ESE's works engine tuner

[ief]

Attachment 269880

I tried to get a more even and better radius like the dotted line with a 1.3 entry area ratio and a nice radius out of the cylinder.

Attachment 269881

But maybe I need to make it more like this Cagivea cylinder but then I wouldn't have a 1.3:1 entry to port window area ratio ...... I must be missing something.

I guess the 1.3:1 ratio is only part of the equation and duct volume is another and my guess is that the latter is being compromised to much now. If I understood Jan correct then the more volume crated at the top of the duct allways improved things...

Compromises, yet again

And while I'm thinking out loud here... The shape of the duct is from smallisch to big on the rsa and I wonder if that could have anything to do with blowback having less influence then (?)

[Buckets4Me]

So whip up one of these systems over smoko will you Rob


EILE MIT WEILE

you know he will try

[wobbly]

The trend has been for a long time to reduce the volume of all the ducts in modern engines.
Aprilias Ex duct had the bottom filled in such that it was higher than BDC and the corners filled to reduce short circuiting from the A ports.
And the cylinder duct vol was CNC machined to be smaller and smaller in total vol,but in the process heavily promoting flow from the Aux ports to increase effective blowdown flow.
One of the transfer duct entrys was smaller than the port area ( the B and biggest port ) and for sure the ratio between the A and B port duct entry areas was tested
to death within the limitation of the case available area between the studs, by several of the 100 R&D festerers.
The idea here is to reduce the inertia of the initial volume available to the cylinder,that has to be accelerated out of the duct by the negative pressure ratio across the port.
That Cagiva cylinder is very "old" technology.

[ief]

Ehm, not sure if I get all that but none the less, how would that translate to TZ and his devconned barrel?

[wobbly]

TZs devconed cylinder had HUGE area of the A transfer duct at its entry, I pointed this out ages ago and suggested that the outer wall should be filled
to reduce the duct vol and smooth the entry flow.
But that would involve filling the case as well to match it, so he filled the inner radius as it was alot simpler.

[F5 Dave]

Ok ...

140 psi Compresion tested after reassembly, the cylinder was oily and cold.



130psi Tested hot after a dyno session, I expect this is a truer reading as its what the engine would be like when running.

So about 10lb/psi between cold and oily and dried out and at running temperature.

So now we know ......

So now we know what?

That they are a pretty coarse tool? The comparison is still of unknown variability.

Presumably the ring seal should be better after the bike was run-in (to an unknown quality). You should have tested it once it was cold after run-in to draw any conclusion, but even then you don't know how much oil has settled & got thrown onto the bore seal. I think the only thing it proves is that "results may vary"

[ief]

@wob #9050

Ok, that I get but... it seems it didn't help, in the contrary.

So I opted to rethink the choices made... still do I'm afraid.

Or..it has nothing to do with the devcon at all then all this is ehm... useless

[TZ350]

So now we know what? ...

Wait for it .......

That they are a pretty coarse tool ... comparison is of unknown variability ... it proves that "results may vary"

Just like you and Wob said, "results may vary" .....

[TZ350]

TZs devconed cylinder had HUGE area of the A transfer duct at its entry, I pointed this out ages ago and suggested that the outer wall should be filled to reduce the duct vol and smooth the entry flow. But that would involve filling the case as well to match it, so he filled the inner radius as it was alot simpler.

Ok, that I get but... it seems it didn't help, in the contrary.

To early to say, all that can be said, is with the mixture going rich, that the latest simple changes have had quite an effect on the carburation.



The loss of power is consistant with an overly rich mixture. I will sort that, then see where we are, with good carburation it may make more power than it did before.

[ief]

Oops, where did I come to this assumption then?



Must have misread some previous posts then, ma bad, just wait and see what comes out then all though I still can't shake the idear the shape/ radius could be improved upon but who knows ai?

Carry on

[kel]

The trend has been for a long time to reduce the volume of all the ducts in modern engines.
The idea here is to reduce the inertia of the initial volume available to the cylinder,that has to be accelerated out of the duct by the negative pressure ratio across the port.

Agreed. Everything we know (which for myself comes from what I've read rather than proven) tells us that Devcon in the transfer will produce more power, its just a matter of finding the right combination of area, inner radius, inner wall width etc.

Or..it has nothing to do with the devcon at all then all this is ehm... useless

Im confident we are on the right track as the bike sounded horribly flat yet still produced 27.5hp. Correct jetting, ignition timing and possibly compression and TZ's heading over 30hp! Watch this space.

[TZ350]

Im confident we are on the right track as the bike sounded horribly flat yet still produced 27.5hp. Correct jetting, ignition timing and possibly compression and TZ's heading over 30hp! Watch this space.

Hopefully get a chance to run it up again tonight ......

[Brian d marge]

Agreed. Everything we know (which for myself comes from what I've read rather than proven) tells us that Devcon in the transfer will produce more power, its just a matter of finding the right combination of area, inner radius, inner wall width etc.



Im confident we are on the right track as the bike sounded horribly flat yet still produced 27.5hp. Correct jetting, ignition timing and possibly compression and TZ's heading over 30hp! Watch this space.

Why don’t you try openFoam CFD , its free and in 2d not so bad to use , will give you a good idea of the flow

Stephen

[FastFred]

Why don’t you try openFoam CFD

http://www.openfoam.com/features/mesh-manipulation.php
https://sites.google.com/site/engcal...nfoam-examples
http://openfoamwiki.net/index.php/2D...ial_using_GMSH

openFoam Tutorial ... plenty on the net about openFoam

[TZ350]

Im confident we are on the right track as the bike sounded horribly flat yet still produced 27.5hp. Correct jetting, ignition timing and possibly compression and TZ's heading over 30hp! Watch this space.

Kel and I finished off last night pretty sure it was rich.



The target is 30+hp with the more reliable exhaust port width of 70-72% instead of 75.

Ok ... last time on the dyno the Beast sounded very flat and rich and only made 27.5 hp it has done better, so I changed the mainjet from a 135 to a 125 and the pilot from 38 to 32 and ran it up again.



Ooops the power started falling off with each consecutive run. The last time I saw that the new piston in NedKellys bike had cracked and was about to disintegrate.

I felt pretty down thinking there was a problem and the night was done. I was not looking forward to pulling the cylinder off to see what had gone wrong. Bummer .....

But wait, I have a "compression tester" and know what the motor should read hot because I was smart enough to check it before when it was good.

I guess if I hadn't done that I would have had to pull it down to find out there was nothing wrong.



Turns out it needed to be richened up, go figure, because it sure sounded rich before. Changed the main to a 145 and pilot to 42 and gained 2hp. Fiddling with the ignition didn't do anything but bring on det. So not 30+ yet and still sounds flat so I will look at the compression ratio next.