Chainsaw Porting Theory

[tree monkey]

12;04 is it nap time?

 

[XP_Slinger]

Z-zzzzzzzzzz

 

[jmssaws]

I'm gonna try it with my ported cylinder first and see what happens.

The 288 piston cylinder I'll try with no port work.

040 from the chamber and .100 or so from the base?

 

[tree monkey]

something like .100, yes

 

[jmssaws]

I should be able to get 122-123 or 115

 

[jmssaws]

040 should make 210 or so?

 

[tree monkey]

keep in mind that you can run wider ports so less dur

 

[tree monkey]

040 should make 210 or so?

yes, you can always go more but it is hard to back up.

 

[jmssaws]

Intake maxed at 76-78?

 

[tree monkey]

epoxy for sure, I would start at 150

 

[tree monkey]

I might be way off base here, never did a full circle 660. the saws I have done needed much lower numbers

 

[jmssaws]

I might be way off base here, never did a full circle 660. the saws I have done needed much lower numbers

Well find out

 

[wigglesworth]

I might be way off base here, never did a full circle 660. the saws I have done needed much lower numbers

I've never even heard of anybody doing a full circle 66.

Could be interesting...

 

[jmssaws]

The way a 66 loves velocity it should work well. I'm gonna find out.

 

[Mastermind]

I'm excited.

 

[paragonbuilder]

I've never even heard of anybody doing a full circle 66.

Could be interesting...

Teach. Is detention over yet? Can I go home? I need some cookies and milk.


Sent from my iPhone using Tapatalk

 

[David Young]

If you have more base pressure what do you think about widening the transfers instead? Possibly creating more blowdown. Or you could keep the ex low and wide. Lower the exhaust the higher the corrected compression ratio is. Maybe you don't need as much out of the chamber?

 

[drf256]

You'll need physically lower transfers J.

Edit:missed hours of interesting posts.

 

[drf256]

So less timing for all ports, less volume through saw per rotation.

Wider ports to flow more volume with the increase in pressure.

So higher RPM power output.

Fascinating stuff.

@TreeMonkey, does your 026 have a full circle crank?

 

[drf256]

What actually determines max engine RPM in a non-limited coil engine?

Is it power vs. parasitic drag? Overall port flow?

I've heard it has a lot to do with actual engine design, now I'm wondering if that design is (at least in part) case volume to displace the ratio.