tuned pipe
 

I have bought a tuned pipe for a .21 os max.. I have cut and rewelded the manifold so the exhaust goes out the cowling on my Pay n Pak hydro, so now I cannot change the length of it. need to shorten the pipe up for high speed performance. Can I cut some length off the front of the pipe? Seems to be plenty there. Can someboly explain to me why not? Thanks for any help.

RE: tuned pipe
 

You can remove material from the front of the pipe.

JD

RE: tuned pipe
 

Make your pipe adjustible .. after finding the right tuned-length with a decent prop . you can weld it again.

But I'm not a fan of that ... a different prop may need another tuned-length.

Here in Europe the proper tuned-length for a .21 is between 8.2 and 9.4".

Measured over the center-line from glowplug to exhaust belly-seam.

RE: tuned pipe
 

If I measured right I have about 10.75".  Do I understand correctly?  I measured from the glow plug to the widest part of the pipe, and that's after I cut off 3/8" of the pipe.  I'm not going to get too carried away though.  I will be able to adjust it.

RE: tuned pipe
 

Correct.

10.75" is too long to maximize rpm's. Any way to get it shorter?

RE: tuned pipe
 

I shortened it up so I can adjust it from about 9.5" to 8.5".  I would like to thank you guys for the GOOD advice, I just ran it on the hose in my yard and it sounds like it is ready to scream , a big difference.  Seems to run good at all rpms.  Again THANK YOU VERY MUCH.  :D

RE: tuned pipe
 

And if you have found the right prop/tuned-length , cut-off the manifold-length that is INSIDE the exhaust.

RE: tuned pipe
 

HendricX,   I don't understand what you mean.  Could you please explain further.

RE: tuned pipe
 

<span>Hi hydronut

Direct</span> <span class="hps">drive</span> <span class="hps">is</span> <span class="hps">to use</span> <span class="hps">240</span><span class="atn">-</span><span>260m.m</span> <span class="hps">Scope....<span>Important that</span> <span class="hps">you use</span> <span class="hps">propellers</span> <span class="hps">large and small.....<span>Percentage</span> <span class="hps">of</span> <span class="hps">nitro (<span>Need</span> <span class="hps">each other,</span> <span class="hps">cooperate</span> <span class="hps">with)
<span>Propeller Use</span><span class="hps">Octura</span> <span class="hps">1445</span> <span class="hps">or</span> <span class="hps">the ABC</span> <span class="hps">the H5</span> <span class="hps">or H7 is O.K.
<span>Exhaust</span> <span class="hps">joint</span> <span class="hps">position</span> <span class="hps">not to</span> <span class="hps">be</span> <span class="hps">longer</span> <span class="hps">than tunepipe Diffusion part of .</span></span></span></span></span></span>

RE: tuned pipe
 

What they are telling you is that if the header extends inside the pipe, it changes the way the pipe works. You need to cut the header so that it's exit end is approximately in the same location as the inlet end of your tuned pipe. I would recommend moving the pipe back out to the end of the header and run it on the water and then start cutting it off a little at a time, running the boat so that you can monitor how the engine reacts to the changes under load