Thread: What pulley do i have and why so much boost.

17 psi of boost seems way to high. measure with a ruler or tape measure across the hole diameter, should be more accurate then approximating the center. 3.0 pulley should not be 17psi, maybe 13 or 14psi peak before a shift. I'm not sure you gen get a Gen 5 to 17psi.

How are you measuring the boost pressure, the scanmaster or a mechanical gauge?

P.S. MSD coils are none to fail, they don't offer any added performance and are less reliable than stock. But they are RED!

Take a pic of the pulley. Is it a press on one or a MPS?

Originally Posted by sseilmnop

17 psi of boost seems way to high. measure with a ruler or tape measure across the hole diameter, should be more accurate then approximating the center. 3.0 pulley should not be 17psi, maybe 13 or 14psi peak before a shift. I'm not sure you gen get a Gen 5 to 17psi.

How are you measuring the boost pressure, the scanmaster or a mechanical gauge?

P.S. MSD coils are known to fail, they don't offer any added performance and are less reliable than stock. But they are RED!

Fixed.. None to fail could be interpreted very differently

Buy a bigger pulley, before the motor blows.

sounds to me like something is wonky with the tune.
too much boost and not enough timing? idk, im a noob.

Originally Posted by thomas mcnulty

What proof do we have that msd coils suck? Just curious. Did uncle jeb run one with little success?

you'll just have go buy a set, and then tell us how you like them them.

Your prolly seeing so much boost because your not flowing the air as much as you should be through the motor. 3.0 on genV = 2.8 on genIII. IIRC you need a cam and full size IC to run that small of a pulley with an agressive tune. You are prolly running very rich and low timing to keep your KR down. My guess would be to pulley up and get re-tuned and you will run faster.

Originally Posted by thomas mcnulty

What proof do we have that msd coils suck? Just curious. Did uncle jeb run one with little success?

I've heard on many forums they're known to crack, in fact I can remember several cases of defect returns at work (Advance) on MSD coils because they did indeed crack and/or just stop working after very short mileage.

In regards to GM vehicles, I believe they have less output than stock coil packs... this article is from ZZP on useless mods...

Aftermarket coil packs
The stock ignition on a Grand Prix is very good. It is so good that we run stock coil packs on all of our cars at ZZP. Failure rate of stock coil packs is low and the spark output is extremely high. We have A/B dyno tested aftermarket coil packs and seen no difference in HP. We have seen many aftermarket units fail and when customers have a problem it’s very hard to diagnose with extra unneeded mods on the car.


The ignition control module sits under the coil packs. It sends a limited current to the coils for a predetermined pulse (dwell). You cannot change the wires or the coils to get ‘more spark’ because the ignition control module will not send more power to the coils. You would have to change the ignition control module for a significant increase. The MSD coils and/or the MSD wires are a downgrade in your ignition system in regards to the 3800. The best you can do is run a wire with slightly less resistance or more insulation. These are very small improvements but the only meaningful ones.

maybe the boost gauge is hooked up in the wrong spot and your getting inaccurate boost readings?

Stock MAP only goes to 14.5 psi. So if this is true your maxing out your MAP.

.035 is a really small gap on the plugs

.350 is really big! .035 is really small.

Without a cam that could be possible he's seeing boost pressures that high. On my Gen 3 with an xp cam and IC I would see 13-14 psi on a 2.8 pulley. But without a cam and a with a gen 5 and a slightly smaller puelley I can see his boost getting that high, especially if hes shifting higher.

One question: Do you still have a cat?