type.

Anyone know of some example engines? Probably some K&B?

[loucrane]

Walt,

Seems many modern engines have a modified 'squish band' head , which tapers from the cylinder wall a bit up toward the plug. This modifies the intention of a squish band, which is to allow ordinary compression until the piston is very near Top Dead Center, then - hence the word - 'squish' the unburnt fuel/air mixture into the smaller 'bowl' shaped combustion chamber.

A flat squish band - parallel to the piston face - squirts the fuel/air mix into the bowl with a lot of energy and swirl. Both help get it burnt in the least possible time, and help get the max of it burnt in that time.

A smaller 'band' (parallel to piston face), and some taper towards the glow plug, seems to 'soften' the hammer blow of combustion in a 'flat-squish and bowl' arrangement. That makes things nicer, less vibrating, and easier to set to do what you need done.

[walt]

Many Thanx to you also, Lou.
Walt

[david brooks]

What are the effects of a corner radius between the end of the squish band and the start of the bowl area? Sharper the better?

What are the notches I've seen cut into bowls? Some heads I've seen have three or four notches in one section, others have a smaller section across from them.