ESE's works engine tuner

[wobbly]

It has been my experience with many reed engines that do NOT have any where near all the design elements correct ( like the Derby did after Jan )
for making big bmep numbers - that going under 1.3 CCR yields no better power.
As always there is alot more to this than meets the eye, as I have recently done a little more work on a KZ10B kart engine.
I spent hours stripping and machining 5mm off the reed face on the case and enlarged the trenches for the reed block screws to make it fit.
Now this ( my ) engine makes 47 Hp at 13,000 so must have most of the ducks in a row - but it now has a 5 mm spacer behind the reed.
So a blanket statement that claims big cases make more power in reed engines is over simplifying rubbish.
But as part of that test session I fitted some experimental plastic plugs to the piston and ground the Aux around to bore centre with
nice radial pockets on the rear entry walls.
This added 3.8 Hp at 14,000, a 10% increase in power over the stock setup at that rpm - now thats a result.

[Martin1981]

yes muciek, i know all that because i read every post of wobbly. but i am a little bit confused because jan thiel obviously went the other way and enlarged the crankcase more and more not only on the rotary valve engine but also on the reed valver.

so what is right? the bigger the better or a certain ccr like wobbly is saying?

[Flettner]

Off the pipe you want a reasonably small crank case, on the pipe it almost can't be too big. Assuming a good pipe and port design.
You kind of need dual cankcases volumes.

[Martin1981]

ok and that spacer BEHIND the reed keeps the intake tuned length correct?

[Frits Overmars]

i am a little bit confused because jan thiel obviously went the other way and enlarged the crankcase more and more not only on the rotary valve engine but also on the reed valver.

Jan did not enlarge the crankcase volume on the Derbi reed valve engine; it was already big; a reed case has a lot more volume than a rotary valve duct.

[Frits Overmars]

Off the pipe you want a reasonably small crank case, on the pipe it almost can't be too big. Assuming a good pipe and port design. You kind of need dual crankcases volumes.

True, Neil. Off the pipe you need a pump with the minimum amount of dead volume; on the pipe you'll want the engine to breathe directly from open air (mixed with a bit of fuel and oil). But that oil has to pass through the crankcase to keep the bearings happy. Hence my 24/7-setup

[wobbly]

There are several issues involved with the reed engine and its case volume - that has effects not seen in an RV setup.
The bigger the case the less are the pressure swings from piston movement and the pipe action ( assuming the same depression at the Ex port created by the pipe )
around BDC.
This changes the tuned frequency of the case vol, but this also requires thinner reeds to get them open fast and far enough.
Of course changing the reed stiffness then changes the intake tuned frequency,they then hit the reed stops and flutter uncontrollably - and so it goes on and on.
I tried machining the KZ10B case back to make the volume smaller as I already had the 5mm laser cut spacer from a test making the case bigger by pushing the reed block outward.
This failed miserably, so of course you then go the other way - this also failed,but only partially in that I did not then try differing reeds to compensate as I should have.
Adding a spacer behind the reed block HAS NOTHING to do with the intake length, this is already as short as it can be, with the rubber manifold recessed into the reed stuffer.
All I can say is that from a huge amount of sims and real world reed engine testing, that a very well tuned engine with good power capability ( bmep ) likes the case down near 1.3.
An engine with less power ( bmep ) capability ( for whatever reason ) tends to respond better to the case closer to 1.4.
When you are making 8 Bar and or 14 Bar BMEP of course these exceptions to the norm tend to prove the rule of thumb.

[Flettner]

True, Neil. Off the pipe you need a pump with the minimum amount of dead volume; on the pipe you'll want the engine to breathe directly from open air (mixed with a bit of fuel and oil). But that oil has to pass through the crankcase to keep the bearings happy. Hence my 24/7-setup

Might get to try that soon, the sleeve engine cases are not too far off finished. First I will be running just normal reeds.
You may have seen earlier, LM13 plates well. I've had all my Heat Ranger cylinders done. I sent them an offcut from the casting process to test first. FOS pattern has stalled due to having to get these Heat Ranger engines out.

[peewee]

Summary: you need a large crankcase volume. Ideally all of this volume should be situated in the transfer ducts. In real life you will also need to lodge part of this volume between crankshaft and piston, i.e: use a long con rod. Avoid nooks and crannies. Crankshafts should be small and smooth. Big end bearings must never be shrouded by recesses in the crank webs or by stuffers.

this is why i was thinking you could stuff the voids near the big end pin (but not shroud the big bearing) on these twin cylinder cranks like the pic i posted, either with carbon fiber, the material that wobbly suggested or simply using plastic like ktm has done for years, then of course just screw the stuffer into the side of the cheek. then the lost volume from stuffing the voids, you can gain that volume back via longer conrod. if my thinking is correct, this would now put all your volume above the crank cheeks and at the transfer entry, rather than have voids down low in the crankcase during the transfer phase. maybe the performance difference wouldnt be much but atleast you would end up with a rod ratio probly around 2.15-2.2 ( just guessing as i havent calculated it), which doesnt seem like a bad thing for high rpm

[wobbly]

But by adding the stuffers into the crank you loose more volume than you gain by adding 115 long rods ( that fit straight in )

[peewee]

But by adding the stuffers into the crank you loose more volume than you gain by adding 115 long rods ( that fit straight in )

from my calculations i think your right but who said anything about using 115 rods . theres even longer rods that fit right in . might even be something around +120mm that would fit right in, or require just a alittle machine work, i havent looked into this option yet though. just eyeballing the size of the stuffers needed, im guessing somewhere around 120mm is what would be needed to be at 1.33ish, this is just a guess though. i had it written down somewhere but with 64 bore,58 stroke, 118 rod and 513 series piston (standard wristpin location), it was 1.31 if i recall, ill try and find my notes. i do have a crank sitting around i could check the volume of the voids and get a pretty good idea what length of rod would be needed to recoup the stuffer volume, based off my previous calculations. ill have a answer in the next few days as im curious to this

[TZ350]

Things going on at Team ESE



Chambers is trying his hand at water cooling a GP100 cylinder.

He made 22 hp with this cylinder before when he ran it at Taupo a few years ago, but now that we know a bit more about 2T tuning I expect he will be able to improve on that.



Husa put me onto this KE175 rotary valve cover.

Much bigger RV disk than the GP125's one. And it looks like I will be able to get it to fit Ok, so its looking ever more promising for the air cooled, plenum chambered, power valved, variable chamber pressure, digital ignition, fuel injected, broad power spread 36rwhp GP/RGV125.

Richban sent me a good NSR250 cylinder for version 2. I already have some RS pipes so with a few mods to make the cylinder as close as possible to an RS125 cylinder (but with a power valve) and a re stroke of the GP crank, I won't hold my breath, but who knows, maybe it could be the first Bucket to touch 40.

[Flettner]

Things going on at Team ESE



Chambers is trying his hand at water cooling a GP100 cylinder.

He made 22 hp with this cylinder before when he ran it at Taupo a few years ago, but now that we know a bit more about 2T tuning I expect he will be able to improve on that.



Husa put me onto this KE175 rotary valve cover.

Much bigger RV disk than the GP125's one. And it looks like I will be able to get it to fit Ok, so its looking ever more promising for the air cooled, plenum chambered, power valved, variable chamber pressure, digital ignition, fuel injected, broad power spread 36rwhp GP/RGV125.

Richban sent me a good NSR250 cylinder for version 2. I already have some RS pipes so with a few mods to make the cylinder as close as possible to an RS125 cylinder (but with a power valve) and a re stroke of the GP crank, I won't hold my breath, but who knows, maybe it could be the first Bucket to touch 40.

Make a cylinder.

[husaberg]

Things going on at Team ESE

Chambers is trying his hand at water cooling a GP100 cylinder.

He made 22 hp with this cylinder before when he ran it at Taupo a few years ago, but now that we know a bit more about 2T tuning I expect he will be able to improve on that.
.

Make a cylinder.

Aren't those GP100's 3 port anyway?

[chrisc]

Nope. Single like the 125