Let's Talk Transfers

[Moparmyway]

I like that idea Deets was using in the transfers

I think speeding up velocity through the runners is smart !

 

[Keith Gandy]

I think speeding up velocity through the runners is smart !

Me too and I think u r right on the stuffers if the hybrid drops off that quick on the bottom. Stuffers should speed her up alil more ?

 

[paragonbuilder]

Do you think you would have had the same results if you added crank stuffers or found a different way to lose case capacity ?

Deets said he thought it didn't have enough case capacity. Not that it had too much.


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[Keith Gandy]

Deets said he thought it didn't have enough case capacity. Not that it had too much.


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Maybe he is thinking not enough trapped compression?

 

[Moparmyway]

Deets said he thought it didn't have enough case capacity. Not that it had too much.


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Exactly !!
He removed even more case capacity by narrowing the runners

 

[Moparmyway]

Maybe he is thinking not enough trapped compression?

IIRC, that saw is close to 220#

 

[Deets066]

Do you think you would have had the same results if you added crank stuffers or found a different way to lose case capacity ?

I don't think case stuffers would have the same affect. They would gain velocity, but with even less fuel in the crankcase I think it diminish quickly when it hit the large transfers and fingers. (These fingers were deep). I think filling in the tunnels created more velocity and also directed more flow to the fingers.

 

[Deets066]

IIRC, that saw is close to 220#

210

 

[Nitroman]

Being the port in between the two others, transfers seem to be much more interdependent than the other ports.

Case volume, intake closing point, exhaust roof geometry all seem to affect transfer shape and location for optimal performance.

The OEM's have moved towards 4 ports. 4 ports seem great because you are getting the best of both worlds. Good velocity and good area all mixed into one design.

4 ports seem to run at a much physically lower region than 2 ports. Why? They can flow more and fill the cylinder the same as a 2 port in a smaller amount of time? Because of this, there's less risk of backfilling?

Then there are the varying entry angles of the quad ports. It seems that the ex sides enter flat and purge the piston crown off, but the mains focus the flow towards the intake wall.

Number of ports prolly dictated by cost. The four ports opening lower almost certainly due to emissions; open late, close quick, less charge to go out the exhaust, and two additional ports to make the necessary scavenging possible while having greater control over the direction of the incoming charge.

 

[spencerpaving]

I read a post by Terry in OZ.....

He said that boost ports on some engines opened after the mains. The idea was to get under the main charge and lift it into the chamber.

Really got my head to running some ideas....

I hear ya there....I've been told the same thing by several race saw builders...not only to open the fingers or boost ports a couple degrees after the mains but to bevel them into the cyl at the top gradually to aim the charge up...not out....I have not tried it yet for myself yet. I talked to a racer/builder from down south and in ten min conversation he's really got me rethinking alot of stuff

 

[drf256]

Opening fingers after, with and before the mains should be an easy experiment with the same jug.

It would be sick to hook a smoke machine up to a case and jug with the chamber lopped off and see where flow occured and how with different changes.

 

[jmssaws]

I hear ya there....I've been told the same thing by several race saw builders...not only to open the fingers or boost ports a couple degrees after the mains but to bevel them into the cyl at the top gradually to aim the charge up...not out....I have not tried it yet for myself yet. I talked to a racer/builder from down south and in ten min conversation he's really got me rethinking alot of stuff

I have not opened them on a upward angle yet but have gave considerable thought to it, the cylinder in front of me if it gets fingers they will be that way.

There is a harmony that needs to be found between all the ports, raise the transfers till you find it,you will know when you do cause it will feel "free"

 

[Mastermind]

 

[jmssaws]

Funny stuff

 

[Sty57]

Opening fingers after, with and before the mains should be an easy experiment with the same jug.

It would be sick to hook a smoke machine up to a case and jug with the chamber lopped off and see where flow occured and how with different changes.

That would be a great thing to see.

Could put a piece of plexiglass on the top so you could see how it comes up and around.

You could do it on a Husky with removable transfer covers too.

I got a junk X-tork jug if you want to play with it.

 

[jmssaws]

I hear ya there....I've been told the same thing by several race saw builders...not only to open the fingers or boost ports a couple degrees after the mains but to bevel them into the cyl at the top gradually to aim the charge up...not out....I have not tried it yet for myself yet. I talked to a racer/builder from down south and in ten min conversation he's really got me rethinking alot of stuff

I've opened them with the mains,2 degrees before the mains, 4 degrees before the mains and it gained every time I raised them.
4 degrees is as far as I've gone though.
I push one thing at a time and I do one thing at a time that way you know exactly what gains and what doesn't.

 

[jmssaws]

Didn't mean to quote you again spencerpaving, it was supposed to be docs post. My bad

 

[tree monkey]

Transfers are where a lot of the gains are IMO. Too big and the saw seems to get lazy. But where it gets tricky for me is if that is true, then adding fingers shouldn't help. But they do, so is directional flow more important than velocity?

yes

I get confused with this. Mains open first, on exhaust side. Then secondary's on intake side.
But when you add fingers they seem to always be on the intake side and open first.
Anyone care to explain?
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fingers should be looked at as boost ports, angled up and open last.

I read a post by Terry in OZ.....

He said that boost ports on some engines opened after the mains. The idea was to get under the main charge and lift it into the chamber.

Really got my head to running some ideas....

been telling you this for awhile now. finally sinking in?

 

[Redfin]

I've opened them with the mains,2 degrees before the mains, 4 degrees before the mains and it gained every time I raised them.
4 degrees is as far as I've gone though.
I push one thing at a time and I do one thing at a time that way you know exactly what gains and what doesn't.

Have you tried after mains?

 

[jmssaws]

fingers should be looked at as boost ports, angled up and open last.

Indeed