jasent
Well-known member
Higher exhaust timing is more torque and lower is more speed typically
High exhaust roof is lower timing numbers
Ported Saws... Lets see your work fellas
- Thread starter BigSachsDolmar
- Start date
High exhaust roof is lower timing numbers
Nutball
Active member
It depends on the design, and where you want your torque in the rpm range. Ideal timing numbers are not copy and paste across various engines especially when it comes to different displacements, at least when the job at hand is cutting wood with common bars, chains, sprockets.
Fabz
Active member
I’d concentrate on a getting the highest BMEP possible before I even take a file to the barrel
BigSachsDolmar
Member
Bmep.... bitchin max extra power?
Fabz
Active member
Bmep - stands for “Brake mean effective pressure”
Very nice grinding.
jasent
Well-known member
How do you measure bmep?
Fabz
Active member
BMEP Calculator - Find the measure of an engine's capacity
Calculate engine efficiency with our BMEP calculator using the BMEP formula. Accurate and easy to use for all your brakes mean effective pressure needs.
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Nutball
Active member
I just make some timed cuts, it seems to work well for me.
Fabz
Active member
That’s fine if your competition is yourself, but if ya wanna get off the porch and run like the big dogs ( or cats 
n this instance) knowing the engines bmep is critical! Ask Ol Bird legs about it - he knows everything 
n this instance) knowing the engines bmep is critical! Ask Ol Bird legs about it - he knows everything
Thanks!
Fabz
Active member
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Thanks, I'll post a video once I get it back together.
Nutball
Active member
Hard maple in the USA is no joke, that stuff is unusually hard to cut. Oak is like speedy soft wood in comparison. 23 seconds in 28" hard maple is not bad, but lets see the side by side run with the 592 to see how far off it is stock with the same chain. Dyno Joe says they do about 8.8hp stock, 5.45ft/lbs, so they are no joke stock. You never know, a muffler modded 592 might end up pretty close to that 660 if not better with the new tech stock porting they use. I have a 550 mkII that only has a muffler mod because it is already that good, not that there isn't an extra .5hp left over if it was ported, but it runs a 24" well enough for my needs.
Fabz
Active member
I’m using an off-the-roll chain on this test run ... A good square-ground will net 10-12% faster cut-cut.
The base gasket is stock so installing a thinner base gasket and tightening the squish to .023 is going to p/u some torque/hp for sure (maybe .5-.8hp). Fabricating a tuned-tube exhaust instead of the deflector style that’s on there now will also net some gains. If I used a sqr/sqr chain , .023 squish and a different tuned tube exhaust it “woodnt” be a stretch to claim 20sec thru that timber, If that was BC or PNW timber (FIR log)where the trees are made of cheese heck she’d probably go thru 1.5-2x as quickly 
. Dyno Joe rated the 660 at 7.1hp and the 592xp at 8.8hp so I’m down 1.7hp from jump street. IF that 660 was Mtronic or autotune it wood STOMP a stock 592xp something fierce! Unfortunately I do not have a 592xp In my hands but I do have a ported 395xp to compare and it’s a wash. Imho it will be difficult to coax as much power from the 592xp as they are relatively “hot out of the box” and the easy to be had gains may not be available. Imho A muffler mod isn’t going to get you as much gains on these new stratos saws and as far as intake/filter goes Husqvarner really has that down - so much so that it’s really not worth to mess with it Other than carb work
The base gasket is stock so installing a thinner base gasket and tightening the squish to .023 is going to p/u some torque/hp for sure (maybe .5-.8hp). Fabricating a tuned-tube exhaust instead of the deflector style that’s on there now will also net some gains. If I used a sqr/sqr chain , .023 squish and a different tuned tube exhaust it “woodnt” be a stretch to claim 20sec thru that timber, If that was BC or PNW timber (FIR log)where the trees are made of cheese heck she’d probably go thru 1.5-2x as quickly . Dyno Joe rated the 660 at 7.1hp and the 592xp at 8.8hp so I’m down 1.7hp from jump street. IF that 660 was Mtronic or autotune it wood STOMP a stock 592xp something fierce! Unfortunately I do not have a 592xp In my hands but I do have a ported 395xp to compare and it’s a wash. Imho it will be difficult to coax as much power from the 592xp as they are relatively “hot out of the box” and the easy to be had gains may not be available. Imho A muffler mod isn’t going to get you as much gains on these new stratos saws and as far as intake/filter goes Husqvarner really has that down - so much so that it’s really not worth to mess with it Other than carb work
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jasent
Well-known member
I’d love to hear some tips on doing a 660. One saw I have the least experience with. Stock numbers seem strange to me. High exhaust roof and long intake already. Seem pretty different from the 90cc saws I’ve worked with. My 660 builds have tons of torque but just don’t seem to get the speed I want. Should I raise exhaust a bit more. At 97 now
Nutball
Active member
Do you know your peak power rpm and peak torque rpm in the cut? I don't care about max no load rpm in my saws. What's your intake at?
I'm going to do some research on the 660 and 064 this winter to see if I can figure out what makes the 064 so good as far at the cylinder goes. I will try to get similar performance from some cheap aftermarket cylinders if I am able to get the ports sized and shaped how I want, and it's looking like I should be able to much better than on a farmertec cylinder.
I'm going to do some research on the 660 and 064 this winter to see if I can figure out what makes the 064 so good as far at the cylinder goes. I will try to get similar performance from some cheap aftermarket cylinders if I am able to get the ports sized and shaped how I want, and it's looking like I should be able to much better than on a farmertec cylinder.
jasent
Well-known member
Intake is at 80. Hyway cylinder with pop up
Checked all my cylinders with this case and crank. All were 98 on exhaust and 80-81 on intake. Will have to check my notes on the blow down
So far all I’ve done was polish and widen exhaust port and transfer shaping how I like.
Have not run it with the tach
Checked all my cylinders with this case and crank. All were 98 on exhaust and 80-81 on intake. Will have to check my notes on the blow down
So far all I’ve done was polish and widen exhaust port and transfer shaping how I like.
Have not run it with the tach
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