ESE's works engine tuner

[Flettner]

Is it 4301? At least available easily enough.

http://nz.rs-online.com/web/p/plastic-rods/2577136/

They don't give it away do they, that's real expensive! In anyone's book.

[Grumph]

They don't give it away do they, that's real expensive! In anyone's book.

It's expensive in my book anyway...You'd want to run the CNC programme on something cheaper a few times before you hit start on the good stuff.

Was that a broad hint that when you do them, they won't be cheap ?

[Ocean1]

They don't give it away do they, that's real expensive! In anyone's book.

I had occasion to buy some silicone filled PEEK a couple of years ago, haven't looked at current prices but it was well more than that then.

[F5 Dave]

You'd get a fair few out of that. 30 odd.

[Frits Overmars]

Is it 4301? At least available easily enough. http://nz.rs-online.com/web/p/plastic-rods/2577136/

Yep, that's the stuff. Like I said, it ain't cheap.

[husaberg]

Using high temp? The temp reached by a piston pin in normal use may already melt the silver and send the plugs on an exploratory expedition through the engine.

Good suggestion, except that the small end bearing needles like to have some firm (hard) surface under their feet.
But then why not go all the way and use ceramic pins? They're even lighter and much, much harder than aluminium, and not affected by temperature at all. But they still wouldn't solve the aux/transfer short circuiting. Aprilia closed their big end pins with conical plugs, but that wouldn't solve the aux/transfer short circuiting either.

Torlon ® is the highest performing melt processable plastic. It has superior resistance to elevated temperatures. It is capable of performing under severe stress conditions at continuous temperatures to 500°F (260°C).

Silver solder melts about 800 deg C, so i am confused?
whoops that Degrees F
OK some of the silver solder alloys are 710 deg c is that not high enough.
What temp does it see?
http://www.silfos.com/htmdocs/produc...ion_guide.html

With the solid AL Alloy pin you could use as i suggested, a steel sleeve as the vincent Grey Flash did for the big end bearing to run in?
Actually the MMC rods made for some of the current MX bikes run the bigend direct with no bearing at all and are lighter as well.
Granted they have a proper pressure oil supply but there are coating available for severe use
https://www.highpowermedia.com/blog/...composite-rods
MMC Same stuff that AP pioneered for brake calipers in the 90's.


PS What held in the Aprilia conical big end covers? just a press fit?


To maintain a proper seal is a mater of changing the design of the piston. ie piston manufactuers problem, where is Ken?
closing the ends is all that was originally asked
I do silly ideas not R&D.

[Hemi Makutu]

www.belonptfe.com/ptfe-products/ptfe-rods/

[wobbly]

Teflon, hell no.
Look at the Tensile numbers 14 MPa Vs 164 for the Torlon.
About as strong as the skin on a rice pudding.

The Aprilia pins had the cover plates laser welded - same process used to attach fine wire earth electrodes on racing plugs.

[jfn2]

I bought a Torlon rod # 4203 last march and I paid $116 plus shipping USD for a 12" long x 1" dia piece. It would have been cheaper for a smaller dia.
I made my plugs for a KTM 250 per Frits' picture and they are working fine. Lets say you use 1/2 " per plug you can make 12 sets and Frits is correct they seem to work ok for at least 2 times. I used the same clearance for the plugs as the piston uses against the cyl wall. They just snap into the circlip groove. I did have to give the plug some clearance for the piston pin hole in the piston. Also I found out that the chamfer that you use at the beginning of the plug is critical without having to chamfer the piston pin hole. Also you should use a rounded design that fits into the circlip groove instead of the pointed one shown on Frits' drawing. Also had to cut 6 slots instead of 4 as in Frits' drawing. I had a very hard time installing with only 4 slots and could not get out. But once you have it right it installs with a very distinct snapping sound. We'll see how long they last.

[Hemi Makutu]

Teflon, hell no.
Look at the Tensile numbers 14 MPa Vs 164 for the Torlon.
About as strong as the skin on a rice pudding.

What if you cut a length of the squashy teflon rod sausage-wise, & filled the pin with it entirely?

The internal pin taper ought to keep it located, perhaps?

[Larry Wiechman]

Trouble is I have tried several variations of "plastic " plugs that use the clip for retention, and discovered that this limits the lubrication of the pin in the piston.
The pin ends up getting locally overheated.

I'm curious why the pin is allowed to rotate in the piston bores. It would seem that is a job for the small end rod bearing.


Are you coming to Vegas next week, Wob?

[wobbly]

Yep, you can pick me up from the airport on Tuesday lunchtime, as long as I make it thru security with a bag full of newly tested reeds, manifolds
and mufflers smelling of hydrocarbons.

[Grumph]

Yep, you can pick me up from the airport on Tuesday lunchtime, as long as I make it thru security with a bag full of newly tested reeds, manifolds
and mufflers smelling of hydrocarbons.

Good luck with that - a mate coming back from The BS at Philip Is a couple of years back got picked out by a sniffer dog who liked avgas....

[Peter1962]

The KZ10B piston skirt does close off completely the boost port exit at TDC, but I have narrowed and shortened a piston skirt
thinking that it would help intake flow at BDC - sorry no free lunch.
At BDC there is no intake flow till the piston timing edge is approaching TPC, and at TDC if the boost port is open, the other end is subjected to the same case depression
so there can be no flow.
Re port linking on this engine.
The stock setup has virtually no linking of the Aux and the A transfer by the pin hole as it passes them. Plugs in this case make NO power at all.
But widen the Aux top edge around to bore center, extending the teardrop shape along with a good angled/radiused back corner, and huge gains in peak and overev power suddenly appear.
This is at the expense of around 2 to 3 Hp at 10,000 - drivers hate this even if the lap times are well faster.
My feeling is that if the transfers were left stock and the main/aux Ex port were lowered with this mod that increases blowdown flow, good gains would be had everywhere.
Plug the pin and you get most of the bottom end back, but this mod has little effect approaching and past peak power.
Trouble is I have tried several variations of "plastic " plugs that use the clip for retention, and discovered that this limits the lubrication of the pin in the piston.
The pin ends up getting locally overheated.It never actually failed on me in use, but I now see the value in why Jan used Pankle at great expense to weld a thin plate
over the pin end on his Aprilia.
Also here is what happens if the plug is too close to the bore - one National title of the last 4 gone up in smoke.

Wobbly, would a similar modification on a KTM 250 be a good move ? Or is the shape of the main exhaust and the auxiliaries of better design than that in the KZ10b ?

[ken seeber]

The plugs of Frits’s design are axisymmetric in the outer end whereas Wob’s were of the full piston side skirt shape, hence requiring indexing and unfortunately, more end clearance and were of a single use design. The Torlon was incredibly expensive, but in our case, the freight from the US was even greater (despite our requests to use another freight company).
From Wob’s pic, they do look overly warm at the ends, this being within the pin boss area, suggesting that both the lubrication and cooling ventilation have been reduced with the plugs. This in itself probably isn’t a problem, as LW rightfully points out that the pin bearing should be able to cope with the bearing function, even if the pin was fixed in the piston. So why do we let it rotate in the piston?
A 4 stroke which has the benefit of a total load reversal at TDC overlap allowing an oil film to be re-established every cycle, is quite happy with a plain bearing giving it good/excellent durability. A 2 stroke doesn’t, so at higher speeds, the load of the piston via the pin is always downwards. Here a needle roller bearing is quite good under these conditions, whereas a plain pin bearing struggles. I know old Villiers etc had plane bush bearings, but these were hardly high revvers.
Ultimately the engine must be assembled and disassembled, and the removable pin, as we know it, allows that. By allowing the pin to rotate within the piston does allow an oil film to be sort of maintained. At Orbital we did have a problem with the 3 cyl DI engine of piston pin poundout of the pin bores in the piston. One thought was that the pin wasn’t rotating, allowing cold welding of the aluminium onto the pin, initiating failure. We cut a hole in the front of the #1 cylinder such that we could see the piston pin when at BDC. We then marked the end of the pin and set up a high speed camera. Sure enough. The pin rotated, albeit slowly, in relation to the rpm of the engine. In that case, we solved the problem by roller burnishing the pin bore after boring and then having the bore hard anodized. Mahle did this in Oz for the compression ring grooves in the Turbo Falcon to prevent cold welding to the sealing face of the rings.
So, if the pin ends in Wob’s case were overheating a bit, but didn’t cause any problems in the interface between the pin and the pin bosses, then it’s probably a non-issue. However, if the higher temp carries across to the needle roller bearing and pin interface, causing softening of the pin (from the usual 62 Rc hardness), then that may be an issue. On that, I would think that anything softer, like an Al alloy, in conjunction with a roller bearing would be doomed to failure.
Carrying this thought process across, maybe that if the pin boss bore was slotted (say like Frits’s and others webbed piston design) then this, perhaps in conjunction with some cross drilling of the pin that might align with the slots as the pin rotates, might allow for improved ventilation and lubrication, despite the blocking off due to the plugs. See shitty sketch.