Increasing Novi 1220 Sl Boost?

When comparing the Vortech to the Paxton, there are a few similarities and a few differences. Bearing tech is the same in both blowers as they are manufactured in the same facility, while the cases, volutes and impellers are all different they still perform similarly with the Si ultimately supporting more HP than the 1220. When increasing boost with your Paxton, you will need a new pulley (are you using a 6 or 8 rib?) you will also need a bypass valve when running more than 5-6 lbs of boost. The only other mod's will be fuel system which you seem to have covered and tuning. I personally would use an impeller speed calculator to verify your desired pulley size against impeller rpm to ensure you'll be operating in the recommended rpm range of the blower. Too much blower rpm will result in increased heat, less efficiency and can ultimately destroy a blower ( but what do I know about that...lmao)
If you need any help with this feel free to hit me up, I'll be more than happy to help.

Spot on @84Ttop!

JohnnyK81 said:

Thanks for the reply! So I guess my confusion stems from, what makes the Si a 'better' supercharger, for someone who wants say, 400-500hp (let's just imagine nothing explodes on my car).

I think I recall reading the Sci can push 1050cfm and the Si, 1150, or some numbers close to that.

How does that affect me in the real world? Is there an advantage to (me) choosing the Si head unit over the Sci? Why would someone choose it?

I suppose if I was buying a brand new kit, the Si may come with the BOV, and the fuel pump, injectors, etc, but I am probably buying used, or may even be piecing it together.

Thanks! Appreciate it.

Click to expand...

It's really a matter of fluid dynamics. Both blowers while very similar in construction have different compressor maps due to the impeller vane construction. To boil it all down without getting overly technical: Hypothetically speaking here (the numbers i'll use are pulled from a hat) If you have two compressors with different impellers/volutes you would derive two different compressor efficiency maps. While both compressors can move similar amounts of air, they do so differently. Lets say compressor A moves 1000cfm of air with an effeciancy rating of 78% while compressor B moves the same 1000cfm of air at a 72% efficiency rating. Compressor B will create more heat in the discharge stream than compressor A. They also may move that 1000cfm of air at different impeller Rpm's with one being better at moving air at a slower speed and one being better at moving air at a higher speed.
Long story short, the Sci is more so designed to support the 5 or 6 lbs it is designed for and the Si is better suited for supporting a greater amount of airflow. It is very easy to use these blowers outside of their efficiency range with the biggest side affect being higher inlet temps. I'm not saying that an Sci wont support 500hp because it will, I'm saying that a Si will support that same 500 hp better.

Here is some literature that will spin your mind a touch: www.vortechsuperchargers.com/pdf/papers/efficiency_paper.pdf

Sci Compressor Map:


Si compressor map: