Re: Cryogenic Super Finish?
 

A lot of BS there.

Back to basics, engine components don't actually touch most of the time, they run on oil films, the surface finishes used are to suit the film thicknesses so the asperities don't get to touch each other (mostly) and there is enough oil retention volume (e.g. honing in bores).

Losses in journal bearings are down to shear in the oil film, the losses depend on film thickness, shear rate (rpm and diameter), shear area (total journal surface), oil viscosity etc.

Total losses are not that great, you won't get another 15BHP out of a 1.0L bike engine by "improving" the surfaces slightly. The breakdown of engine mechanical friction is well known, a lot of work goes into reducing it, engine manufacturers don't just guess these things.

As a useful empirical guide, Barnes-Moss came up with the equation (friction mean effective pressure)
FMEP = 0.97 + 0.15(N/1000) + 0.05(N/1000)*2
Now that's somewhat out of date but it's a guide.
The constant term is seal friction, piston rings etc (constant torque loss)
The speed (N) proportional term is journal bearings, viscous losses.
The N*2 term is pumping (oil, air, water)

Say at 8000rpm in a 1.0L (=V) engine, viscous losses are around
0.15(N/1000) = 1.2Bar FMEP,
Torque = 7.958 x V x FMEP = 9.5Nm
Power = FMEP x V x N/1200 = 8kW

A modern bike engine would be less than that empirical number.

If you did a really super job on reducing viscous losses, say even halving it (unlikely), that would be around 4kW. I reckon 2kW would be very good going indeed and if I managed 1kW reduction I'd be pleased (otherwise all manufacturers would do it as standard).

Total losses will be in the ballpark of
FMEP = 0.97 + 1.2 + 3.2 = 5.4Bar
T = 43Nm
P = 36kW

Well over half the losses are from pumping.

I'm sure there are applications where these sort of surface finishings and treatments can be applied, but the claims for reduced engine friction don't stack up IMHO.

Just looking at one of the tech papers on the site shows some of the problem, they were measuring the effects of car diff nose angle (propshaft joing misalignments) on an inertia chassis dyno without controlling temperatures etc, that's just not accurate enough to get anything technically meaningful other than trends.

A couple of years ago I was doing some friction developments on 4.2L V8 engines, we were controlling oil and water temps to +/-0.5degC, anything more would dominate the friction changes we were looking for, and using steady state motoring dynos (speed control better than +/-1 RPM at 7000RPM)

Re: Cryogenic Super Finish?
 

embee talks sense :-)

Though the bits about reducing residual stresses in the pre machined components (eg, as forged) make (some) sense, though at this point you're looking at making things stronger or more fatigue resistant, not at making more power.

You could use this to your advantage to tune the engine more before it explodes but without some science behind the process your still at the situation that you don't know when the parts are going to give. If an engine blew up with standard components it might survive if you put the cryo parts in it but tbh unless you have pushed every other bounary to the limit this kind of thig is pointless.

Re: Cryogenic Super Finish?
 

thank you for the explanation I don't trust a product that doesn't calculate and publish its results..

from a material point of view how would the process change the surface finish of the material?

Its been a while since I did materials at college but surface finishes that could be achieved during the manufacturing process required mechanical input as the natural process of making metals leaves oxidisation on the surface, effectively making it rough r smooth depending on the make up of the metal?

How can freezing it change the surface finish of an already machines and produced metal?

im off to stick my rearsets in the freezer and see if the look any shinier?

Re: Cryogenic Super Finish?
 

think I may have gotten my wires crossed on 'cryogenic' superfinishing vs. isotropic superfinishing (as featured in the PB magazine).

http://en.wikipedia.org/wiki/Superfinishing

and then there's this thread about it on another forum: http://www.sportbikez.net/forum/f4/s...nishing-23615/

Re: Cryogenic Super Finish?
 

so will my motorbike go faster now I let it freeze up outside over winter then...




;)

Re: Cryogenic Super Finish?
 

Fade, you can do something like that but it's heat treatment, cold won't do it. Where it works, it's already done in manufacture.

Thanks Embee for the griff