Setting Pipe Length for NR Powerhead

[David Santistevan]

I have a new tunnel with a 3.5 NR Powerhead and SPP pipe. What is a good starting length for this pipe and what is the best way to measure that length?
Thanks,
D

 

[Carl Van Houten]

What boat are you running it on?

 

[David Santistevan]

One of your new Taboo hulls I got from Ron Shaw.

 

[Carl Van Houten]

The carbon pipes do pose an issue when trying to measure to a reference point like you would if you were using an aluminum pipe. When I setup for a new pipe design it can be a little time consuming because you set it long and tune the pipe length as you go. I rarely care what anybody else does because I am going to tune it myself as setups can vary quite a bit.

I found years ago that what you need to do is establish a reference point to measure to that is generic to all your pipes (like measuring to the transition point of an aluminum pipe) but it does not matter how you do it as long as you do it the same way and to the same point every time.

Once you have done the pond work needed to established the length that works best for your setup, take a measurement from the center of your plug to the farthest outside edge of the diffuser cone and write that down in your records: Pipe "A" length =3.2" . This is how I keep up with all my pipe lengths. Who cares what other people do? Measuring to the beginning of the belly or the end of the belly...you really cant do it that way with carbon pipes. I have posted a picture for you to see what I am talking about. I used a yellow ruler just so you could see it better.

Mine is set to 3.1" but you should start out longer than that and work your way to that. If you don't get all the way to that dimension it doesn't mean that you are not fast. You may be pulling more prop and need the extra length to keep your needle from being too narrow.

Hope it helps.

 

[Kris Flynn]

Carl has nailed it.

Only difference for me is to measure from inside of radius on pipe bend to outside diameter of header comig down from motor. Bit easier to measure i think, bit as Carl said, how ever yoi do it does not matter, just be consistent .

 

[David Santistevan]

Good info, thanks alot gents!