ESE's works engine tuner

[SwePatrick]

Why does everyone leave the transfer duct outer walls uncooled.
I have measured the temp of a race engine at the case deck line on the outside with a press in probe, and its over 80*C when the water temp is at 45*C.

Yes, i have asked myself the same question.
If i would have run petrol i would have done it without any thought at all
Methanol is so superior in keeping things cool that i figure i don´t need it,, yet

[SwePatrick]

Very interesting question about cutouts in piston skirt.
Reed and rotary engines works in different way. Zeta MTX is reed valve and this windows can help. But rotary engine exhaust, at the closed inlet condition , can't suck additional fresh mix from carb and this is one of the major difference, that playing on crankcase volume, exhaust, conrod, carb....
When RSA piston (in pic), with very low cutouts, is at TDC, transfers, maybe not open at all ( we need to ask Jan ). Maybe strong fluctuation in transfers is very important on rotary engine with closed crankcase ( more than with reeds) and any holes in the duct, can destroy this nice exhaust-crankcase orchestra.
Interesting, if 125 cc rotary engine with 30 mm carb can reach 47hp like TM.

In addition to this, last year tested piston with deep pockets on sides (add pic ), and when piston moves up transfers open very early, and some part of fresh mix goes directly to trans duct from boyesens. From first ride feels different in comparison with std. piston: from 10500 to 12500 rpm more power, but little less from 8500 to 10500 rpm. Can't remember how many times change these pistons for comparisons and always this piston was a winner. Plus 1000 revs more than with std. piston. But again,this is reed engine, not rotary.

Interesting experiances =)
As i see a twostrokes crankhouse and transfers: one need to help with every little thing one can do, to help effective filling of the crankhouse.
If completely filled there will be more for piston to pump up above the piston.
Basic rules =)

[SwePatrick]

I like your version Patrick. But why did you alter the lower part of the inner transfer duct curvatures?
Attachment 335218

Second quote of this post

I forgot to mention, in a curved runner one also want as small length differences as possible on inner radius and outer radius.

[peewee]

If try continue from where Jan stopped, why not to try exhaust bottom at transfers upper edge level, and then grinding in small steps.
Interesting how bottom exhaust duct shape should look like with this configuration, parallel with upper and oval cross-section or something different,
of course with ......G, H,.......

im surprised nobody still has tried it yet ? maybe you can get the answer finally . I raised the bottom about 6mm on 82mm stroke but I had no way to test it. I hope it is giving some extra power ! without knowing for sure I didn't want to raise it any further

[Muhr]

This is a favorite hobby horse of Ken Seeber and mine.
Why does everyone leave the transfer duct outer walls uncooled.
I have measured the temp of a race engine at the case deck line on the outside with a press in probe, and its over 80*C when the water temp is at 45*C.
Seems so obvious, especially when it is such a mission to cool the inner duct radius.
Here is crude idea to add enclosing covers down to the the split line.
The other thing that is monkey see monkey do is the insert spigot down into the bore.
This means the squish has no cooling from the side,and is miles away from the water above.
Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.
This is an extension of having the cold water regime flow over the transfers first,next the Exhaust then up into the head and across and out.
My latest dyno result on here show this is superior to any other scenario.

Thanks for the input!

I like it but not the job that would be required to get it done. draw a new cylinder more or less.
Yes the insert spigot is a lazy mans job, makes it easy to raise and lower the cylinder head but can definitely make some adjustments there

[TZ350]

im surprised nobody still has tried it yet ?

Exhaust port floor higher than BDC. It has been tried before and the results posted on this thread. Use this search term "floordam site:www.kiwibiker.co.nz" to find references to it.

The stuffer plate is held down by screws through the exhaust port floor, the glue is only there to seal it.

The floor of the exhaust port is higher than BDC. I have no idea how high the exhaust port floor should be.

The glued and screwed in port floor dam held up OK and the dyno results were better.

The idea of rasing the exhaust port floor seemed to work and the results were encouraging but the cylinder was ruined by other porting work so that experiment has stalled for now.

[peewee]

i think many people , including myself, have raised the floor to some extent. but ive never seen anyone raise it to the transfer tops. i think this is what katinis is planning to do

[TZ350]

i think many people , including myself, have raised the floor to some extent. but ive never seen anyone raise it to the transfer tops.

Take a look here, a modified Suzuki RG50 engine with the exhaust port floor at TPO. These experiments were previously posted on this thread including dyno graphs of the results.

Blue = Exhaust dam level with TPO. Red = Dam opening 4 deg after TPO.

Exhaust port dam ... Blue = Standard "A" ports, Red = Widened "A" ports. Useful improvement in bottom end power.

Also the 50cc engines single exhaust port was successfully widened out to 85% of bore diameter.

Our results gave us some idea but I think you are right, starting with the exhaust floor at TPO and progressively grinding it down would be a very interesting experiment.

[TZ350]

.

There really is a lot of good information on this thread, making use of Googles "site:" function is a great way to find it all.

Search Term site:www.kiwibiker.co.nz

[Muhr]

I wrote about it on http://www.pit-lane.biz/ and I think I also posted a couple of links here to that French thread, some time ago, but I don't remember where exactly, so here are those links once again:
http://www.pit-lane.biz/t117p318-gp1...-part-1-locked
http://www.pit-lane.biz/t117p333-gp1...-part-1-locked

Thanks Frits very interesting reading no one can blame you for not sharing your experience.
Tried to look at the pictures but did not understand the French and what they wanted me to do

[Frits Overmars]

next week im going to a local machinist and making a new reducing exh spigot but unfortunately it wont be water cooled.

If you're planning to fit a watercooled spigot eventually, why not make one right away? You've still got a week to make a sketch.

I still need to determine if the fuel flow is ok but I think it will be.... I haven't yet checked the flow rate of the float valve in the carb...

You're joking, aren't you Peewee? Please tell me you're joking.
Methanol flow should be 16 cc per hp per minute. That's easy enough to check, but you must flow all relevant parts simultaneously, starting with the tank breather and certainly including the float valve. And if you add nitromethane, the flow requirement increases steeply, depending on the nitro percentage of course.

Thanks Frits very interesting reading no one can blame you for not sharing your experience.
Tried to look at the pictures but did not understand the French and what they wanted me to do

Thanks for the flowers Muhr.
I hear you about not understanding the French. The lingo I can handle, but the natives sometimes... Anyway, with kind permission of the Pit-Lane forum moderator I'm writing in English there (or at least my version of it).
Oh, wait a minute. Do you mean you can't see the pictures? I guess you'll have to register first. I can't go into that now but it can't be too hard finding a school boy or girl who has sufficient French. Or you could try Google Translator; always good for a laugh.

[jamathi]

Yes, interesting, is not that a bit of 1/2 what Frits did with FOS cylinder? Or what do you say Frits?
In general, it seems interesting to do more of the processually larger surface area you have in a 50cc. And especially with regard to blowdown.
Tried to find some more info about RSA's blowdown area, without success.

I don't really know the RSA's blowdown area, we never calculated such things......
It was made as big as possible, by trial and error.
But we tested a lot at the flow bench!
On most moped engines you are very limited by the cylinder studs.
We were fortunate enough to be able to cast our own cylinders, making our own casting models.

Of course I fully agree with Wobbly about cylinder cooling: The outside of the transfer ducts should be cooled as well.
I am 99,9% sure that this will give more power!!!
My compliments Wobbly!

[JanBros]

The other thing that is monkey see monkey do is the insert spigot down into the bore.
This means the squish has no cooling from the side,and is miles away from the water above.
Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.

any suggestions as to how thin the wall's of the combustion chamber (above squish/chamber itself) can be made, let's say for a 54mm bore ?

[Muhr]

Thanks for the flowers Muhr.
I hear you about not understanding the French. The lingo I can handle, but the natives sometimes... Anyway, with kind permission of the Pit-Lane forum moderator I'm writing in English there (or at least my version of it).
Oh, wait a minute. Do you mean you can't see the pictures? I guess you'll have to register first. I can't go into that now but it can't be too hard finding a school boy or girl who has sufficient French. Or you could try Google Translator; always good for a laugh.

I'm going to practice my French

Edit: I finally managed to understand the French!
Thought it would be 40-50mm2 bigger. I have a lot to learn (don't know how the time area distribution looks like)

I don't really know the RSA's blowdown area, we never calculated such things......
It was made as big as possible, by trial and error.
But we tested a lot at the flow bench!
On most moped engines you are very limited by the cylinder studs.
We were fortunate enough to be able to cast our own cylinders, making our own casting models.

Of course I fully agree with Wobbly about cylinder cooling: The outside of the transfer ducts should be cooled as well.
I am 99,9% sure that this will give more power!!!
My compliments Wobbly!

Thanks Jan

In my first attempt with Wobbly's cooling, I've managed to destroy all forms of flow distribution. I hope I can come with a cylinder 1.2 but I will get forced to broaden the cylinder and then new crankcase so hopefully to the 2 cylinder version. The first engine is singel cylinder test.
Then I can also see what tradeoff the longer intake due to wider cylinder will bring if i cant find a solution to the studs.

any suggestions as to how thin the wall's of the combustion chamber (above squish/chamber itself) can be made, let's say for a 54mm bore ?

Do you mean before this happens (picture) that is 2mm 7075 50 bore

Wobbly

Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.
This is an extension of having the cold water regime flow over the transfers first,next the Exhaust then up into the head and across and out.

Updated cylinder head

[tdc211]

Raising the ex floor by the bore a good amount will require different pipe. Correct?
going from 180 degress up to 150 has a big change in delivery in sim ..