Exhaust power valve...i was thinking about making one that...

[joeak47]

I was thinking about making a power valvle that will fit inside the ported exhaust port of a blaster cylinder.
I just finished work on a 2000 suzuki RM80,and was have a few ideas in my head while boring and honing the cylinder.

I believe it may be possible to make a self regulating unit that may fit in the exhaust port or head pipe. Just ideas on the chalk board.

My "Aggresive Desert" port work, works incredible in the format that its in right now.However,I was thinking that if I was to port for more top end rpm's (bansheeish powerband),perhaps a power valve would restore low end grunt that a high rpm cylinder would be lacking? Things that make you go Hmmmmm?......

I'm sure that this has been thought of many times before.

 

[sicivicdude]

The LT250 and LT500's used a chamber hidden in the case and an opening under the exhaust port that changed the characteristics of the pipe. It wasn't as effective in modulating the powerband as the YPVS or KIPS systems but it did work. Those systems raise the exhaust port roof to increase port timing at high engine rpm's

Unforunately, it's governor driven and made into the engine (not something you could add easily).

 

[joeak47]

I've been doing lots of thinking about this. I believe that it would be fun to experiment with. I was thinking some type of spring tention,so it would be self regulating. I think I could get this to work. I'm going over a few things right now in my head.
The K.I.S.S method (Keep It Simple Stupid) would probably be best for this.

 

[joeak47]

I know the DT200 use servo motors to regulate they're power valve,however I'm looking to a simple,possibly "slip in" construction. Just an idea. Sometimes the simple way is the best way...sometimes not.

 

[sborns]

how does FTZ do it then? they make powervale 250R honda engines. i think their 370 is a powervalve engine. http://www.ftzracing.com/PowerValveMtr.htm

 

[sicivicdude]

I've been doing lots of thinking about this. I believe that it would be fun to experiment with. I was thinking some type of spring tention,so it would be self regulating. I think I could get this to work. I'm going over a few things right now in my head.
The K.I.S.S method (Keep It Simple Stupid) would probably be best for this.

Adding a powervalve to an engine that is not equipped with one isn't a "K.I.S.S" situation.... There will be a LOT of engineering involved.

The vacuum actuated models are the most prolific (Rotax "RAVE" valve) but not as well controlled as mechanical (goverened) models.

Simple spring loaded and utilizing exhaust pressure will be wildly difficult to control except under VERY specific conditions (WOT and idle being the two operation modes where it'll be predictable) . It can be done but it won't be as effective as one that opens and closes controlled and gradual as rpm's rise.

The best way (most predictable operation wise) would be to make a governed model using the governor from a dirtbike engine adapted to the blaster bottom end somehow. It will open and close at specific rpm's and remain open solid at high rpm's and remain closed solid at low rpm's.

I've toyed with the idea of making a modified pipe before to take advantage of the changes that could be made to tune the pipe at other rpm's without having to modify the blaster cylinder itself.

 

[sicivicdude]

how does FTZ do it then? they make powervale 250R honda engines. i think their 370 is a powervalve engine.

The FTZ's are complete replacement cylinders. CP industries replacement cylinders for banshee's also have powervalve options.

Another thing to think of here, is the decrease in cooling capacity that will result from installing something in front of the exhaust port.

The banshee head and RZ350 heads coolant pathways are vastly different at least in part due to the loss of cooling capacity in the RZ cylinders because the powervalve is placed directly above the exhaust port. In the blaster, you cannot simply redesign the coolant path to include more coolant lag time the in head just above the powervalve.

The best option if you do go this route is to investigate putting your blaster on alcohol to keep cooling issue at bay. It requires more fuel to get the same range but basically, overheating issues are non-existant.

 

[joeak47]

A purpose built pipe seems like the best bet perhaps?

 

[sicivicdude]

You want to go wild and crazy? I was thinking about trying this on a custom headpipe.

The idea is to basically add a "boost bottle" to the section of the exhaust tuned pipe where the charge resides after the pipe pulls the charge out (before it stuffs it back into the exhaust port) with a valve that can close after the engine begins to get really efficient. I think it could be done if the headpipe was designed around it....

That's how the suzuki LT system worked. It stored a small amount of charge inside the chamber made into the case before the pipe is efficient enough to ram a great deal of the charge back into the cylinder. It makes the bottom end more efficient....

 

[Paulie B]

I think the easiest system to adapt would be the exhaust presure activated system used of banshee cheetah motors and many others.
Adjustment is just a simple spring change.

 

[Awk08]

i searched again but can't find it, but once i saw a PV operated by a second cable from the throttle ??
it was actually the dual cable throttle i saw for sale somewhere, and the second cable was described as for the PV.

 

[Larry's Shee]

i searched again but can't find it, but once i saw a PV operated by a second cable from the throttle ??
it was actually the dual cable throttle i saw for sale somewhere, and the second cable was described as for the PV.

I kinda thought along the same lines but thought I might get clowned 8-|. My thought was a hot start lever from a 4poker, kinda like a NO2, use it or not.

 

[Awk08]

I kinda thought along the same lines but thought I might get clowned 8-|. My thought was a hot start lever from a 4poker, kinda like a NO2, use it or not.

oh, we'll all get clowned with the "if i can't do it, nobody can" attitude above.