Arboristsite's
Popup vs Flat Top?
- Thread starter Mastermind
- Start date
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Arboristsite's
super3
Addicted to ArboristSite
windthrown
361 Junkie
This thread is isn't doing anything but go down hill. At least brush ape is gone
Yah, the BA succubus swirled around the bowl fighting with the toilet paper before it went glug glug glug... and was flushed back to hell.
Mastermind
Work Saw Specialist
Same here.....bumped a 372 up to about 220.
Strong runner......but it's sorta silly to do both.
Adirondackstihl
Flyz, Fuel & Fotos
Oh.....sorry. My bad.
super3
Addicted to ArboristSite
Same saw here, my thoughts on it mirrored yours.
Farmertim
ArboristSite Operative
What is it with chainsaws anyway? Not really on any other forums, but here on AS drama is never far around the corner. Always seem to be guys jostlin for superiority - its a frickin chainsaw! I get it, some guys are passionate about it and some do it for a living, but the fake high road, moral tone, condescending, I am just a good ole boy who does it like this, you are just a cookie cutter, blah blah blah always seems to get outta hand! Plus, there are always a pack of fan boys showing up adding to it!! Just an observation of weirdness that I have observed for many years - sucks me in to, as I am usually reading this stuff when I am procrastinating more important things - must be something in the virtual air ?!?!?!!
bryanr2
Addicted to ArboristSite
I dont mind the bickering, Ive picked this side. I really could care less about the topic, bc it doesnt sway my decision on where I spend my money. Friendship means more to me than anything, and time and time again, Randy has shown that honor and friendship mean more to him than "the almighty dollar". Both Brad and Randy have all the work they want, no need to sling sh!t at eachother to get the "marketing advantage". Fans of each builder do plenty of marketing for their favorite builder behind the scenes. Ive sent dozens to Randy. Yall just need to focus on innovation and taking the porting scene to the next level, and not on eachother. There's bad blood between you two. Everyone knows it. If the builder's will work together (on a professional level- saws only), then the customer's would benefit, and everyone would be covered up with work. Look what the two monkeys (scott and randy) have come up with on the 661. The customer's are the ones benefiting from that.
Mastermind
Work Saw Specialist
Scott and I get along very well......he's smarter than I am, and I listen pretty good. 
l can't believe l read all 13 pages of this thread....…kinda like a bad movie you keep watching anyway. l like the contribution and knowledge builders put on AS regardless of their cordial flavour, skin color or sexual orrientation. l know myself if l have one of those days when l want to strangle those around me perhaps posting on a permanent public forum is not the best idea....much harder l know for those that make a living here.
I just skipped to 13 tl:dr
tree monkey
Addicted to ArboristSite
there is more to this then one way is better then the other.
you can get more compression from a cut squish, if you need or want it, if the skirt or intake allow it.
you can alter port timing better.
improves squish velocity.
this takes more time and effort.
a pop up will only give you a small increase in compression.
it's much faster to make.
you can get more compression from a cut squish, if you need or want it, if the skirt or intake allow it.
you can alter port timing better.
improves squish velocity.
this takes more time and effort.
a pop up will only give you a small increase in compression.
it's much faster to make.
windthrown
361 Junkie
CapitaineHaddoc
European Westcoaster
My english become better day after day, because i'm pretty sure I guess what the last word is
About this popup thing, I don't have enough knowledge to know what's good and what's not. I have 3 ported saws, 2 with popups, one without. All of them are great.
For cons, Randy's or Brad's topics aren't for "marketing", or maybe just a little. For me, it is more to share their knowledges, and that's the reason I like this website. It is normal that each of them wants to do the best saws, but I hope it will stay healthy competition. I also think that it is through this competition that Randy and Brad make such good saws.
In my case, I'm sure I'll have lots of fun working with a saw made by one or the other.
Even if mine will probably outcut both of yours
l think we need to be talking about a squish bands function and 'what' can be done to increase turbulance. The treemonkey alters this by re-shaping entrance angles of the transfers which l can see how that would benefit. l think we need to look at what modifications can be done to the squish chamber itself to increase turbulance. l can see either an altered pop up or some grinding of the top of the chamber in a pattern to promote a swirling turbulance. A multipoint flamefront would make better use of the incoming fuel charge and can be possibly achieved in a number of ways. l would love to do some testing grinding out shapes in the squish that promotes swirling of the charge. I think significant gains could be had by achieving a more complete burn directing more power to the crank, less emissions, less heat and greater fuel efficiency. I don't think the answer comes down to pop up or not but this subject interests me as there is far more to this.
drf255
BAD CAD
According to Jennings, a tight squish helps make power because the charge in the area is too thin to combust. Ignition in the squish area caused increase heat where you didn't want it and increased detonation risk. Surprisingly, he didn't mention mixture swirl as a power issue.
I've seen Brad's pop ups. They appear to be cut to match the combustion chamber quite well.
If one were to spend enough time to make the popup have the same squish at TDC along the flat and side ramps up the dome, wouldn't that effectively increase the diameter of the squish band? It should just cause an angled squish band.
With the exception of possibly increasing turbulence with a popup or interference with flame travel, I can't see how a properly cut and designed popup could be a bad thing.
If you make a turd popup, like I did when I welded my 025 piston, I could see it hurting power by affecting flow across the piston.
Also, unlike a 4 stroke combustion chamber, how does a perfectly concentric squish band cause turbulence?
I think Stihl got it right with the 028S combustion chamber. The chamber is asymmetric with a much larger squish on the exhaust side. The small dome fits just right and is tighter to the exhaust side of the chamber. All of these forces should force and swirl the mix towards the plug.
I've seen Brad's pop ups. They appear to be cut to match the combustion chamber quite well.
If one were to spend enough time to make the popup have the same squish at TDC along the flat and side ramps up the dome, wouldn't that effectively increase the diameter of the squish band? It should just cause an angled squish band.
With the exception of possibly increasing turbulence with a popup or interference with flame travel, I can't see how a properly cut and designed popup could be a bad thing.
If you make a turd popup, like I did when I welded my 025 piston, I could see it hurting power by affecting flow across the piston.
Also, unlike a 4 stroke combustion chamber, how does a perfectly concentric squish band cause turbulence?
I think Stihl got it right with the 028S combustion chamber. The chamber is asymmetric with a much larger squish on the exhaust side. The small dome fits just right and is tighter to the exhaust side of the chamber. All of these forces should force and swirl the mix towards the plug.
I was just reading about turbulence benefits in low speed 2t diesels.
Also how swirl grooves cut in to the squish band on 4 stroke car engine gives power and economy.
What behaviour do we really need from the fuel air mix in a high rpm worksaw? Wouldn't that dictate exactly whats best?
Also how swirl grooves cut in to the squish band on 4 stroke car engine gives power and economy.
What behaviour do we really need from the fuel air mix in a high rpm worksaw? Wouldn't that dictate exactly whats best?
Scott's point is totally true. If you want >200 PSI, cutting the squishband is how you do that, in most saws. I don't want that much compression, so don't need to use that tool. A popup makes more sense for my build goals. For those reasons, this whole debate makes no sense. IMHO, we're arguing something that doesn't really matter.
I'm no saw builder, I just use them and work on them.
To me, I like the idea of a squish band being cut vs a pop-up, just as the end user and someone who works on my own stuff.
I know that with a squish band cut if something goes south with my saw I am able to throw in a new piston and go to town.
With a pop-up, that's not the story. I am not able to throw a new piston in anymore.
Maybe this has been talked about in the last 13 pages. That was all tl;dr for me.
To me, I like the idea of a squish band being cut vs a pop-up, just as the end user and someone who works on my own stuff.
I know that with a squish band cut if something goes south with my saw I am able to throw in a new piston and go to town.
With a pop-up, that's not the story. I am not able to throw a new piston in anymore.
Maybe this has been talked about in the last 13 pages. That was all tl;dr for me.
