ESE's works engine tuner

[F5 Dave]

Err, squish should be 0.5. Never got that high a reading on the dyno I use, but hadn't redone on that dyno since Sketchy reshaped the head.

Don't remember it falling off quite so steep, but certainly was never ideal there. Sub ex ports were left close to std size as this was done well before I'd seen a modern barrel with enormous sub's. That would have to help blowdown and overrev, but mean a replate.

[speedpro]

It's not the ignition killing it? That is so steep it almost looks deliberate, as in a limiter kicking in.

[F5 Dave]

Actually that'sworth checking, we messed around with a curve on sketches dyno but got no gain over a flat line, but we were like super pressed for time, Icould have used one of the MB files and that was only peaking at 12.
So it got put in the worry about it later file.


I never rode it after myself.

[CunninghamJames007]

For a quick experiment, we tried running a 25mm long PVC tube on the end of the carb. No peak power was lost and about 0.5-1hp was gained in the mid range. No change to the over rev wall.

If I could add my 2 cents' worth, I found a good article on designing openings for carburetors that may be of some use.
http://www.fxr150.co.nz/forum/showth...tor-Bell-Mouth

[Jvenni]

Depending always on the track you need to try many combinations of pipe length and timing.
Less timing ( 1.2 ) = more egt and more overev power, this usually compromises the off corner drive ( but this is easily fixed with a 1/2 tooth on the back ).
Depending upon the fuel, you may find that even more timing ( 1.8 ) will give you plenty of bottom end, allowing slightly
taller gear ratio to gain the speed.
The short exhaust manifold also increases the overev power even more, but again what you gain on top you loose down low .
But with the correct combination, the short gearing and the ability to rev harder is always quicker.
Just changing the gear,and reving hard wont be fast unless the whole engine package is set to run that way.
You need to find the combo that works best for that particular track, and especially where the first 5 karts are maybe 2/10 apart, every tiny detail counts.
We regularly rev to 14,8000 with a ton of timing, a short pipe and run at 680*, but you will need really good reeds ( nothing like stock at all ) to get power up at that level.

What I dont understand is that even with the shorter gearing you are pulling way less rpm out of the hairpin,and way less corner speed, so of course it will be slow.
In that case the shorter gearing ( yellow ) should have the exit rpm way higher, and then accelerate faster - but its not,so something else is badly wrong

Thanks for answering !

we try to run as short as possible but the available grip at is also part of the puzzle. If i go too short we will lose time by having too much slip at corner exit. I adapt to make the turn tighter to settle more into the grip available. gives lower speed in the corner but at corner exit and straigth shorter gearing is certainly faster. Beeing in the rev area of 10700 makes the engine a bit tricky to handle on exit In race conditions we sometimes use a longer gearing to be more defensive at the long straight.

So if'm right we will lose some bottom end with the higher blowdown but we have to figure out how to win more at top ( and how to use it ) .We have checked the ignition timing and it was set a bit at the early site, next week we go to the next race track for training and try out what works best.

If I compare the pistons before and after grinding the moons, the piston is more clean at the exhaust site. This is also caused by the exhaust length / ignition timing not ok ? With this latest type of the engine we also have a lot ( need to clean it after every race weekend ) of carbon build up at the exhaust site of the cylinder head. A nice perfect triangular starting from the spark plug towards the squish edge.
What has changed on this engine type is that the cylinder has less angle/more straight on the engine block and the main transfer ports are made smaller. Maybe the booster port too strong ?

[Jvenni]

Thanks for answering !

we try to run as short as possible but the available grip at is also part of the puzzle. If i go too short we will lose time by having too much slip at corner exit. I adapt to make the turn tighter to settle more into the grip available. gives lower speed in the corner but at corner exit and straigth shorter gearing is certainly faster. Beeing in the rev area of 10700 makes the engine a bit tricky to handle on exit In race conditions we sometimes use a longer gearing to be more defensive at the long straight.

So if'm right we will lose some bottom end with the higher blowdown but we have to figure out how to win more at top ( and how to use it ) .We have checked the ignition timing and it was set a bit at the early site, next week we go to the next race track for training and try out what works best.

If I compare the pistons before and after grinding the moons, the piston is more clean at the exhaust site. This is also caused by the exhaust length / ignition timing not ok ? With this latest type of the engine we also have a lot ( need to clean it after every race weekend ) of carbon build up at the exhaust site of the cylinder head. A nice perfect triangular starting from the spark plug towards the squish edge.
What has changed on this engine type is that the cylinder has less angle/more straight on the engine block and the main transfer ports are made smaller. Maybe the booster port too strong ?

..The main port ducts are smaller..

[F5 Dave]

Actually that'sworth checking, we messed around with a curve on sketches dyno but got no gain over a flat line, but we were like super pressed for time, Icould have used one of the MB files and that was only peaking at 12.
So it got put in the worry about it later file.


I never rode it after myself.

hmm, no curve on this laptop & I set limiter at 14000.

[TZ350]

Good things take time. That is Mr Bigglesworths front engine mount. Even with Chambers help with the welding it was a weeks worth of work. Took two nights to figure out what to do and another three to make it and get it so it slips on easily and the head can still be removed without any trouble.



The gap is so that when the head nuts are pulled up, the selastic bushes on the cross member are loaded and take the weight of the motor.



A lot of air just bypasses a flat radiator. To make a radiator efficient it needs some ducting to prevent the air from spilling around the sides.

It is hard to have much ducting on a Bucket, but a curved radiator should reduce spill of the sides.



The pump is 25 l/min so a bit small. I had no idea what sort of water flow would be required but fortuitously Wob has just posted the answer, 1 L/min per hp. There is also one of Wob's thermostat arrangements for holding the motor at 45-50 deg C.

Hopefully get the radiator mounted and all plumbed up this week. I say hopefully because if a simple bracket can take a week .......

[peewee]

A lot of air just bypasses a flat radiator. To make a radiator efficient it needs some ducting to prevent the air from spilling around the sides.

.......

don't bother telling the sand sprinter guys in america this. they wont hear of it . don't waste your breath explaining to them why the radiator shouldn't go directly in front of the aluminum fuel tank either

do you know about how far the ducting should protrude in front of the radiator to be affective ? 4" seems like it would do the job but I don't know. I was going to either get some thin aluminum plate and weld it together so basically there will be ducting on top/bottom and both sides of the rad. other Idea I had was use some type of thin plastic in the same way but the alum is probly a better way. I may use one of them small trailtech fans also http://www.trailtech.net/digital-gau...ankit/732-fna1

[Frits Overmars]

do you know about how far the ducting should protrude in front of the radiator to be affective ? 4" seems like it would do the job but I don't know. I was going to either get some thin aluminum plate and weld it together so basically there will be ducting on top/bottom and both sides of the rad. other Idea I had was use some type of thin plastic in the same way but the alum is probly a better way.

Use plastic. Aluminium sheet is twice as heavy and it cracks.

[manolis]

Hello all.


Quote from the post #23,190 of Frits Overmars (July 12, 2016):

“I had a pleasant exchange of thoughts with CITS-inventor Basil van Rooyen (picture) last year. I think I did comment on the CITS engine before, didn't I?”


I searched but failed to find anything. Any help?


In a couple of months it is to be granted the UK patent for the PatTwo engine:



With a single piston and conventional kinematic mechanism it makes better what the CITS-engine tries to achieve with its two pistons (for more: http://www.pattakon.com/pattakonPatTwo.htm ).

Depending on the angular displacement of the “yellow” throttle valve, the engine “feels” as having from a quite small “crankcase dead volume” (the two spaces inside the piston are isolated) to a huge “crankcase dead volume” (the two spaces inside the piston communicate freely, i.e. as the piston moves towards its BDC there is no increase of the pressure in the space just under the piston crown).


Here is the “harmonic version” of the PatTwo:



It doesn’t need other throttle valve than the “dark” throttle valve in the middle of the cylinder (that with the yellow” lever).

The crankcase can be isolated / sealed (“purple” separator) from the space(s) “under” the pistons.

In comparison to the CITS Vee engine wherein the total volume of the space underneath the two independent pistons cannot help vary during a crank rotation (FIG A, curve C):



in the PatTwo the total volume underneath the piston(s) is constant (curve C in FIG B and FIG C).

Think what this means for the light loads and the idling (for instance, can the CITS operate without an external / additional throttle valve?)



Take the Harmonic PatTwo of the above animation and think what is the “crankcase compression”.

When the throttle valve is completely open (i.e. the two spaces, one under each piston, communicate freely), there is no “crankcase compression” (the ratio of the total “crankcase” volume to the dead volume of the “crankcase” is 1). It is like having an infinitely big crankcase in a conventional 2-stroke.

When the throttle valve is completely closed (no communication between the space under the one piston and the space under the other piston), the crankcase compression can get too high (it can get substantially higher than in any normal 2-stroke).

In the intermediate positions of the throttle valve, the actual “crankcase compression” appears something between the above two extreme values.

To make it simpler:
when with the throttle valve partially open the top piston crown moves towards its BDC with the transfer ports still closed, a part of the charge previously being into the space under the top piston crown passes to the space under the bottom piston crown so that, when the transfer ports open the quantity of the fresh charge under the top piston is reduced, etc, etc.


With the throttle valve completely open, the engine idles and the pumping loss is eliminated (like in the Atkinson - Miller cycle (Toyota PRIUS etc) in the 4-strokes).

As the throttle valve closes and the revs increase more and more power is provided .

When the throttle valve is completely closed and the revs substantially high, a local peak of power happens.

In case of tuned exhaust, the engine can provide even more power at even higher revs with the throttle valve completely open, i.e. as open as in the idling!
Follow the animation and think how this happens: a good part of the charge that enters into the top cylinder comes from the intake port of the bottom cylinder.


It may be confusing, but think how much it can change the way the 2-strokes operate.



As for the kinematic mechanism of the PatTwo Harmonic (you can see photos of it used in the PatRoVa rotary valve project at http://www.pattakon.com/pattakonPatRoVa.htm ), it achieves to give perfect balancing of all inertia forces, inertia moments and inertia torques; .in simple words, the Harmonic PatTwo is as vibration-free as the Wankel engine.


Thoughts?

Objections?

Thanks
Manolis Pattakos

[tjbw]

Hi Manolis

The only comment on CITS engine, that I recall, made reference to a Ryger patent.

[breezy]

hi Manolis, have you managed to knock up a working example yet?

[WilDun]

Hi Manolis

The only comment on CITS engine, that I recall, made reference to a Ryger patent.

I'm not really sure if the guys on this thread want it to be used for anything other than "real world" Bucket Race engine experiences, experiments and solutions etc.
I could be wrong of course - Maybe TZ could advise us or keep us straight here?

However it might be appropriate on the "Oddball Engines and Prototypes" thread. So I'll put a link to the CITS engine on there, (I've had that link for a long time and I think was already mentioned on that thread somewhere) .

Anyway what do you think TZ?

[manolis]

Hello Tjbw.

You write:
“The only comment on CITS engine, that I recall, made reference to a Ryger patent.”


For a long time I read about Ryger’s project / engine and about Ryger’s patent(s).
See in how many posts of this thread the Ryger project is mentioned.


In the patenting system there is a significant time limitation.
In 18 months from the first application for a patent the patent application has to be published (unless the applicant / inventor rejects it or unless he/she asks specifically for “non publication”; even in such a case, if a patent is eventually granted, it is obligatory to be published and to become available to everybody on earth.

The principle is simple:
the inventor takes the patent (which means the exclusivity in making and selling it for a 20 years period of time),
while the public has full access to every detail of the patent.


Asking for more details about Ryger’s project (in this and in other technical forums), nobody could (or was allowed) to provide them.

Unless I am wrong, till today there is no publication of a recent patent application (or of a patent) for a 2-stroke engine under the name of Hurry Ryger.


By the way, I asked (the question was actually for Frits Overmars) about the “pleasant exchange of thoughts with CITS-inventor Basil van Rooyen”
because Basil van Rooyen refused to respond to my messages.

Thanks
Manolis Pattakos