Porting torque vs hp

[Mastermind]

I see. I need some more experience I guess...


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Maybe not. LOL

Treemonkey and I were chewing the fat one day, and he said to me....."The fastest saws I built weren't my first ones, or my last ones. The fastest ones were somewhere in between".

 

[MustangMike]

My question is somewhat similar to Dan's, do you guys ever run into a cylinder that just does not need porting?

 

[Mastermind]

My question is somewhat similar to Dan's, do you guys ever run into a cylinder that just does not need porting?

Many times I've torn a saw down to find that I thought the timing numbers were perfect. Some 346s, and some 044s come to mind. But there are always gains to be had. A bump in compression, a little more intake timing, maybe a little width increase. Deflashing, deburring, smoothing of transfer passages....

 

[jmssaws]

I can only speak about 1122 but the better it is stock the better it will be ported,filling the intake will get the same number but not the same results.

 

[jmssaws]

Same with the transfers,I'd you have to raise them a mile to get the number you want it just won't run as good.

The roof becomes to steep and there's not enough material there to get it back to the shape it needs. They will still run good but to make a beast you need everything right,grind a 660 cylinder to dust and it will never run as good as a well timed older cylinder.

 

[jmssaws]

My question is somewhat similar to Dan's, do you guys ever run into a cylinder that just does not need porting?

Timing is a part of it but not all of it

 

[exSW]

How much variation are you guys seeing in stock cylinders that are the same run.

 

[Nitroman]

A vette stands out and will be caught, a Benz though now adays if you are driving one from the 80's people think you are old. I should know lol

I have a 87 300TE summer driver. Get some looks once in a while.

Sent from my non internal combustion device.

Johnny Johnstone told me that in 1979 when I was at a vocational school learning heavy equipment mechanics. He had a new 1979 Mercedes 300SD turbo-diesel. It had this yellowish kind of paint that actually looked really nice. He let me ride in it once. Smooth.

As for torque and horsepower...all the saws I have had built, three, will cut like crazy. If I want to cut a stump, I switch to a 7-tooth on the 3120. I just gear down. With the exception of cutting stumps, I cannot find wood that will allow me to just stand there and watch as the saw works its way through the log. The cut, for me, is over too fast. That is the measure of power for me.

 

[Fairways_and_Greens]

I am going to disagree with the bore/stroke statement. Generally, when they want torque, they increase the stroke, and a high RPM motor will often have a large bore & short stroke, the piston travels a lot slower that way.

Maybe it's the opposite with dirt bikes. When I put a big bore kit on my 250f (same stroke, bigger bore) I got a ton more bottom end with no gain on top end.

 

[exSW]

Maybe it's the opposite with dirt bikes. When I put a big bore kit on my 250f (same stroke, bigger bore) I got a ton more bottom end with no gain on top end.

Did you change the rod also?

 

[sawfun]

Back pressure does do interesting things in four strokes for sure and likely two strokes as well. In the early 80's I had a Firebird that would run low 11's with Mitchell race mufflers with a 2 & 1/2" flow through, that car would only lift the front wheels around 3" upon launch. I tried 2" flow through Cherry Bomb's and the restriction cut my ET's down a 1/2 second. However the car would almost stand up on the launch with the wheels a minimum of 2 foot up. So that must be torque vs horsepower.

 

[jmssaws]

I'm at the point with a 064 or 066 that the muffler restriction and airfilter become a very important part. They have to be right or it will hurt them.
My old saws liked more in and out but the saws I'm building now have to have some restriction on both ends to be as strong as they can be. I don't really know why but I can open the muffler by just removing a screen and kill them.
There twice as strong as my old way with less in and out. Took a long hard time to figure that out

 

[Mastermind]

That still blows my mind.....and proves that we all got a lot yet to learn.

 

[Chainsaw Jim]

I've been running a 064/066 since Saturday that is to this point the best running one I've had my hands on,ahead of the hybrid up to a 36" 404,the strange thing about it is im using a basically stock muffler.

Which one? 064 or 066? i believe the 064 is larger and would be a better performer.

 

[Simondo]

It strikes me that a engine design that is "fixed" will be more tricky to set up to give the wide range of delivery we may want. VVTI "variable valve timing" is one way that helps to give a engine ..2 halves ..some torque to start and high revs when you get up the top end. Its a limitation of the fixed geometry port cylinder without valves, moving advance and retard, micro adjustable fuelling.....etc . I would say its impressive what everyone gets out of the current 2 stroke motor.

 

[jmssaws]

Which one? 064 or 066? i believe the 064 is larger and would be a better performer.

064 with a 066 cylinder
It's no different,almost stock muffler and a oem airfilter, if I pull a screen on the muffler it slows down,if I put a better flowing airfilter on it,it slows down.
And it's some kind of strong.
My 066 that Shaun ported is that way,it thought putting a big carbon it would help but it didn't,088 boot and a 1" carb didn't gain a single thing and the muffler couldn't be changed either.
The 056 hybrid made a giant gain with the carb and boot and there all ported the same.

 

[sawfun]

I think bar length and application come into play as well. For 60 + inch bars I would much prefer torque over high chain speed. Now I realize that use of this this is a rare occasion these days, and raker depth & sprocket diameter can help fine tune things. But long bars need more truck like performance and 200t's, sports car type. Maybe 70cc - 90cc saws need a better balance of both.

 

[Chainsaw Jim]

064 with a 066 cylinder
It's no different,almost stock muffler and a oem airfilter, if I pull a screen on the muffler it slows down,if I put a better flowing airfilter on it,it slows down.
And it's some kind of strong.
My 066 that Shaun ported is that way,it thought putting a big carbon it would help but it didn't,088 boot and a 1" carb didn't gain a single thing and the muffler couldn't be changed either.
The 056 hybrid made a giant gain with the carb and boot and there all ported the same.

I was asking about which muffler not which saw. Original 064 muffler or 066/660 muffler.

 

[Chainsaw Jim]

I think bar length and application come into play as well. For 60 + inch bars I would much prefer torque over high chain speed. Now I realize that use of this this is a rare occasion these days, and raker depth & sprocket diameter can help fine tune things. But long bars need more truck like performance and 200t's, sports car type. Maybe 70cc - 90cc saws need a better balance of both.

Tell that to my back!! It would have been awesome to run your 090's at 14,000 rpm to let the chain do some self feeding. Those things have a ton of torque.

 

[jmssaws]

I was asking about which muffler not which saw. Original 064 muffler or 066/660 muffler.

Either,makes no difference but it has a oem 064 muffler and dp cover.
If I replaced the cover with a solid one it kills them also. I know now how much they need. Can't be to open or to restricted.