Forum whore
One of the down sides of not doing complete drawings (or any drawings) is when it comes time to actually fitting stuff in can be a challenge. The throttle Gibbs were always one of those 'I'll work it out when I get there' , well I'm there now and the mind's eye is still blank.
What usually happens now is just start and make something, then the right idea will introduce itself.
Muddler/Dabbler.
The upside (for you) is that you have all the gear required to be able to do it the trial and error way!Originally Posted by Flettner
One of the down sides of not doing complete drawings (or any drawings) is when it comes time to actually fitting stuff in can be a challenge. The throttle Gibbs were always one of those 'I'll work it out when I get there' , well I'm there now and the mind's eye is still blank.
What usually happens now is just start and make something, then the right idea will introduce itself.
I have been told that there is much more trial and error used (even by the high tech big boys!) than we are led to believe and I think that a lot of guys here would be able to testify to that! - meaning that designiing it properly on paper really just gives you a good idea on how to get going!
Well, that's my take on it anyway!
Strokers Galore!
Hardcore Biker
Question: Is there a phone app (Android) that one can stick on a phone in one’s pocket and do a (straight line hopefully) acceleration run and this is recorded. Essentially the output will be velocity vs time or preferably, acceleration rate vs speed. Don’t care whether it is just GPS based or utilizes the phone’s accelerometer.
Why? I have been working on the sliding cylinder engine https://www.youtube.com/channel/UCg2...E0nEmf8YrX0RYQ and have tried to run it against a water brake dyno. So far, I just can’t make it work, seemingly the engine power curve exceeds the absorption curve at some point and the engine just revs up to infinity (well, just over 70,000 rpm). Figuring I don’t want to be developing a dyno, I reckon that for cheap thrills I am just going to wack it onto a kart and drive up some bitumen road or track.
Given this, if I could record the accel (at varying cylinder height steps), it’d be extremely useful. I can back calc the engine rpm from the kart speed.
The few apps I have looked at seem to have things like 0 to 60 mph, 1/8 mile, ¼ mile test ranges, but I just want to be able to press start, do a run and then press stop and have an accel run log.
Any ideas?
"Success is the ability to go from one failure to another with no loss of enthusiasm.”
Forum whore
I don't doubt the perfect regularity of the app, but what about the regularity of track conditions, wind, tires? Building an inertia dyno can be quite simple, there will be hardly any need to develop it as the necessary software and electronics can be found all over the internet, and it will be a much better tool for engine development.Quote from the above website: "It will also allow you to perform motor development with efficiency thanks to its perfect regularity"
A couple of examples of simplicity:
Low personal B.M.E.P.
Interesting visit yesterday. Had to go to see Wallace (marsheng) and was in time to see and assist at the first run of the rebuilt 350 Koenig engine.
He may well post up a vid of it running and I didn't have a camera with me anyway.
Turned into quite a social affair - the owner, Wallace, myself, Russell Bleach arrived with a load of 250 Suzuki parts - and Glenn Hayward (of the Flying Kiwi sidecar record crew) turned up to collect a couple of bikes.
Good to hear the crackle and scream of the unsilenced Koenig echoing across the neighbour's paddocks.
Hardcore Biker
Just saw the latest (in Oz anyway) homologation docco update for the Rotax Max kart engine cylinders.
Pity they didn't actually show the actual ports (a typical failed homologation procedure of not showing the specific & important details) so we could see the finish. I can guess the process is similar (same) as this one:
https://www.youtube.com/watch?v=LFGnjkoeDng
Would think the finish and resolution would be mainly dependent on the sand grain size used.
Fletto, you need one of these. Not exactly a low cost consumer item as yet.
"Success is the ability to go from one failure to another with no loss of enthusiasm.”
Forum whore
König engines deserve to be unsilenced, as does the Honda 250-6. There should be a law against silencing such jewels.
https://www.youtube.com/watch?v=A0BwMeRTQ0E (concert starts at 1:39)
http://www.youtube.com/watch?v=eaRop_ZMwo0
Forum whore
Good on Rotax for developing a new technology that was used for the Aprilia racing cylinders ten years ago."Rotax have developed a new manufacturing technology where the sandcore is a single piece that is printed with a digital printer, creating less variation of the casting geometry".
Frankly the casting quality of the previous Rotax cylinders wasn't all that bad, with the exception of the coolant passages alongside the exhaust duct,
that were often partially or even completely blocked by casting skin.
Hardcore Biker
Frankly the casting quality of the previous Rotax cylinders wasn't all that bad,
With karting and the classic karting rules that you can't touch anything, put them under pressure to be consistent in this area. As always though, there were rumoured to be good and bad cylinders, whether real or not.
Yeah Frits, I remember looking at those core pics ages ago and figured something smart was going on. No flash lines, the interlocking coolant and transfer passages and the coarse finish. Good on them. Do you have any memories or pics of the actual cast surfaces? Looks like it might be coarse, but then again they could have coated the cores in some form of wash that might have smoothed things a bit, or a lot.
Have also seen some Max cylinders that have those passages almost blocked off with flash. These are cast by Gilardoni.
"Success is the ability to go from one failure to another with no loss of enthusiasm.”
Hardcore Biker
My son and I wanted to know how many kW our Fiat Punto used at different speeds.We had a very straigth and level road close by with very clear marks per 200 meter at the sides.Illegal speed(more than 80 km/h) neutral gear and take times for 200 m marks.
Excell can then easily make a fourth order polynomium giving distance run as function of time.Differentiate once and You have speed and once more and You have acceleration.method will also function In Your case going faster and faster.
https://imgur.com/kAifQZ6
Today I think I would try and make a side looking mobile phone video of passage of at least 5 coloured premeasured roadside buckets and then analyse.
The internal clock in phone is more accurate than a stopwatch,
Forum whore
Jolly old gyro engine, will not run smooth down low, acts like one cylinder is not firing right and won't pull above 6000 revs. The whole engine vibrates, everywhere not smooth like it used to be???
So today I stripped the bugger again looking for perhaps an air leak. Ha Ha, on inspection I found it! Cranks are twisted out of phase, perhaps one of the press fits was not as good as it should have been? Best to press it apart and measure I guess, bugger, and I was all ready to fly it like that. Build your own aviation engine from scratch, how hard can it be I said to myself, seems harder than I anticipated.
Running the drive off the center shaft I thought might lessen the twisting seen from the cranks but there is still a lot of force with load reversals, with one cylinder being pushed up to TDC while the other is being forced violently toward BDC rotationaly apposing each other continuously.
Hardcore Biker
If You have any drawing of cylinders and crankshaft as is ,let me scheme a 90 degree V2 .This can be lower mass and much smoother powerflow.
Mr Overmars has shown torque variations for different cranks somewhere called Fallacy of Big Bang or something like it.
Muddler/Dabbler.
Got to be just the press fit surely, ie if everything was smooth previously,nothing really different is there? - It's still good to know what the problem is and that it's not going to happen again, ie before you go flying!
Strokers Galore!
Low personal B.M.E.P.
Weld the critical bits. You know I do a lot of post classic stuff - some with pressed up 4 cyl cranks. Running a bead round the visible ends of press fits is often the only way to keep a crank in phase at power levels around twice what they were designed for.
Forum whore
All back together and back in the gyro frame. Yes I did tig weld assist the press fit, both ends just to be safe, spent today running it up again. Doesn't shake like it did and seems it will rev out more now but still under 4000 rpm it runs like a bag full of arseholes, rough as guts.
I guess a process of elimination, back to the original cylinders, just need to re nikasil one of them. I've pissed around with the jetting, timing and power valve settings, seems to make no difference?
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