Power valves ??????

[azzy522]

What do the Power Valves really do.
I have had them out to clean them several times and have looked into the ports and cannot figure out their purpose. I understand they open at higher RPM's but what happens when they are open?
Friends 98 SRX does not have them.

 

[Netefrog]

They allow the engine to breath more efficiently by allowing the exhaust gasses to escape faster.
And to the best of my knowledge ALL SRX's and Vipers have exhaust valves. But I could be wrong.

 

[azzy522]

Buddy's sled is a 98 is a V-max 700. It has no power valves, my mistake.

 

[stein700sx]

All engines need a certian amount of back pressure. The power valves help create back pressure by restricting the exhaust in the lower rpm range. As the rpm's climb they open up allowing the back pressure to be a little more consistent thru out the rpm range.

 

[cumminsdsl]

what would happen if you did remove the powervalves completley??? has anyone ever done this, even on a race sled.??? never really thought about it.

 

[daman]

PV's change the port timing with the valves closed it lowers the timing which creates more bottom end torque. then when the valves opens at around 6500 it advances the port timing by raising the exh. port, this makes more top end hp.

 

[azzy522]

Now I am starting to understand, Thanks guys.
Removing the PV all together, that was one of my questions. Or if you left them in and did not let them move.

 

[Netefrog]

PV's change the port timing with the valves closed it lowers the timing which creates more bottom end torque. then when the valves opens at around 6500 it advances the port timing by raising the exh. port, this makes more top end hp.

So was I incorrect when I gave this answer???: They allow the engine to breath more efficiently by allowing the exhaust gasses to escape faster.
And to the best of my knowledge ALL SRX's and Vipers have exhaust valves. But I could be wrong.
__________________

 

[daman]

So was I incorrect when I gave this answer???: They allow the engine to breath more efficiently by allowing the exhaust gasses to escape faster.
And to the best of my knowledge ALL SRX's and Vipers have exhaust valves.

Ahh yes and no
yes

 

[cumminsdsl]

Now I am starting to understand, Thanks guys.
Removing the PV all together, that was one of my questions. Or if you left them in and did not let them move.

I've heard of people running sx cdi's on srx's for a hotter timing curve and locking the valves open on race sleds.