Biggest perpetuated Myths about Modded Saws.

[romeo]

I will agree that .020 is a safe number to shoot for. I have ran as low as .013 without smashing a piston into the combustion chamber and adding .007 to that gets you safe due to different discrepancies.

 

[Mr.]

hang on Mr.

in post #8 you said "For saws without a custom combustion chamber, i.e. two piece heads........

the squish does not mean much."

then in post #13 you said "I said that it doesn't matter much for a stock 288 head. It comes into greater play with a custom combustion chamber"

now post 8 seems to contradict post 13????

what am i missing?

cheers, Serg

Where I come from, both of those quotes say the same thing. The quotes are inverse, but not opposite. Sorry if that is confusing to you, it was not meant to be.

Fred

 

[Mr.]

Now for you TW. Where do I start. LOL

1)

I don't know what you are doing on mods that lowers thermal efficiency, but the way I am working at it I make every effort to turn heat into motive power and in that shoot for high thermal efficency.

I am doing the same things that you are doing to lower thermal efficency. For instance I use alot of fuel because it cools the engine. Don't you use the same technique from time to time? If you want thermal efficency from you race saws, then you are playing for 4th.

2)

The chart does not have anything to do with the effect of turbulence on output, it has to do with the squish velocity, and when it occurs.

WTH I never used the word turbulence, I did say squish velocity....

3) (~) means about. I was giving an educated estimate off the top of my head. I will not delve into the matter further, but way to steer the conversation from your flawed figures.

Fred

 

[J.Walker]

Perpetuated Myths about Modded Saws

You saw will be finished in 2-3 weeks!

 

[Mr.]

You saw will be finished in 2-3 weeks!

HAHAHAHA

That's definately a good one. Wait that's me right now.

Fred

 

[04ultra]

I want my saw woods ported......I mean race ported so I can call it woods ported....

 

[redprospector]

HAHAHAHA

That's definately a good one. Wait that's me right now.

Fred

I know that feeling, not on saw's, but on chain's.
I seem to be "chained" to my work.

Andy

 

[Crofter]

Quote:TW
"The chart does not have anything to do with the effect of turbulence on output, it has to do with the squish velocity, and when it occurs."

Quote MR. "WTH I never used the word turbulence, I did say squish velocity...."


Is not turbulence and squish velocity all about the same or directly related?

TW said the chart does not relate to the effect of turbulence or squish velocity on output, but is purely a chart showing when and where it occurs with a given set of mechanical conditions; in other words a means of calculating squish velocity in itself.

Quote MR. "3) (~) means about. I was giving an educated estimate off the top of my head. I will not delve into the matter further, but way to steer the conversation from your flawed figures".

I really think you should "delve into the matter further" and demonstrate to everyone just exactly where TW's flawed figures are, and with which you insinuate he is attempting to "steer" the conversation from. I think that exercise should be most entertaining!

 

[Mr.]

I really think you should "delve into the matter further" and demonstrate to everyone just exactly where TW's flawed figures are, and with which you insinuate he is attempting to "steer" the conversation from. I think that exercise should be most entertaining!

When did we ring your bell Sweetheart? We all know that math isn't your strongpoint.

I'll go ahead and take the lumps. I assumed the charts were backing up TW's figures and didn't look at them close enough. The normal progression of a discussion is to state one's opinion and then back it up. My bad on that one.

I disagree with two assumptions in particular.

1) Increase of power output is linearly related to an increase of cut speed.

2) Increased compression will affect all saws the same. We must assume that these calculations are also linear or subject to some arbitrary exception. Combustion chamber configuration seems to not play a part in his calculations either.

Fred

 

[Crofter]

When did we ring your bell Sweetheart? We all know that math isn't your strongpoint.

I'll go ahead and take the lumps. I assumed the charts were backing up TW's figures and didn't look at them close enough. The normal progression of a discussion is to state one's opinion and then back it up. My bad on that one.

I disagree with two assumptions in particular.

1) Increase of power output is linearly related to an increase of cut speed.

2) Increased compression will affect all saws the same. We must assume that these calculations are also linear or subject to some arbitrary exception. Combustion chamber configuration seems to not play a part in his calculations either.

Fred

That is an interesting comeback to having called someone on being misleading! Seems like lots of assumptions on your part about a few different things. My math gets me by but I am not in the league with TW. I am somewhat familiar with his process of developing solutions and his method of cross checking for error. He doesnt make many assumptions. His credibility is quite good in that respect but have a go at it.

There are lots of other parameters that can be input to that formula to fine tune for more precise calculating of squish velocity. Certainly the density of the charge as affected by dynamic compression is a factor in any instantaneous squish velocity calculation but that is an ever moving target.

Was this thread really abut debunking myths or could there be, as I suggested, some other undercurrents.

 

[Mr.]

Some people try to act like modifying a saw is rocket science. Hell, half the guys doing it read at a third grade level. Can it really be that hard???

It requires skill, knowledge and patience. It does not require any college level math.

Too many people try to make this way too hard, that's what this thread IS about.

Fred

 

[Jacob J.]

Over-complicating things is an inherent trait of humans in modern society. At the same time however, some of the biggest problems I've seen with modified saws were from lack of forethought or planning.

 

[Crofter]

It seems like a lot of whittling that has been done with the assumption that a saw is so simple nothing can go wrong, has had some disappointments. Most of the oops get swept under the table as being the price of learning. 20 or 25% gains can usually be had quite easily if someone has told you approximately what and where to grind but it certainly is not transferrable from saw to saw and it would not be of much use applied to a different style of engine without reentering the trial and error mode. That is a case where the ability to do calculations and achieve the same critical relationships that relate to high performance saves a whole lot of the trial and error. If you dont have it you have to work with what you got, but I think it is laughable to knock the advantages of technology or the application of theory. People come out with the strangest ofstatements when they are trying to discredit someone.

"Hell, half the guys doing it read at a third grade level"

"When did we ring your bell Sweetheart? We all know that math isn't your strongpoint".

"I will not delve into the matter further, but way to steer the conversation from your flawed figures."

I wonder whose credibility is suffering from this exercise.

 

[Mr.]

I'm good to go Frank.

You have been preaching gloom and doom to anyone wanting to modify saws for at least a couple of years. I'm fairly glad I didn't listen to you.

Add something positive or at least specifically negative to the conversation or leave it.

At least make an arguement that 5% is alot of gain or just a little.

I hope TW is right because if he is, it seems I can gain 5-10% (or more, it's not my story) by setting the squish at 20% on my 288 ON TOP OF THE current figure you guys quote for a muffler mod.

Just like compounding interest. I get paid on my investment and then off the interest.

Fred

 

[Mr.]

PPSSTTT

Tell Brian you are keeping him in this arguement. He might already be done with it. It's the polite thing to do, you know.

Fred

 

[Mr.]

Over-complicating things is an inherent trait of humans in modern society. At the same time however, some of the biggest problems I've seen with modified saws were from lack of forethought or planning.

I agree skill and knowledge is definately required. Also, a scholarly approach is always rewarded.

Fred

 

[husq2100]

Where I come from, both of those quotes say the same thing. The quotes are inverse, but not opposite. Sorry if that is confusing to you, it was not meant to be.

Fred

well i am a complete novice with no mechanical background, so when i read your statements and veiwed them from my prospective i thought:

2 piece heads referred to race saws and the like which ARE custom....

Fred, do you build ######## and compete, it sounds like you are talking from alot of experience. just curious

cheers, Serg

 

[husq2100]

He is saying that the squish height means little compared to the combustion chamber area. If all saws had the same dish in the top it would matter but they don't. This 372 head has .025 squish but it builds around 197 lbs of compression. I wish the pic came out cleaner, but I'm not going to pull it apart to take another one.

is the high compression because the squish band is wide and the combustion chamber is small so all the gas is getting cramed into a smaller space?

if so i could achive this buy milling the squish band wider and dropping the jug down to compensate, while still maintaining the same squish.... forget what happens to timing of ports im just talking top end here.

cheers, Serg

 

[Crofter]

Originally Posted by Jacob J.
Over-complicating things is an inherent trait of humans in modern society. At the same time however, some of the biggest problems I've seen with modified saws were from lack of forethought or planning.

___________________________________________________________________
"I agree skill and knowledge is definately required. Also, a scholarly approach is always rewarded.

Fred

Hell, half the guys doing it read at a third grade level. Can it really be that hard???"


It is hard to know whether you are sucking or blowing, Fred, with all your contradictions ! Your score for unbiased objectivity is not good. You appear sometimes to draw whatever conclusions suit your agenda at the moment.

When did we ring your bell Sweetheart? We all know that math isn't your strongpoint.

Actually one of my fairly well developed abilities is trapping rats, Fred. I can spot them even when they are trying to appear to be something else. What would you say is your "strongpoint" Fred?

 

[romeo]

is the high compression because the squish band is wide and the combustion chamber is small so all the gas is getting cramed into a smaller space?

if so i could achive this buy milling the squish band wider and dropping the jug down to compensate, while still maintaining the same squish.... forget what happens to timing of ports im just talking top end here.

cheers, Serg

Yes, squishing into a tighter chamber causes more compression. The port timing needs to be radically changed since you a raising the piston so much. The limiting factor is gaining way too much intake duration when milling the combustion chamber, unless you build a two piece head.