Low boost for a 3.4?

[Boosted_GR33K]

So, after my awful track debut with my 97 SSEI, Ive been trying to brainstorm and trouble shoot why its been running so slow. I came to find out that apparently stock boost with the stock pulley is around 6psi and that with my 3.4 should be somewhere in the 9-10 range for boost pressure. Im at a solid 4psi...hmmm. First, I thought maybe my gauge was in a bad spot. So I re-ran the aftermarket boost/vacuum gauge to right under the supercharger snout to be as close to the action as possible. Drove the car, 4psi boost pressure. I thought 'maybe a bad gauge?' so I tested 2 brand new and one used vac/boost gauges and they all came back the same - 4psi. I then thought 'hmmmm maybe the wastegate is messed up and letting all my boost pressure escape? So, I put a new wastegate valve on it and went for a drive. You guessed it - 4psi! At this point, I just wanted to get mad and break something, so I waited a bit n calmed down over a meal. I decided lets just unplug the wastegate and see if it'll run hellbore boost!' Undid the valve aaaaand....survey saaaaaays.... 3PSI now Supercharger whines nice, loud and free - no rock tumbler or any strange noises. Only thing I can think of is that this supercharger has become self-aware and just refuses to make boost..... What do you guys/gals think? -Ben

[nos4blood70]

Sounds like a BBV issue. Boost will be different in almost every car, it's a measure of flow more than anything else. Shoot for timing, not boost.

[MattStrike]

Boost will also depend on the cam you're running. The NIC on a stock pulley will run about 2-3lbs of boost but it flows a lot more air.

If you disconnect the BBV from the solenoid it should force it to stay in the 'closed' position so you can use that to help diagnose. The other possibility is the valve is actually stuck, so confirm that it goes to the closed position and stays there.

[Boosted_GR33K]

The BBV (aka the wastegate? ) wasnt moving originally when I put the motor together, so I replaced it. Seems to be moving freely now. Should it be adjusted all the way up or down with the slider bolt holes? Im running the VS cam from ZZP with 1.7 aluminum rockers, 105springs and ls7 lifters. So its not so much boost but timing?

[nos4blood70]

That doesn't sound low for your set up.

[Boosted_GR33K]

That doesn't sound low for your set up.

From the reading/what Ive been hearing from other people they've boasted 9-10PSI on a 3.4 pulley with similar/less mods. So really I would I benifit more from 4* extra timing than 4-5PSI boost? Still new to the supercharged lifestyle....

[gonzo4191]

i tied my valve down to the blower case with a zip-tie cause i got 4psi with my 3.4 too

[repnatl]

Had the same issue on my 03 ssei when I swapped to the 3.4 mine ended up being the boost solenoid. FYI zzp says a 716 belt on the 3.4 and had bad slippage I dropped to a 710 without issues but eventually changed to a 3.5" belt tensioner pulley and the 716.