ESE's works engine tuner

[jbiplane]

Is it direct drive or belt-reduction between crank and airscrew?

Hi Niels. We produce 90, 120, 183, 236, 294 and 350cc opposites, as direct drive as belt-reduction. We made one engine with planetary gearbox.

Now we want add to product line 141cc inline, V90 141cc and V90 274cc. Some engines would be tailored for paramotoring. We want make much less vibrating then novadays one cylinder stuff.

One question to comunity. We sucseed to plate cylinders by our nikasil like coating. It have + and -. We got very high 17% fraction of ceramic, much more than in third party engines we analysed. It very hard, but piston rings survive only 70 hours. What is better - try to source better rings or decrease ceramic content in the coating?

[Frits Overmars]

We sucseed to plate cylinders by our nikasil like coating. It have + and -. We got very high 17% fraction of ceramic, much more than in third party engines we analysed. It very hard, but piston rings survive only 70 hours. What is better - try to source better rings or decrease ceramic content in the coating?

My experience with average nikasil is that the first piston ring wears away very quick; the second ring lasts a bit longer, and then the sharp nikasil peaks are polished away and the third ring lasts forever. So maybe you should concentrate on honing.

[lohring]

You can use a common pipe on a 180°-firing twin, on a 120°-firing triple, etc, but not on a 90°/270°-firing twin; not if you want any pipe efficiency.

A flat twin with a common crankpin will be 180 degree alternate firing. It will need a 1:1 balance shaft for good balance.

Lohring Miller

[varthrix]

A question to Frits or Wobbly, what method should one use to find needed reed petal area for a certain carburetor size? I read about a rule of thumb reed area = 0.8 carburetor area. Is that an okay way to calculate things?
I wish everybody a Merry Christmas!

[TZ350]

.

The perfect Xmas Day. all the family stuff done and dusted Xmas Eve and today can be spent thinking about the reason for the season and enjoying a quiet day playing with the Aduino Nano.

Lookup a comparison of "interrupts" vs "polling", using interrupts could/should be more reliable.

Following up on Askors suggestion of using Interupts I was able to write a short bit of code that counts 3000 pulses and then turns on the relay for half a second.

Now that I know the Nano can see the simulated 12,000rpm pulses quickly and reliably enough, in fact it can do this at several times the speed required. I can now try my hand at writing some code to discriminate between Ignition and Cylinder pressure pulses and identify when there is combustion or not.

[chrisc]

Sounds like a winner of a day Rob. Merry Christmas everyone. I'm rebuilding my NX4 RS125 engine and my Christmas presents are all HRC parts. Stoked.

[lodgernz]

Christmas Day and I'm working on my bucket 50 engine. I guess my life is in the bucket.

Anyway, I have a question for Wobbly, Frits or anyone else who feels like contributing:

The exhaust duct of this engine has a bit of a bottleneck about halfway down, whose CSA is about 66% of the port window area.
We now know that I need to reduce the CSA steadily from the (single) port to achieve a flange area of 90% of the port area.
If I open this bottleneck up to say 95% of the port area in keeping with that philosophy, I will be increasing the volume of the duct.
Some of this extra volume will be reduced by the insert I will add to the outer part of the duct, but the overall volume will still be larger.
We know increased duct volume is not good, so I'd appreciate any comments or advice on what would be a good course of action.
Perhaps a bottleneck like this is not an issue. Does anyone have experience of this?

[Niels Abildgaard]

Hi Niels.
Now we want add to product line 141cc inline, V90 141cc and V90 274cc.

What OEM cylinders and pistons are You planning for the 141 engine?

Hope Your X-Mas morning is as nice as mine.

Niels

[Frits Overmars]

The exhaust duct of this engine has a bit of a bottleneck about halfway down, whose CSA is about 66% of the port window area. We now know that I need to reduce the CSA steadily from the (single) port to achieve a flange area of 90% of the port area. If I open this bottleneck up to say 95% of the port area in keeping with that philosophy, I will be increasing the volume of the duct.
Some of this extra volume will be reduced by the insert I will add to the outer part of the duct, but the overall volume will still be larger.
We know increased duct volume is not good, so I'd appreciate any comments or advice on what would be a good course of action.
Perhaps a bottleneck like this is not an issue. Does anyone have experience of this?

That bottleneck CSA is probably bigger than the blowdown CSA, and in that case it need not hurt blowdown, provided there are no abrupt CSA changes in the duct.

Wobbly's rule of thumb is based on the total exhaust port area and I can very well understand his approach because it is more practical than my blowdown area-based method: you can establish the total port area fairly easily whereas the blowdown area is something you cannot measure at all because there is no measurable way of knowing at what crank angle the blowdown phase is completed. You'll need something like EngMod for that.

Having said that, in your case it may be possible to raise the exhaust floor so that your bottleneck is no longer the tightest point. It might promote flow and reduce the duct volume at the same time.

[jbiplane]

What OEM cylinders and pistons are You planning for the 141 engine?
Niels

Hi Niels. We mill most of our cylinder in 5-axis from alu alloys. The reason is weight. Says 70cc cylinder with integrated head weight just 380 gramms. But as a common our rule 141cc compatible with OEM Husqvarna 372, other engines with Stihl 090, 660...

Related cylinder coating. Does it have any reason to try use Nitrid Boron aditions together or instead of Silicon carbide? Does anyone know any supplier for Kawasaki Electrofusion? My objective is 750+ hours rings and cylinder life on medium loads.

Merry Christmass all forum folks

[TZ350]

Got my Arduino Nano project working Ok on the test bench. Next step is to try it on the bike when my new pressure sensors arrive.

Full code can be found in the link below.

// Arduino Nano map switch routine.
// Routine for Switching between Alpha-N maps on a 2T engine.
// By determining from residual cylinder pressure if the EFI 2T engine has fired or not.
// Switches to an alternative map if the engine did not fire on the last cycle.

Computer programming, who said an old dog can't learn new tricks ...... Woof.

[lodgernz]

That bottleneck CSA is probably bigger than the blowdown CSA, and in that case it need not hurt blowdown, provided there are no abrupt CSA changes in the duct.

Wobbly's rule of thumb is based on the total exhaust port area and I can very well understand his approach because it is more practical than my blowdown area-based method: you can establish the total port area fairly easily whereas the blowdown area is something you cannot measure at all because there is not measurable way of knowing at what crank angle the blowdown phase is completed. You'll need something like EngMod for that.

Having said that, in your case it may be possible to raise the exhaust floor so that your bottleneck is no longer the tightest point. It might promote flow and reduce the duct volume at the same time.

Thank you Frits. I imagine Wobbly's philosophy might also consider that, at maximum over-rev RPM, when exhaust gas is heading down the transfers because blowdown is incomplete, then the exhaust port area IS the blowdown area.

My cylinder has been decked and raised, so the bottom of the exhaust port is already 2mm above BDC, but of course this has not reduced the duct volume. In fact, by the time I widen the top of the port, the volume will be even larger.
I hesitate to try and raise this floor further by other means, as I know of no published experimental data on the effects of the floor being higher than about that amount. I believe Jan tried 2mm on the RSA125 with some improvement but did not go any further than that.

In case you're wondering about the consequently raised transfers, I have lowered them to an appropriate point by grinding the lower edge, using Devcon to fill the top edge, and hoping the latter can stand transfer temperatures and ring battering. I'll let you know...

[peewee]

Christmas Day and I'm working on my bucket 50 engine. I guess my life is in the bucket.

Anyway, I have a question for Wobbly, Frits or anyone else who feels like contributing:

The exhaust duct of this engine has a bit of a bottleneck about halfway down, whose CSA is about 66% of the port window area.
We now know that I need to reduce the CSA steadily from the (single) port to achieve a flange area of 90% of the port area.
If I open this bottleneck up to say 95% of the port area in keeping with that philosophy, I will be increasing the volume of the duct.
Some of this extra volume will be reduced by the insert I will add to the outer part of the duct, but the overall volume will still be larger.
We know increased duct volume is not good, so I'd appreciate any comments or advice on what would be a good course of action.
Perhaps a bottleneck like this is not an issue. Does anyone have experience of this?

currently your flange face is 66% of port area at the bore and theres a bottle neck midway in the passage ? if i understand you correct it sounds like you need to grind out the midway pinched section and open the passage to get your 90%

ive never seen any one ask this but what if the passage is far shorter in length than ideal. should the flange face still be 90% (single port) and 75% (triple port) or should it be more like 95 or 85 etc ? my big ktm has only a 50mm long passage. far to short i rekon but packaging limitations wont allow more or the front tire smashes the pipe. still i made the flange face 75% but i question if it was the best decision since the passage length is very short for such a large capacity engine

devcon putty is pretty good stuff. ive filled my transfer ports with it and used atleast 10gal methanol and about 1gal nitromethane and the devcon seems to be doing fine but i do flush the engine with petrol. recently i picked up a jar of devcon titanium putty as ive read it may be even better than the type F alumi.

you should be fine if you grinded the putty down a hair shallower than the bore wall so the rings dont snag it

[lodgernz]

currently your flange face is 66% of port area at the bore and theres a bottle neck midway in the passage ? if i understand you correct it sounds like you need to grind out the midway pinched section and open the passage to get your 90%
ive never seen any one ask this but what if the passage is far shorter in length than ideal. should the flange face still be 90% (single port) and 75% (triple port) or should it be more like 95 or 85 etc ? my big ktm has only a 50mm long passage. far to short i rekon but packaging limitations wont allow more or the front tire smashes the pipe. still i made the flange face 75% but i question if it was the best decision since the passage length is very short for such a large capacity engine
devcon putty is pretty good stuff. ive filled my transfer ports with it and used atleast 10gal methanol and about 1gal nitromethane and the devcon seems to be doing fine but i do flush the engine with petrol. recently i picked up a jar of devcon titanium putty as ive read it may be even better than the type F alumi.
you should be fine if you grinded the putty down a hair shallower than the bore wall so the rings dont snag it

Thanks for the info on Devcon peewee.
No, the flange face of my exhaust port is about 110% of the port cylinder window area, which is why I will add an insert there. It's the bottleneck about halfway that is 66%.
The distance from piston to flange face is 39mm on average, the same as the bore, so about right, but your question about that dimension is interesting. I hope someone can answer it.

[Frits Overmars]

Thank you Frits. I imagine Wobbly's philosophy might also consider that, at maximum over-rev RPM, when exhaust gas is heading down the transfers because blowdown is incomplete, then the exhaust port area IS the blowdown area.

That would imply that the blowdown period lasts all the way from exhaust opening to where the piston reaches the exhaust floor. Then at the end of blowdown,
the transfer ducts will be completely filled with exhaust gases, and it will take a similar amount of time and crankshaft degrees, i.e. from BDC to transfer closure,
to expell those exhaust gases again. In other words: the 'scavenging' will be performed with exhaust gas only. I can guarantee that no engine will run like that.

My cylinder has been decked and raised, so the bottom of the exhaust port is already 2mm above BDC... I hesitate to try and raise this floor further by other means, as I know of no published experimental data on the effects of the floor being higher than about that amount. I believe Jan tried 2mm on the RSA125 with some improvement but did not go any further than that.

That is more or less correct, but it needs some explaining. Jan had cylinders cast with the exhaust floors much higher-up than that, but he realized that at age 67
he would be retired by the time those cylinders would perform their tricks on the dyno (a lot of time used to pass between casting and running).
Knowing the mentality of some who would grab any opportunity to boast that they had improved on Jan's work, Jan decided to grind those experimental exhaust floors down to their conventional position before leaving.

The distance from piston to flange face is 39mm on average, the same as the bore, so about right...

Assuming (and hoping) that your exhaust duct diameter is smaller than the bore, then the duct volume will be a lot smaller than the cylinder volume. And this would imply that part of the washed-through charge makes it into the hot exhaust header before being shoved back by the pipe effects. Not quite what you want.