Drilling lightening holes in cylinder barrels

Status
Not open for further replies.
Fast Eddie

Fast Eddie

VIP MEMBER
Joined
Oct 4, 2013
Messages
21,908
Country flag
Is drilling lightening holes in iron cylinder barrels a good idea or not?

See pic below of some 500 Nourish barrels currently on ebay.

I’ve heard apposing arguments.

Those ‘for’ say it saves weight (obviously) and increases cooling due to the fact that the holes drilled increase the surface area exposed to air flow (you would have to calculate the thickness of the material and size of the hole to be correct about this).

Those ‘against’ say that the holes distube air flow through the fins and have an overall negative effect on cooling, worst case scenario could be hot spots that cause seizures etc.

Wadya all think ?

D78C4579-6551-4902-98FC-91DA7AD23268.jpeg
 
I think "devils advocate" Eddie
Are you looking for opinions or facts or both?
 
To me it looks like it would improve the cooling
I'd guess the air could travel through the holes and away taking more heat with it?
But who knows,if that were the case surely more people would do it ?
I have read somewhere drilling holes in fairings allowed bubbles of air to form on the surface that was more (slippery) aerodynamically than a flat surface!
I would also like to know what the facts are
Cheers
 
Holy smokes, lol, I would think that there is much less material for the heat to sink into like that and that could be crucial when there is not much air flow. I would think if you wanted better cooling you would add fin material, just my opinion.
 
On the Buells when they started the XB series bikes they added fin material to where the barrels almost touch at the bottom.
 
Isn't it basically the same train of thought for drilling disc brake rotors?
 
Waste of time, and it looks like crap unless on a rat bike where everything is supposed to look like crap. How many guys on the top of the podium do it?

I can't imagine there is any benefit.
 
Holly cheese some people have to much time up their sleeve, how long would it have taken to drill all them holes and what about the head fins while you are there, no thanks I like the fins the way they are, if you want to run cooler run a oil cooler, what about the wind blowing through them holes will they make a wind noise, cast iron fins are easy to break be even easier with all them holes drilled in them, but then if that rocks your boat then go for it.

Ashley
 
Well I'm standing over my Norton right now with a fully charged cordless and my grandads bit n brace as backup awaiting the results of this in depth analysis!
Cheers
 
I suppose you'd need to find out at what thickness/diameter the surface area of a cylinder's walls become larger than twice the surface area of its bore... Simple math when I was 'O' level student, but brain frazzling now....
 
In addition to the beautiful holes in the cylinder fins, isn't metal scroll work on the cases also required to improve cooling and reduce weight?
 
Drilling dimples as opposed to holes would increase the surface area and reduce weight... Though to what advantage in the real world?
 
Status
Not open for further replies.
Back
Top