Power surge in turns?

[Scott Miller]

I had both my scale and my F hydro out today. Both boats would take off about half way through the turns during hard rudder deflection. Then they would settle down in the straights.

Temperate was about 88F with 80% humidity.

Should I have selected a hotter plug? I was using odonnell blues. Nitro 50%

 

[SayMikey]

Id say you might be a hair rich

 

[Glenn Gates]

I've only seen that happen once Scott and it was kind of a freak thing. The Cal Craft stuffed pretty hard and displayed the same behavior. Speed up in the turns and slow on the straights. When she dunked the wood screws holding the radio box in place(fore and aft) bent and would allow the radio box to move. Under a hard rudder box would move leaning out the needle and when the rudder was straightened the box moved the other way making the motor run rich at less than full throttle.

 

[Dan Kramer]

could be too much prop, or not sharp enough

boat could be running too "tight" to the water,

pipe wrong length

 

[shoboat]

Scott,

More load is needed.

Keep Testing,

Mark Sholund

 

[Will Gallagher]

more prop or push pipe.....

 

[JimZaremski]

too lean, too much prop, or pipe length wrong.

 

[anthony_marquart]

A few possibilities I think are:

- As mark mentioned, not enough load on engine. The engine gets loaded up in the turns and frees up in the straight. If the engine wants more load you may see it in the turns.. More prop and or shorter pipe.

- Prop running too deep in the straights. TF or rudder causing the prop to unload a bit in turns.. this may be getting the engine to a better RPM range where you have more power.. This would look like the boat speeds up in corners and then drags down in the straight. - Check the ride attitude and height in the straight. Does the transom seem to drag lower that it should and lift up a bit in the corner? Maybe a little negative in the strut,,.. or a smaller prop to get the engine in a higher RPM (higher power) range.

Just a couple thoughts.

 

[Scott Miller]

Thanks for all your feedback gents. I brought the pipes back about 1/4 to 3/8" . All is well now.

 

[anthony_marquart]

Shorter or longer?

 

[shoboat]

Scott,

You should leave the pipe length alone once you get them short enough.

A better way is to have more propellers in that pitch and diameter range.

Why?

When the air density changes in Charleston you will then be able to just prop

Up a little more or prop Down a little more. This is how we tune our boats all around

the country. It is a much better way of tuning instead of playing with your set up.

Enjoy Testing,

Mark Sholund

 

[Dan Kramer]

so, prop up denser or prop down?

 

[julianconde]

Scott,

You should leave the pipe length alone once you get them short enough.

A better way is to have more propellers in that pitch and diameter range.

Why?

When the air density changes in Charleston you will then be able to just prop

Up a little more or prop Down a little more. This is how we tune our boats all around

the country. It is a much better way of tuning instead of playing with your set up.

Enjoy Testing,

Mark Sholund

thats correct different props for different places.

 

[shoboat]

Julian,

You still buying rubber for your dragster?

Have Fun,

Mark Sholund

 

[julianconde]

Julian,

You still buying rubber for your dragster?

Have Fun,

Mark Sholund

Mark;

Pistons, Rods, Cams, turbo header and turbo, blow off valve and wastegate are at the house. Just need boost controller and to port and polish the heads and engine studs and I'm ready ;-)

Julian

 

[Scott Miller]

Shorter or longer?

Longer