ESE's works engine tuner

[andreas]

I am finishing of the sim results for a 20,000 rpm 35cc RC boat engine and was asked if it was possible to turn the cylinder 90* such that the small end pin faces the Ex on one side and the boost port
on the other . This would give a dead straight pipe out the back of the hull , making a very tidy package .
The new engine design has a reed box added on one side pointing upward under the cylinder like a KZ.
I know there are various pro's and con's with turning the cylinder , but I am most concerned about the ring bulging into the Ex port - sideways, not on a thrust face , but the ring pin
could still be positioned opposite the Ex port.
Plus then the inlet flow will be asymetric , a bit like a RV on one side.
But there will be no small end port linking.
What have I missed as being a good or bad technical reason if doing this .

I assume it doesn't, but in the event of piston transfer cut-outs there may be two problems.

[Vannik]

I am finishing of the sim results for a 20,000 rpm 35cc RC boat engine and was asked if it was possible to turn the cylinder 90* such that the small end pin faces the Ex on one side and the boost port
on the other . This would give a dead straight pipe out the back of the hull , making a very tidy package .
The new engine design has a reed box added on one side pointing upward under the cylinder like a KZ.
I know there are various pro's and con's with turning the cylinder , but I am most concerned about the ring bulging into the Ex port - sideways, not on a thrust face , but the ring pin
could still be positioned opposite the Ex port.
Plus then the inlet flow will be asymetric , a bit like a RV on one side.
But there will be no small end port linking.
What have I missed as being a good or bad technical reason if doing this .

Biggest issue would be, I think, the piston cam being in the wrong direction, but I am not sure how big this is on small engines.

[Muhr]

What have I missed as being a good or bad technical reason if doing this .

maybe you'll have problems with piston rocking in BDC if you have some unfavorable geometry between piston and cylinder when you turn the cylinder?

[breezy]

Can I just remind everyone that the name of our 2-Stroke Stuffing hero is Alex Degnes, not Agnes. His KB id is adegnes.

there you go, got my glasses on now

[wobbly]

Neels , something I had not thought of ! , but arent both cam and taper to correct for the temp delta down the skirt , along with the naturally greater expansion of the mass around the pin bosses.
The pistons are being custom made ,so skirt cutouts and cam can be reorientated to suit as is needed , if I take the plunge and spin the cylinder.

[TZ350]

but arent both cam and taper to correct for the temp delta down the skirt , along with the naturally greater expansion of the mass around the pin bosses.

Yes, the taper compensates for the greater expansion at the piston crown and the cam for the greater expansion of the mass around the pin bosses. I expect the orientation of these should be the same regardless of the position of the exhaust port. A four stroke piston will have the area of the ring lands turned down smaller than the skirt. My 2cents worth.

[lohring]

I am finishing of the sim results for a 20,000 rpm 35cc RC boat engine and was asked if it was possible to turn the cylinder 90* such that the small end pin faces the Ex on one side and the boost port
on the other . This would give a dead straight pipe out the back of the hull , making a very tidy package .
The new engine design has a reed box added on one side pointing upward under the cylinder like a KZ.
I know there are various pro's and con's with turning the cylinder , but I am most concerned about the ring bulging into the Ex port - sideways, not on a thrust face , but the ring pin
could still be positioned opposite the Ex port.
Plus then the inlet flow will be asymetric , a bit like a RV on one side.
But there will be no small end port linking.
What have I missed as being a good or bad technical reason if doing this .

For some reason, our testing showed slightly lower power on rear exhaust engines over conventional side exhaust engines. We couldn't come up with a good reason and set records with both side and rear exhaust Quickdraw engines. If the engine has open transfers like the early RCMK engines, you will get very rapid piston wear. Most of us have figured out how to package engines in hulls by tilting the engine when necessary, ie scale boats.

Boaters worry about air resistance, but it is insignificant compared to water resistance. The water drag on an object is 800 times its drag in air. Exposing the cylinder and pipe won't slow down a model boat a measurable amount at the sub 100 mph speeds we run. I won a free lunch from my partner on this issue. We did gain 6 mph at 100 mph with a rudder redesign to a thinner and smaller rudder.

Lohring Miller

[lohring]

My measurements on my 32 to 36 mm bore pistons show very straight and round sides. We often turn down the ring area .001 to .002" to prevent seizing. The water cooled cylinders are slower to expand than the pistons at our considerably higher than stock power. Stock engines, even with tuned pipes, don't need this.

Lohring Miller

[TZ350]

Attachment 347767 Attachment 347768 Attachment 347769

Sick Dyno. The Team ESE Dyno has become sick. Apparently there is a keeper battery inside the WinPEP electrical stack that keeps everything alive.

According to DynoJet the battery needs replacing and the firmware re flashing. But they no longer support this legacy model.

Replacing the battery looks straight forward.

But ... Help Needed. Has anyone faced this firmware problem before and can help with advice about getting the stack going again.
.

I measured the old battery’s voltage and it still had 1.7Volts so fingers crossed and following Chambers suggestion I piggy backed another battery onto it.

The Computer now communicates with the Stack.

When I roll the drum by hand the computer registers a change in speed on the screen. So looking hopeful.

I will know more later when we try a dyno run. Hopefully the Stacks brain has not suffered any brain damage from being starved of electrons.

[TZ350]

Flettner riding his 350cc Fuel Injected Kawasaki F5 BigHorn.

[wobbly]

Lohring - the engine is an all new design and will have a CNC case and printed cylinder , with scaled Aprilia inspired teacup transfer ducts so piston wear wont be an issue.
My main + for turning the Ex to the back was getting rid of a 100* bend in the header , but hey , if you have tried this and made less power , thats good enough for me.

[jamathi]

Lohring - the engine is an all new design and will have a CNC case and printed cylinder , with scaled Aprilia inspired teacup transfer ducts so piston wear wont be an issue.
My main + for turning the Ex to the back was getting rid of a 100* bend in the header , but hey , if you have tried this and made less power , thats good enough for me.

Those who tried this had BIG failures, on 50cc engines.
Better have a bend in the exhaust pipe I think.
An engine like this was made for Garelli by an Italian engineer.
In one year it failed to finish one single lap at Monza.
A big failure, it ended in a tribunal.....
One friend of mine in Holland tried the same, also on a 50cc.
It went hopelessly wrong!

[andreas]

Soon it will look all new

[lohring]

Lohring - the engine is an all new design and will have a CNC case and printed cylinder , with scaled Aprilia inspired teacup transfer ducts so piston wear wont be an issue.
My main + for turning the Ex to the back was getting rid of a 100* bend in the header , but hey , if you have tried this and made less power , thats good enough for me.

We run nitro engines with a 180 degree header bend because they were originally designed for airplanes, not boats. All the side exhaust engines run a variety of pipes with various bends. It doesn't seem to matter from a power standpoint. By the way, how are you going to machine teacup transfers?

Lohring Miller

[mantonakakis]

Soon it will look all new

Did your RD lose a cylinder??
My RD125 is running again as of yesterday, with freshly-rebuilt crank (new rods, big-end bearings and pins) and bottom end. I chose double the fun for my first attempt at a crankshaft rebuild... Time for a little tuning today, then starting work on porting and pipe plan. One of the main restrictions will be the stock reeds, do you have the main dimensions of your RD250 reed block, or happen to know of bigger reeds to fit the 125?