Wrench (1k)  Turbo System & Motor Build
After looking back at what I've done with my cars over the years, I made the decision that it was time to take on a new challenge.  There aren't a lot of turbocharged S-Series Saturns around.  It was not something that could be purchased from the factory.  A number of small vendors have attempted to fabricate and sell custom "kits", but many of them were quite expensive and had questionable design/construction quality.

TurboSaturns.net began to gain popularity, attracting many people to their forced induction message forum.  There was a lot of participation and sharing of experience and ideas, mostly from people who had chosen to fabricate their own turbo systems.  After a lot of reading (spanning more than a year), I gained enough knowledge and confidence to begin the project myself.

The first step was to set a few goals & objectives.

Planning & Objectives

Goal #1: it has to be durable

On the dragstrip, it will need to handle between 6 and 10 back-to-back runs, for a duration of about an hour with no cool-down time necessary in-between in temps as high as 90 degrees. Boost level will be set high, between 15 and 20 psi.  It will also need to perform well on the road course, with a session length of 20 - 30 minutes, on and off of redline. There will be a minimum of 1 session per hour in 90 degree weather. Boost level will be medium, between 8 and 10 psi.  With those requirements in mind, a design was put together and the proper parts were chosen:

Strong well-constructed turbo manifold, engine block from 1998+ (stiffer than prior years), lower block stiffening brace, heavier crank & stock harmonic balancer/dampener, JE forged low-compression pistons and rings, forged Crower rods, additional four injectors on underside of stock intake manifold using additional fuel rail (both stock Saturn parts).  Manifold & exhaust would need to be Jet-Hot coated to reduce under-hood temps and to keep stuff from melting due to extremely tight clearances under the hood. Heat shielding on underside of hood will be added if necessary. Engine oil cooler will be used with its own thermostat and fan. Braided stainless lines will be used throughout (oil cooler, turbo coolant, turbo oil). Twin SPAL fans will be mounted on the Fluidyne radiator.  The Quaife differential makes diff pin failure not a concern. Wheel hop will be minimized with Delrin front suspension bushings, and the main torque-axis motor mount will be stiffened as well. Plugs will be used with a higher heat range, and the motor will run synthetic oil.

Goal #2: it has to be adjustable

Boost level will be varied with Tial wastegate with low-PSI spring and adjusted upward with electronic control. More fuel will be provided by 4 additional injectors and adjusted via SDS EIC (using feedback from an AEM WBO2 & Autometer EGT gauge).

Goal #3: it has to be done as simply as possible

I don't want to have to rely on any additional electronics that require computer control or elaborate dyno tuning (Megasquirt, Motec, Electromotive, etc). Forged pistons will be sized to the stock bore. I'll find a healthy donor block.  If the bore measurements are as-expected, no machining will be necessary other than a quick hone. Except for pistons, rings, and rods, the remainder of engine internals will be stock. The main reason for no machining and use of stock parts: replacement of motor will be cheap and fast when it is necessary.

Goal #4: do all the work myself and allow the project to take as long as it takes

I intentionally do not want to set a timeframe for when I want to have everything together and running.  The majority of fabrication will take place on a spare motor.  What can't be done in that manner will either be done during the winter when the car will not be participating in track events, or done so that the car can be restored to its prior condition quickly.  I want to minimize the amount of time that the car will not be able to be used.  Even though it's not a daily driver that I would need to get me to work or anything, it is a car that I expect to be able to use during the summer months for planned track events.

With a good idea of what I want to do and a design that would get me there, I was ready to start accumulating the parts.  I had no idea so damn many parts would be involved, but I began to watch many of the Saturn-related message forums and eBay for good deals.


Even before I had made the decision to start this project, I had an idea what was coming down the road.  Modifications to the car were done with the future in mind.  While these modifications may not have been absolutely necessary, or may not have performed up to their full potential at the time I did them, they will be even more useful once the turbo system is in place.

Click the thumbnails below to view a larger-sized image.

I picked up an XRC 55mm throttle body as part of a bunch of parts I'd bought used.  Dyno tests have shown repeatedly that this throttle body doesn't provide any benefit on a naturally-aspirated motor.  But that will change when a turbo is force-feeding air through it.  More info about this addition can be found HERE.

I went through a few exhaust configurations but finally settled on one that incorporated a 3" Dynomax muffler and 3" / 2.5" piping.  This isn't optimum on a motor with mainly bolt-on parts, but the decreased backpressure will definitely benefit a turbo system.  More info about this addition can be found HERE.

The plastic end tanks on Saturn radiators eventually crack.  To remedy this problem, I couldn't pass up a great buy I received on a 2nd-hand Fluidyne aluminum radiator.  I had never had cooling-related problems in the past so it wasn't something that was all that necessary.  But when the motor will run more than double the horsepower of stock, it will be a great benefit.  More info about this addition can be found HERE.

I had been through a few different clutches, but the design of the ACT showed that it wasn't simply a re-worked stock clutch being marketed as a high-performance model.  I bought it in the past knowing it would improve clutch longevity.  But with the upcoming addition of horsepower, it should also provide more holding power.   More info about this addition can be found HERE.

Even without a turbo system, the Quaife torque-biasing differential made a huge affect on performance.  Add more horsepower, and it will do even more.  What's amazing to me is how few people running high-horsepower Saturns are still doing it with one-wheel drive.  That's a lot of horsepower being turned into wheelspin and tire smoke.  More info about this addition can be found HERE.

Mickey Thompson drag slicks didn't do very much toward improving my ETs in the past.  But add more horsepower (along with the benefit of the Quaife differential and ACT clutch), and they will soon be doing a LOT more.   More info about this addition can be found HERE.

I had HUGE problems with SRW's delrin bushings in the past - they made a noise like I had a burlap sack full of dying cats in the car with me.  At one point they were in the trash can, but luckily, I'm a very conservation-minded person.  I saved them from a future in the landfill for a use I didn't even think of at the time.  These will be added to the '92 in an attempt to help reduce the suspension bushing compliance that I'm convinced contributes to the significant wheelspin on launch that many Saturns suffer from.  More info about this addition can be found HERE.

In the interest of stiffening up the motor mounts and removing some of the drivetrain motion that contributes to wheelhop, I did some informal testing of a motor mount insert that SDA sells.  Another benefit I'm hoping that it will provide will be to minimize the vertical movement of the turbo itself (which will hang off the front of the motor) and reduce the chances of the downpipe being knocked into the swaybar/cradle when there is motion.  More info about this modification can be found HERE.

While relocation of the battery to the trunk was done primarily to improve the vehicle's balance and weight distribution, it also freed up a lot of space under the hood that will definitely be used.  More info about this modification can be found HERE.


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