ESE's works engine tuner

[peewee]

guys this might not be easy question to answer considering different fuels, comp ratios , pipes, carb settings, spark lead, but do you think its possible to cool down to much the exh passage ?

[jbiplane]

Piston forces. Then a couple of days ago, Michael Moore successfully posted his spreadsheet.
Attachment 341197

Great. Thanks Ken. Will modify and play with

[wobbly]

Considering that the Aprilia had 1L/Hp/min of cold coolant flow entering the cylinder, all of it fed in under the duct I doubt its
an issue.
But having said that rerouting the flow on a 125 kart engine to all of the cold flow fed across the transfers first ( with only a small 3mm feed each side
under the duct ) resulted in a good power increase.
Maybe by default not over cooling the duct ( and thereby overheating the transfers ) is a superior methodology.

[peewee]

Considering that the Aprilia had 1L/Hp/min of cold coolant flow entering the cylinder, all of it fed in under the duct I doubt its
an issue.
But having said that rerouting the flow on a 125 kart engine to all of the cold flow fed across the transfers first ( with only a small 3mm feed each side
under the duct ) resulted in a good power increase.
Maybe by default not over cooling the duct ( and thereby overheating the transfers ) is a superior methodology.

im still fiddling with the exh outer shell on the yami twins. debating to use alittle bigger shell than i first planed but im not sure if it would have to much water around the duct. ill get a photo and see what you think

[guyhockley]

Possible bike applications?

https://newatlas.com/acoustic-metama...not-air/58818/

[flyincat]

I'm in search of some advice on case porting a case reed motor, see attached pictures. As you can see, at BDC the piston covers quite a bit of the reed box exit into the crankcase. Plus, the cylinder tang blocks a good part of the center of the duct. Once the piston moves out of the way, things open up a bit, but the flow around the cylinder tang still doesn't look optimal. I did a lot of searching but couldn't find much info on directing flow front the reed tunnel to the crankcase. I assume Wobbly would be full of asymmetrical reed tricks to direct the flow up the sides, but I'm more curious about port shape for now. The other thought I had was on the edges of the reed box, where they aim at the transfer ports. Is it a good idea to radius the sides and top of the tunnel to turn the flow out and up, into the transfer ducts?

P.S. the intake and exhaust port are on the same side of the engine.

[wobbly]

Contrary to the old wives dept pronouncements there is no useful flow from the reed tips until near TPO.
Thus cutting the piston skirt narrower does all but nothing - been there done that.
But cutting the tang into a tongue shape with a radiused face both vertically and horizontally does help flow,as does the side rads
as you have drawn.
If you can draw the reed block triangle shape on the side walls of the box, then tapering outward as they go inward , extra pockets above and
below the triangle will take advantage of spill over side flow from the reed.

[peewee]

wob dont you meen TPC ?

flycat there should be some rsa crankcase photo around here that will give you good ideas. as you probly already know, air fuel mix will be more willing to follow a radius corner (bigger the better) as opposed to something sharp, like your inlet sides where they enter the crankcase. ive also noticed on a few case reed designs that the inlet floor has some what of a upward ramp. i seen a cr250 with such a ramp . had a look at a new ktm which had a floor ramp also. cant figure out why the photos always go sideways from my phone but you get the idea

[flyincat]

Thanks, wobbly and peewee.

Regarding the tang, remember this is a non-conventional setup with the exhaust above intake. The top of the crank is rotating towards the intake, which makes that tang the primary thrust surface. I think your idea of making the tang tongue shaped would definitely open up some flow area, just not sure how much is safe to remove. Then again, the bottom of the tang is probably doing jack nothing for structure. Plus, the boost port (c port) is on the opposite side so the tang doesn't help divert flow into the boost port as it might with conventional engines. Most of the tangs on other engines I've seen are much smaller on the intake side. Is there any value in adding a 'splitter' to the roof of the duct to attach some flow to the tang?



I couldn't find pictures of the aprilia reed duct but I found some good TM pics. Wob, I see what you're saying about the reed duct walls. My question is, what shape are the walls where they diverge from the square walls. Square walls in RED. What shape does the BLUE area actually take, looking from the top view? Is there a strategic aiming point (A duct, B duct, etc.) that the wall aligned with? Also, the radius on the top and side of the duct exit into the transfer ports is relatively small, maybe 6mm or less. Is there a reason not to make this radius much bigger? Maybe this gets back to the aiming?

[jfn2]

flyincat
Here are some pics (I hope) of some reed entries into the crankcase.
First is of the stock case, then cut down to the crankwheels and rounded into intake, metal permitting.
Last pic is of tangs hanging down into port that need rounded.

[flyincat]

jfn2 - Awesome pictures of the zuke! Thanks for sharing. That's quite a bit like I was imagining, except for the tang situation of the laydown engines. What power levels does that intake porting start to make a big difference? In the last picture, what's with the upwards boyesen ports??? Do those point up into the B duct? I'm having a hard time looking at the screen upside down and sideways to visualize where those go. haha

[wobbly]

My apologies yes TPC is correct - fingers slower than brain.
What you have here is a classic catch 22.You are trying to promote flow forward and outward , around the corner into the
cavity below the transfer duct entry.
But at the same time trying NOT to increase the area/volume in front of the reed block tip , as this does nothing in helping energy recovery
from the slowing intake velocity.
I have not actually tried this in a TM yet, but as you mentioned that biasing the flow regime to the upper reed ports works very well, then
by inference biasing the reed tip exit flow ( from the sides as well ) by creating a tapering outward ( as it goes forward) extra duct in the top
1/2 only above the triangle , would seem to be the logical extension.
But being a 2T this of course probably has no truck in reality.

[flyincat]

What is the reason, or sequence of events, that makes aiming the intake up into the transfer duct advantageous? If there is minimal flow through the reed until after the TPC, why worry about flowing into the transfer duct first? It can't be that it helps on the current intake/compression cycle. Is there a reason it's better to fill the hard to fill places (transfer ports) first?

[jfn2]

flyincat
Here are some more pics of the extra ports. This is not my engine so my info is limited. I have not done this to my cat yet but it is on one of the back burners.

[wobbly]

Dunno what the actual flow regime is inside a working engine - except to say that every time TM have angled the carb/reedblock downward
and angled the cylinder backward such that more flow exiting the reed tips is aimed at the transfer duct entries , it makes more power.
Same with agressively biasing the reedblock exit flow out from the upper reed ports.