Power surge in turns?

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Scott Miller

Scott Miller

Well-Known Member
Supporting Member
Joined
Oct 1, 2011
Messages
719
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%
 
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.
 
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.
 
Last edited by a moderator:
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
 
shoboat said:
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
Click to expand...
thats correct different props for different places.
 
Last edited by a moderator:
shoboat said:
Julian,

You still buying rubber for your dragster?

Have Fun,

Mark Sholund
Click to expand...
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
 

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