Tune Pipe Pressure

[Mark Bullard]

Jose, I'll PM you about running in Knoxvegas. It's the same as Huntsville as far as distance from Chattanooga; 100 miles either way.
One thing to remember; when the tanks are 1/2 empty, there is more air volume; and air is compressible. So my theory is that the potential for the lean condition you describe is more apt to happen with a completely full tank. THe half full tank has an expansion volume of air to help get through the momentary tansition. To check it out, try launching with the tanks 1/2 full, and see what happens. Let us know your results.

We ran today. The increased tune pipe pressure helped but I am not completely satisfied with the launching torque of my rigger. Ran at least 10 fuel loads. I think it is time to experiment with a more broad pipe, maybe bigger TP volume and/or longer TP.

What pipe are you running?

 

[Piston1]

Jose, I'll PM you about running in Knoxvegas. It's the same as Huntsville as far as distance from Chattanooga; 100 miles either way.
One thing to remember; when the tanks are 1/2 empty, there is more air volume; and air is compressible. So my theory is that the potential for the lean condition you describe is more apt to happen with a completely full tank. THe half full tank has an expansion volume of air to help get through the momentary tansition. To check it out, try launching with the tanks 1/2 full, and see what happens. Let us know your results.

We ran today. The increased tune pipe pressure helped but I am not completely satisfied with the launching torque of my rigger. Ran at least 10 fuel loads. I think it is time to experiment with a more broad pipe, maybe bigger TP volume and/or longer TP.

What pipe are you running?

MAC 13cc @ 12 inches measured from the side center of the motors.

 

[BigChuck]

A small HINT for you: "THEY ARE STILL ANDY BROWN MAC MOTORS................"

 

[Piston1]

A small HINT for you: "THEY ARE STILL ANDY BROWN MAC MOTORS................"

MAC pipes.

 

[BigChuck]

MAC.............AB Or those NEW Things. Look at the the Rs Vs, Hr post. Look at the pipes on the SG with HR 91's. ALL AB!! B)

 

[Mark Bullard]

Jose, I'll PM you about running in Knoxvegas. It's the same as Huntsville as far as distance from Chattanooga; 100 miles either way.
One thing to remember; when the tanks are 1/2 empty, there is more air volume; and air is compressible. So my theory is that the potential for the lean condition you describe is more apt to happen with a completely full tank. THe half full tank has an expansion volume of air to help get through the momentary tansition. To check it out, try launching with the tanks 1/2 full, and see what happens. Let us know your results.

We ran today. The increased tune pipe pressure helped but I am not completely satisfied with the launching torque of my rigger. Ran at least 10 fuel loads. I think it is time to experiment with a more broad pipe, maybe bigger TP volume and/or longer TP.

What pipe are you running?

MAC 13cc @ 12 inches measured from the side center of the motors.

I am running the same at 11.25 from the same place. The pipes are starting to pull the elements down to where they want them.

 

[Piston1]

Jose, I'll PM you about running in Knoxvegas. It's the same as Huntsville as far as distance from Chattanooga; 100 miles either way.
One thing to remember; when the tanks are 1/2 empty, there is more air volume; and air is compressible. So my theory is that the potential for the lean condition you describe is more apt to happen with a completely full tank. THe half full tank has an expansion volume of air to help get through the momentary tansition. To check it out, try launching with the tanks 1/2 full, and see what happens. Let us know your results.

We ran today. The increased tune pipe pressure helped but I am not completely satisfied with the launching torque of my rigger. Ran at least 10 fuel loads. I think it is time to experiment with a more broad pipe, maybe bigger TP volume and/or longer TP.

What pipe are you running?

MAC 13cc @ 12 inches measured from the side center of the motors.

I am running the same at 11.25 from the same place. The pipes are starting to pull the elements down to where they want them.

Thats too short Mark.

 

[John Knight]

Jose,

I tried many times to use the MACS 13CC pipe with my CMB 90's (single engine boat) and found them to be very picky for the needle and torque. Jerry Crowther told me they would be that way. I use the 15CC and have very good power and torque. May want to consider them as an option. Lengths were 11.5 to 12" but closer to 12".

 

[Piston1]

John, I agree with you.

 

[BigChuck]

Yes Gentalman you are all correct, However the ONE facter that is not anything like the current EVo OR Rs motor is that the HR was built on an TOTALLY different Design.

I wall say this one last time and them no more!!! " IT IS A MAC MOTOR!!!" B)

 

[Piston1]

Charles I heard you. The fact is that I am just simply experimenting with props, pipes, setup, etc. in preparation for Charleston.

 

[BigChuck]

Jose

Just back from the lake. All of the experiments look promsing. But I will go with what got me there the first time.

13cc pipes with a little less than standard length and small props. And stand on it.

I would think that you will need to do the same with the HR motors. See you there. :lol:

 

[Rick Doane]

Jose.......have you found any additional information that helped your pressure problem?

 

[Piston1]

Jose.......have you found any additional information that helped your pressure problem?

Yes, to maintain good fuel flow to the carb. the AB big bore TP fitting works very well.

 

[Rick Doane]

Jose.......have you found any additional information that helped your pressure problem?

Yes, to maintain good fuel flow to the carb. the AB big bore TP fitting works very well.

Jose:

Keep in mind that the motor(s) draws negetive pressure on the tanks. You have to at least match that with the positive pressure that the pipe(s) put out. When there is a sag, the motors are pulling more negative (due to drag, prop pitch, etc.) than can be replaced. The large pressure fittings should work due to the volume. You can also try moving the fitting closer to the exhaust, however that may create a whole different set of problems. You are just running too d... good! Wish I was going with you to S.C. I'll be in Lake Charles for the next 2-3 weeks. I need to find anyone here that runs boats. I'm having withdrawing symptoms.

Regards..........Rick

 

[Piston1]

Rick, I am aware of the neg. pressure effect on desceleration. I can see it in the stand by reving the motors. It is another one of those transitional moments of running tune pipe pressure. We are going to the lake later today. Ready to pick more pitch as we previously discussed.

 

[Tom w]

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