How much vaccuum?

[04LS6]

Hey everybody,

I've got a 2008 Apex with an MCXpress 290 kit installed running 17lbs. I'm just curious how much vac the throttle body lines should be producing. I got a new Turbosmart Veeport blow off valve to replace the one included in my MCXpress kit. When I had everything hooked up, I was just curious to see how much vac the sled would pull, so I started the sled up with my finger over the line, and when i pulled it off there isn't really that much vacuum at all. I'm wondering if this is why I was getting some turbo flutter and the old blowoff might not have been lifting at all.

The sled didn't even change in RPM when I would take my finger off of the hose and put it back on. There is a slight vac, but not much. However, the apex runs like a freakin dream and I have no issues other than just that question... Any help would be appreciated. Thanks.

 

[zebiraross]

They don't pull much vac especially with a head shim. -3 to -5 psi on my prologger.

 

[Polarisrocks]

the sled should chugggg and almost die if you pull a vaccum hose open. It should throw a code 14 too. At least the three I work on have some vaccum. mine has a shim and it idles at 12-14 inches of vaccum and when you chop the throttle on it you can see 20 plus inches.

 

[BCBOOST]

Sleds only Idle with about 5-8 inches of vac. When throttle is chopped with enough RPM you will see 10-20 inches of Vac. Hope this helps.
BC.

 

[04LS6]

thanks for the replies. I am going to get a vac gauge, and next year just before I take it out I will measure what it makes at idle. There is some vac there, I just want to make sure that my BOV opens when I let off the throttle.