Hi Guys,

I see the Powermaster Pipes have adjustable outlet tips to adjust back pressure. How do you use back pressure to tune your engine? ???

-Mike

It has alot to do with heat.Too much is no good but to cold is not good.The stinger will let you adjust the flow which will change the pipe temp.Im sure Scott why have a good theory on it.

One thing we found is that the higher the rpm, the bigger the best stinger size. Gas engines don't loose power as quickly as nitro engines with a big stinger diameter, but too small a diameter really hurts.

Lohring Miller

IMHO, speaking in layman's terms .....

Back pressure in directly related to the pipe internal air density, The more it is restricted, higher the density.
* Heat however also effects density, higher the heat = lower density, lower heat = higher density.

So .... By having a pipes outlet tunable, you can tune within a greater application of the pipe.
* A pipe hanging out in the breeze will run a LOT cooler that one enclosed under a cowl. So the thermal dynamics and it's effect on air density will differ between those applications.

??? This is only the tip of the why & how pipes work. Internal pipe back pressure also effects how a cylinder scavenges.
* So another twist is how engine is used in it's application, are you requiring very High torque or High RPM ?

A tighter stingered pipe typically makes more torque, but rev less .... a big stingered pipe better high RPM, but less torque.

It is a TUNING tool ... But one must play and do some R&D specific to the application pipe is used in.

It is not Black or White .... Sorry ;D

: On my own Rigger using a 2 inch band ACE pipe, it hangs off to the side in FULL AIR FLOW, and runs quite cool. Have found the smallest stinger to give the best performance.
It causes more heat to be created within pipe (Higher BTU's) and increases air density making better torque ... High rpm is not an issue here.

On my sport boat which also has pipe in the breeze, RPM is my need and high torque not needed. Here I use the Zero band pipe with a mid size stinger for best overall power.
(Note as RPM is increased, so is the pipes heat & gas flow threw it)

The O.A.L of both pipes are within 1/4" of each other.

??? ??? ??? :o

OK, I think I get it.

It gives you one more thing to adjust to try and squeeze a little more performance out of your engine. Which one works best depends on your setup and can only be found by R&D.

Thanks for the explanation guys.

-Mike