Hard Industrial Chroming of Aluminum, Brass or Steel Cylinders

[Ken Retallick]

Jim, can you explain why the first piston is not what it should be?

It has a nice even wear/sealing ring near the top.

 

[Jack ODonnell]

Hi Mike ; That's a easy one. The car guy's pay much more attention to the head temperature than the boat guy's do

 

[Terry Keeley]

Thanks for all the info guys!

Ken: Never thought of that before but it "kinda" makes sense depending on the play in the rod/wrist pin etc. I might try that even tho the ports will be blocked a little at the bottom of the stroke.

Jim: Thanks for all your numbers for the Nelson and your own design. Those taper numbers for both the piston and sleeve are fairly typical of other motors from what I've measured. Do you relieve the lower part (skirt) of the piston as well?

Jack: Yup! I've messed with stinger size a bit and found gains with smaller diameters but you havta be careful not to overheat the piston!

Here's what I'm talking about from one of my CMB 90's:

It's looking like it's trying to come out of the exhaust port!

The top of the same piston, hasn't been run lean or overly stressed:

Funny, here's a VAC 45 piston with about the same number of runs on it:

 

[Jim Allen]

hey jack or jim,could you go a little into stinger size and length and the effect it has on piston wear. I notice that my on-road car engines from nova rossi that come with pre made pipes and headers that the piston wear is more even then in some of the boat engines I have seen.thanks,mike.

Mike,

One of the first things we discovered when building tuned pipes, concerning any tuned pipe's stinger ID & any tuned pipe's stinger length, is the adverse effect that to small of a tuned pipe volume can have on engine performance. To small of a volume, even when using a short, large ID stinger, will raise the engine's head temperature. Also keep in mind that any thing that approximates the shape of a tuned pipe can be made to work. We found that tuned pipes that had an adequate volume, 26 to 32 times the engine's displacement, would allow a long , small ID stinger. These long, small ID stingers always increased the engine's performance. However, when the tuned pipes volume was large enough, there would be only a very slight increase in the engine's head temperature. We began using stinger's with an ID that is approximately 46% of the head pipes ID. The stinger's length is lengthened to 13.5 times it's ID without any over heating problems.

JA

 

[Jim Allen]

Jim, can you explain why the first piston is not what it should be?

It has a nice even wear/sealing ring near the top.

Ken,

From the photos, it appears that these pistons have to little taper at the top or no taper at all. Remember that there are two things working at the same time, the cylinder's taper & the piston's top taper. To Determine what was best for our engines we tested many cylinder taper amounts & piston top taper amounts. These test were done in .001" increments, both for the cylinder tapers & the piston top tapers.

JA

 

[Jim Allen]

Terry,

Your piston photos show what a typical straight sided piston will look after running. It appears the piston is tapered at the bottom, similar to the FMV pistons. There also appears to be a great deal of rubbing going on down where there should be no rubbing. Most manufactured engines do not use the best alloy for pistons or the hardest chrome.

"Jim: Thanks for all your numbers for the Nelson and your own design. Those taper numbers for both the piston and sleeve are fairly typical of other motors from what I've measured. Do you relieve the lower part (skirt) of the piston as well?" No. We tested this as well as the so called oil groove. Nothing to be gained here.

"I've messed with stinger size a bit and found gains with smaller diameters but you havta be careful not to overheat the piston!" Build a tuned pipe that has an adequate volume & watch what will happen to the stinger's ID & it's length!

JA

 

[John Beardslee]

Hi Jim

Are you using hard chrome on the aluminum liners or is it hard anodizing i.e.: aluminum oxide?

Thanks John

 

[Jim Allen]

John,

All of our aluminum cylinders (#4032 Alloy), brass cylinders (#360 free machining brass, #544 Phosphorous Bronze) & steel cylinders are hard chrome plated. Over the past 4 years we have developed the chroming process to a very high level. There are no more pitted or blistered cylinders & no more problems with chrome peeling off in assembled engines. Our process also gives very reliable results as to the amount of chrome being deposited in sleeves that have the taper machined in them before chroming. The first photo shows cylinders recently removed from the chrome tank after chroming. They only need to be cleaned outside & honed inside. We have also developed the honing process to a very high level with the special holding fixtures used.

JA

 

[Mike Rappold]

On the tuned pipe volume measurements, how are you measuring it? Are you filling the pipe with water and measuring the amount of water?

Also what is being considered for the "ends" of the pipe? Is it the end of the header and the end of the stinger?

Thanks in advance.

Mike

 

[Jim Allen]

Terry,

I'm sorry for missing your #14 post referring to the MB engine, which clearly shows the necessary wear band & its position in relation to the piston's crown. Rob Metkemeijer, Henry Nelson & I have had many discussions about this "Wear Band" when they visited the Julian air races. Any AAC or ABC engine that does not have this will rapidly lose it's piston to liner fit, & therefore it's peak HP over a very short period of time. I have witnessed MB 40 FAI speed engines routinely operate at 35,000 RPM in the air while maintaining their piston to liner fit.

https://fiorimet.hom....nl/Running.htm "This should be done very lightly & carefully, especially at the "ring", approximately 2.5 mm (.0984") from the top of the piston where it seals."

Jim Allen

 

[Jim Allen]

On the tuned pipe volume measurements, how are you measuring it? Are you filling the pipe with water and measuring the amount of water?

Also what is being considered for the "ends" of the pipe? Is it the end of the header and the end of the stinger?

Thanks in advance.

Mike

Whats up Mike,

Did you ever get the Toroidal head design to work on your engines? I'm still using them on both the gas & nitro engines, but there have been some small changes as a result of tuned pipe changes.

I "Do Not" measure any tuned pipe I am designing & building. However, I have measured with alcohol many manufactured chambers. I use; volume = 3.1417 X the radius squared x the height, for parallel sections. I use; volume = 3.1417 X the height ( radius #1 squared + radius #2 squared + radius #1 x radius #2) divided by 3, for any tapered section. Measurements are made from the pistons face to the end of the stinger.

JA

 

[Jim Allen]

Take a close look at the tuned pipe used on MB 40 FAI speed engine. (https://fiorimet.hom....nl/Running.htm) Scroll down to the home page. This is called a "curvy pipe" because there is no straight section anywhere, except in the stinger. Also notice how long & small in diameter these stingers are. Tuned pipes such as this can be easily machined on a CNC machine.

JA

 

[Terry Keeley]

Terry,

I'm sorry for missing your #14 post referring to the MB engine, which clearly shows the necessary wear band & its position in relation to the piston's crown. Rob Metkemeijer, Henry Nelson & I have had many discussions about this "Wear Band" when they visited the Julian air races. Any AAC or ABC engine that does not have this will rapidly lose it's piston to liner fit, & therefore it's peak HP over a very short period of time. I have witnessed MB 40 FAI speed engines routinely operate at 35,000 RPM in the air while maintaining their piston to liner fit.

https://fiorimet.hom....nl/Running.htm "This should be done very lightly & carefully, especially at the "ring", approximately 2.5 mm (.0984") from the top of the piston where it seals."

Jim Allen

No worries, some very good info there. https://fiorimet.home.xs4all.nl/Running.htm

 

[Jim Allen]

There is still very good & adaptable information in the original FMV story by Enrico Flores (F); Rob Metkemeijer (M) & Hans Visser (V). I'm amazed that they developed & proved their ideas in 1976, wining the 1978 TR world championships. Their ideas on how to build a reliable front end apply to both nitro & gas engines in use today.

I'm debating on releasing the chemical information about chroming cylinders, especially aluminum cylinders. The chrome tank itself should only be used in a contained, controlled, ventilated environment, or in the open air. The fumes generated when chroming will instantly rust even the hardest steels. A very high quality respirator, quality rubber gloves & a rubber apron should be used at all times when handling these chemicals. This information DEFINITELY applies when using the chemicals required for cleaning & etching aluminum cylinders! The chemicals used for aluminum cylinders are also very time sensitive! Any electrical connections made to the anode or cathode MUST be absolutely positive, otherwise very high heat will be generated at these points! A quality amperage meter & voltage meter mounted in a sealed case will also be required! A power supply, with variable current, capable of 30 amps at 6 volts will be needed. We use a switching type power supply rated at 50 amps at 6 volts.

I have posted some photos of our tank in operation. When first placing the fixture into the tank, the current is reduced to 7.5 amps for approximately 5 minutes. It is then raised to 12 amps for 75 minutes.

Jim Allen

 

[Jim Allen]

In order to make effective use of the necessary chemicals involved in hard chroming plating of aluminum alloys, the simple cylinder holding fixtures shown were made from 1/8" diameter soft aluminum rod. Only the cylinder & its holding fixture are inserted in the chemicals for the specified amount of time. The only other contact with the cylinder is when it is removed from this fixture before being placed in it's brass holding fixture. This is done with rubber gloves by touching only the cylinder's lip! This may sound complicated or difficult, but it is really very easy to do when the holding fixture is properly made. The holding fixture also makes it very easy to wash the cylinder & the 1/8" diameter holding fixture in hot tap water in between each insertion in the chemicals.

Jim Allen

 

[Michael Costanzo]

thank you jim and jack for the replies.very interesting topic. you guys are like the mad scientist I could only dream to be.even after 35+years in the nitro hobbies I love the fact that people are always willing to share knowledge and ideas and I am like a sponge waiting for more.thank you again,mike.

 

[Jim Allen]

The simple chemical removal process for hard chroming plating of copper alloys such as #360 free cutting brass or #544 phosphor bronze allows a cylinder to be used indefinitely. There is no chemical removal process for hard chroming plating of aluminum cylinders! The chrome could be removed from aluminum by ID grinding or ID honing of the cylinder. Any chemical strong enough to dissolve the chrome off the aluminum would also dissolve the aluminum. A 50% solution of hydrochloric acid will dissolve any amount of hard chrome plating applied to a copper alloy without effecting the copper alloy, no matter how long the copper alloy is left in the acid solution. This means that any brass cylinder could be used indefinitely by stripping it & then re-plating it again. Also, the only chemical needed to clean a brass cylinder before chroming would be a strong alkaline solution.

JA

 

[Rudy Formanek]

Jim, do you know of any chemical that would dissolve a steel bolt from an aluminum case, leaving the aluminum alone? Rudy

 

[Jim Allen]

Jim, do you know of any chemical that would dissolve a steel bolt from an aluminum case, leaving the aluminum alone? Rudy

Rudy,

I do not. When necessary we have broken taps & steel screws removed from expensive to manufacture aluminum pieces with an EDM process.

JA

 

[Terry Keeley]

Jim, do you know of any chemical that would dissolve a steel bolt from an aluminum case, leaving the aluminum alone? Rudy

Nitric acid works but you havta be patient.