LoungeFor casual talk about things unrelated to General Motors. In other words, off-topic stuff. And anything else that does not fit Section Description.

Moved to the Lounge. Your topics are not a typical application for us, and having this information in Forced Induction where a new inexperienced Bonneville owner may find it could prove confusing.

Your posts can be in Forced Induction only as long as they follow the 'norm' for us. Like replacing bearings. Application issues in how they relate to your drivetrain cannot remain there.

Do the math on your drive ratio. Then figure out how fast the SC will be spinning based on the RPM you normally shift at.

Then go to Eaton'* website and look at their data. That will get you in the ballpark, but there are still too many variables to put an accurate number on it.

That is a huge friggen pulley!!!! An M62 with that size pulley is not going to move much air. Even on a 2.5L.

Do you know what your volumetric efficiency is on that engine? 2 valve per cylinder or 4?

Assuming 100% volumetric efficiency your engine flows 265cfm.

Your pulley ratio is 1.47. So your blower is spinning 1.47 times what the engine is. So at 6krpms your blower is spinning ~8842rpm. Assuming your blower is 100% efficient it pushes 312cfm at 6krpms based on my calculations...which are prolly wrong cause I suck at math. But anyways, looks like you need a much smaller pulley to me. 312cfm = not a whole lot more than 265....

With a 3.5" pulley so your pulley ratio is 2.0 and your blower will be spinning 12k at 6krpms. Thats 423 cfm air at 6krpm. Which looks like ~8.7psi.

These are just rough estimates and I could've easily screwed something up along the way so take these with a grain of salt.

That is a huge friggen pulley!!!! An M62 with that size pulley is not going to move much air. Even on a 2.5L.

Do you know what your volumetric efficiency is on that engine? 2 valve per cylinder or 4?

Assuming 100% volumetric efficiency your engine flows 265cfm.

Your pulley ratio is 1.47. So your blower is spinning 1.47 times what the engine is. So at 6krpms your blower is spinning ~8842rpm. Assuming your blower is 100% efficient it pushes 312cfm at 6krpms based on my calculations...which are prolly wrong cause I suck at math. But anyways, looks like you need a much smaller pulley to me. 312cfm = not a whole lot more than 265....

With a 3.5" pulley so your pulley ratio is 2.0 and your blower will be spinning 12k at 6krpms. Thats 423 cfm air at 6krpm. Which looks like ~8.7psi.

These are just rough estimates and I could've easily screwed something up along the way so take these with a grain of salt.

Thanks for those calculations, you sound dead on, that helps with my decision on a pulley size.

I'm tapping the only vacuum line my car has, T'd from the pressure regulator to my FMU, to my BOV, to my boost gauge.

My manifold looks like a stock manifold? I didn't make a custom one, i just routed piping to an adapter plate on the charger.