Anyone have done some datalogging (at Wide Open throttle) to see what is the pressure (vacuum) before the supercharger ?

 

wouldnt it just be atmospheric pressure...which is why the supercharger produces boost...its above atmospheric...I dont think there is any vacuum in there.

 

If your intake is restrictive, you'll see vacuum !

 

In a perfect world, theoretical best case, it should be exactly atmospheric. But as Jmc007 said, your intake tract (filter, plumbing, throttle body, etc) creates some restriction, so in fact you will see some vacuum there. And it'll be pretty much linear too, so that any vacuum there will reduce the amount of air the SC flows. (ex if you saw say 0.5psi of vacuum, you're flowing about 0.5/14.7 = 3% less air than you would in the "ideal" atmospheric case)

Edit: I just have a K&N drop-in in the stock airbox. I've never actually logged the data, but just watching it, I've never seen over about 0.3-0.4psi.

 

It shows somewhere around 9 when at idle and 0 when at WOT

 

Glad to see the Fujita has no restriction at all at higr RPM's. At idle it must be minus 9 PSI ?

 

That PID is SC Inlet VACUUM. It's physically impossible to have anything higher than atmosphere there, so the number MUST be zero or positive (positive vacuum). If anyone's gauge is sending a negative number, than you probably have an early version when AFTech was still getting the conversion right. Email them, and I'm sure they'd be happy to reprogram it for you!

 

That sounds like MAP sensor readings.

 

Thats the intake presure or what ever they call that, i'll double check the next time i drive it.

 

Yep, SCIP will behave very similar to a MAP reading in an NA car. Med-high vac at idle, very high vac at decel, close to 0 vac at WOT. That's normal.

 

Mine also reads 0 at WOT running the airbox mod and SMS TB.

 

About the pressure at WOT before the supercharger (MAP sensor 1) :

Someone with the airbox mod get 0 PSI (at WOT) and another one with a CAI got the same result, we see that the 3" stock airbox intake isn't causing any restriction at all (with a high-flow filter).

The stock airbox have been designed by Donaldson, and only the stock air filter is restrictive. So replacing only the filter is a good idea.

Nonetheless, a CAI will give more look and probably a better whiiiiiiiiine too !

 

We need to see what someone gets with a normal airbox and get the data at idle and WOT for the three types.!!!!

 

Can we make a sticky for the data recorded with this gauge on the SS ?

 

Not if you are trying to twin charge your cobalt. I bet thats the single reason that little sensor is there, to keep people from boosting before the blower on the stock ECU.

 

I doubt that's the reason the sensor is there in the first place. GM isn't in the business of running around putting costly extra parts everywhere to prevent you from doing something. But you're very right that its presence could cause a little bit of a problem for people trying to twincharge.

 

SC Inlet Pressure was reading today 0.2 PSI (vaccuum) at WOT with airbox mod (lower lid removed and K&N filter).

What are your reading guys with which intake ?

 

Common guys we need more readings with different types of intakes ...

 

Anyone?