CaddyInfo.com & XMS
Northstar Supercharger Kit Project

Emblem for the trunk

Update Status
This project is now on indefinite hold/abandoned due to an inability to reprogram the Cadillac Northstar PCM.  On the bright side, Cadillac now offers a supercharged Northstar in the STS-V and XLR-V.
Apr 2003 Update on the Northstar Supercharger project:

The system is in the final stages as we e-mail, believe we found someone to handle the computer programming. Should be done soon we hope.

> What about the intake pressure relief valve issue?

It looks good at this point all issues except the programming have been worked out, and the people
working on it now have already done a DTS so I feel good about it.

> Will the first kit be for the 00-current engine, and then tweaks will have to be done for earlier models to follow?

The first kits will be for current models, then will go back and do the models for people who have paid and been waiting forever.

> Ported cylinder heads for Northstars?

The [ported] cylinder heads are doing great, conservative # 84hp increase drives great and the customers love it.
Feb 2003 The project is still not done working on the pressure relief valve in the intake, and a fuel control program for the OBD2, after these are done will take about 1 week to complete. About 30 to 45 days I hope.

Aug 19
Test car back to the Engineering Firm next weekend to continue Supercharger fitting.

Aug 07
Test car to be back at the Engineering Firm 3rd week of August to continue development.  Hopefully 3-6 weeks later development will be complete.

Mar 07
Oh the drama of real life -- our Chief Engineer at the Engineering Firm developing the Supercharger had Appendicitis and went into the hospital, delaying the project.  Get Well Soon!

Jan 31
A new CNC machine has been received and installed, and new Northstar supercharger photos are available here

Jan 10
The CNC Mill at the Engineering firm up and died.  New one on the way, but delays the project for 2 weeks or until the new machine is in place.
   This mounting plate supports one end of the driveshaft housing, and from this side a pulley will be situated to drive from a longer than stock serpentine belt. It will also incorporate an idler pulley, running on the
 back side of the belt, to ensure an adequate surface area for the serpentine belt to wrap around the driveshaft pulley. The mounting plate attaches to the cylinder head with two M10 countersunk capscrews. It is
 machined on the inside to accommodate the area of the valve cover protruding past the machined area on the cylinder head.
The final mount will be manufactured from T-6061 aluminum, 0.750" thick. It will closely resemble the mount shown in the pictures, excepting that it will look similar aesthetically to the cylinder head mount, with pockets, webs etc. Final design has been approved, and the finished prototype in currently in the CNC mill.
   This support will attach to the top of the water neck on the engine, and attach at the other end to the driveshaft housing support at the supercharger end. The purpose of this support is to assist in preventing the side to side movement of the supercharger, and retain correct belt alignment, etc. Pictures will follow upon completion, preliminary design has been approved.
Nov 27 The CNC mill is running making the main mounting bracket for the supercharger. We should get pictures and some info in the next day or so, as soon as we have it done.  We also may get a picture of the CAD model out soon.
Nov 20 The main supercharger bracket is going into the CNC mill
tomorrow (11/21).  Some pictures and CAD models may be available early next week.
Nov 15 Due to the SEMA show in Oct/Nov, and now the Thanksgiving and Christmas Holidays, the Supercharger Prototype should be ready for test drive in Mid January to early February 2002.  Once we get slightly further along (next week??) we should see photos and weekly updates.
Oct 20 Added questions from Readers from the survey, with responses to the bottom of this page.
Oct 10  Project is on schedule.  Right now the prototype parts are being reproduced using production processes.  Digital images with the production parts should be available soon, and posted to this page.

First drive testing scheduled for weekend of December 1st.

Ready for more orders! 

Bob McAuliffe is the point of contact for orders at XMS, phone toll free (877)490-4967, email x-m-s@x-m-s.com  

Sept 27 Components:
  • Vortech V2-SQ ("super quiet") Supercharger
  • Powder-coated aluminum ducting with urethane seals
  • CNC machined billet aluminum mounting brackets
  • Auxiliary fueling device with 9th injector
  • New transmission oil cooler line
  • New power steering reservoir low pressure line due to reservoir relocation
  • Relocation brackets for PCM and power steering reservoir

System Design:

The Supercharger will be positioned in the location of the existing air filter box, with a drive-shaft of approx. 1" in diameter, positioned on top of the engine, slightly behind the forward valve cover, under the top engine cover. This drive shaft will be driven from a longer serpentine belt on the front of the engine, utilizing the stock belt tensioner.

The pressure side of the Supercharger will be directed toward the rear of the vehicle, and the ducting will incorporate a 90-degree bend toward the throttle body. The ducting will be of a two piece design, in order to accommodate the MAF sensor, and to enable the 9th injector to be located aft of the MAF sensor. The intake side of the supercharger will collect cold air via the same location through the inner fender as per the stock vehicle.

Installation time is expected to range between 3 4 hours inclusive of the auxiliary fuel system.

Expected gain to be approx. 90 120 horsepower (30-40%) and expected torque gains of a similar percentage.

It has been ascertained that the transmission should not have any reliability problems with these expected gains.

Aug 7

Project Status: Everything is looking good.  The pulley mechanical test results are good for adding the load of a supercharger to the water pump pulley/shaft.  Supercharger trades are still on-going, so the final selection of supercharger manufacturer is not complete.  One brand has been eliminated.  Considerations in the supercharger selection include size, fuel requirements, torque spec, and ease of installation.  The firm doing the selection and fitment has successfully designed a lot of products for original equipment usage, and may yet do a custom supercharger for this application, since they are about to market their own line of superchargers.

Testing Status: A test car is on loan to the Supercharger Engineering group for fit testing of the supercharger.

Interested Buyers -- Please take this New Survey:

Northstar Supercharger Buyer Survey

The Northstar Supercharger Kit Project is dependent on getting more buyers who are willing to commit to purchasing the product.  

What will motivate you to order a supercharger now for December delivery?

Current Results

What is it?  

A Supercharger kit for the Cadillac Northstar System

Who makes it?  

Engineering for the systems is being funded by Xtreme Motorsports (XMS) in San Diego.

What will it cost?  

The target price is $3,500 + S&H for the kit.  Each kit will have a fuel management unit unique for a particular year of Northstar; the majority of the kit will be common across the various years.  Early orders -- received before the kits start shipping -- get a discount price of $3,000 plus S&H.

Will it be hard to install?  

No, but it will require installation.  If you are comfortable replacing spark plugs and a bit more, you may also be comfortable installing the Northstar supercharger system.  You might also consider taking the system to a local tuner who specializes in superchargers if you don't feel up to a do-it-yourself install.  Full instructions and info will be included with the kit.  It is expected that the install will take 4.5 hours.

What is a supercharger? 

An automobile engine is basically an air pump.  Air and fuel are brought in, the sparkplug ignites the mixture, and the expanding gases drive the pistons.  If you can put in a larger air charge (and more fuel), you can build up a larger, more powerful expansion.  A supercharger is an air compressor.  It runs off a belt from the engine, and pumps air into the intake, increasing the air charge that the car can bring in.  A fuel management unit ensures that additional fuel is added to keep the air/fuel ratio in balance.  The result is more horsepower. 

How will this affect my car's warranty?  

By law a dealer may not refuse warranty work due to an add-on unless he can show that the add-on was the cause of the problem, and/or if the add-on is specifically called out in the warranty.  Expect that the latter is the case, and the supercharger addition will void your engine/powertrain warranty.  If you have an extended warranty contract, please contact the Issuer to determine how installation would effect your coverage.

What type of performance are we talking about?  There is not a prototype available for testing yet.  Just to whet your appetite, I have put together a simulation study based on facts known so far.  Note that a supercharger is normally rated in PSI or pounds per square inch of input pressure above atmospheric.  So to determine expected boost, take (14.7+supercharger PSI)/14.7.  To attain a 33% boost, a supercharger output of 5 PSI is needed.  I the case of the Northstar, this yields approximately 102 hp.  Figure around 8 hp to pull the centrifugal supercharger at 5 PSI, and a target of 94-96 hp is achievable.

What type of marking/logo/emblem are planned?

The current plan is to include the Supercharged emblem from the Buick Riviera with the kit.  This would be placed above the 32V Northstar emblem on the trunk lid.

Will this work on my STS, or ETC, or DeVille, or SLS, or Eldorado too?

Yes, if you have the 4.6L DOHC Northstar engine.  The plan is to provide kits which cover each year Northstar, from 1993 to present.  

When can I get one?  Can I order one today? 

Bob McAuliffe at XMS reports he is ready to begin taking orders for the Northstar Supercharger project.  Please call Bob at XMS toll free at (877)490-4967 to place your order. VISA or MasterCard accepted.    

Early orders will be charged a US$1,500 down payment now, and $1,500 plus shipping of around $50 when the units actually ship. California residents should add 7.5% tax.   

Bob McAuliffe is the point of contact at XMS, phone toll free (877)490-4967, email x-m-s@x-m-s.com  

Why early orders?

This is not a "bolt it on and see if it explodes" approach, but a full engineering study and custom design for this application by a company that regularly does OEM supercharging for major auto manufacturers.  

Taking early orders will reassure XMS that there are Buyers who are serious enough to put up their money so that they know there is a ready market for the Northstar Supercharger Kit.

If you always wished there were more performance adders available for Cadillacs, this is your opportunity to participate in Cadillac performance development.

New: Questions from Readers:

Great idea. Do any changes have to be made to the OBD computer?


Will Northstar handle the much increased stress of a supercharger?

Engineering studies and testing suggest that yes, it will do fine.

The idea is great, but I would also want to know if the stock exhaust is up to the task of evacuating the spent gasses.

I think an aftermarket exhaust such as the Corsa will be a good match for the supercharger.

Is there GM oversight? 

No, this is strictly an aftermarket project. 

Bruce, are you a GM employee?


Do you have any advice or recommendations on installers?

XMS in San Diego would be my first choice.  Locally I plan to use a shop that is experienced in supercharger installations for other types of cars.

Are there any instructions available that can be shown to potential installers to assess their willingness and cost estimate? 

Not yet.  These should be available in December. 

You state that the kit has no impacts to transmission.  Are there any unknown or suspected impacts to any other components?  

No way to speak to unknown impacts, but the engineering study done by the design shop does consider changes to the life of the pulley due to turning the supercharger, for example, so I feel pretty good about the project

Do you have any pre-test drive estimates of torque-steer impacts? 


The kit will dislocate current air filter.  Are there any other impacts to engine compartment?  

There will be a supercharger drive shaft that runs across the top of the engine from the accessory drive to the supercharger.  The supercharger will be plumbed into the engine oil supply.  There will be a 9th fuel injector.  None of these are particularly unusual for aftermarket supercharger installations.

Is kit all inclusive, or will additional parts be required?


 How much time remains for "pre-ship"/intro 3K price?  

Until the units begin shipping in December.


    Email for more Info

Please feel free to participate in the supercharger poll but now we are 
really counting the number of orders that come in to XMS.

Northstar Supercharger Poll

Would you buy a low-pressure supercharger for your Northstar if it added 90 horsepower for $3,500?

Yes, I would love it.
Maybe; Tell me more.
No, too much money.
No, I'm keeping mine stock.

Current Results

Copyright Bruce W. Nunnally 2001