Nova 45 DD going lean?

[Tom Foley]

Who is running the low speed needle and who is not ?

 

[Marty Davis]

I am on anything that I can.

 

[anthony_marquart]

A question.. For years people have told me that they were getting better performance when the pipes where able to get hotter. Now the opposite? Or maybe we are looking for a temp range in a certain pipe material that provides the resonance it was designed for? AND, if that is correct,.. how would we know what temp we are looking for? I have never water cooled a pipe except back in the day with a OPS exhaust header insert..

curious..

Ill be happy when I have time to finish this sport40 I've been working on for years..

 

[Tom Foley]

I am on anything that I can.

LOL ! I hear you !!

 

[Andy Brown]

A question.. For years people have told me that they were getting better performance when the pipes where able to get hotter. Now the opposite? Or maybe we are looking for a temp range in a certain pipe material that provides the resonance it was designed for? AND, if that is correct,.. how would we know what temp we are looking for? I have never water cooled a pipe except back in the day with a OPS exhaust header insert..

curious..

Ill be happy when I have time to finish this sport40 I've been working on for years..

Hot is good, but you have to remember that heat is being communicated back to the combustion chamber. So there is a point when the heat in the pipe becomes too much for the combustion process, causing the ignition point to become too advanced.

 

[Marty Davis]

AND, you start getting a lot of detonation which will reduce the life of your engine greatly. Stinger diameter can have a huge effect on this, as I have personally found. "Band-aids" have been brass head buttons, etc.

 

[Jeff Schindler]

8-16-2014. Mendota, IL

Phil Thomas Sport 40 w/ Novarossi .46 wrap around. 60% fuel Prather 235

Boat took off gurgling good and rich. By the second mill lap it was running like it did in practice, about 55 mph. Boat started bogging down so I went into survival mode, 1/3 throttle and full rich. The boat started speeding up at this throttle setting until it reached full speed. I tried to milk the throttle, surging up and down for 2 laps. I stayed inside to let the leaders by and popped a bouy. This is the Eureka moment.... The cowl came off the boat. The boat ran better the next lap, starting to go rich again. I leaned the needle back down and it ran great, just bogging the corners a bit. I leaned it some more and it was back to full song. That pipe is getting too hot.

I have an inboard video showing the spray hitting the pipe and you would not believe how fast the water boils off.

I should have held off on this as the boat was worse the next two heats. I ran with the cowl, but drilled the pipe from .365 to .375 and removed the back hatch for more air flow. I saw something strange on the beach and am going to check for a combustion chamber leak between the button & the sleeve. I think it might be leaking under load when It gets up to temp.

 

[Ron Zaker Jr]

8-16-2014. Mendota, IL

Phil Thomas Sport 40 w/ Novarossi .46 wrap around. 60% fuel Prather 235

Boat took off gurgling good and rich. By the second mill lap it was running like it did in practice, about 55 mph. Boat started bogging down so I went into survival mode, 1/3 throttle and full rich. The boat started speeding up at this throttle setting until it reached full speed. I tried to milk the throttle, surging up and down for 2 laps. I stayed inside to let the leaders by and popped a bouy. This is the Eureka moment.... The cowl came off the boat. The boat ran better the next lap, starting to go rich again. I leaned the needle back down and it ran great, just bogging the corners a bit. I leaned it some more and it was back to full song. That pipe is getting too hot.

I have an inboard video showing the spray hitting the pipe and you would not believe how fast the water boils off.

Witnessed this, dead on.

 

[anthony_marquart]

Another question:

If we are talking about the pipe getting too hot, and pushing to much HOT air back into the engine, where does lack of engine cooling and too much pipe heat / back pressure start and stop? Are we talking about too much heat from pipe or too little water to the engine? or are we saying that the balance between those two things must fall in a certain range? Can more of one or the other compensate for too little of the opposite?

I'm trying to think about how I how go about addressing this issue at the pond.. I have never thought the solution to a problem was getting more water, but maybe it can be as I begin to run bigger engines. And I always seemed to get better performance when I could run hotter and richer! So this is sending my brain into panic mode! Most of my experience is running small riggers,. .12s and .21's,.. also.. but I've decided to go to bigger engines only now..

fantastic information though guys.. we should write a book based in ITLwaters threads.. Model Boat Bible..

 

[Blackout]

Anyone run this water cooled pipe?

 

[Rudy Formanek]

Just to throw another variable into the equation. Consider this, big stingers equal big noise, if you run somewhere where noise is a big problem, like Europe or Japan or a few places in the US, running a big stinger will mean some kind of additional muffling above and beyond the typical muffled pipe.

 

[Terry Keeley]

I have an inboard video showing the spray hitting the pipe and you would not believe how fast the water boils off.

Would love to see that video, any chance to post it to Youtube?

 

[Jeff Schindler]

I'll try and post it tonight

Here is the video

 

[Terry Keeley]

Video is marked "private"...

 

[Jeff Schindler]

I fixed the private thing, took 3 attempts,

 

[dwb2620]

Shaft log has a split end?

 

[anthony_marquart]

It's hot,.. I guess really hot for for the external surface of a quiet pipe. But on my non muffled pipes I saw this pretty often.. hmm,.. maybe I was running too hot,.. .21's and .12's though..

 

[Terry Keeley]

I'll try and post it tonight

Here is the video

Very cool! Sounds like it's running pretty good to me.

Amazing how violent things rattle around from just normal running. Cool hearing the motor being pulled down in the corners too.

I'm sure that's a pretty normal running temp for a pipe, betcha the gas pipes run twice as hot!

 

[Charles Perdue]

Good video .

Also shows how the Zoom carb richens the mixture in the midrange of the throttle opening. The meter readings on the flow bench show this but I could never see the change in the spray pattern itself. I like that, very nice. Thanks Jeff. That deserves a beer.

Charles

 

[ALLAN YUEN]

Wow Look clear video my NR 46 wrap need break in ( tight piston/sleeve) Sold to Jeff S . He told me that he worked on engine so he was very glad with it run very well