I was given some bar with tool steel welded to it and ground. There'll be people reading this throwing their hands up in despair but it worked pretty good. Very hard to stop chatter in the lathe but I finished it with a bit of sandpaper. Nowadays I might still do it with the same tool but I would profile the tool steel part in a CNC to get the exact right curve to cut the chamber I wanted. My mate Kev machined a piece of carbide the other day using a CBN endmill I think, so machining tool steel is easy in comparison. It wouldn't be hard to get proper rake and backcut etc.
Flett , I have slung serious shit at RK on another forum as well , as he spouts on about how effective his design is , but not once have we seen a direct back to back dyno sheet with equal
CC and MSV. I seem to remember a snake oil line about it only works as it allows higher com without deto - my reply was why then does a normal toroid chamber make more power in a back to back , and then
makes more power again with higher com and no deto - no answer.
Fly , many years ago when we had what was called 125 National ( MX motors only ) in karting , those motors made high 40 sprocket power on Methanol.
Thus the bmep was similar to what we have now in KZ2 on pump gas ( just on 50 Hp ) - and as I said before the 152cc KZ2 engine was over 60 Hp @13800 rpm on a single DC DC CDI
I used a single cdi in a DC DC CDI P2 as at that stage the P1 didnt have a PV servo controller and I had no idea about paralleling outputs back then.
That setup worked just fine with the cheap Ebay Aprilia RS125/250 coil and R7376 -11 plug on 17:1 compression.
Using twin paralleled CDI and a very low primary resistance coil with very high inductance , only became necessary with super high com and super rich Methanol mixtures.
I suggested that to TZE for his Aircooled engine as running high com with very rich Methanol mixtures virtually eliminates the heat soak power loss issue , and allows way more power
from the flawed thermal efficiency of aircooling compared to the same spec in a water cooled engine.
EDIT - forgot the burn period of the Crane coil - it increased from around 50uS to near 150uS
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
Yea well Myron I still havnt " seen the money " from that particular stouch.
What would help solve the mystery would be to replicate a shootout that was held even more years ago on a Forum , where the same setup file was used
by all participants in the same software ( Dynamation 2T ).The idea was to see who could design the best pipe for a stock RD250 I think it was.
It went on for months , until someone came up with alot more power , way more than anyone else - impossible numbers in my opinion , even ignoring the fact that fat pipes overscavenge and short circuit.
to hell that a single dimensional code cant account for.
This severely dented my narcisistic ego , till I figured out they were transplanting Methanol into the combustion file instead of 91 pump.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
I enjoy lurking and perusing all the discussion here, and also enjoy your posts Wobbly. I was disappointed to see this whole thing resurrected from the 10 plus year grave.
Im not sure I know about this "dynomation shootout" to be honest, and thats fine. I have little interest in Sim shootouts which prove zilch.
The whole champ thing should have definitely gone away. To be honest, that whole episode cost a close friendship that had spanned almost a lifetime. It was very unfortunate. It cost someone a sunk livelihood FYI. . About the actual attempt at champ, I admire your attempt. I actually ran a sim on your pipe just to remind myself from so many years ago. I have my opinion on the pipe, but that matters little. I have nothing negative publicly to say about it. There have been several Jaws pipes stamped for champ. At this level, these stamps are tailored to individual bore/stroke ect. settups. To call this one stamp as mediocre is somewhat naive. It is by no stretch mediocre. It has won its share on the track. Your claim of your pipe exceeding the previous best was in sim only. Your comment of 30 or whatever more hp at 11 grand is again not useful to the application. Cvt efficiency wont allow it. Smooth left side curve with a spread of torque/hp is much more valued than huge overrev. To spend a day at Jaws and observe the amount of pipes being produced, and further, to pick the brain of Greg would leave anyone very inspired. The dyno room itself with twin eddy current dynos is intoxicating.
Two other observations if I may. As far as sims, I have a pile of them, I love Vanniks and would highly recommend to anyone. I wore my keyboard out on Dynomation years ago. That was after wearing out another keyboard using a custom program. I will say this about the "outdated" dynomation, if used correctly, I'm not at all afraid to design a full mod pipe for most any application from 70cc to 600 plus cc per cylinder, roll it, and head straight to the dyno with high expectations.
Second observation as regards heads et al. I know its fashionable to unload on RK, I'm not about to defend him, thats his job and prerogative. I will only say that a race head really becomes very application specific. To simply dismiss a certain design ect for all race motors is not warranted imo. Thats all. I will sit back and continue enjoying the discussion as it continues.
Myron, why sit back when you can aid in development with your experiences. I am a newbie to two strokes and would love to hear your knowledge with snowmobile engine and pipe design. I have built many pipes for my Yamaha GPX and have been getting onto something good as of late. Tested my pipes once on an eddy current dyno and synced the dyno results to simulation results in post2t. Getting very close to my goal in real life and sim as they are now close to one in the same.
At first I put garbage in to the sim I got garbage out.
Myron, were you developing cylinder reed engines or case reed? What were your findings on different pipe designs? Where did the header percentages trend on your champ? I would love to see and hear what you learned.
Last time I will throw stones at rk tek. The reason we all think it is snake oil is the lack of evidence with logical proof of anything. That and the shady webpage that consistently over exaggerates everything in an attempt to shmooze unsavvy buyers with a product that only sells because it has a different appearance. If you are in fact lurking Kelsey, please throw some stones back. I am sure we would all love to get some sense slapped into us. That is all.
The good thing about this thread, if Rob will allow me to speak for him in a legally binding way: is that its intention is to share knowledge. I think that is why it has kept going so long.
Slinging with a couple of exceptions tends to Peter out quickly. Sorry any Peters.
PS a few carriage returns would aid ability to read a clump of text, much appreciated.
Don't you look at my accountant.
He's the only one I've got.
Good on ya Myron for making your enlightening post.
Gotta remember as you point out though that was 10 years ago , and when I made the error of generating shit tons of power at the wrong overev rpm it was simply me showing off ,
and with a major ignorance of the application requirements at the time.
This was quickly pointed out to me , and the fix was easy implemented and then dyno proven, but very non public after the first shit fight that occurred.
But you have an inherent flaw in your comments I must point out - the pipe I designed and then published the back to back result of , against a reverse engineered Jaws effort was shown in a sim result ,
and you imply a distain of that sim only result as being an unreliable proof of superiority.
You then go on to say you have no problem using that sim to regularily design and then produce superior dyno results directly - surely cant be both can it.
I spent years ( like you ) using and working with , and on the hundreds of code changes needed for Dynomation with the owner, whom I met before he started HotRods.
But Neels code has been for a long time now , also after years of refinement , light years ahead in being able to a: replicate a dyno result and b: accurately predict the result of tiny changes in an engines specification.
As as always though , with this level of computational accuracy - but a single dimensional codes inherent limitations , even a tiny bullshit input in = an even greater bullshit output.
And I fully suport TZE's original brave intent , as its something I really believe in , is passing on our 2T knowledge as much as possible - including the fuckups.
TZE gets really pissed with people as he puts it , happily eating at the dinner table but contributing nothing.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
cutting hemispheres on a knee mill
the best way i can come up with to visualize why this process works is to think of taking a large glass and placing the open end on a globe and note that the rim of the glass is in contact with the globe at all points. If the rim of the glass is the cutting tip of the tool and the globe is rotated, then it will cut the surface of the globe.
If the edge of the cutter touches the axis of the hemisphere then the cut is controlled by a combination of the radius of the cutter and the angle of the spindle. CAD makes quick work of fixing one and calculating the other.
Here we are cutting the squish with a 1.25" end mill and using the CAD to tell us the angle needed is 5.0°.
Here we are cutting a hemispherical combustion chamber, fixing the spindle at 45° and adjusting a boring bar to the needed 28.3mm diameter.
After setting the angle of the spindle and the diameter of the cutter, the rotary table is positioned so that the lowest pass of the cutter is on center with the work in the rotary table. Once aligned the knee can be raised or lowered to control the depth of cut but everything else should be held in position.
Patrick Owens
www.OopsClunkThud.com
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