I call B.S. on Stihl. My dyno doesn't lie. MS 461 is king over MS 660

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I ran two ported Smittybuilt 660s at the Upstate NY GTG (one was also over bore). They were throwing chips 25' and going through Black Locust like it was cotton candy.

And those guys are Western Tier NY, they could drop right down into PA!
 
Chad, Thanks for all of the wonderful information, and enjoy your break.

Next Step: My 2 Cents

The 660 obviously benefited enormously from your dual port muffler mod, with power increases across the usable range. However, peak Hp is still at a rather anemic 9,000 RPM. Based on this information, I believe an increase in timing would be the best "next step". It only makes sense to increase timing after you increase the flow of air/fuel. As I recall, we always used to advance the timing a good bit when we opened the headers on our cars (22 of us did it on the Bicentennial 4th of July, and yea, we got law enforcement awards!). The WW II Marine who lived across the street said we sounded like a Battleship coming down the road! He heard us before he could see us and could not figure out what it was.

Also, just for my information, is that 660 running a HD-2 filter?

Thanks again.
 
I'm not sure Brad, i can't seem to find that info, but I do think a timing advance would help, just makes sense to me. If you can move peak HP up and increase it, cut speed will increase. Obviously, the saw can breath much better now and should benefit from an increase in timing.
 
How much would you recommend on a stock saw with HD-2 filter and dual port (& baffle removed)? Would removing the base gasket also be a good idea? I was thinking of doing that to the 044, but it does not have C/R and I did not want to make it any harder to start when hot on hot days (the cord just pulls through my hands).
 
Not meaning to cast any dispersions or anything, but it seems that a reasonable prerequisite for this course would be Physics 101. Seriously, a common understanding of the rotarional stuff could really simplify discussions.
Stuff like torque, angle, rotational speed, work, power, force, energy. "Horsepower" is just another unit. Calculus later.
With the basics in place, we could readily digest the importance of the curves, where & how the "rubber meets the road"; and how peak readings can be totally misleading.
Thanks, Chad, for all the discovery and demystification you've done and will do. Marketeers must hate you. :rolleyes:
With your texts open, discuss.
 
How about opening the single port 660 muffler to a 1" square hole? Mine has one and it's quieter than the dual port while making same power.
 
And Timing, only makes sense to increase timing after you increase the flow.

Back in the day, we would not think of opening the headers w/o increasing the timing. I had the distributor positions memorized, I did'n bother using a light.
 

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