cuttinties
ArboristSite Guru
That's why I mentioned it. I'm not too keen on cutting a lot off the base on these
MillerModSaws plays with 440R/046D Hybrid
- Thread starter MillerModSaws
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You've done a very good job of explaining your point, and I thank you for that. Help me with this. My following questions are not meant to come across as defensive or accusatory. I'm simply looking for further understanding your theory.
In my experience, I have found that more intake duration makes my saws hold more RPMs in the cut. In order to help you understand what I'm looking for in a saw, my build theory is that torque alone doesn't get it. I want a saw with an attitude that holds significantly higher than factory RPMs in the cut. A longer intake duration has done that for me on several models, the hybrid, 461, and 390XP included. If I'm understanding you correctly, you're suggesting that the same benefit could be accomplished by raising the intake roof, rather than increasing the duration like I have been. Interesting idea. Quite frankly, I've not paid real close attention to how much room there is to raise the intake on various models of saws. Currently, I will often raise the intake about the amount that I drop the jug, then raise the corners to square it up. But, I've also been using more intake duration than you're referring to. It has worked for me. The question that comes to my mind is, if it works, why not do it? I suspect that the answer will be...efficiency. Then my next thought is, what if I don't care about efficiency, as it pertains to fuel economy? Perhaps that's not the kind of efficiency you mean. Help this make sense to me. Basically, if what I'm doing has worked so well for me, why change that?
Torque is what we all try to gain, and hold on to it long as possible to make the most hp. There is different build formulas for different applications(long bars, cant saws, and etc.). Don't be afraid to try new things.
Good examples of needing different build specs
NHRA Pro Stock
NHRA Comp Eliminator
Pulling truck engines
Nascar restrictor and non restrictor
Dirt track engines
Good examples of needing different build specs
NHRA Pro Stock
NHRA Comp Eliminator
Pulling truck engines
Nascar restrictor and non restrictor
Dirt track engines
cuttinties
ArboristSite Guru
Well what I'm gathering from you're saying is what you do works for you. What I do works for me just fine. I'll post a video of a saw that runs a relatively short intake duration in a bit and I'll let you decide if it's nasty enough. The point I'm making is that fuel that is spit back isn't making power and never makes power. From my standpoint when my paycheck comes from the mill the more efficient power/chain and fuel costs I have the larger my profit margins are. I don't log full time so when I'm in the woods the job needs to pay enough to make it worth my time. I get paid by the board foot not a half second.
Yes, but I'm interested in hearing what you have to say. Am I correct in my understanding of what you're saying?
Relax everyone, I enjoy hearing everyone's opinion and theory.
Fully agreed.
cuttinties
ArboristSite Guru
Yes. When it spits back it decreases case pressure. When that happens charge velocity is decreased.
Thank you. You have helped me to understand some more about these things. I do appreciate your input.
cuttinties
ArboristSite Guru
Efficiency is what works for me. I've tried longer durations, short durations, bigger carbs smaller carbs, big combustion chamber and small combustion chambers, piston swaps and full circle cranks. I do what works for me. If mileage isn't a concern for you then I'd be willing to challenge you to a cookie cut off. 1 tank of fuel same bar and chain and cut until it's empty. Most cookies cut gets a coke.
cuttinties
ArboristSite Guru
Sounds like a good time. No way to loose on this one. Running saws and drinking Coke. Doesn't get much better than that
cuttinties
ArboristSite Guru
I feel like I need to apologize for hijacking this thread.
wigglesworth
Booned
WTH happened in here??
Carl, cut .050 off that piston skirt and make another vid. That'll increase the duration like brad wants.
I'll buy u a couple Pistons to play with if need be.
I'll sponsor this "see what really works" debacle.
Hopefully there will be some snellerized and masterminded 390's here in September.
That'll settle that crap IMHO....
Carl, cut .050 off that piston skirt and make another vid. That'll increase the duration like brad wants.
I'll buy u a couple Pistons to play with if need be.
I'll sponsor this "see what really works" debacle.
Hopefully there will be some snellerized and masterminded 390's here in September.
That'll settle that crap IMHO....
drf255
BAD CAD
Not trying to fuel the fire here. 2 legitimate questions.
1st @ Cuttinties...
My understanding is that the intake opens and closes at it's floor. If your raise the roof, I see how it increases the area of the port. How does that not increase the duration that the port is open for? Isn't the bottom of the piston skirt above the intake port roof at TDC? Clearly I'm not understanding something everyone else is.
2nd @ Mastermind...
I understand that you Strongly Favor squish band cuts over popup pistons. I see the merits of a larger Squishband and a smaller combustion chamber. In the case of the 660 (IIRC) jugs you've been using Devcon on to raise the intake floor, would saws with a intake floor that comes out too low benefit from a hybrid Squishband cut AND popup? I can see how this method wouldn't lower the exhaust as much as you'd like, but it would prevent the need for filler. The popup dome could be kept quite shallow.
1st @ Cuttinties...
My understanding is that the intake opens and closes at it's floor. If your raise the roof, I see how it increases the area of the port. How does that not increase the duration that the port is open for? Isn't the bottom of the piston skirt above the intake port roof at TDC? Clearly I'm not understanding something everyone else is.
2nd @ Mastermind...
I understand that you Strongly Favor squish band cuts over popup pistons. I see the merits of a larger Squishband and a smaller combustion chamber. In the case of the 660 (IIRC) jugs you've been using Devcon on to raise the intake floor, would saws with a intake floor that comes out too low benefit from a hybrid Squishband cut AND popup? I can see how this method wouldn't lower the exhaust as much as you'd like, but it would prevent the need for filler. The popup dome could be kept quite shallow.
Mastermind
Work Saw Specialist
Good plan.
The base must still be cut, whether a popup or a cut squish is used. It's cutting the base that lowers the intake. You used the MS660. On that model the exhaust is far too high (power band above realistic chain speed) for a strong work saw. So, we cut .060" out of the squish band and "X" off of the base to set our squish clearance. Cutting the base physically moves the exhaust and the intake port down. If I can't get the exhaust where I want it, the whole build is a bust. The advantages of the intake at say 78 over 83 in this saw are not clearly known until the wood gets really large, or the user cares about fuel usage. Even with 28" bars the saw with long intake duration still runs very strong (not as much lugging power)........but it sucks fuel like you wouldn't believe. Much of that fuel is lost to spitback, and over a long day of cutting can saturate the air filter. When that happens, tune changes and the saw uses even more fuel.
cuttinties
ArboristSite Guru
If you go back and look I said that you're not going to get time area without affecting duration some.
