crank web filling
Moderator: rztom
crank web filling
which material would you guys recommend for fillingn the crank webs, not only the 2 small balancing holes but the whole pockets around the pin? I wanna achieve a full circle web for increased crank pressure. Epoxy, nylon, alloy? It should be as light as possible but strong enough not to explode at 12000 RPM.
Luther,
The other problem is that the guy who will assemble and true the crank afterwards may destroy the sleeve with his copper hammer.
Our current best idea is to fabricate the inserts for the 2 pockets in the web from a kind of teflon (need to find right one) or epoxy mixed with glass fibres and bolt it on the web. Still searching for something better though. I searched for the pic you are referring to but with no success.
Twinsport,
Thanks a lot for your inputs, we will keep them in mind as plan B
regards
Wolfgang
That is what my engine guy has done in the past (20 years ago), but it requires modification of the crankcase due to the bigger crank web diameter, even though it is only 1 mm or so. Cost of machining time in Austria prohibits that solution.A thin steel or aluminum sleeve pressed over the wheel to trap cork and epoxy. I've seen a picture on the www like this
The other problem is that the guy who will assemble and true the crank afterwards may destroy the sleeve with his copper hammer.
Our current best idea is to fabricate the inserts for the 2 pockets in the web from a kind of teflon (need to find right one) or epoxy mixed with glass fibres and bolt it on the web. Still searching for something better though. I searched for the pic you are referring to but with no success.
Twinsport,
for some reason I feel uncomfortable with welding on a crank.What about welding thin sheet metal to the crank to make hollow fillings? It's made like that on my Puch 250 SGS (with factory crank). Strong, light and cheap
Thanks a lot for your inputs, we will keep them in mind as plan B
regards
Wolfgang
My crank web fillings are completed, crank will be sent for assembly now. All 8 webs have this epoxy fillings, the inner webs have a thicker layer since the clearnace to the conrod is bigger.
This is an aerospace grade epoxy, resistant against oil, gas etc and heat up to 130°C
[img][img]http://img233.imageshack.us/img233/3822 ... lling1.jpg[/img]
[/img]
This is an aerospace grade epoxy, resistant against oil, gas etc and heat up to 130°C
[img][img]http://img233.imageshack.us/img233/3822 ... lling1.jpg[/img]
[/img]
Heat in the crankcase can exceed 130°C in some engine's .
I remember you saying you wont stress this engine, so you might not get to much heat into the crankcase, or was that a different engine?
I remember you saying you wont stress this engine, so you might not get to much heat into the crankcase, or was that a different engine?
And that's all I have to say about that.
http://www.youtube.com/watch?v=vG8UJZzYHDs" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=yHFsoHd0nZI" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=JJ5pCjnMQQg" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=OyZfNKHPRs8" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=vG8UJZzYHDs" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=yHFsoHd0nZI" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=JJ5pCjnMQQg" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=OyZfNKHPRs8" onclick="window.open(this.href);return false;
No, this engine will be stressed indeed, we are aiming for much peak power, pure trackbike...although crankcase temp should not be more than 130° deg?? The gas temp will go up and down in sync with the pressure pulses each rotation, but the average temp should be much lower. I dont even expect 110°C, but I really dont know for sure
Our target is a power to weight ration of 1:1,2.
Not the world nowadays with the most recent superbikes, but for sure lots of fun!
Our target is a power to weight ration of 1:1,2.
Not the world nowadays with the most recent superbikes, but for sure lots of fun!
Last edited by zomaardan on Wed Jan 04, 2012 10:55 am, edited 1 time in total.
And that's all I have to say about that.
http://www.youtube.com/watch?v=vG8UJZzYHDs" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=yHFsoHd0nZI" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=JJ5pCjnMQQg" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=OyZfNKHPRs8" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=vG8UJZzYHDs" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=yHFsoHd0nZI" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=JJ5pCjnMQQg" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=OyZfNKHPRs8" onclick="window.open(this.href);return false;
- not the woose
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Hi Robert,
this mod was done by an experienced fellow engine builder who raced all kind of 2-strokes. There is much more modifications to the crankcases done, including plugs on top where only the rods pass through with defined transfers etc.
I have seen similar web fillings on other 2-stroke racing engines as well.
I cant comment your statement since I dont understand enough, but I assume my engine guy knows why we are doing all this - and its a lot of work involved believe me.
He built similar RD500 engines in the 80´s and 90´s, with ca. 120 HP but without modern electronics like programmable ignition, etc.
Lets hope he is right.
this mod was done by an experienced fellow engine builder who raced all kind of 2-strokes. There is much more modifications to the crankcases done, including plugs on top where only the rods pass through with defined transfers etc.
I have seen similar web fillings on other 2-stroke racing engines as well.
I cant comment your statement since I dont understand enough, but I assume my engine guy knows why we are doing all this - and its a lot of work involved believe me.
He built similar RD500 engines in the 80´s and 90´s, with ca. 120 HP but without modern electronics like programmable ignition, etc.
Lets hope he is right.