Superpolishing / Superfinishing

[dhtmbowen]

Anyone know where I can get it done and is it worth the hype?

[theo]

These guys do it (for bearing journals at least) for very reasonable cost too.

www.daverushton.co.uk

You wont tell much/any different on a road bike, i dont think, but as to being worth doing?

Absolutely definately. F1/LMP/NASCAR etc. engine builders dont do it for no reason. plus it looks the tits.

Have a look in SEPTEMBER/OCTOBER 2010 Racecar engineering. Ill scan some photos and upload them later.

[theo]

This is a superfinished NASCAR crank:

Uploaded with ImageShack.us

[dhtmbowen]

That looks AMAZING!

I think I'll get the crank and cams done (my cams run in journals) cost permitting.

Thanks v.much.

[madmike]

You wont tell much/any different on a road bike, i dont think

But will it not increase the life of the engine?

[theo]

By superfinishing any parts, you are removing any roughness (peaks and troughs [superfinishing can often achieve 0.0125 microns RA or better]) that would be left by 'covnentional' grinding, and so yes, stress risers will be decreased, ultimately leading to a stronger part.

However, in my experience (reasonably limited as it is) its very unusual for a snapped crank to be the cause of an engine being scraped (though a snapped crank or rod would go round like a bacon slicer, destroying a set of cases at very least), especially with modern mass produced units such as japanese IL4s.

I think that if a standard engine failed at say 100,000 miles, it would be impossible to predict that the same engine, with just superfinishing applied to the crank or cams, would last any longer.

I could just be talking bollocks though, that has been known before.

[dhtmbowen]

I'm interested because I am getting into endurance racing post classic bikes which, in my case, means Z1000s.

The limiting factor on engine performance on big air-cooled motors is heat. You can tune a Z1000 motor to produce 165bhp for short circuit, 10/12 lap races but 120bhp is about the limit for a reliable endurance motor. Anything that reduces internal drag has got to be a help in improving engine longevity and, if it allows us to get an extra 5 - 10bhp, that would be a mahoosive bonus.

BTW: Dave Rushton doesn't advertise superfinishing on their website.

[dhtmbowen]

Dave Rushton doesn't do superfinishing. They do polishing with a belt which is what I do at the moment.

[theo]

Sorry for the duff info regarding dave Rushdon.

As it says on their site, the can offer micropolishing on ground surfaces (such as bearing journals) which amounts to superfinishing as they can get to very similar values (0.0125Microns Ra) but, doesnt include all over finishing which i take it is what you want on your crank.

[theo]

You dont really want the oil layer to adhere to the component. This causes shear layers, which is a major source of friction as a component rotates relative to another.

The oil pressure is (should) be sufficient that the crank etc. float and never comes into contact with the housing.

[blow_away]

<Daft question time>

If you superfinish something, why does that not increase the drag on the component next to it?

eg.1 A slick tyre creates more drag on the road surface than a treaded tyre.

eg.2 I have a set of slip gauges at work, they are very finely polished and stick to each other when you push them together - they are polished in one direction, you can only separate them by moving in them apart in the right direction.

Yours, Confused of Bristol.

I hope I understand the answer! It does look incredible. Would there be any benefit in superfinishing surfaces where gas flows, cylinder heads, inside of exhaust etc?

[theo]

As tot he question of polishing heads exhausts etc.

The photo below shows a cutaway of a 2009 Toyota F1 engine (RVX-09), which shows the whole inlet tract to be as shiney as fcuk!

Uploaded with ImageShack.us

This side on photo shows a cutaway head. Look at how the double barrel throttle disappears into the inlet tract wall at WOT, reducing any pumping losses. Also look how thin in section the hollow cams are.

Uploaded with ImageShack.us

They found with the V10 before that as they increased peak revs from 17,500 (2001) to 19,200 (2005) BMEP actually increased!

[jaycee]

Hasn't Mark from PB, he of the furry R1, had parts of his engine superfinished? I seem to remember an article (written by him?) about superfinishing. It was the first time I had ever heard of it.

[Superdunc]

<Daft question time>

If you superfinish something, why does that not increase the drag on the component next to it?

eg.1 A slick tyre creates more drag on the road surface than a treaded tyre.

eg.2 I have a set of slip gauges at work, they are very finely polished and stick to each other when you push them together - they are polished in one direction, you can only separate them by moving in them apart in the right direction.

Yours, Confused of Bristol.

I hope I understand the answer! It does look incredible. Would there be any benefit in superfinishing surfaces where gas flows, cylinder heads, inside of exhaust etc?

I'll try not to use any big words Al Wouldn't be able to spell them anyway.

1. A slick tyre has more drag, because it's made froma softer sticker rubber, the fact that it has a bigger contact area isn't as significant.

Comparing slick tyres to a crankshaft, isn't correct as engine parts have lubricant between them.

A better analogy would be a tyre on a wet road the water is the lubricant and we know which sort of tyre will have the least drag in this situiation.

2. The slip guages you talk about have a ringing surface. When you slide them together, the surface is so smooth there are no low spots for air molicules to sit and you end up with a vacuum between the 2 blocks, smeer a bit of oil on them and they wont stick.

As for superfinishing cylinder heads, the Exhaust and combustion chambers benefit from having a layer if carbon on them to act as a thermal insulator. The inlets aren't so simple, current theory is that a slight roughness on the wall of the inlets is good, we're talking 120grit finish here, it creates a small amount of turbulance helps that flow in a way I don't fully understand. The polishing you can see in Theo's excellent pictures is for show like the red paint.

The biggest advantage of superfinishing some thing like a crankshaft is not reduced friction on the journals, there is no metal to metal contact here so as long as the are smooth enough to maintain a contiuous oil film it's good enough, though smoother will increse the operating envolope.

The real gains are in the finish on the webs, 4t engines suffer from windage in the crankcase, this refers to the mist of oil that fills the engine bellow the pistons, it's very dense and costs power to drive the crank through it, to counter this engine builders knife edge crank webs, to make them more hydrodynamic, and run dry sump systems which in the case of F1 run the crank case in a partial vacuum.

In addition to windage you have the situation where oil sticks to the crank webs, particularlly an issue in wet sump engines, the amount of oil on the crank webs adds significantly to the mass of the crank assembly which is not good as we know, especially on a high reving bike engine, race engine sumps have intricate scrappers in them to remove the layer of oil on the surface of the crank webbs , superfinishing would help massively with this, and I would say is the biggest contributer to the improved feel people talk about after superfinishing engine parts.

[theo]

Whilst there is a great deal of sense in Superdunc' s post, there are a few things I don't agree with.

With regards to the superfinishing and reduction in amount of oil stuck to the webs during operation, I think this is something that doesn't have a definate answer. Some crank manufacturers agree with this, others cite it as something that brings not gain. The volume of oil, and hence it's mass, can only be minimal (especially considering the crank's speed and hence the centrafugal force flinging the oil from the crank and the fact that some high end stuff runs in a partial vacuum).

I also used to be of the opinion that a layer of carbon in the combustion chamber was desirable during operation however, I bought this up with the head of Engine Development at uni (a guy who has his fingers in a great many pies and who has worked with more than a couple of engine manufacturers) and he was of the opinion that this wasnt the case. At high rpm in engines with high compression ratios (like race engines), the rod elongation causes the piston to almost hit the head, so that carbon is unable to build up the squish area.

As with the inlet tract debate, this is one that is always ongoing. Although yes definately the toyota display engine will have been 'tarted up' for showing, I am sure that the inlet tract would be finished as it is in the photos for normal race use. I have a friend who works in the engine build departments of one of the F! engine suppliers, who ill ask about this. Watch this space....

One of the biggest reasons for superfinishing will undoubtably be that a polished surface is better with regards to fatigue than a ground surface, which is in turn better than one simply machined (mill or lathe etc.). When a component is running at its absolute limit, this can be a major factor.

[Superdunc]

Whilst there is a great deal of sense in Superdunc' s post, there are a few things I don't agree with.

With regards to the superfinishing and reduction in amount of oil stuck to the webs during operation, I think this is something that doesn't have a definate answer. Some crank manufacturers agree with this, others cite it as something that brings not gain. The volume of oil, and hence it's mass, can only be minimal (especially considering the crank's speed and hence the centrafugal force flinging the oil from the crank and the fact that some high end stuff runs in a partial vacuum).

It still takes energy to pick the oil up, and although it might be small amounts each revolution, at 14,000rpm it becomes significant.

I also used to be of the opinion that a layer of carbon in the combustion chamber was desirable during operation however, I bought this up with the head of Engine Development at uni (a guy who has his fingers in a great many pies and who has worked with more than a couple of engine manufacturers) and he was of the opinion that this wasnt the case. At high rpm in engines with high compression ratios (like race engines), the rod elongation causes the piston to almost hit the head, so that carbon is unable to build up the squish area.

I have observed this phenomenon on torn down race engines, but the squish area only acounts for 10-20% of the combustion chamber

As with the inlet tract debate, this is one that is always ongoing. Although yes definately the toyota display engine will have been 'tarted up' for showing, I am sure that the inlet tract would be finished as it is in the photos for normal race use. I have a friend who works in the engine build departments of one of the F! engine suppliers, who ill ask about this. Watch this space....

One of the biggest reasons for superfinishing will undoubtably be that a polished surface is better with regards to fatigue than a ground surface, which is in turn better than one simply machined (mill or lathe etc.). When a component is running at its absolute limit, this can be a major factor.

Undoubtedtly a benefit of superfinishing, but dosn't account for the other improvements people describe with treated engines

[theo]

Superdunc All good points.

With regards to the carbon build up, ill go see the head of engine developments at uni this week coming up, hopefully have some more answers on this front.

[porter_jamie]

2. The slip guages you talk about have a ringing surface. When you slide them together, the surface is so smooth there are no low spots for air molicules to sit and you end up with a vacuum between the 2 blocks, smeer a bit of oil on them and they wont stick.

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

i don't think it is a vacuum - it is supposed to be molecular bonding.

[theo]

Superdunc:

With regards to the intake port polishing, at least 4 of this years' F1 cars run engine that have the ports very finely machined, but not polished. I dont know what level of finish this gives (in terms of roughness scales), but it is, as you said, to improve pre-mixing due to boundary layer turbulence.

Therefore, I must apologise, you were right on this.

[Superdunc]

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

i don't think it is a vacuum - it is supposed to be molecular bonding.

Reading that wiki link, it does mention atmospheric pressure, or molecular bonding. Who ever submited that entry wasn't sure.

I'm off to google molecular bonding

[Superdunc]

Superdunc:

With regards to the intake port polishing, at least 4 of this years' F1 cars run engine that have the ports very finely machined, but not polished. I dont know what level of finish this gives (in terms of roughness scales), but it is, as you said, to improve pre-mixing due to boundary layer turbulence.

Therefore, I must apologise, you were right on this.

Thats cool, no need to apologise. It's always good to definite answers on these things.

[Superdunc]

From Wikipedia,

Molecular attraction occurs when neutrally-charged molecules nevertheless experience the uneven distribution of electrons over their structure due to London Forces induced by random variations of electron density occurring in non-polar compounds, hydrogen bonding due to the production of what is essentially a bare proton when it is bonded with a strongly electronegative element such as fluorine, oxygen or nitrogen, and the dipole-dipole interaction between compounds that are polar, such as salt. The properties of liquids and the expansion of water ice when it freezes are due to molecular attraction.

So that clears that up then

[porter_jamie]

http://www.starrett-webber.com/GB46.html

http://www.tresnainstrument.com/slip_gauges.html

in my experience the longer you leave them the harder they stick. kinda welding themselves together..

[porter_jamie]

Squish, and what we've learned.

We used to obsess about getting the compression as high as pos, and the squish as low as poss. This actually doesnt really do you any good. It makes starting difficult. Made it necessary to use 98 fuel with boosters or it would det. Broke many crankcases. One missed gearchange and you need to change the rod incase the piston touched and brinelled the big end. Just not worth the effort for little or no measureable power increase.

it's not pretty but was worth about 8bhp. which is a huge amount when you only got 64!

There is not a lot of squish area left on the head, it's all been hacked away to get the bigger valves in. The standard bore is around 89mm for an Mt500, this one is 102mm.

If you set the squish clearance too low, the piston can have totally clean bits on it, or even witness marks. There is no head gasket - you can see where the top of the liner sits on the headface.

The flat bits would be near enough to the mating part on the piston to prevent carbon build up.

[Superdunc]

Out of interest Jamie, what compression ratio do you run? and what clearance on the squish? I always been told the tighter the squish the more power you get, with 0.85mm being the limit in most cases, though obviously this depends on a lot of other factors.

Have you any idea what effect the size of the squish band has, as you say it's normaly determined by the size of the valves.

[porter_jamie]

compression is about 11.5 or 12:1 more or less, if the swept volume is bigger then it is a bit higher (we have a couple or three options)

squish clearnace 1.25 to 1.6

I always thought tighter squish helps prevent det, so you can run a higher compression. I think this is true, but i think chasing high compressions is something to do when you have nothing else at all left to do, or are artificially restricted in some way - stock cam/valve sizes etc.

http://www.amazon.co.uk/Modern-Engine-Tuni...l/dp/0854299785

We bought everything Graham Bell has written, four stroke and two stroke. Quite handy for designing exhausts and so on. What ever he said would happen, did happen when we tried it.

It is all very empirical, and proud. Classroom theory is all well and good, and also very interesting but when you have limited resources and a race in a few weeks you just need to know what works and what doesnt.

http://www.amazon.com/Smokey-Yunicks-Power...k/dp/0931472067

You also need to buy everything Smokey ever wrote. Again, it is all learnt the hard way. If i had read and understood everything Smokey and Bell had written years ago i could have saved probably thousands and also won championships a lot earlier.

[sennidott]

This guy goes into some detail about squish and the effect of running steel versus titanium conrods.

Also mentions inlet port 'tuning'

You will have to scroll down the page a bit to find the info.

No mention of 'Superfinishing' tho.

[Superdunc]

This guy goes into some detail about squish and the effect of running steel versus titanium conrods.

Also mentions inlet port 'tuning'

You will have to scroll down the page a bit to find the info.

No mention of 'Superfinishing' tho.

Cheers for the link, there's probably some interesting info in there. Unfortunatly there is also more bullshit and mis-information than I can handle.

Book marked for when I'm feeling a bit more patient .

[theo]

Big yes to Smokey Yunick's books, and also a big yes to Gordon Blair's 'Design and Simulation of 4 stroke Engines' [Kinda like a bible this one, bit maths heavy in places but defo worth the read]. Don't think I've ever read any of bell's so ill take a look now.

Ive spoken a bit with Rudiger Kamna (ducati dealer/tuner as well as aprilias etc. in germany), and he recommends a squish clearance of 1.00mm for Ducati engines. [As you have run many Ducatis, what do you use Superdunc?]

[speedy sie]

my xro9 engine is running .6mm............

titanuim rods and valves .5 mm gasket.10mm vavle lift.