Author Topic: Grooving the cylinder  (Read 336 times)

0 Members and 0 Guests are viewing this topic.

Offline joe_indi

  • 5 cube
  • ***
  • Posts: 92
  • Karma: 29
  • Location: Cochin, India
Re: Grooving the cylinder
« Reply #20 on: March 22, 2015, 12:07:53 am »
Joe,
In my case, the grooves on the piston, wouldnt it be a shortcut/easier method to fill the syringe with water, top up the grooves to piston top height and read off how many ccs of water is on the piston?
Maybe kerosene instead of water?
Joe (from India)  ;D

Offline 1manband

  • Nitro Hotsaw
  • *******
  • Posts: 759
  • Karma: 52
Re: Grooving the cylinder
« Reply #21 on: March 22, 2015, 08:26:27 am »
Joe,
In my case, the grooves on the piston, wouldnt it be a shortcut/easier method to fill the syringe with water, top up the grooves to piston top height and read off how many ccs of water is on the piston?
Maybe kerosene instead of water?
Joe (from India)  ;D

very true, good point.  the difference in methods, is mainly in accuracy.  we are talking about maybe 10 to 15 very small drops of liquid = 1cc.

if the top surface of what you will need to find the volume of is flat, it's standard practice to use a glass plate with the method you describe.  "CCing heads."

suggested using clay or silly putty, because it would work for many different kinds of situations where surface is irregular or crowned etc.

liquids leave a depressed cup type of shape on the top surface.  the wider the area is that you will be measuring.... leaves a deeper depression. reason for using clay or glass below.

it all depends on what you are trying to accomplish.

-joe

hiatus

Online srcarr52

  • 6 cube
  • ****
  • Posts: 288
  • Karma: 93
  • Location: IA
Re: Grooving the cylinder
« Reply #22 on: March 23, 2015, 10:41:02 am »
It's more common to use plexiglass or lexan to CC heads since you can cut and drill it much easier than glass.

Offline joe_indi

  • 5 cube
  • ***
  • Posts: 92
  • Karma: 29
  • Location: Cochin, India
Re: Grooving the cylinder
« Reply #23 on: March 23, 2015, 02:59:36 pm »
You are trying to tell me about the inaccuracy in using a liquid because of the surface tension which would not give an accurate level, ok I understand.

Could you tell me what happens if the squish area is increased beyond limits?

Offline aclarke

  • Nitro Hotsaw
  • *******
  • Posts: 1676
  • Karma: 172
Re: Grooving the cylinder
« Reply #24 on: March 23, 2015, 05:05:28 pm »
Excessive squish velocity will transfer too much heat from the gas to the head/piston and could detonate fuel mix. Excessive velocity would also degrade any cooling effect provided from latent transfer of fuel droplets under squish area.  There are some interesting GP bike head designs that incorporate several corners or sharp edges in the combustion chamber where an eddy of trapped fuel/air droplets improve cooling.


Offline 1manband

  • Nitro Hotsaw
  • *******
  • Posts: 759
  • Karma: 52
Re: Grooving the cylinder
« Reply #25 on: March 23, 2015, 05:13:19 pm »
...the same thing that happens when squish is set to the bare minimum....just more of it.

the further away the fuel is from the plug, the longer amount of time it takes for the burn.  inefficient.

depends on fuel mix quality, purpose, and load the motor will mainly see in operation.
hiatus

Offline 1manband

  • Nitro Hotsaw
  • *******
  • Posts: 759
  • Karma: 52
Re: Grooving the cylinder
« Reply #26 on: March 23, 2015, 05:28:20 pm »
Excessive squish velocity will transfer too much heat from the gas to the head/piston and could detonate fuel mix. Excessive velocity would also degrade any cooling effect provided from latent transfer of fuel droplets under squish area.  There are some interesting GP bike head designs that incorporate several corners or sharp edges in the combustion chamber where an eddy of trapped fuel/air droplets improve cooling.

the diameter of these tiny pistons used chainsaw motors already give about 30 m/s velocity in the chamber, which is better than fine... just as they come from the factory.

hiatus

Offline aclarke

  • Nitro Hotsaw
  • *******
  • Posts: 1676
  • Karma: 172
Re: Grooving the cylinder
« Reply #27 on: March 23, 2015, 05:38:02 pm »
I agree. Lots of folks over the years have taken the squish down into the teens in an effort to increase compression without realizing the squish velocity is excesssive.

Offline 1manband

  • Nitro Hotsaw
  • *******
  • Posts: 759
  • Karma: 52
Re: Grooving the cylinder
« Reply #28 on: March 23, 2015, 06:38:36 pm »
I agree. Lots of folks over the years have taken the squish down into the teens in an effort to increase compression without realizing the squish velocity is excesssive.

...
hiatus

Offline aclarke

  • Nitro Hotsaw
  • *******
  • Posts: 1676
  • Karma: 172
Re: Grooving the cylinder
« Reply #29 on: March 23, 2015, 09:18:15 pm »
Joe,  what are your thoughts on why saw mfgs  use a flat squish in lieu of tapered squish band?

Adam

 

Related Topics

  Subject / Started by Replies Last post
3 Replies
1197 Views
Last post March 01, 2012, 08:34:40 pm
by Old Iron Logging
044 Cylinder

Started by farmboy « 1 2 3 4 » Stihl

38 Replies
892 Views
Last post June 02, 2013, 10:02:21 pm
by HolmenTree
19 Replies
445 Views
Last post September 09, 2013, 09:51:10 pm
by doreadeal
3 Replies
432 Views
Last post December 21, 2013, 02:21:40 pm
by Cut4fun .
54 Replies
1182 Views
Last post January 03, 2014, 02:14:59 pm
by Adirondackstihl
14 Replies
328 Views
Last post February 25, 2014, 12:38:59 pm
by jacob j.
1 Replies
149 Views
Last post August 22, 2014, 08:33:48 pm
by 660magnum
Echo cylinder

Started by Giles « 1 2 » Echo

11 Replies
367 Views
Last post December 04, 2014, 01:14:03 pm
by Giles
4 Replies
120 Views
Last post November 06, 2016, 10:35:55 am
by SawTroll
7 Replies
201 Views
Last post August 25, 2017, 06:40:44 am
by jmester