I have an older Whipple kit from "back in the day" on my 2000 Silverado. It has been on the truck for about 80k miles and I have done other mods over the years. One thing I did was put a smaller pulley on it to raise the boost to 8-9 psi. Over time the boost started to decrease - I am thinking that it was due to the valve springs in the stock heads wearing out and bleeding boost. It was down to around 6-7 psi.

Anyway, I put some PRC 2.5 heads on the truck and a Comp 224/228 114 lsa cam in it and it really woke up the old motor. Now I see 8-9 psi on the gauge until 4500 rpm where it starts to fall off steadily down to around 6 psi by redline, which is set at 6400. The guy at Whipple says it should stay up around 8-9 psi to redline and I may have a vacuum leak.

So over the weekend I replaced all of the vacuum lines and tightened the belt to make sure it wasn't slipping. I even disconnected the vacuum lines from the bypass valve and clamped it closed. Same result.

So my question after all this is - has anyone ever had to replace the bypass valve on a Whipple? Mine is an older AXO compressor and is considered by today's standards to be small. Also, is the only place to get a replacement from Whipple?

Thanks!

 

Can you zip tie the valve closed and run it to see what your max boost is? Is you valve vacuum controlled or are you using the Whipple electronics on it?

 

I removed the vacuum from the valve and did the zip-tie method yesterday and it had no effect. All of the Whipple-tronics and extra injectors were removed years ago. It is now only vacuum controlled.

 

It should be a metal valve, I cannot see it wearing out. What size pulley do you have on the blower? And is your crank pulley pinned?

 

It is a 4 inch pulley on the Whipple. Crank pulley is not pinned.....Hmmm

 

Ya.... Might want to look into that..