Need help with Paxton SN89 supercharger

[Michael]

Hi guys,

I'm new to the forum and to supercharging in general so you'll have to forgive me if I seem a little nieve or start asking stupid questions. I'm still getting my feet wet.

I just picked up a used but relatively complete Paxton SN89 supercharger kit. It was originally installed on an '89 L98 TPI Corvette, which is the same as my own car (please don't hold that against me Mustang guys - props to the FoMoCo!). Altough the kit seems fairly complete, it didn't come with any installation manual or instructions of any kind. Oh, and it's also my understanding that the supercharger itself needs to be rebuilt too.

I'm no novice when it comes to working on cars, but I've never tangled with something like a blower before so I'm a little hesitant to crack this thing open. And I certainly don't want to start without some form or reference material like an engineering drawing or assembly drawings/instructions or something.

Does anyone here have any kind of assembly information regarding these old SN89 units that might be helpful? If so, please email me at: thecorvettekid@rogers.com. I'll take anything anyone is willing to send since I have absolutely no reference material at all.

Thanks very much in advance guys!

[F=MA]

The install on the engine becomes fairly obvious if you lay out all the brackets. I rebuilt my SN head unit the "hard" way, without instructions. If you carfully note where everything that came out came from, you will be able to do this too, with ease.

Anyone who can handle rebuilding a carb or installing a set of cylinder heads is overqualified for this job, trust me.

The vital info you need are the torque values for the critical fasteners, as the unit relies on pressure to spin its impeller. You need an inch-pound torque wrench. I have a beam and a cheapy clicker and, all ended well.

Critical torques: The case bolts: 120-160 inch pounds, this can be used to tweak the pressure on the balls slightly; start low side. The torque to turn the unit over, full of fluid and ready to go, about 44-55 inch pounds for 4-5 pounds boost. You can measure yours presently and if it ends up similar afterwards, in the range mentioned above, it'll likely be ok. If it's way whacked out, you'll have to add a shim to built the pressure. These shims can be got from the vendors mentioned below.

Any other values can be guaged from any standard torque value/bolt size table present in any decent automobile manual.

DON'T damage the rear seal! The front one is store counter cheap, the rear has to be ordered from a place like Paradise Wheels or Superchargerrebuilds.com and isn't cheap.

Do a search of this forum using the term "rebuild" and, you'll likely find plenty of info, as many of us have been there before. Any qs as you go, ask.

F=MA

Good thing you got a blower...might actually make the C4 slightly interesting...:)

[Michael]

Thanks for the feedback F=MA!

You're right, by laying out all the piping and brakets and stuff, it's seems fairly straight forward, but I'm just concerned about all the washers, bolts, and spacers that came with this kit. I mean, I could probably bump-and-grind my way through it all, but I'd much rather get my hands on some instructions so that I don't screw things the first time I turn the key. And knowing my luck, it'll be something like not realizing that a washer or a shim should have been installed somewhere so that the belt lines up properly or something.

After looking at the charger a bit closer, it seems as though it has been apart before, so I have no idea what the condition of it's 'internals' are like. A part of me wants to rip into it right now so that I have a better idea of what I've actually got. Hopefully, that expensive rear seal you mention is still present and in tact.

And I'm glad you mentioned the in-lb settings - thanks! I have two torque wrenches, both of which have recently been calibrated, unfortunately they are both ft-lb units. I'll head out either today or tomorrow and pick myself up an in-lb unit (any excuse to buy a new tool :) ).

And I'll take that C4 comment. :laugh:

Thanks agian for all the advice!

[pavement pounde]

What F=MA says,
Do a search here on rebuilts.
Here are some pic's of my rebuilt, I did it the hardway to before I met this forum.

http://photobucket.com/albums/v129/p...ton%20rebuild/

I also wrote a little story back then.

http://www.454ss.com/Articles_new/paxrebuild.asp

The most important is the amount of shims you use behind the race in the backplate, becouse with those shims you control the torque you need to turn the puley, witch is between 40 -45 inch/pound

I like to know how the pulleu turnes now before uou open it up, does it turn smooth ?

[Michael]

Hi Pavement Pounder.

Actually, I've done a search on this forum for the term "rebuild" and have found some very good information, including your own rebuild/photos. They are a huge help. I'm amazed as to how few parts there actually are inside these things.

I've also sent an email to both Paradise Wheels and to Carroll Supercharging (now called Blower Works) asking if they have any information like drawings and an installation guide available for this kit. I think that the kit I have originally came from Carroll Supercharging, but I'm not sure. Greg at Blower Works has already gotten back to me and said that he will sell me the installation guide which contains all the information I will need. Still haven't heard back from Paradise Wheels though.

As for turning the pulley, it actually turns very easily on my SN89, but the five balls in the ball drive have been removed. They where chewed up very badly so the previous owner removed them so that they wouldn't score their races. There's no risk in turning the pulley now, but there's no connection to the impeller either, and like I said it turns quite freely.

Thanks for the help!

[Dirk Diggler]

I think I have the install manual for my Iroc Z28. But I do not have a scanner to put it online for you:( Any questions, I can try and help you. I do know that you have to put the power steering pump on the charger bracket. I can take digital pic's of my setup if need be.

[Michael]

I think I have the install manual for my Iroc Z28. But I do not have a scanner to put it online for you:( Any questions, I can try and help you. I do know that you have to put the power steering pump on the charger bracket. I can take digital pic's of my setup if need be.

Thanks for offering!

I'm a ways off from actually attempting to install this system (the blower still needs to be rebuilt), so there's no point in you running out and taking a bunch of pictures right now. My main interest is he supercharger itself - drawings, schematics, torque settings, etc... so that I can rebuild it properly. But once I get to the installation stage, if I have any specific questions I'll be sure to send you an email or a private message.

Thanks again Dirk.

[Dirk Diggler]

I do have the rebuild manual for the sn blowers and I took pic's when I rebuilt the ball drive unit in stages. I have the sn2000 which is a little different that the sn89-93 blowers. I think pavement pound has pic's of his rebuild except his pic's are on a website.

I also have a VR4 kit for sale if your interested.

[Michael]

I do have the rebuild manual for the SN blowers

Really? There's a manual? I'm very interested to hear where you got it. Is it available through Paradise Wheels?

I think pavement pounde has pic's of his rebuild except his pic's are on a website.

I've seen Pavement Pounder's website, and it's been a huge help actually. There's not alot of difference between the SN89 and the SN93 that he's got so it's relevant too; I don't know the differences between the SN89 and the SN2000.

I also have a VR4 kit for sale if your interested.

Yeah, actually I read in another post that you where selling one. I don't really know anything about the VR or VF series of Paxton superchargers, so you're gonna have to fill me in.

I'll admit, the small voice in my head is saying, "don't ask, you just bought a supercharger", but the octane coarsing through my veins is making my heart scream, "WHO CARES, HOW MUCH?!?".

Blood IS thicker than brain matter. How much?

[Dirk Diggler]

Really? There's a manual? I'm very interested to hear where you got it. Is it available through Paradise Wheels?

I've seen Pavement Pounder's website, and it's been a huge help actually. There's not alot of difference between the SN89 and the SN93 that he's got so it's relevant too; I don't know the differences between the SN89 and the SN2000.

Yeah, actually I read in another post that you where selling one. I don't really know anything about the VR or VF series of Paxton superchargers, so you're gonna have to fill me in.

I'll admit, the small voice in my head is saying, "don't ask, you just bought a supercharger", but the octane coarsing through my veins is making my heart scream, "WHO CARES, HOW MUCH?!?".

Blood IS thicker than brain matter. How much?

The VR4 pumps twice the CFM as the sn series impellers. You just change the impeller and tighten up the ball drive. Kind of like putting a new charger on all together. YOu can get up to 14psi with teh VR4 impeller.

Shoot me your email address and I'll send the pic's and manual to you, but you need a high speed connection for the info. THe rebuild manual is not available from paradise.

[Michael]

The VR4 pumps twice the CFM as the sn series impellers. You just change the impeller and tighten up the ball drive. Kind of like putting a new charger on all together. YOu can get up to 14psi with teh VR4 impeller.

Shoot me your email address and I'll send the pic's and manual to you, but you need a high speed connection for the info. THe rebuild manual is not available from paradise.

Hi again Dirk.

Here's my email address: thecorvettekid@rogers.com

I'm on the high speed stuff, so any time you're ready.

Thanks Dirk!