Upgrading the Impeller in an SN89?

[Polecat_Racing]

What options are available for upgrading the impeller in an SN89?

What are the differences between the impeller in an SN89 and those in the later models? Basically I'm looking to increase the cfm output and/or boost psi without going to a smaller pulley.

Also, to change only the impeller do I need any seals or o-rings?

thanks

[speedytang]

You don't need any Seals or O-rings. I have never seen much difference in the blade designs to increase total boost but maybe when the boost starts to build or max out. The impellers are usually designed to allow more boost by you increasing the speed you rotate the impeller. You will need a pulley change to increase you impeller speed to increase boost. Others I am sure will post what they have been able to increase with different impellers or pulley size. To usually get the power increase over the stock 'SN' we have had to change over to the VR4.

[Polecat_Racing]

So an SN89 and SN2000 with identical pulley sizes would produce the same level of boost?

From past posts I've searched I thought that the later model SN's used a better impeller that was responsible for a higher boost or cfm rating.

[bryanscycle]

I think that they offer an H.O. impeller for the SN2000.I'm not sure if it interchanges with your SN89! Look on Paradise Wheels web page and it list a H.O.impeller upgrade...If you havn't already call Craig @ Paradise Wheels.Good luck,Bryan

[pavement pounde]

Here you see the difference of the 2 impellors.

http://img.photobucket.com/albums/v1...d/Pic_0019.jpg

To the left is the high flow impellor installed.
There is a slight difference in the blade curfs

[speedytang]

You might or should see a increase in CFM but your PSI will probably stay the same or not much of a difference. CFM is probably more important to most. I will say that my unit at 8psi @ 1600 cfm and a SN2000 pullied up to 8psi @ 850cfm feels nothing a like. Driven in many Paxton 'SN" cars and 'VR4' cars and even at 6psi they are probably 50hp-75hp difference at the same boost level.

[Polecat_Racing]

Thanks everyone for the replies.

How hard is it to change just the impeller? Just remove the rear cover, swap the impeller and torque the bolt? Is it that easy?

[pavement pounde]

Yup, take care prying of the old impellor after unbolting the bolt.
I used severeal screwdrivers to wiggle it loose, all at different points.

[speedytang]

You keep saying impeller, do you also have the new rear cover to match the impeller.

[bryanscycle]

If I'm not mistaken the H.O. impeller goes behind the stock scroll cover..Correct??

[Polecat_Racing]

From what I've figured out there are two impellers available to upgrade to - the first one being the VR4 version which requires a different rear cover - the second being a modified version of a stock SN impeller which DOES NOT require a different rear cover.

Someone please chime in if this is incorrect.

[speedytang]

Right, I just was not sure if your trying to change over to a SN or a VR4 style impeller. Check the clearance after you install the impeller to make sure if you need to add shims or install a smaller one to clear the rear housing.