PontiacBonnevilleClub.com

I've tried to do a number of searches to find answers to the following, but had no luck...


When I purchased my current Bonneville in November, I was normally seeing about 6.5-7 psi of boost according to the gauge (and closely mirroring what the ECM was seeing, checked through the scanner).

I've been slowly doing all of the mod's to support a tune and smaller dia. pulley (coming next week...), but am now seeing lower boost (about 5 psi max, maybe 6 at most at higher RPM) all the time.

Is this a situation where the efficiency of the system has been improved to the point, the boost level that can be attained by the stock pulley diameter has dropped?

I ask only because I would think if that were the case, the POWER OUTPUT should remain the same or improve...but it hasn't. Right along with the lower boost readings, the car actually feels slower now than it did before I started ANY of the "improvements".

Any insight from others?

Thanks,
Ken

Mods like freeing up the exhaust or higher ratio rockers will make the indicated boost go down. With easier flow, there is less "boost stacking" created due to lower end pressure in the cylinder after the exhaust stroke. In actuality, it's still moving more air which *should* mean more power.

Have you tested the fuel pressure?

That's what I was thinking but wanted to confirm.

Thanks.

No, I hadn't checked the fuel pressure as I hadn't seen any symptoms pointing me in that direction (hard starts, loss of top-end, etc.)

I can check it though...

Any idea what pressures I should be expecting (ignition on not running, at idle, and with throttle)?

It's been a while and I can't remember what it should be. It might be in our techinfo.

I found it, checked it, and found all's A-OK on that front as well.