SP Quick Spool Valve

jdub

Official SM Expert: Motor Oil, Lubricants & Fil
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Is that what the instructions from Sound Performance says to do? (block the inner port)
 

tekdeus

Pronounced Tek-DAY-us
Jan 23, 2006
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That's how they run them. Most Mk4's have the turbo at an angle that would not allow the valve to be flipped over to close the other port. In their thread on SF they said they did not notice a difference, so I assume they dyno tested both ports. Maybe the difference is negligible?
seq25.jpg
 

jdub

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Could very well be negligible...the whole idea is to use a larger hot side AR and getting it to spool like a smaller AR. By the time you've got the faster spool, it opens anyway. I still think blocking the outer would be better, but we might only be quibbling over a couple hundred RPM. If fitment is an issue, I would do what's easier.
 

IJ.

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Mar 30, 2005
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Had a play around with mine the other day while the CNC was doing it's thing ;)

Hooked it up to a mini reg and now I understand why SP used such a large actuator!

It's opens easily at the barest hint of pressure, this also explains why they suggest using a solenoid to control it as it would be ineffective otherwise.

Very well made piece of gear and well worth the purchase price.
 

tekdeus

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I agree. Looking at one up close, you can see that some thought and engineering went into it.

It's funny how looking at the cross section of a divided housing, it almost looks as though it was designed specifically for the SP valve. Instantly half the nozzle size and double the gas velocity :)
Cutaway_enlarge.jpg
 

tekdeus

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Also: do you suppose it would be better to rig up my solenoid line to the valve to be normally open? And then have ign 12v to close the solenoid while driving and have the hobbs switch interrupt at the chosen psi? Otherwise the valve would be stuck closed if the switch or solenoid failed (at high boost). Might this cause compressor surge?
 

IJ.

Grumpy Old Man
Mar 30, 2005
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Can't see how it would get compressor surge?

Worst case scenario is it fails closed and the motor won't make power so safe enough.

I was impressed how the butterfly is chamfered on the edges so it closes properly.