Lower Boost

[Banshee]

Just picking your brains,

But what condition can cause a lower than expected boost?

These are things that I've came up with, but can you guys think of any other?

1) Slipping belt
2) Boost leak
3) pinched vacumm line

Can any of the following cause lower boost?
1) Too rich
2) lower compression

[Tom @ Fast Forward]

Coldsides with stock internals should make close to the same boost for all model years with the same pulley ratios. Worst case 1 PSI difference. With that said, the 105mm pulley should get you into the 8-9PSI range at redline, 110mm pulley about 10-11 PSI and the 115 about 12-13.

If boost goes up and power down, that is typically a stuffed cat or exhaust. If you have head work done and it flows better and the exhaust is free, you will see lower boost and better flow and more HP. If you have lower boost AND lower HP, that could be a slipping belt. Is your crank pulley anodized or plain aluminum?

[Banshee]

Tom, I have the black one that you sent me. The 100mm pulley. As you know, I've been getting 9.5# with the 100mm pulley setup ever since the install. But all of a sudden last week, I've only been getting 8.5#max. It correlated with my too rich fuel ratio problem.

If the car is pulling a lot of timing, will that affect boost?

[Tom @ Fast Forward]

Timing and fuel can effect boost as it upsets the smooth flow of air through the head. It is all about flow. My old signature "More flow, less boost" still holds. Fix the fuel/timing problem and the boost and power will probably come back. Normally though, when you upset the flow, boost goes up and power goes down. You might want to check for leaks.