wastegate spring
04-27-02, 12:34 AM
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wastegate spring
Hello,
I have yet to take my new setup out on the road yet but I noticed tonight that if the car is revved up real quick into boost while sitting still that the wastegate opens enough that you can hear it. The wastegate is a HKS standard bled open to the air. It has 5.9 psi spring in it now. I was wondering if this is normal. If I unplug the feed line of course it won't open at all. The most boost that the gauges are showing is around 3 psi. If I use a hand pump and pump it very fast to keep pressure built up then it will open enough to hear at around 6 psi.
Thanks,
Ben
I have yet to take my new setup out on the road yet but I noticed tonight that if the car is revved up real quick into boost while sitting still that the wastegate opens enough that you can hear it. The wastegate is a HKS standard bled open to the air. It has 5.9 psi spring in it now. I was wondering if this is normal. If I unplug the feed line of course it won't open at all. The most boost that the gauges are showing is around 3 psi. If I use a hand pump and pump it very fast to keep pressure built up then it will open enough to hear at around 6 psi.
Thanks,
Ben
04-27-02, 12:53 AM
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I can't even make boost in neutral... Damn big turbos 
Make sure that all your vacuum lines are as short and to the point as possible. Avoid vacuum T's except when necessary.
Your 5.9 psi spring is made such that the turbo will be kept from boosting over that amount. In order to be smooth, (remember that a spring is progressive) it starts to open usually at about 50%, or in your case, 3 psi. It continues to open progressivley up until 100%. A good electronic boost controller will keep the gate from cracking until 70-80%, hence a faster boost rise due to less 'waste'.
If you unplug the feed line, the wastegate will crack when the pressure in the manifold reaches 50% of the spring rate and be full open at 100%. This for me happens when the boost pressure is a little over double the spring rate. I had this problem once, and it took me a while to trace it down... I had in a 7 psi spring, but my car was boosting 16-18 psi. When I put in my 10 psi spring, it wanted to boost 23+ psi. I wouldn't let it... That was how much boost pressure it took to create an amount of backpressure in the exhaust manifold that was sufficient to overpower the wastegate spring.
This is your brain on rotors. Any questions?
~Jeremy
Make sure that all your vacuum lines are as short and to the point as possible. Avoid vacuum T's except when necessary. Your 5.9 psi spring is made such that the turbo will be kept from boosting over that amount. In order to be smooth, (remember that a spring is progressive) it starts to open usually at about 50%, or in your case, 3 psi. It continues to open progressivley up until 100%. A good electronic boost controller will keep the gate from cracking until 70-80%, hence a faster boost rise due to less 'waste'.
If you unplug the feed line, the wastegate will crack when the pressure in the manifold reaches 50% of the spring rate and be full open at 100%. This for me happens when the boost pressure is a little over double the spring rate. I had this problem once, and it took me a while to trace it down... I had in a 7 psi spring, but my car was boosting 16-18 psi. When I put in my 10 psi spring, it wanted to boost 23+ psi. I wouldn't let it... That was how much boost pressure it took to create an amount of backpressure in the exhaust manifold that was sufficient to overpower the wastegate spring.
This is your brain on rotors. Any questions?
~Jeremy
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