#360 free machining brass for a head button?

[Jim Allen]

After reading information recently posted on this web site pertaining to the use of #360 free machining brass for tether race car head buttons. I decided to give John Ellis a phone call, since the source of that information remains un-named, thus far.

John Ellis is a very well known & respected tether race car builder who builds his own car in which he uses an engine made to his specifications. Both the car & the engine, that John holds the world record in his class with, can be purchased. John's engine uses a titanium roller rod which can also be purchased. The head button material used on this engine is #4032 silicon aluminum.

When I asked John about the use of #360 free machining brass for head buttons on tether race cars, he said the following; "#360 brass would never be used on any size tether race car engine as a head button material! This includes engines from 1.5 to 10 cc." He continued to say, "the alloy that does work & is used by some tether car racers is Ampcoloy # 940 nickel copper." When comparing Mat Web's material data specifications on both alloys, it can be easily seen why #940 nickel copper is used instead of #360 free machining brass. #940's high tensile, yield & compressive strengths, as well as a low coefficient of thermal expansion coupled with a high thermal conductivity make it's use very desirable. It should be noted that the #940 alloy is 25 times more expensive than the #360 alloy.

-------------------------------------------#940-----------------------------------#360

tensil strength-------------------------96,000psi-----------------------------68,000psi

yield strength--------------------------74,000psi-----------------------------45,000psi

compressive strength----------------80,100psi-----------------------------52,000psi

CTE, linear-----------------------------9.72uin/in/F*-------------------------11.4uin/in/F*

thermal conductivity------------------1440BTU/in/hr/(ft)(ft)/F*------------789BTU/in/hr/(ft)(ft)/F*

What this says is, even though the #940 has nearly twice the thermal conductivity, it's linear expansion is 17% less.

Jim Allen

 

[mercguy]

After reading information recently posted on this web site pertaining to the use of #360 free machining brass for tether race car head buttons. I decided to give John Ellis a phone call, since the source of that information remains un-named, thus far.

John Ellis is a very well known & respected tether race car builder who builds his own car in which he uses an engine made to his specifications. Both the car & the engine, that John holds the world record in his class with, can be purchased. John's engine uses a titanium roller rod which can also be purchased. The head button material used on this engine is #4032 silicon aluminum.

When I asked John about the use of #360 free machining brass for head buttons on tether race cars, he said the following; "#360 brass would never be used on any size tether race car engine as a head button material! This includes engines from 1.5 to 10 cc." He continued to say, "the alloy that does work & is used by some tether car racers is Ampcoloy # 940 nickel copper." When comparing Mat Web's material data specifications on both alloys, it can be easily seen why #940 nickel copper is used instead of #360 free machining brass. #940's high tensile, yield & compressive strengths, as well as a low coefficient of thermal expansion coupled with a high thermal conductivity make it's use very desirable. It should be noted that the #940 alloy is 25 times more expensive than the #360 alloy.

-------------------------------------------#940-----------------------------------#360

tensil strength-------------------------96,000psi-----------------------------68,000psi

yield strength--------------------------74,000psi-----------------------------45,000psi

compressive strength----------------80,100psi-----------------------------52,000psi

CTE, linear-----------------------------9.72uin/in/F*-------------------------11.4uin/in/F*

thermal conductivity------------------1440BTU/in/hr/(ft)(ft)/F*------------789BTU/in/hr/(ft)(ft)/F*

What this says is, even though the #940 has nearly twice the thermal conductivity, it's linear expansion is 17% less.

Jim Allen

Wow Jim, that is a huge difference in thermal conductivity. No wonder they like that material.

Bill Hoch

 

[Andy Brown]

Good info., Jim!

Since John uses the 4032 aluminum I added that to your chart also Jim. Note that I used the properties given @ 212 F since they were availible. Most alloys lose strength at elevated temps.

4032 has around 12% Silicon.

-------------------------------------------#940-----------------------------------#360------------------------------------------#4032

tensil strength-------------------------96,000psi-----------------------------68,000psi----------------------------------50,000psi ............@212F*

yield strength--------------------------74,000psi-----------------------------45,000psi----------------------------------43,500psi.............@212F*

compressive strength----------------80,100psi-----------------------------52,000psi----------------------------------N/A

CTE, linear-----------------------------9.72uin/in/F*-------------------------11.4uin/in/F*------------------------------10.8u-in/in/F*.........@212F*

thermal conductivity------------------1440BTU/in/hr/(ft)(ft)/F*------------789BTU/in/hr/(ft)(ft)/F*------------------960BTU/in/hr/(ft)(ft)/F*

 

[Charles Perdue]

Mr. Jim, this is an Apples to oranges comparisions.

The tether car engines are air cooled and run on 80% methanol/20% castor, the boat engines are water cooled and use a large percentage of nitro in the fuel, totally different requirements for the head button materials.

Charles

 

[hugh hargett]

Re read Mr. Allens post.Jims, point was someone said they got it from tether car guys to run 360 brass he has not said run #4032 or #940 on a boat motor - YET!

 

[Andy Brown]

Mr. Jim, this is an Apples to oranges comparisions.

The tether car engines are air cooled and run on 80% methanol/20% castor, the boat engines are water cooled and use a large percentage of nitro in the fuel, totally different requirements for the head button materials.

Charles

Yes Charles. I noted that on a different thread where we have been discussing this same subject. Jim has just moved the subject out into the open.

 

[Jim Allen]

Mr. Jim, this is an Apples to oranges comparisions.

The tether car engines are air cooled and run on 80% methanol/20% castor, the boat engines are water cooled and use a large percentage of nitro in the fuel, totally different requirements for the head button materials.

Charles

Charles,

If you would check with John, he would tell you his tether car does not run with the 80-20 fuel. I'l let you ask him how much nitro he uses with the O'Donnell 99T plug he uses.

Jim

 

[Jim Allen]

As a side note, John's engine uses 4 to 6% oil. The same amount as used in my .90 cu in, 30,000 RPM engine. The name & number of the oil is proprietary information.

Jim Allen

 

[Charles Perdue]

OK, but it is still air cooled VS water cooled. That is a major difference.

 

[Jim Allen]

OK, but it is still air cooled VS water cooled. That is a major difference.

Could you explain that a little further, considering, every one who wants to make more HP with a boat engine is restricting the water flow?

 

[dwilfong]

Why are we restricting the water to heat up the head.

I f you use a material that will suck the heat out of the chamber I feel you are going in the wrong direction.

If the 360 brass is keeping the heat in the chamber than a better heat conductor will undo what is happening.I posted a paper on a test done to evaluate the emission out put of a nitro eng. it was a FOX .40 If I remember.

There was some thing about a boundary layer on the chamber and how the surface temp of the chamber controls the burn rate across the surface.

If the material used pulls the heat away from the surface it degrades this effect.

I think that if the surface of the chamber is kept hot it will burn better.

The trick is keeping the surface hot by not migrating the heat away to fast.

the wave that is migration needs to be of a certain rate.

just my take on it.

I will pull the paper back up and post the relevant findings.

This was done as a doctoral theses for a diaphragm nano eng.For use as a power source generator.

David

 

[Jim Allen]

Why are we restricting the water to heat up the head.

I f you use a material that will suck the heat out of the chamber I feel you are going in the wrong direction.

If the 360 brass is keeping the heat in the chamber than a better heat conductor will undo what is happening.I posted a paper on a test done to evaluate the emission out put of a nitro eng. it was a FOX .40 If I remember.

There was some thing about a boundary layer on the chamber and how the surface temp of the chamber controls the burn rate across the surface.

If the material used pulls the heat away from the surface it degrades this effect.

I think that if the surface of the chamber is kept hot it will burn better.

The trick is keeping the surface hot by not migrating the heat away to fast.

the wave that is migration needs to be of a certain rate.

just my take on it.

I will pull the paper back up and post the relevant findings.

This was done as a doctoral theses for a diaphragm nano eng.For use as a power source generator.

David

What test have you done to prove or disprove this theory as it applies to a high performance two cycle engine used in a boat?

 

[Jack ODonnell]

After reading information recently posted on this web site pertaining to the use of #360 free machining brass for tether race car head buttons. I decided to give John Ellis a phone call, since the source of that information remains un-named, thus far.

John Ellis is a very well known & respected tether race car builder who builds his own car in which he uses an engine made to his specifications. Both the car & the engine, that John holds the world record in his class with, can be purchased. John's engine uses a titanium roller rod which can also be purchased. The head button material used on this engine is #4032 silicon aluminum.

When I asked John about the use of #360 free machining brass for head buttons on tether race cars, he said the following; "#360 brass would never be used on any size tether race car engine as a head button material! This includes engines from 1.5 to 10 cc." He continued to say, "the alloy that does work & is used by some tether car racers is Ampcoloy # 940 nickel copper." When comparing Mat Web's material data specifications on both alloys, it can be easily seen why #940 nickel copper is used instead of #360 free machining brass. #940's high tensile, yield & compressive strengths, as well as a low coefficient of thermal expansion coupled with a high thermal conductivity make it's use very desirable. It should be noted that the #940 alloy is 25 times more expensive than the #360 alloy.

-------------------------------------------#940-----------------------------------#360

tensil strength-------------------------96,000psi-----------------------------68,000psi

yield strength--------------------------74,000psi-----------------------------45,000psi

compressive strength----------------80,100psi-----------------------------52,000psi

CTE, linear-----------------------------9.72uin/in/F*-------------------------11.4uin/in/F*

thermal conductivity------------------1440BTU/in/hr/(ft)(ft)/F*------------789BTU/in/hr/(ft)(ft)/F*

What this says is, even though the #940 has nearly twice the thermal conductivity, it's linear expansion is 17% less.

Jim Allen Jim; Been using 4032 head buttons for the last 15 years,also have used 940 copper for sleeves in my 10cc engines works REAL good. J.O'Donnell

 

[Charles Perdue]

Mr. Jim, let me tell you my thoughts.

I have played with a lot of different materials for making head buttons. Aluminum in 2024, 2011,4032, 2017, 6061, 7075, 7068 and more. Stainless steel 303. Alloy steels. 110 copper. 544 bronze and 360 brass.

From what I can tell, there is an optimum chamber temperature for horsepower and RPM on our nitro engines. Not too cool and not too hot.

With a water cooled head, using 360 brass for the head button material, I have found that is very close to maintaining this optimum combustion temp during a run. It even makes the water flow rate less sensitive.

With an air cooled head the 360 brass with not work because the heat dissipation rate is too slow. This allows the combustion chamber temps to run away causing the engine to detonate and this adds even more heat to the chamber. The aluminum alloys are much better in maintaining these optimum chamber temps with their higher heat flows.

When using aluminum for a head button even with regulating the water flow it is difficult to keep the chamber temps in the sweet spot temp as it is above 212 degrees, the boiling point of water. A pressurized system is then needed, adding to the complexity of our toys.

These are just my thoughts after playing with the different head button materials. What do you think?

Charles

 

[hugh hargett]

".....aircooled head......" that would make a thesis on a fox .40 crud then or was it a diaphragm nano eng. Heck I cant find that online.

 

[dwilfong]

Here is a link to the paper I am referring to.

http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=574802&fileOId=574803

If you spend the time there is the latest in combustion engineering data in this sight.

Things have progressed in the last few years as to testing.

I love the pics taken of the combustion kernel as it formed with the high speed camera.

Now this is a cool tool!!!!

David

 

[dwilfong]

O and check out the dino he made.

 

[hugh hargett]

David, arent you fitting pistons? got the impression from your thread you didnt want to talk about brass anymore ????? or the dyno? Jim moved it here. When you attach the link we can go to it .

Guy has a dyno huh? Goes to show there are more than 2 in the whole US. Imagine that!!! Is his of the "scientific" variety? or is it a non scientific dyno?? :lol:

Mr. Allen seems like if you hold in too much heat with too much compression ie (shallower bowl) that would surely lead to detonation . Yea or nay?

 

[dwilfong]

If any of you would like to check this out just copy and past the link in the address bar.

 

[Jim Allen]

Charles,

Have you ever seen steam or boiling water comming out of the H2O outlet? I haven't, even when running the engine 30,000 RPM+ for four minutes. My H2O outlet was never larger than .032" once the detonation problem was solved.

What I will post now, is not "what I think", but what I know from the results of thousand of dyno tests done by myself & other engine builders of high performance two cycle engines over the past 25 years.

Eminent engine builders such as Frits Overmars & Jan Thiel, who worked on engine heating problems also faced the number one enemy of any high performance two stroke,DETONATION.

Once the engine becomes thermally sound, very large amounts of HP can be developed. To deliver 1,000 watts of mechanical energy from an engine, approximately 3,000 watts of heat energy must be developed. This means 2,000 watts of heat must leave the engine by some means. If the engine in question can get rid of this heat it will be thermally sound.

What are some of the things that lead to detonation problems? If needle settings, different head alloys, improved cooling, different head designs, etc., do not help, what is the answer?

Some things that help create detonation are;

1) poor stinger design, usually not long enough but to small in diameter

2) poor scavenging, resulting from poor port geometry

3) poor combustion chamber design

4) poor exhaust out & in flow

5) large diameter piston bores with inadequate piston crown cooling, resulting in holed piston crowns

To be continued:

Jim Allen