#360 free machining brass for a head button?

[Jeff Schindler]

Interesting that Doc mentioned not holing the piston since switching to brass. This may clue us in one what is the the primary culprit of detonation in our motors? Could it be the the heat near TDC is influenced as much or more by the piston temp than the head temp? What would be the ideal relationship between piston crown temp and head temp? Equal? Cooler on the Piston?

Perhaps my theory of cooling more with fuel, rather than with water is effectively keeping the piston cooler, thus keeping the detonation away? This would be supported by Doc's observation that the Pistons are in better shape after switching from Al buttons to brass

 

[Andy Brown]

Apples to apples the brass will not make the difference.

It is the ability to raise the CR to make more power.

Make two buttons with smaller chambers same plug and compare it.

Would be interested in the results.

David

Not disagreeing, but why was the brass so slow. 5mph is a lot on a 21! I have made/tried tons of heads and never seen + - 5mph.

Years ago when I tried the std. plug/ turbo plug comparison back to back in the boat, the turbo was worth 3 mph in a set-up that was running 70 mph. In that test I used identical CNC'd heads and a turbo plug & std. plug of the same # from the same glow plug manufacture. It was definately an Apples to Apples, Oranges to Oranges comparison. I'm sure the turbo plug gave the aluminum head the big boost.

Hi Andy; You say you are sure the turbo plug gave the alum. head a big boost. Can you tell me how you arrived at that. or why you think the the turbo plug is better. I/we have not seen that kind of difference between the std. and turbo seat. Most preference problems we see are in the stem seal's

Jack,

I did this test in the boat back to back. I had posted this above.

"Years ago when I tried the std. plug/ turbo plug comparison back to back in the boat, the turbo was worth 3 mph in a set-up that was running 70 mph. In that test I used identical CNC'd heads and a turbo plug & std. plug of the same # from the same glow plug manufacture."

This test was done with a .21 engine.

I also did the same exact test on a different .21 engine, but this time the engine was on the bench with an aero prop. The the turbo plug showed an rpm gain of around 1000 to 1300.

Both of those tests were run about 20 years ago. I have not done any other similar tests on larger size engines. Some of the European boat racers who use turbo plugs in all sized engines say that the bigger engines also get an increase, but not as much as the small engines.

Why I think the turbo is better? The only conclusion that I have come up with is that the interface between the plug and the combustion chamber surface is smoother with the turbo. I believe the uneven joint that is caused by the exposed threads on the std. plug interupts the flame front and retards the speed of the flame propagation. This in turn limits the total burn rate. The the mixture must be burned quicker in order to turn more rpm.

 

[Jim Allen]

"Why I think the turbo is better? The only conclusion that I have come up with is that the interface between the plug and the combustion chamber surface is smoother with the turbo. I believe the uneven joint that is caused by the exposed threads on the std. plug interupts the flame front and retards the speed of the flame propagation. This in turn limits the total burn rate. The the mixture must be burned quicker in order to turn more rpm."

Excellent, valid information!

 

[Joe Warren]

Interesting that Doc mentioned not holing the piston since switching to brass. This may clue us in one what is the the primary culprit of detonation in our motors? Could it be the the heat near TDC is influenced as much or more by the piston temp than the head temp? What would be the ideal relationship between piston crown temp and head temp? Equal? Cooler on the Piston?

Perhaps my theory of cooling more with fuel, rather than with water is effectively keeping the piston cooler, thus keeping the detonation away? This would be supported by Doc's observation that the Pistons are in better shape after switching from Al buttons to brass

......... NO porosity in the brass head button vs a pile in the alum ....

 

[Jack ODonnell]

"Why I think the turbo is better? The only conclusion that I have come up with is that the interface between the plug and the combustion chamber surface is smoother with the turbo. I believe the uneven joint that is caused by the exposed threads on the std. plug interupts the flame front and retards the speed of the flame propagation. This in turn limits the total burn rate. The the mixture must be burned quicker in order to turn more rpm."

Excellent, valid information!

I/we did a bench test last year on a 21 car engine. Std. screw in plug/ turbo seat plug. Plug used were od77 & od77t .Both head's had the same volume.Base line test was with the std.od77plug. Next test was with the od 77t plug. last test was with the od77 with a thinner copper washer (std washer is .045 thick) made a new washer .022 thick this put the threads out of the head by app. .013 . Of the three test there was not more than 500 rpm diff. This test was done with a strob light

 

[Jim Allen]

I'm not sure what you think this test shows. Wouldn't be better to place both plugs at the same depth in the same chamber & just change the plug type?

 

[Jack ODonnell]

I'm not sure what you think this test shows. Wouldn't be better to place both plugs at the same depth in the same chamber & just change the plug type?

Jim you said the exposed threads interupts the flame front. The test. shows that the threads exposed in the chamber made no diff. in rpm. I dont understand your answer,you cant put both plugs in the same chamber. one plug uses a copper gasket to seal the other is a taper seat

 

[John Knight]

I'm not sure what you think this test shows. Wouldn't be better to place both plugs at the same depth in the same chamber & just change the plug type?

Jim you said the exposed threads interupts the flame front. The test. shows that the threads exposed in the chamber made no diff. in rpm. I dont understand your answer,you cant put both plugs in the same chamber. one plug uses a copper gasket to seal the other is a taper seat

Jack,

I believe that Andy was the one that speculated about the threads possibly affecting the flow characteristics.

 

[DON MAHER]

Jack,

Of the 3 tests witch gave the most rpm?

Don

 

[Jack ODonnell]

Jack,

Of the 3 tests witch gave the most rpm?

Don

Hi Don; I believe it was the turbo seat plug, they were all close. And good luck at Hobart !!

 

[Jim Allen]

I'm not sure what you think this test shows. Wouldn't be better to place both plugs at the same depth in the same chamber & just change the plug type?

Jim you said the exposed threads interupts the flame front. The test. shows that the threads exposed in the chamber made no diff. in rpm. I dont understand your answer,you cant put both plugs in the same chamber. one plug uses a copper gasket to seal the other is a taper seat

Jack,

I believe that Andy was the one that speculated about the threads possibly affecting the flow characteristics.

I don't know about affecting the flow characteristics. When I did this test with the same head shape, the same plug depth, the same fuel on the same day, I thought the difference was because the turbo plug sealed better & there was less metal of the plug body exposed to the flame front. I did not have have part of the non turbo plug body protruding into the chamber to get the depths the same. I used #99 & #99t plugs with 82% nitro.

 

[Andy Brown]

Jack,

Of the 3 tests witch gave the most rpm?

Don

Hi Don; I believe it was the turbo seat plug, they were all close. And good luck at Hobart !!

So if it was the turbo that improved by 500 rpm that is nothing to sneeze at. 500 here, there and over there = 1500 and that is 4 or 5 mph in a 21 rigger. Probably a lot more in a tethered car. Jack, how much nitro did you use too make that test?

For us is made enough difference in our novarossi, that we would never go back to the std. plug in that engine.

 

[Jack ODonnell]

Jack,

Of the 3 tests witch gave the most rpm?

Don

Hi Don; I believe it was the turbo seat plug, they were all close. And good luck at Hobart !!

So if it was the turbo that improved by 500 rpm that is nothing to sneeze at. 500 here, there and over there = 1500 and that is 4 or 5 mph in a 21 rigger. Probably a lot more in a tethered car. Jack, how much nitro did you use too make that test?

For us is made enough difference in our novarossi, that we would never go back to the std. plug in that engine.

Andy the test was to see how much difference there was between the std plug and the turbo seat plug, not much. The reason to try the std. plug with a thinner washer was to see if .013 of the thread being in the chamber made much difference.And it did not.The fuel used was 40% with 5% oil. The engine was a 3.5 Novarossi.I agree with you on the turbo seat being the best.I have been trying some aluminmun body turbo plugs in the tether car,and they look real good

 

[Andy Brown]

Jack,

Of the 3 tests witch gave the most rpm?

Don

Hi Don; I believe it was the turbo seat plug, they were all close. And good luck at Hobart !!

So if it was the turbo that improved by 500 rpm that is nothing to sneeze at. 500 here, there and over there = 1500 and that is 4 or 5 mph in a 21 rigger. Probably a lot more in a tethered car. Jack, how much nitro did you use too make that test?

For us is made enough difference in our novarossi, that we would never go back to the std. plug in that engine.

Andy the test was to see how much difference there was between the std plug and the turbo seat plug, not much. The reason to try the std. plug with a thinner washer was to see if .013 of the thread being in the chamber made much difference.And it did not.The fuel used was 40% with 5% oil. The engine was a 3.5 Novarossi.I agree with you on the turbo seat being the best.I have been trying some aluminmun body turbo plugs in the tether car,and they look real good

I still have some old Glow-Bee plugs with aluminum bodies from mid 1970's. The ones I have are way to cold for the engines that I have tried them in.

 

[Joe Warren]

Jack,

Of the 3 tests witch gave the most rpm?

Don

Hi Don; I believe it was the turbo seat plug, they were all close. And good luck at Hobart !!

So if it was the turbo that improved by 500 rpm that is nothing to sneeze at. 500 here, there and over there = 1500 and that is 4 or 5 mph in a 21 rigger. Probably a lot more in a tethered car. Jack, how much nitro did you use too make that test?

For us is made enough difference in our novarossi, that we would never go back to the std. plug in that engine.

Maybe we have seen a Large gain due to.... 1 - RS101 Flows 3 times the fuel thru it in the Same 10 laps the .21 is running. And being it is in a Twin Hydro you can mutiply the increase X 2 for Twin Engines... Whatever it is..... You will Be SMILING...

 

[hugh hargett]

How did the brass fair in Hobart?

 

[Buckshot]

How did the brass fair in Hobart?

The winner in Twin and F had no brass head buttons.

 

[hugh hargett]

Umm <_<

 

[dwilfong]

Did any one run one? :huh:

 

[DON MAHER]

"E" hydro did not have a brass head

Don