bead blasting piston domes and combustion chamber

[philipl]

:icon54:Just Wandering If Anyone Has Ever Heard Of Beadblasting Piston Domes And Combustion Chambers To Reduce Carbon Buildup During Engine Operation My Friend At Work Builds Motors And Says This Will Reduce Buildup As Well As Let The Piston Top And Chamber To Run Cooler...any Input On This By Known Engine Builders Out There!!!!!!

[stroked_Z]

new one to me! wouldn`t that cause damage.

[woldson]

Couple things, the medium used to blast can leave a residue that can cause damage to engines.

Also, (guessing), I would think that a roughen combustion chamber could be more prone to detonation.....

[ZZZeee]

My concern would be damage to the outer crystalline structure of the aluminum.

[Challenger]

Are you talking about glass bead or the plastic bead. I know they sell various different bead medias.

[philipl]

I GUESS IM TALKIN ABOUT GLASS BEAD. IM SEEING THERE ARE A FEW PEOPLE DOING THIS ON THE INTERNET IT APPEARS THAT THE PROCESS SOMEWHAT PEINS THE TOP OF PISTON AND MAKES ITS MOLECULES MORE COMPRESSED MAKING THE ALUMINUM DENSER/STRONGER....ANYBODY OUT THERE DONE THIS SEEMS LIKE A GOOD IDEA FOR TURBOS OR HIGH COMPRESSION MOTORS ANYTHING BORDERLINE DETONATION!!

[Globerunner513]

why do that when you can just get it ceramic coated. That is KNOWN to work well.

[Datsun260Z]

Well, I am immediately cautious that's for sure. I would be especially interested in whether or not "beadbalsting" will remove the parent material. Piston crowns are obviously very crucial and have an Engineered thickness that I would not compromise. If you thin the crown you open the door for material to reach its melting point faster. However, that said I go back to my initial question: Does it remove parent material? If so, I'd let you friend blast all the pistons he wants and hide yours from him.

 

Furthermore, I cannot see how this will reduce any future deposits. IF you used a coarse enough of a media you would actually be giving future deposits more "tooth" to grab onto. Not less. Sure, cleaning them off would be a breeze but I don't see the problem with soaking my piston crowns in carb cleaner (or similar) and utilizing a near by scotch bright pad.

 

Just my pennies worth

 

And why are you yelling? Caps lock means yelling.

[theghosttanker]

Polishing the combustion chambers and piston tops to a mirror finish is a common practice. It helps with heat transference and reflectance and the removal of sharp edges in the chamber also reduces detonation problems.It doesn't make a huge difference but its one of those little tricks.

[stroked_Z]

I GUESS IM TALKIN ABOUT GLASS BEAD. IM SEEING THERE ARE A FEW PEOPLE DOING THIS ON THE INTERNET IT APPEARS THAT THE PROCESS SOMEWHAT PEINS THE TOP OF PISTON AND MAKES ITS MOLECULES MORE COMPRESSED MAKING THE ALUMINUM DENSER/STRONGER....ANYBODY OUT THERE DONE THIS SEEMS LIKE A GOOD IDEA FOR TURBOS OR HIGH COMPRESSION MOTORS ANYTHING BORDERLINE DETONATION!!

 

 

that is what they make forged pistons and high octane fuel for.

[Challenger]

And thats what they make money trees for... oh yeah, they dont exist!

[Globerunner513]

Polishing the combustion chambers and piston tops to a mirror finish is a common practice. It helps with heat transference and reflectance and the removal of sharp edges in the chamber also reduces detonation problems.It doesn't make a huge difference but its one of those little tricks.

 

This makes more sense to me than blasting does. Is this what the OP was getting at?

[thatcarguy350]

You can try WPC treatment.

Here's some stuff on it:

http://www.turbomagazine.com/tech/0608_turp_revolutionary_engine_protection/index.html

[philipl]

thanks for everyones input heres a snibit of info ive found from people who have tried this process.What's wrong with beadblasting pistons?

> this is data from a motorcycle forum...

> Steve

> '72 Commando (with freshly beadblasted pistons)

 

Glass beading will imbed into the aluminum pistons and will score your cylinders like crazy! Regardless of how much you clean them afterwards. The best alternative is walnut shell blasting or nothing at all but solvent baths!

Good Luck

Mike A in NJ

Date: Wed, 24 Jan 96 18:50:41 EST

From: Mel Smith

L. Reiter enquired about cleaning(scraping) pistons a hardwood wedge makes an ideal scraper when de-coking crowns in-situ. Won't damage the bore, easily sharpened with a rasp and material is cheap (screwdrivers and chisels are phillistine-gouges and scratches).

Years ago, Continental Motors(aircraft) found that polished pistons had a higher failure rate than ones with a dull finish. The reason was of the boundary layer that insulated the piston crown from the combustion heat. A polished crown would absorb heat and melt/burn thru. I've wrapped pistons with duct tape over the ring lands & skirt surfaces and bead blasted(cleaned) the crown surface with no failures and minimum carbon build-up.

Another old process that may be of interest to the trident/goldie crowd with sleeved liners is Koethurizing-a shot peen process for pistons. The piston is expanded in a jig about 3-5 thou. A nozzle sprays steel shot inside the piston in a circular pattern up inside the skirt. The piston is allowed to 'grow' a few thou against the confines if the jig (looks like a little circular clamp, adjusted for desired clearance) Saves having to rebore when a little slop or clatter is the problem. Knurling is just a cheap shortcut and warps the piston. The shot peening also stress relieves and stabilizes. -FWIW

Regards, Mel Smith

From: Latte' Jed

Date: Wed, 24 Jan 1996 19:52:47 -0500

> Glass beading will imbed into the aluminum pistons and will score your

> cylinders like crazy! Regardless of how much you clean them afterwards.

> The best alternative is walnut shell blasting or nothing at all but

> solvent baths!

I would hope nobody would try to clean anything but the top of a piston anyway, bead blasting the skirt would be dumb. A wire wheel will clean the crown about as quick as bead blasting will with less risk. Bead blasting generally shouldn't be done to the anything on the inside of an engine. I always polish the piston crown to help avoid carbon buildup, but even I admit it's a bit over the top.

From: Pete Serrino

Date: Thu, 25 Jan 1996 08:04:29 -0500

Regarding glass beading pistons, Mel Smith brings up an interesting point on boundry layer effects. Former list memeber Dr. Rob Tuluie has written an excellent article on the subject which can be seen @ http://www.motorcycle.com/mo/mcrob/rt-fuel2.html.

Glass beading when properly done will not remove metal but has an effect similar to shot peening. It has little effect on the overall dimension. If you glass bead the skirts it will serve the same purpose as honing the cylinder, that is it will improve oil retention. I've rebuilt about a dozen motors in the past 5 years and have never had a problem with scored cylinders due to glass. Cleaning them in hot soapy water is all that is needed.

Sandblasting on the other hand will change the dimension of the piston. A short application of sand, ground glass, or silicon carbide normal to the surface will *raise* it by about .0005" or .001" across the diameter which could help to compensate for a slightly worn cylinder bore. Cheers,

Pete Serrino

[woldson]

At this point I would just go with a coating like ceramic. Well proven, oh, also get it professionally done.

[PurePontiacKid]

My dad runs aftermarket aluminum heads on his Pontiac racecar, and we sandblast the combustion chambers every time we rebuild it, and he hasn't had a problem with it... we just do it to clean up the combustion chambers, so that it's clean going back together...

[shift00]

i've heard it being done on 2 stroke motors alot...

[islanddozer]

there is a find bead meant for the aluminum. Then light brass wheel. It works for me

[jt1]

Bead blasting is very common. Lots of machine shops use it to clean pistons, heads, valves, etc., that have heavy carbon build up from high miles or oil consumption. It cleans the piston very well and smooths the surface. You only bead blast the top of the piston, never the ring land area or wrist pin area. Occasionally you might do the skirts, but that would be unusual.

 

There might be some very slight benefits from reducing detontation by smoothing the surface, or holding oil better, or creating compressive stress in the surface. If so, they are very very small, not nearly as much as smoothing all the sharp edges on top of the piston, putting the proper hone on the cylinder walls, or choosing the right piston alloy.

 

The main benefit is a quick, cheap method to clean up a piston or head you are reusing. It has no negative effects as long as you don't do the lands or wrist pin areas. Beading will change the clearance and surface finish of these areas, which is undesirable.

 

 

If you check out the old tech 302 build thread, i had those pistons bead blasted. They look almost new.

 

jt

[Phred]

jt1 is correct, all you others, relax. Glass beading is commonly used in all race engine shops for domes, combustion chambers, and just about every other area. I have been doing this for over thirty years on every type of racing engine from Cosworth formula engines to Trans-Am, to Turbo'd big blocks. The only concern is complete cleaning after the process. A few glass beads in the wrong area can severely damage an engine. Glass beads come in various sizes for different applications, just like steel shot used in shot peening. And to a small degree, glass will have a similar impact on the metalurgy of the surface being impacted. I wrote the following paper which describes shotpeening, and how glassbeeding can enhance the shotpeening effect.

Phred

The principal function of peening is to increase the fatigue life of cyclically stressed parts.

Small steel balls (shot) hammer the part, coompacting the surface, which relieves both surface,

and subsurface, granular stresses.

This process builds a tough outer layer which is very resistant to fatigue cracking. This protective skin actually strengthens the part.

The useful life of a properly peened part is usually twice to five times that of an untreated part. Shot peening is of most benefit on con rods and crankshafts.

It can also be applied to almost any part subject to fatigue cracking. The following preparation is necessary befor a part is peened.

1. The part should be Magnaflux or Zyglo inspected

2. All sharp corners, nicks, machining flash, and similar stress risers should be removed.

A polished surface is not required.

3. Precision finished surfaces, such as pin bores, or journals, require masking prior to peening.

Intensity is the critical component in successful shot peening. High intensity peening will distort a thin section part.

Peening intensity must be high enough to produce an effective skin, but not so great as to damage or distort the part.

Controlling intensity in the peening process is accomplished by using shot of different density and diameter. It is also controlled by the distance from the gun nozzle, angle, air pressure, and exposure time.

The intensitiy used for different parts also varies with the type of metal being peened. The ideal intensity for a specific part is determined by knowledge of metalergy, experimentation, and experience.

Double Shot Peening

Most parts benefit from "Double Shot Peening". Wherein the part is first peened using larger shot and high intensity.

Then peened a second time using smaller shot (usually fresh glass beads) and lower intensity. This produces a much improved surface appearance and considerably improves the fatigue life over single shot peening.

Double shot peening is a patented process, (U.S. Pat. No. 3, 073,022) issued to General Motors. The rights of which are not being enforced. It is mentioned only to underline the value of the process.

The patent papers cover seven pages and include fatigue life charts showing life cycle comparisons between unpeened, single peened, and double peened parts. They leave no dought in the readers mind as to the advantages of double shot peening.