Assuming your procharger creates a true 9lbs at 6500RPM these are the boost levels you should see at WOT. Boost levels will be different though depending on how wide open the throttle is.

1K = 1.38PSI
2K = 2.77PSI
3K = 4.15PSI
4K = 5.54PSI
5K = 6.92PSI
6K = 8.31PSI

The 7lb pulley, assuming it also creates a true 7 at 6500 RPM would look like this.

1K = 1.07PSI
2K = 2.15PSI
3K = 3.23PSI
4K = 4.31PSI
5K = 5.38PSI
6K = 6.46PSI

Any other PSI levels other than the above that you might be seeing is solely a product of how wide the throttle is open.

 

How did you arrive at those numbers jesse?

 

He is using the 5 scale DFMU I think, which I don't have but I guess the open throttle part makes sense since mine was adjusted. Thanks.

 

I arrived at those PSI numbers with a calculator. Since SC PSI level is based on RPM. I took 9PSI / 6500 RPM and then multiplied it by the various RPM levels. (9/6500)*1000= 1.38PSI at 1k RPM.

Just some simple math that's all, but keep in mind that these numbers are only accurate if you achieve a perfect 9PSI at 6500RPM. Any variation from that will change your PSI levels.

 

Your formula is wrong.......it ignores atmospheric pressure, which the centrifugal supercharger needs to overcome before it starts producing boost.......and that atmospheric pressure will vary with elevation, depending upon what elevation you are at in the atmosphere's air column.......on top of that, the increase in boost pressure is more exponential, than linear as you would suggest.........but don't take my word for it.........do some research.......and please quit making stuff up

 

Yep, you're right, sorry about that. I'll come up with some right numbers now.

 

So did those correct numbers show up yet?

 

I looked at a log with the MAP on the Greddy E-Manage. I tested the MAP with a hand pump and 5" Snap-On low pressure gauge before install to get an accurate baseline for logging after install. If you want to calculate from this data I can tell you that 1.5v is zero and 1.97v is exactly 7psi. I hit 1.5v @WOT@2250RPM and am getting a reading of 2.06v @WOT@6555.

 

Did they ship you the 9lb pulleys accidentally?? You're getting some serious boost. If the greddy MAP increases voltage in linear manner that's around 8.4 PSI.

 

It is difficult to watch the boost guage in the center of the dash near redline so I have never really done so. I need a camcorder to replay the gauges to answer this question. Maybe this is the issue I have been having. This would also explain why my MAF sensor output is at 100% (5v) 300+ RPM sooner than GaryK's. Here's the easy way. How many teeth am I supposed to have on the pullies in my kit? I will count the teeth. My kit was shipped in 2 seperate shipment 1 week apart. They had gone to the SEMA show and blew off getting the kit to me on time. They sent everything but the headunit first and then a week after SEMA they sent the headunit. Yeah, who knows what the hell they sent me. The headunit is for sure a C-2 and all the parts fit ok. They did screw up and send me 7 bottles of oil for the headunit. I thought that was interesting. 4 bottles with the hardware and 3 more with the headunit when it shipped. Does everyone elses SC impeller wheel look like it was rough machined on a CNC machine and never polished? Mine does! Is this normal?

 

Yeah, my impeller blades look pretty cheesy. Like they're made out of aluminum foil. I'll go count the teeth on my pulleys right now.

 

OK, I got

38 on my main cog pulley which is connected to the serpentine belt.

27 on the front pulley next to the SC

22 on the back of the SC itself.

I believe the other pulley I didn't mention has the same amount of teeth. I couldn't count them without pulling that backing plate off of the pulley.

If they did send you the 9lb pulley then that would defnitely explain your problems. It's kind of suspicious that they sent it in two separate shipments. Mine came in one ginormous box that weighed like 100lbs.

BTW, I'm pretty sure I counted correctly, but it's dark outside and I've only got 10 fingers, so that makes things difficult when counting numbers that high. If there is a discrepancy I'll count again and make sure it's exact.