ESE's works engine tuner

[husaberg]

The first is standard hydraulic seal design, quite high drag. Also the moving element is PTFE, not good enough in that environment.
Unless you've got contacts at Boeing or Northrop Grumman, they use some hideously expensive and very proprietorial extreme temp elastomers.

Don't ask NASA they are still working on that one even with aviation contacts

For Frits
With the RSA being gear driven disk was there ever any consideration given to reversing the rotation to allow for a rudimentary retard function along the lines of a centrifugal advance ignition.
I ask because Bell quotes significant high rev gains from a mildly retarded opening and closing and visa versa (He even showed curves). So it would seem (if bell is right) the timings could be varied it could to allow for a broader output if timed for normal peak at full retard. Just a thought possibly retarded.

[Ocean1]

Don't ask NASA they are still working on that one even with aviation contacts

There's a design for a rolling torroidal seal element, (fancy name for rolling “O” ring) I've used before which would minimise silicone's susceptibility to abrasion. Necessitates exposure across the full seal cross section though, and you’d have to allow for that in volume calc’s.
Don’t have my magic crayon here, you have to imagine it.

[Frits Overmars]

Thanks very much for the input, guys. I will pass your suggestions on to Richard Maas (and try to convince him to register as a Kiwibikers forum member ).

[teriks]

The second is a simple elastomeric ring, they don't say what the material is but one of the silicon family is probably a good choice. Might be the best readilly available material for the trombone application too, although it's not very abrasion resistent. Unless you've got contacts at Boeing or Northrop Grumman, they use some hideously expensive and very proprietorial extreme temp elastomers.

I have a similar seal between the cylinder and pipe, the experience from those is that silicon offers nothing or very little over viton, or even NBR, in terms of service life.
Now I need no more than, say, 10 minutes service life, so I can get away with using the simple materials and change often.

IMO, The FFKM material I linked earlier should be a much better candidate for this application.

[husaberg]

Just a thought from RC type engines i know almost nothing about them but i understand many run without piston rings.
could this provide a possible pipes seal solution?

ABC = Aluminum (PISTON), Brass (CYLINDER) Chrome (CHROME PLATED cylinder internally) The compression seal is made by a slightly tapered fit between the piston and cylinder. The brass cylinder has the same expansion rate as the aluminum piston therefore, it maintains a good seal as the engines heats up. Since chrome is substancially harder than the aluminum piston, this is a (semi) bearing surface between the piston & cylinder therefore there's no scuffing or galling, if there's adequate lubrication.

ABN= Aluminum (PISTON) Brass (CYLINDER) Nickle (NICKLE PLATED cylinder internally) The compression seal is identical to the ABC. IE:tapered fit

AAC= Aluminum (PISTON) Aluminum (CYLINDER) Chrome (CHROME PLATED cylinder internally) The compression seal is identical to the ABC. IE:tapered fit
http://tech.flygsw.org/abcvsringed.htm

[twotempi]

My guess is either carbon ring seals - used in aerospace industries and expensive , or a lower tech arrangement using relatively wide ( say 2mm ) cast iron piston type rings running on a machined surface on the outer sliding component.

Probably would try 3 rings in grooves on the inner component rather than the outer sliding component. There should be enough oil around in the exhaust to lubricate the arrangement.

Would be cheap enough to make to find out if it works OK. Rings can be made by most engine shops . Orientate the ring gaps @ 120 degrees to minimise leakage.

[teriks]

Just a thought from RC type engines i know almost nothing about them but i understand many run without piston rings.
could this provide a possible pipes seal solution?

Now this is something I'm very familiar with.. but nah, requires stupidly small tolerances.
Unless the FFKM material is up to the task, I'm leaning more towards your inverted piston ring idea.
A good candidate for rings could be brass or bronze, or anything substantially softer than the pipe material.
Without a polymer dampener (O-rings), I'd guess for that kind of arrangement vibration will be limiting part life unless you do something clever...

[husaberg]

Transitional seals i had never heard of them.

http://www.jetseal.com/translational.php
The Translational Seal is designed for use in applications where moderate linear motion occurs. Typical applications would be a piston mount application where the seal slides up and down in a bore. When friction and driving forces need to be balanced, the Translational Seal ring provides the best solution for moderate linear motion and minimized leakage rates.

Metallic Translational Seals offer reduced leakage rates in piston applications compared to typical Piston Rings or standard metal O-rings. JETSEAL customizes this seal to accommodate platings and unique mating surfaces in pneumatic and liquid applications

Translational Seals thrive in environments like: high pressures to 60,000 psi. temperatures from 320 F to 1300 F, well in excess of typical O-ring and traditional piston ring operating ranges. pneumatics. gas and liquid applications.

[marsheng]

I bought a complete NSR250 MC16 cheep and was going to use the frame for an F4. Once I got the bike, the motor and all else seems fine. I'm looking for reasons to put it into pre 89 F3 Category. Any with info on these, please contact me with PM as this is a bucket forum (and also all the chaps whose opinions I trust.)

Cheers Wallace.

[TZ350]

I bought a complete NSR250 MC16 cheep and was going to use the frame for an F4. Once I got the bike, the motor and all else seems fine. I'm looking for reasons to put it into pre 89 F3 Category. Any with info on these, please contact me with PM as this is a bucket forum (and also all the chaps whose opinions I trust.)

Cheers Wallace.

Hi Wallace, this thread is probably a very good place to find and share any sort of 2-stroke tuning and prep info. NSR250 stuff could be very interesting.

[TZ350]

Race report from Kaitoke

Sat, was Kels first look at the track and he rode exceptionally well. Hamish who normally runs at the front, was happy to tell us how impressed he was with the Beasts acceleration. He expected to be able to easily swing past it exiting the top corner only to see the Beast pull away down the back straight. If the track had not been so new to Kel there may have been a real race for 1st as it was he finished 3rd, behind Rick and in front of Rich.

So there it was, the Beast flew, with no sign of the heat fade that’s supposed to affect aircooled 2-Strokes and Kel was able to peddle it at the very pointy end in A grade first time out on a new track. As Kel got to know the track better, it all looked good for Sundays points racing. I was feeling confident that we were in with a chance on Sunday.

The next time out Kel just quietly putted around in the two warm up laps, grided up and when the flag dropped the Beast had a heart attack and fell over.

WTF ….. The Beast screams around the track on full song then quits when taken out for an easy trot, what is that all about?????

Come Sunday Kel went out in the first points race on his trusty old FXR and finished 3rd, very impressive effort for a basically std chassis. Kel was well into the second race and chasing Rick, with a bit of exciting passing and re passing, then Kel dropped it trying to get around a back marker and that effectively handed Rick the North Island Series Win.

A Great Weekend racing at one of the best F4 tracks and with the nicest people in Motor Sport, what more could you want, a big thankyou to everybody who was there and those that organised and helped run the meeting, we had a great time, thanks.

[TZ350]

WTF ….. The Beast screams around the track on full song for a whole lot of laps then quits when taken out for an easy trot around in the two warm up laps for the next race, what is that all about?????



Damage is in the exhaust port area, and thats a steel ring thats cleanly snapped in two.

I will dig out the dyno graph and ignition curve.

[Kickaha]

WTF ….. The Beast screams around the track on full song then quits when taken out for an easy trot, what is that all about?????

Sounds like the standard life expectancy of a two stroke

[husaberg]

Sounds like the standard life expectancy of a two stroke

Warwick remember people who live in glass houses shouldn't er......throw valves

For Wallace


http://nsr-world.com/

http://www.dreamgate.ne.jp/nsr/

http://www.tygaperformance.com/site/index.php

Did you buy the one at Rangavegas?

[Yow Ling]

Hey Kickaha, thats not that much different than the bsa barrels and piston you brought round today, at least TZ will be able to get the piston off the rod !