Is anyone running one on a Viggen? Is it worth the $$? Does it change the sound of the engine when you let off the throttle in boost? Any feedback is appreciated....
yep yep.
Forge doesnt say one way or another is better, but the general consensus is that running it 'reversed' is the way to go due to mcrowley's point about the spring
well nick at GS still uses the yellow spring on his vig...so you shouldn't need to think about another spring. anything stiffer and i think you can start to damage the turbo.
So I asked this before, but why does one buy a diverter valve with different springs? I understand the concept, but I have a viggen holding around 20-22 psi give or take and I have the hyperboost shorty which comes with one spring and it works great. Seems like a hassle getting one with all these springs/shims as there are many threads pertaining to what spring should one install. Then there are people like vigge who are running the stock bosch unit.
Nobody ever listens and thinks if they run a stiffer spring it will make more boost.. It is not a problem, put the valve in and be done with it. If you want to tinker with it turn directions and that will make a different noise.
The one thing that I have never understood about running it backwards is that it is not only pushing up against a spring under boost. There is a vacuum line there supplying the exact pressure that the boost is. The reason why the spring is there is because the initial boost is not into the intake manifold yet, so the vacuum line is slower to respond.
I feel like running it backwards would be a negligible difference because of the fact there is spring tension plus equal pressures on both sides.
But at the same time, I can imagine high boost cars running backwards would be a better, safer method. Although my car is running 24psi, I have the lightest spring in the valve and it is not positioned backwards, I do not get any boost leaking from it.
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