cranks with Chevy journals

[riorex2002]

Has any one had any experience using the cranks with the Chevy journals?.I read that the diameters are smaller so i expect the weight  would be less, making it  easier to balance with less material added.The rods could also weigh less.As the cost is the same for both cranks i think it is worth looking into.

[Steve]

Has any one had any experience using the cranks with the Chevy journals?.I read that the diameters are smaller so i expect the weight  would be less, making it  easier to balance with less material added.The rods could also weigh less.As the cost is the same for both cranks i think it is worth looking into.

Contact Chris Kleman ckleman@gmail.com He has a nice writeup here:

[riorex2002]

Thanks Steve.
That makes for interesting reading,Reading down i note that he uses a Great Plains hub and thinks that it could be lightened by drilling holes on the flange.As he bolts a weight on this to balance the assembly it might be possible to remove metal from this flange to achieve the same result.Just my thoughts ,Gee it sure is an interesting project.
May be see you at the Rio Vista Legal eagle gathering.
Rex

[Chris Kleman]

Hello Rex
   If you have any questions I could answer about my build that Steve linked, I'd be glad to answer.  I tried to cover as many pertinent aspects of my build in the pdf as possible, but realize there may be other questions out there that I didn't answer.  I chose to go with the bolted on weight as it's the easy way to make sure one wouldn't remove too much material where strength/safety becomes a factor.  Also, before contemplating or suggesting removing material, I'd want to do some strength analysis to make sure that removing the required amount of material would first be possible, and second wouldn't reduce the strength of the hub below a reasonable factor of safety.  Having been balanced and having a known mass added at a known location, one can determine the amount of material removal required from a certain location of the hub to create the same effect.  Unfortunately, it worked out that mirroring across the central axis of the crankshaft to where the material would instead have to be removed places the area of removal in the same general location as one of the prop bolts which would require splitting the material removal to equal offsets from the mirrored central axis of the added weight.  Rough calcs of material removal required were done by treating the added weight as a point mass located at the weight's center of mass and utilizing the mass * the radius from the cranks central axis to the center of mass (m*r, the unbalance).  The centrifugal force of the weight can be calculated with the cranks angular velocity and the force vector of the added weight would need to equal the force vector (or sum of vectors if split locations) of the removed mass.

In the end, it's easier to play it safe-and-easy and spend the few ounces on the added weight and only worry about removing material if you're really looking for a place to scrounge to save weight.

As far as the Chevy vs VW journals, I'd personally have no concerns going with a Chevy journal sized crank, particularly if building a stroker.  As far as overall weight difference in the connecting rods you'd have to look up or weigh them to find the difference.  As for the difference in crankshaft weight, you'd be looking at maybe 5 ounces in difference as a ballpark guestimate.

Chris

[riorex2002]

Thanks Chris for your interest in my project.
When mentioning my idea's i am just putting them out for input from people such as you who have been there before and know a lot more than me on this very interesting subject.I am at the stage where my plane is a quarter built and the power plant is still just a pile of parts.I do have to purchase a lot of new parts ,the crank being one of them and the idea of a complete balance with the hub being used as a sacrificial plane was just one of them , but i do agree that it is not practical.The mention of the journal weight was not the total weight concern but rather the centrifugal weight and the amount required to balance this force.While i have got you on the hook,what do you think of the idea of installing a power balance unit,the same type that is mostly installed on the front of the prop.on the rear of the crank.They do make one as an after market part for the Harley.
Rex