powervalve question

madzx2

madzx2

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Apr 24, 2009
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Osceola Wi
i was checking out a guys watercross sled and noticed he had his powervalves blocked off. i believe it was a viper. what does blocking the valves off do? whats the benifits?
 
madzx2 said:
i was checking out a guys watercross sled and noticed he had his powervalves blocked off. i believe it was a viper. what does blocking the valves off do? whats the benifits?
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I would guess with watercross you're on the bar all the time thus no need for restricting exhaust flow to improve throttle response... same as with a drag only combo. It's only going to see WOT.
 
yup ..powervalves dont open til around 6000 rpms ...so having it pinned there is no need to have powervalves working....how ever i always wondered how it effects air flow from valve being removed instead of just having the cable pulled wide open ...or cutting the valve face off completly so the shaft still fills the hole ...anyone follow me ?
snomofo said:
I would guess with watercross you're on the bar all the time thus no need for restricting exhaust flow to improve throttle response... same as with a drag only combo. It's only going to see WOT.
Click to expand...
 
YA*AM*A*HEAD said:
yup ..powervalves dont open til around 6000 rpms ...so having it pinned there is no need to have powervalves working....how ever i always wondered how it effects air flow from valve being removed instead of just having the cable pulled wide open ...or cutting the valve face off completly so the shaft still fills the hole ...anyone follow me ?
Click to expand...

Agreed. Seems to me you'd want to keep the valve and anchor it in the open position to maintain the port contour.
 
as far as i could see there was just a plate on the cylinder that was blocking it off. not sure whats left insde.
 
when you lock the valves open you can do it a few ways, you can machine the end of the pv shaft where the cable orignally hooked up and thread it,install a bolt and a plate on the cylinder,the bolt goes thru the cover plate and lock it down with a nut acting as a jam nut. You guys are right on to say the valve needs to be in the open spot to maintain the roof,top of the exhport surface. Easy enough to revert back if needed this way.

The other way is to open the valve and tack weld the shank to the cylinder,trim off the left over shank, install a coverplate. Not so easy to revert back if wanted, but no parts to fail.

Last way is weld up the pv slot in the cylinder and machine/port to the roof.

motor wont perform very well at anything but wide open throttle, but thats what these guys are doing,running wide open all the time. so no low/midrange power is required.
 
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