Part Three: The Transfer Ports

[Mastermind]

No... need you to explain it, please?...

I seriously doubt I will ever travel that path again Kenny. The level of frustration from doing that sort of thing is something I never wish to relive.

 

[Lightning Performance]

I seriously doubt I will ever travel that path again Kenny. The level of frustration from doing that sort of thing is something I never wish to relive.

It's just a hole

 

[Mastermind]

It's just a hole

Black.....and bottomless.

 

[Lightning Performance]

Black.....and bottomless.

LMAO

 

[Lightning Performance]

I see now... oh my....

 

[Ketchup]

Am I wrong in thinking you can compensate for an undesirable case volume by changing the intake timing to get the desired long bar performance?

My experience with big saws and long bars is limited. But I’ve wondered the same thing. I think increasing intake port time area has to work in conjunction with increasing transfers port time area. It’s both volume and duration AND the case has to be stuffed AND the transfers have to be big enough to move it. The pisser is if you make the saw too fat it’s just a pig.

now that was very appreciated!!

what about increasing velocity to the transfers.
For example near the bottom of the jug you hog out a little, smooth out edges but you do not increase the port size for the combustion chamber.

This should increase velocity in which fuel flows to the combustion chamber faster than before. you are starting with a wide tunnel and going down in size for the combustion area and thus should increase velocity in the higher rpms? But does that also increase the case volume in what you were saying?

I’m just sharing my opinion, take it with a grain of salt. The blending done at the transfer lowers should match the area of the case that feeds the transfers. Sharp edges or sudden constrictions will cause turbulence that reduces efficiency of flow. That generally will look like a tapering into the transfer tunnels BUT the funneling effect your talking about is not really the point. Any grinding we do on the transfers increases case volume. Every saw has a point where that volume gets large enough that it is no longer as responsive to the pressure generated by the downstroke of the piston. This seems especially true in smaller displacement saws. My opinion is that pressure generated by the piston is more important than long funneling effects. So unless you’re going after all-out long bar pulling power, I would be conservative on how much you remove from the transfer lowers.

Are y'all sure you understand what you're talking about here?

LOL

Nope. But this place helps me think.

 

[kneedeepinsaws]

*edit* made a post in the wrong thread

 

[Mastermind]

Nope. But this place helps me think.

Then we did good building it.

Keep on keepin on.

 

[Darryll]

Interesting series and reading guy's.

Several years ago on a quest to learn something I took a perfectly new Meteor 372 cylinder and chipped away at it till it was a paper weight. It got parked on the shelf with the Ex at 87 the transfers at 120/115 and the intake at 85. My last notes on the cylinder was pretty dismal reading, reporting poor throttle response and a complete lack of torque but it run up to 16,800rpm.
I have one of those Farmtec 372 saws and the cylinder let go on it. Rummaging through my old cylinders I come across this old Meteor. Not that I have learnt a lot in recent years I decided to see if I could get this to work good enough to get the saw going. The ports were very hogged out but I could see a few errors in my thinking back then and made a few changes and upped the comp a bit and lowered the intake to 92 ATDC and bolted it back on. Ye gods this thing burst into life. Still not as strong as a work saw but I bet it would cut cookies quick smart. Most fun I've had with a saw in a while.

The bizarre bit is it has really good throttle response and purred like a kitten at idle. I'm sure you have all done something similar but to be honest it took me by surprise. I really was not expecting that.

I make mention of it here as I don't see to many comments about intakes as low as 92 but then we build work saws and not play saws I guess. I figured the observation would be of interest to someone.

 

[Mastermind]

I'm of the mind that we never know what works till we try it. Keep testing....

 

[MustangMike]

Randy, I got to run one of your Hybrids at the PA GTG. I don't even know who's it was but I think there were about 6 Hybrids there.

It is tough to judge from just a couple of cuts with different b+c on each saw, but I was impressed with your creation.

Seemed like I could really lean on it and it just kept going! I remember when you were not big on doing them, so I just wanted to say "Good Job"!!!

Hope all is well out in TN with your Farm and Family.

 

[Mastermind]

Randy, I got to run one of your Hybrids at the PA GTG. I don't even know who's it was but I think there were about 6 Hybrids there.

It is tough to judge from just a couple of cuts with different b+c on each saw, but I was impressed with your creation.

Seemed like I could really lean on it and it just kept going! I remember when you were not big on doing them, so I just wanted to say "Good Job"!!!

Hope all is well out in TN with your Farm and Family.

I just don't feel like I can get enough gain over the 044/440 top end to justify the extra effort. I have two ported 044s that run really well...or good enough to cut up more wood in an hour than I can deal with in a timely manner. A little faster in the cut? For what exactly?

 

[MustangMike]

No argument on how well a 044/440 can run, but if you can make it even stronger w/o adding much weight ... so much the better!

 

[Mastermind]

No argument on how well a 044/440 can run, but if you can make it even stronger w/o adding much weight ... so much the better!

I understand Mike. I think I've just become used to doing a new saw....using only the factory parts. Anything else seems sorta odd now.

 

[Lightning Performance]

Fuel use is always an issue for me. More intake duration drinks more fuel.




That saw out to 92 intake could be brought right back to 82

@Darryll

Restore 36 degrees or more of duration to the case and you just might have a very good runner.

Try it.

 

[Darryll]

Fuel use is always an issue for me. More intake duration drinks more fuel.




That saw out to 92 intake could be brought right back to 82

@Darryll

Restore 36 degrees or more of duration to the case and you just might have a very good runner.

Try it.

I too have found that. It must just get blown straight out the exhaust. So wouldn't that lean toward the argument that there is too much crankcase pressure at high RPM??

 

[Wonkydonkey]

I too have found that. It must just get blown straight out the exhaust. So wouldn't that lean toward the argument that there is too much crankcase pressure at high RPM??

That and spit-back don’t help

 

[Lightning Performance]

I too have found that. It must just get blown straight out the exhaust. So wouldn't that lean toward the argument that there is too much crankcase pressure at high RPM??

No not really. A high exhaust tuned fat can blow gas right out. Short out the transfers to the exhaust is the most common waste of fuel imo.

 

[Darryll]

No not really. A high exhaust tuned fat can blow gas right out. Short out the transfers to the exhaust is the most common waste of fuel imo.

I agree with that too.

So has there been any consensus as to why a low intake uses more fuel? To my mind it was due to over charging the cylinder and blowing out the high EX at high rpm. So I have figured that the sweet spot was just at that point before over charging. How the hell I define that I still have not worked out. I'd be happy for anyone to correct my thinking on this.

Just running a very slow and pain staking process of trail and error on an other 372 at the moment at the other end of the spectrum. Currently it has an Ex of 106. It's last run was as expected and pretty uninspiring. The ridicules high port thing I have would eat it at every point in the RPM range. I have found a 372 formula I like but I still think there is more in there. Just gotta find it.

Also I note that this is the Transfer thread. Only realized later.

 

[Lightning Performance]

I agree with that too.

So has there been any consensus as to why a low intake uses more fuel?

Currently it has an Ex of 106. It's last run was as expected and pretty uninspiring.

Also I note that this is the Transfer thread. Only realized later.

Longer intake duration sucks more fuel because the intake signal lasts longer. Same thing a bigger bore or longer stroke does.

Your exhaust seems low for even a work saw. Are you milling with it?