ESE's works engine tuner

[jonny quest]

With a counter rotation crank against inlet flow, it cost 1 to 2 HP if I remember correctly.

Wouldn't building a divergent floor above crank wheels on a standard rotation arrangement really have no effect?

[jfn2]

Wobbly ;
Here are some other pics.
http://www.kiwibiker.co.nz/forums/al...p?albumid=5033
Except the radius for the boost port opening, is this something of what you mean?
And am I to add material clear back under the reed block, or at least back to the reed block, top and bottom?
jfn

[karter444]

Lowering the transfer bottom edge to BDC for sure increases the STA, but it also dramatically increases piston cooling
from the transfer streams attaching to it,right from the timing edge.

Hi Wob thanks for the reply I would have thought having a cooler piston edge would be better but are you saying that having the transfer stream attach itself right from the timing edge is not what you want
cheers

[wobbly]

JFN2 - yes adding epoxy/weld to the floor to speed up and direct the flow over the flywheels ( even though they are spinning in the right direction )
will help power.
And if you can fill in the floor and roof so that the petals are just clearing at full lift,then this will help as well.

Richard - as the majority of bulk flow is around BDC,then you want the streams to attach right at the timing edge, not jump over a ledge
then onto the piston crown.

[lodgernz]

JFN2 - yes adding epoxy/weld to the floor to speed up and direct the flow over the flywheels ( even though they are spinning in the right direction )
will help power.
And if you can fill in the floor and roof so that the petals are just clearing at full lift,then this will help as well.

Wobbly, I assume you've only been talking about case reeds in this discussion. Do you have any tips for improving the flow in a cylinder reed engine such as the Honda NSR 50, where the reed box empties into both the case and the cylinder?

[wobbly]

Yep, the whole deal with cylinder reeds to is get as much unobstructed flow area directly into the case as you can.
Thus floor ports and Boyesens should be as big as possible.
Then the piston skirt should be as short as possible, and any holes as low and as wide as you can get them on the skirt.
One idea that works well is to turn normal Boyesens into partial floor ports by hogging them out downwards, and then cut away the rear vertical wall of the B transfer
entry in the case at an angle.
Going higher with the Boyesens upsets the flow regime in the B duct too much, and the flow ends up running across and crashing into the transfer divider wall.

[SwePatrick]

Crazy swedish build, 1st testdrive, no tuning yet.
Evinrude twostroke v8 with pipes in an Volvo amazon(dragracechassi)

https://www.youtube.com/watch?v=mrhs...&feature=share

[FastFred]

Crazy swedish build, 1st testdrive, no tuning yet.
Evinrude twostroke v8 with pipes in an Volvo amazon(dragracechassi)

https://www.youtube.com/watch?v=mrhs...&feature=share

Love it .....

[wax]

Yep, the whole deal with cylinder reeds to is get as much unobstructed flow area directly into the case as you can.
Thus floor ports and Boyesens should be as big as possible.
Then the piston skirt should be as short as possible, and any holes as low and as wide as you can get them on the skirt.
One idea that works well is to turn normal Boyesens into partial floor ports by hogging them out downwards, and then cut away the rear vertical wall of the B transfer
entry in the case at an angle.
Going higher with the Boyesens upsets the flow regime in the B duct too much, and the flow ends up running across and crashing into the transfer divider wall.

That's interesting wobbly thanks for that. I'm working on a cylinder reed now. Would it pay to have the biggest reeds possible in a cylinder reed system then ? What the downside of having to bigger a reed

[wobbly]

The downside is loosing velocity thru the reed ports.
As an example if you take a CPI Cheetah 400 cylinder for a Banshee and use the VF3-CR250 reedblock that its made for
then fit the smaller VF3 - CR125 block with a spacer ( as the reed block is 6mm narrower ),the power increase is 6 RWHp in the mid
and 2 RWHp at peak.
What tends to happen with the smaller reed is that as you push toward its flow limit by making more power, the petals will stay open longer, due to the increased velocity and column inertia.
In most cases a VeeForce in the hole will be able to flow more than is needed, and keeps the velocity up by utilizing low tip lift thru the large port area available.

[wax]

That makes sense. Thanks for that, basically the smaller reed ends up using the mass weight of the air traveling at a higher speed to stuff the cases more. Thanks a lot for that

[wax]

That makes sense. Thanks for that, basically the smaller reed ends up using the mass weight of the air traveling at a higher speed to stuff the cases more. Thanks a lot for that

The cylinder on the right is the one I'm using. As you can see it has a massive reed area. I was looking to use v-force reeds in it. But this may increase the reed volume to much. This is a 550 Kawasaki Jetski cylinder

[dented]

Hey sorry to butt in on this thread, Im trying to get hold of wobbly to see if I can get a custom pipe job done in Tauranga. Wobby, if you see this can you reply with some way to get hold of you please

[wobbly]

Well the smaller reed may not in fact fill the case " more ".
All depends upon how big the " big " reed is and how small the other.
As the small reed can quickly run out of intake area, the Cheetah version I gave is limited to about 120 Crank Hp with the CR125 VF3.
Over that the CR250 beats it.

EngMod gives you the port and tip lift area /power capability of any reed,so if you want to get an optimum setup in the 550 then PM me and
get the stock block sorted first.

[lodgernz]

Thanks again Wobbly.