#360 free machining brass for a head button?

[steve wood]

I think I've read all of this thread - please excuse me if I missed seeing this. One factor that hasn't been mentioned but you may want to consider is the water volume that is in the waterjacket. Even though we constrict flow with inlet or outlet size, the volume contained in waterjacket will have influence on what goes on inside the combustion chamber.

John

this is why we make a smaller jacket for nova rossi's and plug the holes that circulate water to the lower chamber on all cmb evo/rs engines

 

[dwilfong]

 

[Joe Warren]

David can you Make me one of those cooling heads and your type button out of Brass. I would like to TEST it on one of my Rs101s!!!!!

 

[dwilfong]

David is that a RS91,RS101 or VAC91 Button in the pic?

This is RS 1.01 it is the same setup I ran last year for the first time at Charleston.

Keep your eyes open will have some thing new this year to test. h34r:

 

[dwilfong]

No problem Joe.

Give me a call.

(407) 344-2560

David

 

[hugh hargett]

Chris whats the leading edge pitch on the prop on your boat in the video?

 

[Chris Wood]

Dont remember

 

[Marty Slater]

Dont remember

old timers setting in :wacko:

DAM it was good to see you again DAM did i say that out loud

hay you owe me a rib dinner now

maybe we could get together some time again

Marty

 

[Mike Larson]

I WAS the dyno last weekend.... Steve, thanks for the best powerplant I've ever owned in my life.... BRASS included..... Mike

 

[mark voorhies]

I WAS the dyno last weekend.... Steve, thanks for the best powerplant I've ever owned in my life.... BRASS included..... Mike

Yea, you tried alot of differant things over the wk. end, but boat still seemed to get faster,you and Chris did alot,

did you ever get 70% fuel into it?

 

[steve wood]

I WAS the dyno last weekend.... Steve, thanks for the best powerplant I've ever owned in my life.... BRASS included..... Mike

Yea, you tried alot of differant things over the wk. end, but boat still seemed to get faster,you and Chris did alot,

did you ever get 70% fuel into it?

i think he's skeerd to run mor'n 30%

 

[mtruex]

I have played with brass heads on and off for about 2 years, but i never did a back to back test comparing them.. I did a test today comparing an aluminum head to a brass head, they were both the exact same shape size etc, engine was a nova keep21 in my JAE 21.. the only difference was the alloy head had a turbo plug and the brass head had standard plug.. The aluminum head ran 81 the brass ran 76.. the head temp FELT the same when i brought it in, and both would come back on pipe the same after a few slow cooldown laps, neither head showed detonation.. the only thing im not sure on is how much the turbo plug is worth..

 

[hugh hargett]

"I have played with brass heads on and off for about 2 years, but i never did a back to back test comparing them.. I did a test today comparing an aluminum head to a brass head, they were both the exact same shape size etc, engine was a nova keep21 in my JAE 21.. the only difference was the alloy head had a turbo plug and the brass head had standard plug.. The aluminum head ran 81 the brass ran 76.. the head temp FELT the same when i brought it in, and both would come back on pipe the same after a few slow cooldown laps, neither head showed detonation.. the only thing im not sure on is how much the turbo plug is worth.."

uh oh! :blink:

Boat dyno delivering the "TRUEX".I wonder why you didnt see all these great improvements claimed with a simple material change? Looks like the aluminum pulled a few more K in this "DYNO" run :wacko: .

 

[Jim Allen]

I have played with brass heads on and off for about 2 years, but i never did a back to back test comparing them.. I did a test today comparing an aluminum head to a brass head, they were both the exact same shape size etc, engine was a nova keep21 in my JAE 21.. the only difference was the alloy head had a turbo plug and the brass head had standard plug.. The aluminum head ran 81 the brass ran 76.. the head temp FELT the same when i brought it in, and both would come back on pipe the same after a few slow cooldown laps, neither head showed detonation.. the only thing im not sure on is how much the turbo plug is worth..

The testing I have done with turbo plugs shows approximately a 1,500 to 2,000 RPM increase in smaller engines. The amount of increase goes down as the size of the engine becomes larger. Did the increase seen come because the flame front is applied to less of the plugs body; did it come from the excellent seal afforded with the taper; did it come from the smooth chamber in the top of the bowl? Why don't turbo plugs show large increases in larger engines?

 

[jaxracer]

I have played with brass heads on and off for about 2 years, but i never did a back to back test comparing them.. I did a test today comparing an aluminum head to a brass head, they were both the exact same shape size etc, engine was a nova keep21 in my JAE 21.. the only difference was the alloy head had a turbo plug and the brass head had standard plug.. The aluminum head ran 81 the brass ran 76.. the head temp FELT the same when i brought it in, and both would come back on pipe the same after a few slow cooldown laps, neither head showed detonation.. the only thing im not sure on is how much the turbo plug is worth..

Why don't turbo plugs show large increases in larger engines?

Because as engine size increases, so should plug size? Because the plug to chamber size ratio is much smaller. There is more nitro in the chamber so therefore you need a larger flame to burn it?

-Mitch

 

[Ian Inverarity]

Did the increase seen come because the flame front is applied to less of the plugs body; did it come from the excellent seal afforded with the taper; did it come from the smooth chamber in the top of the bowl? Why don't turbo plugs show large increases in larger engines?

Is the increase due not having the 'lost' volume in plug threads that as a proportion of the volume at TDC is largest on the smaller engines?

 

[Tim_Duggan]

When I back to back tested turbo vs conventional plug heads (both in aluminium) in a 21 rigger I swore I could hear the rpm difference but didn't have a datalogger on board to confirm.

Martin,

What prop L/E pitch was that with? Should be able to get an approximate RPM variance for the 5mph difference mathematically if you weren't logging rpm. Are you able to make an Aluminium conventional plug head of the same specs as the brass one for a fairer comparison?

Tim

 

[hugh hargett]

"What prop L/E pitch was that with? Should be able to get an approximate RPM variance for the 5mph difference mathematically if you weren't logging rpm."

Yep! within 3%

Martin your prop guy should know the LE pitch of your prop.

was it #360 free machining brass?

 

[Ian Inverarity]

76 to 81 is approx a 6.6% increase, assuming the prop efficiency doesnt change too much in that range it would also be a 6.6% increase in RPM. Assuming the RPM was 30000 for 76mph, this would become 31980, ie almost 2000 rpm more.

 

[Mark Bullard]

I have played with brass heads on and off for about 2 years, but i never did a back to back test comparing them.. I did a test today comparing an aluminum head to a brass head, they were both the exact same shape size etc, engine was a nova keep21 in my JAE 21.. the only difference was the alloy head had a turbo plug and the brass head had standard plug.. The aluminum head ran 81 the brass ran 76.. the head temp FELT the same when i brought it in, and both would come back on pipe the same after a few slow cooldown laps, neither head showed detonation.. the only thing im not sure on is how much the turbo plug is worth..

That was a good test Martin. But you may not really see a lot of increase in a 21 motor. And I will not say if the turbo head made that much difference. Where we are see the increase is in big motors that move a lot of fuel thru them.