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cuttinties

cuttinties

ArboristSite Guru
Joined
Jan 19, 2015
Messages
777
Location
Midwest
I used a lot of pop ups when I first started.

I wonder if it caused this detonation issue? It seems that the edge of the popup could possibly divide the flame front and leave unburnt gases at the outer edge that could cause detonation.

Laminar flow works with or against. With no strato ports separation of burnt and unburnt is less, so detonation is a possibility with a pop up. Get a little pooling on the flat side of the piston and bang.


All speculation of course. I'm just butt hurt you're hoarding 262s.
 
Mastermind

Mastermind

Work Saw Specialist
Joined
Nov 21, 2009
Messages
36,449
Location
Tennessee
Laminar flow works with or against. With no strato ports separation of burnt and unburnt is less, so detonation is a possibility with a pop up. Get a little pooling on the flat side of the piston and bang.


All speculation of course. I'm just butt hurt you're hoarding 262s.

Pics of the butt hurt? :picture:
 
cuttinties

cuttinties

ArboristSite Guru
Joined
Jan 19, 2015
Messages
777
Location
Midwest
Pics of the butt hurt? [emoji14]icture:
e10e5ce2b406ad05ab410a2488a0a3a5.jpg
 
SawTroll

SawTroll

Information Collector
Joined
Jan 13, 2005
Messages
64,856
Location
Troms, North Norway
It does disrupt the flow. Was this your saw?

Pop-ups seems like a last ditch attemt to improve compression - but does anyone really know that max compression on the top really improves power? I'd think that case compression, transfers, carb capasity and mufflers are more important - but then I am not an "expert".....:)
 
cuttinties

cuttinties

ArboristSite Guru
Joined
Jan 19, 2015
Messages
777
Location
Midwest
Pop-ups seems like a last ditch attemt to improve compression - but does anyone really know that max compression on the top really improves power? I'd think that case compression, transfers, carb capasity and mufflers are more important - but then I am not an "expert".....:)
Well I'll further confuse you. I've got a saw I purposely built with 150lbs of compression. Just happens to be a 268. But I'll confuse you a little bit more. I cut the squish band flat and set my clearance at .020. Any guess as to why I did this?
 
SawTroll

SawTroll

Information Collector
Joined
Jan 13, 2005
Messages
64,856
Location
Troms, North Norway
Well I'll further confuse you. I've got a saw I purposely built with 150lbs of compression. Just happens to be a 268. But I'll confuse you a little bit more. I cut the squish band flat and set my clearance at .020. Any guess as to why I did this?

Surely - but getting a decent top end compression isn't the same as hunting for an extreme one.
 
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