ESE's works engine tuner

[Frits Overmars]

I did once have the faces treated with a PTFE piston coating on a 20,000 rpm RV engine and this reduced the disc and case wear to nil.

Wobbly, I wonder how long the PTFE coated cases would last, what sort of hours did the PTFE coated cases run for, is this something you are going to do again or would you use a more modern coating today?

Emot (www.emotracing.com) recently brought out all-synthetic rotary disk faces and covers, produced from Ertalyte TX (PTFE-filled polyethylenterephthalat); http://www.professionalplastics.com/...lyteTXData.pdf). Wear and friction are ideal, as is heat insulation; ignition pickups love it.

[seattle smitty]

Wobbly, I wonder how long the PTFE coated cases would last, what sort of hours did the PTFE coated cases run for, is this something you are going to do again or would you use a more modern coating today
Cheers

RAW, for a CHEAP, low-tech, effective coating you can do yourself, for an aluminum rotary valve case and numerous other purposes, look at the pages around P. 1021 (#15312) for KG Industries "Gun Kote" heat-cured spray-on moly coating.


(EDIT) I keep hearing from others here that they've tried one or other baked moly coatings and that it "wears quickly." I'm guessing that they are applying a too-thin coating so that they can retain their normal clearances. The way to do it, however, is to start with enough extra clearance that you can put about a .002"/0.05mm coating on the part. The first half-thousandth burnishes down very quickly, but after that the remaining coating holds up rather well (depending on your use). If you do a bad job of coating, and have to remove the coating and start over, you'll find that's not so easy . . . . As for clearancing for coating, that's easy with rotary valve cases: you coat both the inside of the case and the mating surface of the case at the same time and automatically get about the right clearance. I don't argue that that various high-tech plastic coatings suggested here aren't better than the molycote; they surely are better, but this is very cheap, you do it yourself, and you can re-do it easily, as needed.


Poor little bird! Years ago a friend of mine was making a kilometer record run at Devil's Lake, on the Oregon coast. Lucky for him, he was running in one of the smaller stock classes, making 70-75mph, when a big seagull tried to cross the lake in front of him and didn't make it. That big bird was smashed against the forehead section of his helmet, and Bob said it nearly broke his neck and nearly knocked him out of the boat. Another guy I know, a Boeing engineer, used to operate the "chicken cannon," which fired chicken carcasses at the outside of mocked-up cockpits to test aircraft resistance to bird-strikes. He said the chickens frequently "won" . . . .

[F5 Dave]

Don't use frozen ones!
Meh old joke.

Seagulls are proper hard. I killed one at 50kph in the work van as a teen. I stopped and walked back to get it off the road, briefly entertaining the idea of leaving it on the bosses desk explaining the dent on the front of the van.

Halfway back to it The dead bird shook. Picked itself up and flew away. Sheesh.

[jasonu]

Yes its tuning related.

The ram air on the NSR300 is working strong. But maybe some sort of mesh needs to be added. Or this could happen again.

Bird sucked through the front intake and into the carb. Poor thing. Not pretty.

Was not my 300. Happened on the other one today at Manfield.


Attachment 308255Attachment 308254

Many moons ago Dave Diprose did back to back dyno runs with his TZR50. One with and one without a mesh screen covering the carb intake. No other changes. The screen cost HP, one of them IIRC.

[wobbly]

The coating I used on the RV screamer motor was for piston skirts and was done by HPC in Auckland.
This was a "proper" solid etched on coat, not the simple running in dry lube film type that wears away quickly.
It was still intact after a whole season of racing, with no wear on the surfaces, just some scratches around the port from no filter.
But I really like the idea of using a low friction material for the cover - and an insert in the case, easy to do with my Solid Modelling and Fletts CNC machine centre.

Re the Ibea carb - fast 50cc race engines are using 30mm carbs, so that wont be near big enough for a road racing 100cc.
In many applications I have seen of late one big issue seems to be the trouble around getting the intake tract dead straight.
There a several Keihin D slide downdrafts with steep intakes and horizontal bowls in the right size as well as Lectron/SmartCarbs that can be run very steep in the 34/36 bore size you need.
Having no bend in the manifold is an easy couple of Hp free, worth having if you are in the 30 Hp bracket ( or any bracket in reality )

[Tim Ey]

Talking about straight intakes:

I have a question to all the reed valve modificators and EndMod2T users out there, perhaps you, Wobbly? :-)

What kind of Area distrubution would you choose on a reed valve engine from carb to the petals?
Let us say we have a carb with 39,5mm at the slide, 40mm at the flange and a reed with an steamwise area of also 38mm.


Especially when you look on older engines like an RZ350 YPVS, the Reeds have a very big capacity right in the reed valve. I assume that not to be good.
Why? The Petal is opening when the pressure in the crankhouse is lower than the pressure before in the reed. So if the petal opens and a volume element of mixture travels through the reed into the crankhousing, the pressure drop is getting lower. If you have a big volume to feed from in the petal, the petal is closing right away...

The other extreme would be a really tight bottleneck right before the petals - to keep the flow velocity high right before the petals.




Like in this CR125 Boyesen-Reed.

What would you guys do?

Greetings from Germany
Tim

[wobbly]

The only good thing that the Boyesen reeds taught us was that the " stuffer " between the manifold exit and the reed tip exit was developed on
a flow bench to keep the flow area ( and thus the velocity ) virtually constant.
The stuffer takes into account that the reed width is generally alot wider than the entry diameter, and coincidentally the vertical height is reducing as the flow approaches the tips.
Filling in the sides with a well shaped stuffer insert keeps the area constant and directs the flow such that all the petals are opened equally by the same velocity.
What Boyesen did do was to direct the flow around the turn correctly to try and equalise the tip lifts.

One thing you need to realise though is that there is just as much positive pressure ratio developed on the intake side of the petals, from the sonic tuning of the intake length, as there
is a negative pressure ratio pulling flow thru from the case.

Here is an example of the very best setup I have done for the 30mm carb on a KZ2 - 125 engine.
This flows around 12% more air on a bench and makes around 1 1/2 Hp more than stock at peak, and near on 4 Hp at 14,000.
It divides the flow into 4 quadrants feeding each petal equally with the CNC insert,plus the plastic stuffer keeps the area constant right into the reed V.

[Frits Overmars]

....if the petal opens and a volume element of mixture travels through the reed into the crankhousing, the pressure drop is getting lower.

It's even worse than you might imagine, Tim. And that goes for all reeds.
Experiment: take a sheet of paper between your finger tips and blow along it; the moving air will create a depression that will try to move the sheet towards the air stream.
The same thing happens inside a reed valve. As soon as air starts flowing, it creates a depression inside the reed cage which will try to suck the reeds towards each other. In short: the flow through the reed valve will try to close the reeds! Oh, the beauty of rotary valves...

[senso]

Interesting talk about reeds, some time ago I designed a couple stuffers for a YZ80 reed cage, but reading all this and my new SolidWorks skills I might re-visit the topic and redo the stuffers to aim from a more constant area transition than my older eyeballed sort of exponential diffuser.
I think I have not shown them yet:





And another stupid question(sorry, I still have a lot of them to do ), where can I find a sparkplug blueprint, I'm sort of designing a two part head/combustion chamber and for the love of my life I cant find a nice blueprint/diagram with all the dimensions for a common 2 stroke sparkplug.

Best regards.

[peewee]

The RZ/CPI has a severe down bend in the intake, thus the majority of the flow adheres to the roof and of course punches open the upper
reeds way more than the lowers ( made worse by the fact that the Boyesens are on the reed box floor ).
With a VF3 in place you can make a curved blade the same thickness as the VF divider at one end ( with a ball nose radius to fit over the leading edge )
tapering down to a small radius facing the carb.
By raising the leading edge of the blade you can equalise the upper and lower reed opening ( that is the flow ).
Easy to test with a vacuum cleaner hose connected to the exit ( or a leaf blower, or if you are really desperate the exhaust pipe on your car - been there done that ).
Of course the flow bench with a velocity pitot is the real go.
I did this on a CR250 on a kart and picked up 3Hp from memory.

instead of using a curved blade fitted to the divider, what about making a straight intake manifold, then use one of them new pwk carbs (like on the ktm 250/300) that are intended to be used in a forward sloping angle. was thinking about this idea and it would reduce and maybe eliminate the downward kink at the intake manifold/reed block junction. you can see these carbs can function at a fairly steep forward angle. all i would need is to make some straight or nearly straight intake manifolds.

[seattle smitty]

. In short: the flow through the reed valve will try to close the reeds! Oh, the beauty of rotary valves...

Yet we might expect you to be the last person to say this, Frits!

Rotary valves are an almighty PITA to hang on an engine, and I greatly admire the imaginative ways people here resolve this, very cool stuff!! But you came up with the 24/7 concept; shouldn't that render all of this effort unnecessary??

I'm wondering if you have found in testing that as elegantly simple the 24/7 intake is as a concept, maybe it turns out to be a very hard thing to tune in practice. Yes? No? My uneducated guess is that your swing-away valve method of creating a 24/7 intake might make it hard to get the carburetor to work across the whole rpm range. That's why I liked the idea of splitting the job between two carbs, one primary carb (over a reedblock) that's drawing all the time, and a second carb (over the 24/7 intake tract) that is only open for and tuned for when the pipe goes to work. Maybe a little more complex mechanically, but maybe simpler to tune . . . ???

[TZ350]

Team ESE are getting serious about RG50's and the F5 class.

There is a RG/RS setup and a RG50 as a donkey for engine development.

The aim is to build and campaign an original RG50 engine cylinder and head (with insert) that is better than the current crop of European 50's with their after market cylinders.



We are near 14hp with the RG50 now and expect to see 16 or 17 after a bit more development.

Kel drew up an insert design and Sketchy is making a few up for us and machining the original RG50 heads to take them.

A one off could have been done in the lathe but we want to be able to easily and accurately duplicate any good results that we get.

[Tim Ey]

Thanks a lot guys!

@Wobbly, good to know about the KR1 Reed - as its "big" brother incl screw-on cage is going to be my next conversion :-)


My approach was to buy also this reed to test: http://www.adrenalin-pedstop.co.uk/p...25cc-3807.aspx
As It has the same width as the KR1 and I know a lot of guys who gained power with it (on a rotax 123 engine 1hp more than a Vforce3, even 2hp on a honda RS250 engine with JHA Cylinders and pipes from the original reeds)
A question to your CNC Stuffer: Why did you make the dividers in the petal-plane so short? Why not reed petal length (same lenght as the vertical divider)

@senso. It this 3D Printed ABS? I guess that wont survive very long...

[TZ350]

Making progress with mapping the fuel injection.

Did a series of runs at different throttle openings 100-90-80-70% etc and it fell apart at 40%.

I will have to sit down now and look at the recorded run data to see why, it may just be to rich or something else, like the injectors are still to big or not crossing over nicely at 8-9,000 rpm.

[F5 Dave]

In 15years I never managed to get much past 14 from an RG. Mind you I've learnt a lot I'm the last few reading this thread. But its parked now the Derbi is going. . . no better than the RG at this stage.