Knife edging vs. tear dropping?

[El_Diablo]

yeah, sounds kinda weird huh? but if you look into basic aerodynamics it actually makes more since theoretically to shape the counterweights in a teardrop shape rather than knife edge it...

so what do you guys think? as far as windage losses and sheer rev time and speed it seems to make more sense since a tear drop shape will cut through the air better


i know this is kind of an out there theory but if theres power to be made, why not?

[megafreakindeth]

it would depend where the thick part is on the tear drop, if its at the bottom of the weight, furthest from the journal then you wont be doing much. its better to keep the weight more centered even if you cant reduce the weight. fords perf. flywheel for a mustang is like this, weighs about the same but the weights in the middle so the same effect is achieved as removing weight.
if the weight is indeed in the center then itll prolly just end up looking like its been knife edged anyways. eitherway ive had a few people tell me its really hard to balance a knife edged crank.

[El_Diablo]

well idealy you wouldn't fully tear drop it, instead you would just round the face and bottom of the crank throws and tapper back from there... almost like a propeller blade but straight with a fat leading edge

[megafreakindeth]

ah, well that would kinda help if you had tons of windage, but if its bad enough to a point where you need to do that you have other problems. the main thing about knife edging is it removes most of the weight of the crank. it probably would work but would be hard to balance.

[El_Diablo]

im just trying to extract every ounce of performance and why knife edge when i can simply tapper the back end and slightly round the front end? it really wont be that hard, true knife edging isnt about removing weight... its about cutting windage loses, for cutting weight i'll just try and cut the throws around the diameter to bring them closer instead of drilling the crank, then weld up the stock balancing holes, cant hurt, right?

should be noted this is my dream build, not sure if i'll get to do every single thing listed but im gonna try

[megafreakindeth]

can you post a pic of what exactly you mean? im just curious. my only thing about your idea is that while it might have an advantage over knife edging, it also will require a tool or something to do properly. even if you cut it by hand as best as your eye could see, if one side was off slightly it would actually create a misfire in that cylinder(no lie). still its worth noting, as long as it can be balanced. if your dream build had the proper dream budget, you could always cut youre own crank.

even my dream builds dont include that kinda budget

[El_Diablo]

ever seen a machine shop deburr a crank? a lot of them use a large angle or "body" grinder to shave off the metal and make sure there are no sharp edges

you'd basically be "bullnosing" the front and bottom of the crank and tappering the rear, you know those old belly tanks? cut one of those in half and you have the bottom profile only my crank will prolly not be as rounded

essentially im planning to tear drop it as much as possible without throwing things out of wack, the idea isnt to get the face as thin as it is to get the rear to tapper, idealy you want a large front and small rear area because its the trailing edge that causes the most aerodynamic, and in turn, windage issues

this along with a teflon crank scraper should do nicely i believe