Author Topic: Compression and exhaust port  (Read 180 times)

0 Members and 0 Guests are viewing this topic.

Offline The Ripper

  • 5 cube
  • ***
  • Posts: 110
  • Karma: 14
Compression and exhaust port
« on: September 24, 2014, 09:09:47 pm »
Bought a R16 partner and couldn't resist removing the base gasket and compression jumped from 155 to 176psi, question is this compression jump acceptable for a working saw using 87 octane ?  The gasket was .027,so how will this effect the timing and power outcome when removed?

On the exhaust port there seems to be some  casting flaw that protrudes slightly up from the floor,should this be removed flush with the floor and then slightly radius the bottom edge inward. Also the bore is 44MM so would opening up the E/P to 29MM be acceptable, don't want to push it to the edge. 

Share on Facebook Share on Twitter


Offline farmboy

  • Moderator
  • Nitro Hotsaw
  • *******
  • Posts: 1170
  • Karma: 150
  • Location: Hayesville, NC
Re: Compression and exhaust port
« Reply #1 on: September 24, 2014, 09:55:51 pm »
You need to check the squish too tight is bad news detonation, etc.  44mm I'd suggest .020 no less than .018 squish.  Rule of thumb on widening ports for work saw is bore x .65 yours is 44mm x .65=28.6 29 should be fine.  The casting on the floor of ex port is anti reversion ridge.  Porters are actually cutting them in on some saws.  I've seen that ridge in Partners, Jonsered, and Husky.  Having said that I'd leave it.  87 is OK.  Most of us run premium non-e (if available) @ 32:1 w/synthetic mix oil.
Shep

Offline mdavlee .

  • Global Moderator
  • Nitro Hotsaw
  • *******
  • Posts: 1968
  • Karma: 171
Re: Compression and exhaust port
« Reply #2 on: September 24, 2014, 10:08:29 pm »
87 has worked fine with up to 230lbs of compression.

Offline The Ripper

  • 5 cube
  • ***
  • Posts: 110
  • Karma: 14
Re: Compression and exhaust port
« Reply #3 on: September 25, 2014, 09:14:09 pm »
Double checked the squish and it comes in at .035, Which I prefer as I'm not a big fan of those super tight squishes. As for the  anti ridge,I just worked the corners when widening and didn't touch the middle. Opened the port from 23.5 to 27mm mostly on side as the other side was already  a straight shot. Hope to fire it up this week-end. Thanks for the mix ratio tip.

 

Related Topics

  Subject / Started by Replies Last post
9 Replies
1168 Views
Last post November 16, 2014, 01:13:35 pm
by Cut4fun .
56 Replies
1322 Views
Last post December 27, 2013, 02:20:57 pm
by 1manband
Compression

Started by ed McCulloch

8 Replies
2613 Views
Last post February 07, 2012, 03:07:10 pm
by Al Smith
2 Replies
167 Views
Last post March 19, 2013, 04:14:39 am
by Al Smith
20 Replies
557 Views
Last post November 09, 2013, 10:09:18 am
by Moparmyway
36 Replies
643 Views
Last post November 28, 2018, 04:34:07 am
by Al Smith
1 Replies
258 Views
Last post January 25, 2016, 11:21:00 am
by srcarr52
0 Replies
527 Views
Last post April 07, 2016, 01:41:04 pm
by Cut4fun .
4 Replies
356 Views
Last post April 18, 2018, 01:10:06 am
by 660magnum
1 Replies
64 Views
Last post January 16, 2021, 07:16:55 am
by Cut4fun .