Cylinder wall honing surface finish & ring gap

[Fahlin Racing]

Perhaps Greg was speaking of a aftermarket piston of sorts. If I am mistaken, I stand corrected.

With the rings, a keystone design, the pivoting action it does upon up and downward strokes is what I don't want to be truthful, IMO its just a design to make up for any ring-action that may unseat the ring from the ring land it has seated on due to pressure from just the simple movement or compression and combustion cylinder pressure.

Ring flutter is what just may come closer to happening in a keystone design would it not once a certain rpm has been passed?

Has the design of the Keystone evolved to be improved and compete more evenly than the square design? Top fuel engine producing more power/torque don't use barrel faced rings, do they?

 

[S Phinney]

Perhaps Greg was speaking of a aftermarket piston of sorts. If I am mistaken, I stand corrected.

With the rings, a keystone design, the pivoting action it does upon up and downward strokes is what I don't want to be truthful, IMO its just a design to make up for any ring-action that may unseat the ring from the ring land it has seated on due to pressure from just the simple movement or compression and combustion cylinder pressure.

Ring flutter is what just may come closer to happening in a keystone design would it not once a certain rpm has been passed?

Has the design of the Keystone evolved to be improved and compete more evenly than the square design? Top fuel engine producing more power/torque don't use barrel faced rings, do they?

You are comparing apples and oranges. Those engines are torn down almost every pass or so.

 

[Fingers]

He is also mixing technology. Barrel face and keystone.

 

[Fahlin Racing]

You can mix technology plain and simple. Some technologies just don't make it past a certain point. A race engine is a race engine regardless of fuel Phinney, you know that. Do they (top fuelers) use keystone rings? If you intend to stay low in rpms I suppose a keystone will be sufficient. Between me mixing barrel faced rings and keystones, sure I may have thought something else.

Explain to me and anyone else reading how a Keystone would survive high rpms among other designs. Is it really a design that has not been given the credit for doing the duty at higher rpms? I am curious on this, perhaps too much on why things are, you know me. That narrow I.D. has quite a influence on possible ring flutter entailing filling your crankcase with fuel and pressure creating more windage and loss of instantaneaous torque.

So being corrected, thank you. Any Dmaxs running above 6,000 with a keystone reliably?

 

[Fahlin Racing]

Honing, mentioning of the Nikasil bore coating as well.
http://www.enginebuildermag.com/2002/11/the-smooth-science-of-cylinder-honing/

I remember now where I had seen the picture of a barrel faced ring, a tech book from diesel tech school showing what a Cummins L10 was being used as an example and the top ring is barrel faced and is a keystone design. Sorry I mixed up big diesel with little diesel.

Now we get into negative twist and positive twist rings? Differing between the top ring and second ring. The rings are quite a deal to think about guys and gals.

 

[Fahlin Racing]

Another article from Engine Builder concerning the finished surface our rings ride on.
http://www.enginebuildermag.com/2000/09/cylinder-bore-surface-finishes/

 

[Fahlin Racing]

Found this on the axial motion of rings which should be a good addition to the thread even though it has quite a bit of calc in it. :thumb: Thinking deeper than just a basic ring gap spec, just trying to find why we do it.

http://www.federalmogul.com/en-US/Media/Documents/ICES200976080.pdf

 

[S Phinney]

There is nothing wrong with thinking out of the box. That is how new designs come about. The biggest difference in ring design is the application here. You have high rpm gas design vs lower rpm diesel design. You have high boost diesel vs low to naturally aspirated gas design and so own.

 

[Fahlin Racing]

Top Fuel is supercharged to beat the band just like a diesel so in essence I am comparing boosted to boosted. The two fuels cool the engine differently and have different flammability levels.

I do know I will be making piston ring squaring tools for multiple bore sizes to set the end gaps properly. I am still at the fence on if I want to go electric or manual grinder so the rings end up correctly square.

If we want to dig further we could take into consideration of what the OEMs would probably look at. Whom who has the tooling, probably won't be on this forum.

Ring expansion between ring styles
Bore expansion on power stroke
Bore distortion due to thrust of each stroke
Bore distortion due to cylinder block flex during crankshaft revolutions

Is a Duramax block able to flex as much as a Cummins block by hand? Wouldbe great if it did not.

 

[coalroller83]

320 would most likely be the spec for the grit of stone.

The wall finish will be indexed by an RA number.

Does someone have the RA number? I'm running Fingers cast pistons, with steel rings.


LB7 CC SB, 10mm Exergy, 30% injectors, AirDog II 200, billet Stage V Trans, River City 66/74 IHI, Turbonetics Intercooler, PPE up-pipes/manifolds, complete engine ARP studded, Flex-a-Lite fan, AlliLocker, E-Locker, TrueTrac, topped off with EFILIVE, to name a few...

 

[S Phinney]

See post 8 and call your ring manufacturer to verify with them as well. Those numbers should work for your application but it is better to verify instead of taking people's word on thong like this. Make sure your machine shop has the ability to measure it as well.

 

[coalroller83]

See post 8 and call your ring manufacturer to verify with them as well. Those numbers should work for your application but it is better to verify instead of taking people's word on thong like this. Make sure your machine shop has the ability to measure it as well.

Thanks!

 

[West]

Old thread I know but information your should know if having a engine bored. Pistons for several years now are cut on CNC machines to finish size. The CNC machine (computer controlled machine) allows the piston to be custom cut so they take away material where they now know the piston grows the most under hard working conditions. This allows a bigger skirt at the bottom than the top of the skirt to hold down piston slap or rattle. Helps keep the rings stable for better sealing and they last longer because the piston is not rocking in the bore as you run the engine. All good stuff. I know Federal-Mogul started this type manufacturing before 2010, I am sure Mahle followed or maybe did it first. The manufacturer gives you a measurement from the piston head down to the place they want you to measure the piston size. Many leave a window in the skirt coating for this exact place to measure the piston skirt. Measure at this point to confirm piston size and your Piston to bore clearance. The piston will be smaller above this point and larger below this point. Heat at the top makes the piston expand, as you move away from the heat source, (combustion) the piston is cooler and does not grow so much. In the old days the pistons were straight cut because that was all the machines could do. Today you get custom cut pistons that give much better life and run quieter while sealing better. When you set bore size you better know exactly where the manufacturer says to measure for piston to bore clearance or you will be wrong.