I am the process of completely re-doing the FAQ - I really wasn't very happy with the old one as it went into too much depth on too few topics, ignoring the vast quantity of questions I usually get hit with.  The new one will be more like an FAQ should - an overview of those questions which are, in fact, frequently asked.  Detail will be provided where necessary or demanded. 

If you have any additions which should be included, of course let me know and I will add them as soon as possible.  If you would like clarification or have further questions, don't hesitate to ask.

Exterior:  [Replacement & Upgraded Lighting] [Converting bumper & lighting to later styles] [Converting c900s into faux SPGs] [Compatibility & replacement of wheels]

Interior:  [Seating compatibility between years] [Repairing or replacing passive belts] [Replacing the power window switches]

Mechanical:  [Converting automatics to manual transmissions] [Converting non-turbos to turbos] [Emissions Information] [Vented Rotor Upgrade] [Cam Profiles] [Head Displacement]

Performance:  [Recommended fluids] [Recommended tires - sizes & brands]

Electrical:  [Troubleshooting the APC System] [Alarm Installation] [Head unit compatibility & installation] [Installing CD changers] [Speaker installation & upgrades]



Before continuing, I strongly recommend taking a look at the following website.  The owner of this page knows lighting technology and has a lot of good things to say:

Daniel Stern's Lighting FAQ

If you're living in the United States (and possibly Canada), your car came from the dealer equipped with DOT-spec headlights.  With some newer cars this isn't much of a problem (see the above FAQ), but if yours is from the '80s or earlier, chances are you've already noticed how terribly inadequate your forward lighting is.

There are a couple of options.  The first (which also happens to be the easiest and the cheapest) is to locate higher wattage bulbs or uprated sealed beam units.  While there is no argument that this does offer some improvement, it isn't a terribly good solution.  Aside from potentially damaging your wiring harness by drawing too much current across it, this solution overlooks the real problem:  The fundamental reflector design of DOT-spec lighting, quite simply, sucks.  All you really end up doing is increasing the size and brightness of that poorly focused blob of light that's projected in front of you - it won't improve your light distribution one iota.

The second solution is to add some form of auxiliary lighting.  Although not necessarily the cheapest route, the good news is that Saabs come from a land where nighttime road visibility is poor in many (if not most) areas, and Saab has taken steps to facilitate adding extra lighting.  All Saab 900s (and 99s & 9000s, for that matter) have mounting locations for under-the-bumper lighting.  These positions are best used to mount foglights due to their elevation, but they can also be used to hang driving lights from manufacturers such as Bosch or Hella.  On earlier 900s (1986 and earlier) you can actually flip the mounting brackets upside down, and mount lights above the bumper - lights such as the Hella 500 are great here, since they are perfectly sized to clear the hood opening.  If you're truly ambitious, you can actually mount lights above and below the bumper as I have on my 1980 900T; those are Hella 500s (driving lights) above the bumper, and Bosch Pilots (fog lights) below.  

The third solution, which offers the single largest improvement but also happens to be illegal in most states, is to replace your headlight assembly with European specification (H4) units.  On earlier cars, the H4s replace the sealed beam and the plastic bezel with integrated parking lights, on later cars there is almost no visual difference between DOT and H4 style lights.  H4s offer significantly improved light distribution for safer high-speed driving, and have a very sharp vertical cutoff to reduce (if not eliminate) glare for oncoming drivers.  Additionally, factory H4s have a lens, reflector, bulb, and housing which can each be replaced independently, meaning a rock chip or worn out reflector won't necessitate replacement of the entire headlamp.  H4 bulbs can be purchased nearly anywhere, as they've been in use in the U.S. forever on motorcycles and off-road vehicles.  Installing these lights is easy - they slip in where the old ones come out.  On earlier cars, there is no wiring to do, as the old sealed beam connectors plug directly in.  On later cars, you will be required to do a little work, as their 9004 bulbs use different connectors; the easiest solution is to snip a few inches of wiring from a 1986 or earlier 900 at your local junkyard, then splice it onto your wiring.  It takes a few moments, and Saab was kind enough to use the same wire color coding throughout the entire run of the 900 so you don't have to do any tracing.

One note:  Hella does sell H4 units which will directly replace the sealed beam on 1986 and earlier 900s (as well as just about every model prior).  While these are a marked improvement over the standard lighting, they are not the same as the real Saab-specific H4 lights.  You can find them at many auto part stores, and cost under $50 per side.  If you're having trouble finding someone to sneak you a pair of real H4s across the Canadian border (where they got the real deals), these might offer you an alternative. 

This is a question I get asked all the time:  Can I put the later style front end on my early 900?  The answer is Yes.  It's completely doable, and cost notwithstanding, it's very easy on 1983 and later cars.  All the parts bolt right in - the only thing you'll need to do is a little wiring, as the later headlamps and cornering lights use different connectors than the earlier ones.  In the front, you'll need the bumper (complete with lower air dam), the two cornering light clusters, the two headlamps, the grille, and the two bumper extensions (the plastic bits that go between the front wheel wells and the bumper).  In the back, you'll need only the rear bumper and its two extensions.  Your best bet is to either obtain a parts car or get in touch with a dismantler who can package all the parts - trying to buy the stuff piece by piece could be quite difficult, since there are little bits of hardware you'll need that may not be initially obvious.

After doing this, the only remaining visual cue that your car isn't one of the later ones would be the absence of side-markers - those little turn signals on the front fender.  If you're truly ambitious, you can cut the holes in the fender and splice wiring into the turn signal circuit.  The only exception to this would be MY1986 900s - the only year of the early-style bumpers to get side markers.

Do note the following:  900 Turbos have an oil cooler which needs direct airflow in order to function.  On 8v non-intercooled cars, the oil cooler is located just forward of the air box, between the radiator and the inner fender wall.  On 16v cars and all intercooled cars, the oil cooler is located underneath the lower cross-member - almost directly under the intercooler.  Each of these cars has a specific lower air dam designed to direct air towards these coolers.  If you replace the bumpers on an 8v Turbo without also replacing the oil cooler with one from a 16v, you may very well end up cooking your engine or turbo as airflow to the cooler will be almost completely cut off.  Relocating the oil cooler is not particularly difficult, but on earlier cars may require some drilling to mount the cooler itself.

Secondly, on some 1983 and all earlier cars, you will  encounter some problems mounting the aforementioned bumper extensions.  While the holes for their mounts should exist on all 1984 and later cars, they may not be there on all 1983 or earlier cars.  Drilling may be required - and that isn't fun.  Before getting into the conversion, check to see if they exist on your car.  The easiest way to check is by removing the windshield washer bottle from the right fender and checking for the holes along the front fender.

Since Saab was a relatively small company when the SPG was produced, they didn't have the luxury of designing a whole new car when they introduced it.  They had to make use of existing tooling and take care to ensure building an SPG wouldn't entail hours of customizing each chassis.  That fact works out very well for those with regular ol' 900s interested in building a faux SPG.

The first thing to know is exactly what makes an SPG different from any other 900.  I recommend taking a look at Larry West's excellent Guide to SPGs to help familiarize yourself with the core differences.  Assuming you can pull together the requisite parts, creating your own isn't too much of a problem.

To get that SPG look, you'll need:

As long as you're starting with a car built in 1984 or later, you will only need to do extremely minor drilling.  Attaching the airdams, bumper extensions, and most of the panels require nothing special - all the holes and mounting points exist in the body work.  The only exception to this are five rivets which attach the door panel to the door's lowest edge.  You will have to drill positions for these rivets or the door panel will not fit securely.  Test-fit the panel, then use it to mark the correct spots to drill.  Some have suggested using a weatherproof epoxy to attach the lower edge - I've not tried it, but it should work in theory.

Wheel selection involves a number of critical dimensions - it's not just a matter of finding the right bolt pattern.  You must be sure that the wheel offset and hub dimensions are correct as well.  Let's discuss each, first:

-Bolt Pattern

"Bolt Pattern" describes the diameter of the circle formed by the lug bolts.  Earlier Saabs all use a 4-bolt hub, so the bolt pattern can effectively be measured by finding the distance between the center of two opposite lugs.  Easier, of course, is to use the information here: 

Two different bolt patterns were used on 99, 900, and 9000 models.  All 99s and 900s up through and including MY1987 used a 4x114.3 bolt pattern.  All 9000s and those 900s made between 1988 and 1993 used a 4x108 bolt pattern.  Neither of these patterns is especially unique:

Honda Accords & Preludes from 1992 to 1996, Mazda RX-7 (SE only) from 1984 to 1988, Mitsubishi 4-bolt from 1983-, Nissan 4-bolt from 198?- all used the earlier 4x114.3 pattern.

Ford Mustangs from '79 to '83, Ford Thunderbirds and Mercury Cougars from 1980 to 1988, Ford Escort ZX2, Ford Focus, Mercury Cougars from '99-02, and Volvo 850 4-bolt all use the later 4x108 pattern.   


Offset describes the distance between the centerline of the wheel's width and the back of the wheel's mounting surface, where it contacts the hub.  A positive offset means the mounting surface is closer to the outside of the wheel, and a negative offset means the mounting surface is closer to the inside of the wheel.  Zero offset results when the mounting surface of the hub is directly parallel to the wheel's centerline.  Historically speaking, rear-wheel-drive cars use negative offset, and front-wheel-drive cars use positive offset.  Very few remotely modern cars have zero offset wheels.  These days, however, with multi-link and MacPhearson Strut-based suspensions, most cars tend to to positive offset wheels, even if they're rear-wheel-drive.  All Saabs use positive offset wheels.  Remember: the larger the value of the positive offset, the further inboard the wheel will reach.

On a Saab, wheel offset is exceptionally important since the wheel wells are not very deep.  You must be careful when fitting wider wheels that the tires do not scrub the inside of the fenders or the shock towers; this can be quite a task!  Generally speaking, the wider the wheel gets the smaller the positive offset should be. For example, stock 15-spoke (15" x 5.5") alloys fitted to earlier 900s will have an offset of +40mm, whereas Saab Super Aero (16" x 6.5") alloys fitted to 9000 Aeros have an offset of +27mm.  In the middle, asymmetric 3-spoke (15" x 6") alloys have an offset of +35mm.  This provides us with an anecdotal but certainly useful formula - for every .5" that the wheel increases, the offset must decrease by about 5mm.  This will be influenced by a particular wheel's design, but is a good place to start.  As a note, Saabs generally cannot accept anything wider than a 7" wheel as there simply is not adequate clearance between the fender and the shock tower.  Additionally, +22mm is about the smallest positive offset a Saab will handle with a guarantee of rubbing the fenders, and +40mm is the greatest without rubbing the shock towers on a 6" wide wheel.  Lowered cars will have an increased chance of rubbing one side or the other, and maximum wheel widths and offsets must be adjusted accordingly. 

Whatever you do, please remember this is a general rule, and you should test-fit any given wheel & tire combination to be sure there isn't any interference.

-Hub Diameter

The other thing you'll need to keep in mind is that the hub diameter.  If the hub on the wheel you want is too small, you can have a machine shop bore out the wheel slightly to the correct dimension.  If the hub is too large, your best bet is to contact a local wheel shop or the manufacturer of the wheel itself - either may be able to provide you with an adapter ring to snug the wheel up to the hub.  Without this adapter, the only thing centering the wheel will be the lug bolts and you may end up with vibration as the wheel shifts around the hub.  All Saabs have a 65.1mm hub bore.  This is fairly large, but conveniently many Hondas use a 64.1mm hub bore.  A 1mm difference is hardly tangible, and with the beveled edges of the Saab hub, squeezing on a slightly smaller hub may not be a problem.

Note:  If you choose to mount a wheel whose hub is too large, it's critical that all lug nuts/bolts are torqued to specification before lowering the car to the ground.  If you fail to observe this, the wheel will not be properly centered and there is an increased risk (if not a guarantee) of vibration. 


One question which comes up quite a bit is what the compatibility between seats are.  Just because all the seats look the same, it doesn't mean they are all bolted in the same way.

- 900s from '79 to '80 have a unique mounting system.  These seats have a front-mounted angle adjustment and a side-mounted slider mechanism.  This system is in common with later Saab 99s.

- 900s from '81 to '90 have a similar mounting system, except those cars which have passive (automatic) safety belts.  These seats will have a front-mounted angle adjustment and slider mechanism.  The driver's seat is anchored with two allen or torx bolts on the front, the passenger similarly in front but with a pair of locking nuts in the rear.

- 900s from '87 to '89 with passive safety belts share a mounting system.  These seats are secured front and back with a pair of allen or torx bolts on both the driver's and passenger's side.

- 900s from '91 to '94 have a similar mounting system, which they share with the 900s with passive safety belts.  These cars should also be wired for power seat adjustments.  These seats are secured front and back with a pair of allen or torx bolts on both the driver's and passenger's side.

- 9000s from '85 to '98 share a similar mounting system, which is the same as 900s with passive safety belts and those made between '91 and '94.  These seats are secured front and back with a pair of allen or torx bolts on both the driver's and passenger's side.

The rear seats come in five flavors:

-900s from '79 to '80 are unique.  

-900s from '81 to '93 except for convertibles will all be compatible.  

-900 convertibles do not flip down, and are narrower than standard 900s.

-9000s except for CD ("trunked") models will all be the same.

-9000CDs do not flip down.

-Finally, 4-door 900s feature a rear seat with a slightly different shape.  Although all 4-door cars can readily swap seats with '81-'93 2-door and 3-door cars, the outer leading edge of 4-door seats are rounded instead of squared.  This difference is purely cosmetic, although a 2-door or 3-door rear seat placed in a 4-door might made ingress slightly awkward.

When I bought my first car with passive belts, the first thing I knew I had to do was remove the passive seatbelts.  Besides being annoying, as they age they grow unreliable and will eventually fail.  Fortunately, it's possible (if not easy) to retrofit regular, manual seatbelts into the car.  (Before doing so, check local law to be sure altering safety equipment isn't illegal!)  

You'll need to locate the appropriate parts, which can be found on any '89 or earlier 3-door hatchback (obviously without passive belts :).  Here is what you'll need:

NOTE: When removing the driver's side receptacles from a parts car, be sure to cut the little black wire as far from the assembly as possible to make future reconnection easier.  If you trace is back far enough, you should find a small 1-pin connector, meaning no cutting.

The amounts in parenthesis reflect the amount I paid for the items, for your reference

These parts should all be readily available at any junkyard, and won't set you back too much.  The worst part of the job is replacing the headliner, which aside from being difficult can also be expensive.  Chances are you won't be able to find a good one at a junkyard in a matching color, and even if you can getting it out of the parts car intact is a real challenge.  I suggest simply planning on reconditioning it before installing it in your car - doing so is hard work but not expensive if you do it yourself.  $50 in materials and a sunny day is all it takes.  If you do opt to have it done professionally, I strongly recommend delivering your car and having the shop do it all - yes, it'll cost more but you'll know it was done right, especially the sunroof panel (which can prove troublesome)..  

When removing the seatbelts from the parts car, make note of the locations of the bolts.  When you return to your car, you'll need to locate those places and remove the rubber plugs - all the holes are there, tapped, and ready to go.  Pull out the plugs, punch out (they're perforated!) the appropriate holes in the carpet, and bolt it all up.  You may wish to use some solvent followed by WD40 to clean out the holes - debris and corrosion can foul the threads.  You do not want to ruin these threads - they cannot be easily retapped or otherwise repaired.

Be sure to remove the passive belt ECU under the rear seat, as it will disable the blinking warning light on the instrument cluster.


Can it be done?  Absolutely - I've converted both 900s and 9000s from automatic to manual transmissions with great success.  There are no differences in the body between the two cars, so everything is a bolt-in - the mounts in the floor for the shifter housing and the holes in the firewall for the shift rod and the clutch are all there, plugged with rubber grommets.  There are no electronics associated with the automatic transmissions, so you won't have to do any wiring or changing of control units.

If you're planning on attempting this, I strongly recommend having a parts car on hand, since you'll be able to see how and where everything is installed, and you'll be sure you have all the parts handy.  It can be quite frustrating when you're missing one little bolt or nut you didn't anticipate.

If you don't have the luxury of having access to or the space to store a parts car, I recommend taking a bunch of Ziploc bags to a junkyard and bagging all the parts you (or the worker) remove from the car and labeling each bag with the general area the parts came from.  It'll save you trouble later on.

Here's a basic list of the parts you'll need:

- Get the entire shift linkage from the knob to the input shaft on the transmission.  On 900s, the shifter housing also contains the ignition lock cylinder.  To remove the lock cylinder, you need to turn the key to the Accessory position and use a nail or similar poking device to depress a release.  If you don't have the key to the parts car, you can drill "in just the right place," but if possible try to find a parts car with the key still in it.  On 9000s, '93 and earlier cars have a different shifter alignment mechanism than '94 and later cars - make sure you get the linkage that matches with the transmission you plan on using.  On 900s, some '86s and all '85 and earlier transmissions use a spring in the shift housing to center the shifter, some '86s and all '87s and later have the centering mechanism in the transmission itself.  Try to get a shifter housing which matches the transmission you plan on using.  Nothing bad will happen if you end up with two centering mechanisms (as my '86 900S does...) but you don't want to end up without one at all!

- Get the entire pedal assembly including the bracket that bolts to the firewall. You'll obviously need a clutch pedal, and you will need to replace your big ol' grandma brake pedal with a smaller, 5-speed sized brake pedal, so you might as well get the whole assembly.  Installing it in either car will necessitate removing the dashboard, but despite the added trouble I recommend taking this route.  Take the opportunity to replace all the old rubber vacuum hoses down there, and replace the bushings on the brake pedal.  Having the dashboard out will also make it easier to pass the shift rod through the firewall.  On 900s, this might also be an opportunity to replace your leaky or stuck heater control valve.  On 9000s, '93 and earlier cars have the clutch master cylinder mounted in the false bulkhead, '94 and later cars have the master cylinder attached to the clutch pedal.  Make sure you grab one from the right range for the car that will receive the parts.

- Don't forget that you'll need a flywheel, all the clutch hydraulics, and the clutch itself.  The flywheel should come from an engine similar to the one you plan on using (2.0l flywheel for 2.0l engines, etc.).  A complete clutch kit including a new disc, pressure plate, throwout bearing, and slave cylinder will be available for $160 to $200 depending on who your supplier is.  The master cylinder must be purchased separately.  Due to the nature of these components (and the hell you have to go through to replace them on 9000s) I strongly recommend buying new and not used.  I also recommend picking up a new pilot bearing for the flywheel, since now will be the easiest time you'll have replacing it.

- 900s and 9000s have an ignition inhibitor that prevents them from being started unless the automatic shifter is in Park or Neutral.  You will need to bypass this, by shorting the appropriate pins.  I can provide wiring diagrams for either a 900 or 9000 if you need.

- If you are converting a 900 Turbo, you will need the intercooler pipe that goes from the airbox to the turbo, as automatics use a slightly different one.  If you are converting a 9000, you will need the driver's side axle and support bearing, as they are shorter and smaller (respectively) on automatics. 

This is another exciting one.  Many people decide their non-turbo Saabs just aren't fast enough, and logically want to convert.  Unfortunately, doing so is insanely cost-prohibitive and under most circumstances it's better to simply sell the non-turbo and buy a factory turbo-charged car.  

There are some situations, though, which might warrant conversion.  Two good examples concern two-door and four-door cars - Saab only brought over non-turbo two-doors and only for two years, and 16v four-doors were only sold in '85 and '89, making finding them extremely difficult.  In these situations, crazy Saab owners don't have much choice, and a conversion may be required.

I am currently working on a plan to get a turbo into my 1986 900S, so this section is truly a work-in-progress.  Here is the list of differences which I've compiled:

- Turbo itself:  Turbocharged cars have a different exhaust manifold, exhaust downpipe, and larger-diameter exhaust system with a single muffler.  This should all be bolt-up, with no modifications required. Additionally, they have a tap in the block for the turbo oil supply and return, and '88 and later 900s and '87 and later 9000s have supplies and returns for water-cooling.  All cars should have plugged taps for the oil feeds and water feeds.

- Engine Internals:  Non-turbos have a higher compression ratio and different intake camshaft profile (the exhaust cams are the same). The connecting rods and crankshaft should be the same, but piston quality may  be different.  Early turbo cars (b-motors only, I believe) have sodium-filled exhaust valves to help them resist heat.  All h-motor cars (turbo and non-turbo) have such exhaust valves.

- Turbocharged cars use a simple vacuum controlled ignition system, and use the APC system to control knock by adjusting charge pressure.  Non-turbo cars use an EZK (electronic) ignition system, and use it to control knock by adjusting timing.

- Turbocharged cars have an air exchange oil cooler to keep engine oil temperatures down.  The oil cooler is fed via the oil filter housing; the turbo-style housing can be bolted up to the block on non-turbos.

- Turbos have the APC system, which is powered from the main fuse block and has components in the cabin and the engine compartment.  

- Turbo cars have a fair amount of circuitry to deal with turbo charging pressure.  For example, the APC system is tied into the braking system to reduce charge pressure when the brakes are applied, and it's tied into the cruise control system to limit the turbo to base boost while the cruise is engaged.  Additionally, turbos have an overboost switch to cut power to the fuel pump should boost exceed a preset limit (16 psi or so).

- Turbo cars are fitted with a number of check valves to prevent air pressure from getting to places it shouldn't be.  There is a check valve on the valve cover breather to prevent the turbo from pressurizing the valve cover, and there is one in the brake master cylinder to prevent the same which may not be present on non-turbo cars.

-  16v turbos have an intercooler and bypass valve - these can be easily installed in a non-turbo car.  Installing the bypass valve may require swapping intake manifolds, as the main valve cover breather on non-turbos connects to the throttle body where the bypass valve should, and there may not be a connection on the intake manifold to locate it where it normally is on turbos.

- Turbos have different fuel requirements.  On 8v cars this may require using a fuel distributor from a turbocharged car.  On 16v cars, this will require changing injectors.  The fuel pumps are the same between turbos and non-turbos.  16v non-turbos have a higher rated fuel pressure regulator, which can (and arguably should) be used when converting.  The air mass meter and main fuel injection ECU is the same between cars.

Sound complex?  It is.  Doing a complete conversion is a major undertaking, and as I said above, may simply be not worth it.  Here are two approaches I've considered:

- Swap a complete turbocharged engine into the non-turbo car.  The cruise control and braking circuitry aren't exactly required, but I would strongly recommend installing the overboost protection just in case.  APC could be wired in externally - the Volvo APC site gives excellent insight as to how this would be done.  Another possibility would be to use an aftermarket boost controller, such as the ones made by HKS or Apexi.

- Build a "high compression LPT" engine.  The idea here is to install all the turbo parts, but keep the stock, high-compression engine and run low boost - 4 to 6 psi should be safe, 8psi would be a little extreme but should be okay.  Use the turbo fuel system with the non-turbo fuel pressure regulator, turbo cam profiles, turbo exhaust system, install the turbo oil cooler, but keep the non-turbo ignition system.  All the vacuum system differences would have to be accounted for, but due to low boost none of the electronics would have to be installed - just set the mechanical wastegate for one or two psi lower than the actual boost you decide to run (to account for any boost creep).  Due to the low boost pressures, an intercooler would likely not be required, but I would recommend running one anyway.  As a safety precaution, it might be advisable to use higher-flow injectors for extra cooling - look to the aftermarket or grab some from a Saab 2.3l engine.  This is the route I plan to take with my 900S project - I'll let everyone know how long it takes me to grenade my engine... :)

Starting in 1986, 900 Turbos lost their solid front rotors in exchange for vented rotors.  While the caliper design, swept area, and piston size weren't changed, the vented rotor offers superior resistance to brake fade and rotor warping under heavy usage.  For those who tend to be hard on their brakes, upgrading to these vented rotors may be very worthwhile.  This swap can be done to all '79-'87 Saab 900s, and even later Saab 99s with a minimum of fuss.

Likely you'll be sourcing the requisite parts from a junkyard.  Assuming so, you need to grab the entire steering member.  Simply disconnect the balljoints from the upper and lower a-arms, and remove the steering tie-rod balljoint.  Pull back the outer CV boot, and disconnect the driveshaft from the axle by prying open the circlip at the outer CV joint.  Repeat the process on the recipient car, and install the new steering member (complete with axle, hub, rotor, and caliper).  You do not need to swap driveshafts or axles - they're all 100% compatible.  Bleed the brakes and you're good to go!  

The folllowing are stock cam profiles from pretty much all the B-series motors.  Use it when swapping cams, or having stock cams reground to new specs.  Now you know what you're dealing with!

Motor & year      Inlet lift, opens, closes   exhaust lift, open,  close
                       (mm)    (BTDC) (ATDC)       (mm)     (BBDC) (ATDC)

B202t  -1985      8.65/6.65**   16     56          8.65      56     10
B202t cat -86     8.65/6.65**   16     56          8.65      56     10

B202t  1986-          8.65      16     56          8,65      61     13
B202t cat 87-         8.65      16     56          8,65      61     13

B202i  1986-          8.65      16     44          8,65      61     13
B212i  1991-          8.65      16     44          8,65      61     13

B234i  90-93          8.65      13     53          8.65      50     16
B234t  91-93          8.65      13     53          8.65      50     16

B204all 94-           8.65      14     46          8.65      44     16
B234t   94-           8.65      14     46          8.65      44     16

B234i   94-           8.65      13     53          8.65      48     18

** - the difference in the height of the two lobes is for swirl in
the combustion chamber

BTDC - Before Top Dead Center
ATDC - After   "    "    "
BBDC - Before Bottom Dead Center


B = Gasoline (Bransle in Swedish)
20 = displacement in deciliters 20=2l, 21 = 2.1l, etc.
2 = # of cam (or other) shafts 2 = slant block, 4 = balance shaft block
i = injection, t=turbo, all=all variants (i thru t)

cat = means with catalyst

When swapping heads around, it's important to note that the shape & dimensions of the combustion chamber is't the same.  The following info comes from Nick Jacob:

B201 48CC
B202  (1985 only) - 42CC
B202 46CC 
B212/B234 (essentially the same head) - 48CC 

With that information, you'll see that putting a B212 or B234 head on your B202 motor will drop the compression ratio, and putting a 1985 B202 head on any later car will substantially increase it.



The Saab APC  system was one of the most advanced automotive control systems of its day.  It offered unparalleled turbo management, and truly brought functional turbo systems to passenger cars.

Unfortunately, the components which support the APC system have aged with the cars, and they are susceptible to age-related failures.  If your APC system or turbo does not seem to be performing as it should, the following ten steps should help you isolate and repair the problem.

Please note:  These steps assume that your engine is in otherwise good working condition, and you're just seeing lower than expected boost levels.  If you have other running problems, you must correct them before you can hope to accurately troubleshoot the turbo system.

1.  Verify it isn't your boost gauge - they don't fail often, but they do fail.  Acquire a calibrated boost gauge.Pull the driver's side front speaker grille, and locate the vacuum line going to the back of the instrument cluster.  Pull that vacuum line, and connect it to your boost gauge; your stock gauge will no longer be working.  If you're seeing the right numbers (11-12psi on 16v, 7-8psi on 8v cars) then the problem is your gauge and not the car.

2.  If you're not seeing the right levels, it's time to start your troubleshooting.  First, pull the "C" line off the APC solenoid.  This will not only disable the APC system, it will also disable your wastegate.  Go for a brief drive on an open, uncongested road.  BE CAREFUL with your acceleration as boost is completely unregulated.  You should get massive boost, and will probably run into the 15psi fuel cutoff quickly, so be prepared.  DO NOT drive like this for long, as knock will surely set in and can damage the engine surprisingly quickly.  If you get boost, the problem is 99% vacuum or electrical; if you don't, you likely need a new turbo.

3a.  If you did NOT get boost in step 2, pull off the pipe that runs from the air mass meter to the turbo intake.  Try spinning the turbo compressor wheel gently.  It should spin mostly freely; if it does not, your turbo is seized or damaged.  Listen for any screeching or scraping noises as you turn the wheel - these can be caused by bent vanes on the compressor or impeller and will cause abnormal boost.  If it does turn easily, you may have a seriously damaged exhaust manifold or engine.  Troubleshooting that is beyond the scope of this document.  To get you thinking, the problem could be anywhere from seriously off timing (ignition or valve) to bad pistons.  That said, at this point you're probably noticing other drivability problems, too.

3b.  If you did get boost in step 2, you have some work to do.  First thing to verify is that you don't have any massive air leaks.  Check all vacuum hoses from beginning to end, and verify that all rubber couplers on the intake tract are in good shape.  I recommend pulling them all off an inspecting them carefully - small rips or tears (even *pinholes*) can expand to large size under boost which will bleed off the intake charge quite readily.  Also check grommets in the intake manifold for tightness - they can blow out under boost but get sucked in under vacuum, thus appearing okay; be sure to check them with your hands and not your eyes! 

4.  If you check all hoses and vacuum lines and don't find any leaks or tears, your problem will lie with either the cruise control or the APC system and you must check the cruise system first.  There are only a few components - a pressure switch located on the driver's side fenderwall and two pressure switches located (one each) by the clutch and brake pedals.  Check the fenderwall switch first by attaching a short length of hose to its vacuum port and sucking and blowing on it.  You should hear an audible click of the switch opening and closing.  Test electrically by connecting a continuity tester to its two leads - you should get continuity at atmosphere and an open circuit under vacuum.  If you do not get continuity, you've found your problem.  You can bypass it by shorting together the two leads on the car's wiring harness; just remember that while bypassed, the APC system will be ENABLED while cruise control is engaged, and you'll get full boost.  This can lead to poor cruise control performance and potential engine damage (unlikely as it is) and should repaired as soon as possible.

5.  Next, check the pressure switches at the brake and clutch pedals.  Connect a length of vacuum line to each switch (one at a time) and apply vacuum and pressure.  The switches should hold vacuum/pressure with the pedal at rest and should not when the pedal is depressed.  Additionally, you must test electrically by continuity.  Pull the electrical lines off each switch and test; there should be continuity with the pedal at rest and an open circuit with the pedal depressed.

6.  If the cruise control checks out, test at the pressure transducer while you're still under the dash.  It's a little metal cylinder above the driver's feet.  Do not get it confused with the overboost switch; it can be identified by the *lack* of an adjustment potentiometer.  Often times when this transducer fails, you will get extremely low *or* erratic boost levels.  This part is often overlooked, and is responsible for a surprising number of APC failures.  Unplug the two electrical connections and short them together.  Take a test drive, but do note that the APC system will have no way of knowing how much boost is being produced.  The result will be mostly normal drivability, but boost will not stop at normal levels, meaning you WILL hit the overboost switch at some point (and probably quickly).  Check boost levels with a calibrated gauge.

7.  Next check the APC solenoid by applying +12v to it; under power, the solenoid should snap.  Check that it is fully functional by removing the vacuum lines from the "W" and "R" ports, and connecting a length of vacuum line to the "C" port.  With no power applied, air passed through the "C" port will come out through the "W" port; with power applied, air passed through "C" will come out through "R".  Be sure to verify the solenoid does not leak air through the wrong port at the wrong time. 

8.  If your APC solenoid checks out, check the knock sensor.  Unbolt the knock sensor from the engine, wrap in a mess of towels, and stash it somewhere where it will not rattle around or become entangled in moving engine parts.  Use the calibrated boost gauge to check charge pressure while driving around.  Be cautious driving in this fashion, as you will be operating without the APC's protection.  If the car behaves normally and boost pressure is correct, you likely have a faulty knock sensor - replace it, and do NOT drive for prolonged periods with it unplugged or you WILL grenade your engine.  NOTE:  If boost returns to normal levels with the knock sensor unplugged this does NOT necessarily mean that the knock sensor is faulty - there could be engine problems which are in fact causing premature knock.  Trying a known-good knock sensor is a good way to help isolate the problem.  If the problem persists with a known-good component, you may have more serious problems:  Incorrect ignition or valve timing, poor fuel pressure, and excessive carbon deposits (causing heat, thus knock) could be responsible, and they may be subtle enough to not affect normal driving but pronounced enough to set off the knock detector, as it's quite sensitive.  Troubleshooting such problems is beyond the scope of this document.

9.  If all else has failed, you may be faced with an unreliable APC box.  Such problems are rare, but they do occur - and will probably occur more often as these cars get older.  The only real troubleshooting you can do is to verify that the box is getting power and good ground, and that the two sources are reliable.  The next step is to swap APC boxes with a known-good component.

10.  Hopefully, your turbo is working again at this point.  If not, email me and we can see if there is some other stone unturned...

It is not terribly difficult to install an aftermarket alarm system in the car.  Fortunately, Saab doesn't do anything strange with their electronics to make doing so prohibitive, so don't listen to the guy at Circuit City when he tells you that your Saab requires anything special.  After installing a few of these things, my advice is that if you're reasonably good with a wrench and have a good working knowledge of basic car electronics, save yourself the money and do it yourself.  For me, the only incentive I needed was not having to worry about some minimum wage teenager traipsing around my baby's wiring.

Back in the '80s, Saab started selling an optional "Saab Guard" alarm system.  Competent at the time, most of them have either failed or been disabled due to their general lack of feature-set.  If your car has (or had at one time) one of these alarms, half your work is already done.  If not, don't give up hope.  With ay luck, the following tips will make your job easier:

Constant +12v:  To function, an alarm will need a constant supply of power.  If you've got a SaabGuard alarm, you'll find this connection under the rear seat, ready to go.  If not, you can grab it from Pin #29 at the main fuseblock.  Just splice in to the wire that's already there.

Switched +12v:  Most alarms will want to know when the car is running and when it isn't.   If you've got a SaabGuard alarm, you'll find this connection under the rear seat.  If not, grab it from the ignition switch in the center console (labeled "X").

Ground:  Ground locally, or use the ground point located just forward of the handbrake.   If you've got a SaabGuard alarm, you'll find this connection under the rear seat.

Parking Lights:  Many alarms will flash the parking lights when changing status.  You want Pin #58 at the headlight switch - it will usually be red/green.

Starter Inhibitor:  Many alarms will disable the starter when armed.  Most will use a relay to do this - they stick a relay between the starter output at the ignition switch and the starter itself, and control the relay with a lead from the alarm brain.  Consult the alarm for details, but the wire you want is Pin #50 at the ignition switch.  Make sure you use heavy gauge (16 is good) wire if adding length to this connection - there is a lot of juice running through this connection!

Door State Detection:  In order to know if someone is trying to get in, an alarm needs to know whether the doors are open or closed.  Due to the way Saab wired the car, you will likely encounter some problems here.  Saabs use a negative trigger system - when the door is opened, a switch goes to ground.  That part is simple.  The problem is that Saab sticks a pair of relays in the way of an otherwise simple circuit - one relay is the door open buzzer which only applies to the driver's door, and the other is the "courtesy light" relay which leaves the interior lighting on for about 15 seconds after the last door is closed.  The buzzer relay can interfere with some alarms since you'll very likely get different ground potentials between it and the passenger side door - a diode placed in the alarm's input can usually overcome this, and some alarms won't even notice the slight difference.  The courtesy light relay poses another problem - as long as the courtesy lights are on, the alarm won't set because it will think a door is still open.  Your options here are to either live with it, and wait for the lights to go out prior to arming; to remove the courtesy light relay and live without courtesy lights; to purchase an alarm with "defective zone ignore" - it will detect that a zone (the door) is not secured and arm anyway.  In the latter case, the logic is that assuming your car is locked, glass will have to be broken to get inside it, and that will trip the glass or shock sensor anyway, so your car is still secured.  Do note that this detection is different than hood or trunk open detection - that's another ball of wax!  All that said, you can grab this connection at any of the door jamb switches or at Pin T of the Courtesy Light Relay under the rear seat.  If you've got a SaabGuard alarm, you'll find this connection ready-to-use under the rear seat

Keyless Entry:  One of the biggest reasons to get a modern alarm is keyless entry.  Nothing beats not having to fumble with keys to unlock your car.  If your alarm has this feature, you'll need to know:  First, Saab uses a negative trigger system for the power locks - a particular circuit goes to ground to trigger the door lock motors to lock or unlock.  The easiest place to grab the necessary connections is at the door lock relay located above the front passenger's feet, attached to the ventilation plenum.  You'll want Pins #1 and #2 - grounding #1 will lock the doors, and grounding #2 will unlock them.  The problem here is that on all 900s and 9000s the driver's door does not have a motor, only a switch.  You will need to replace this with a functional motor if you want the driver's door to lock and unlock.  There are kits available from most alarm retailers to add aftermarket motors to assist in this situation - you'll have to read the instructions that come with such a kit if you go this route.  My solution is to replace the driver's door lock switch with a motor.  You will lose the ability to lock/unlock all the doors from the driver's door but, in my opinion, with keyless entry you won't need to do that ever again anyway, so it's no major loss.  You can grab one from a junkyard - the switches and motors have the same casing, so get one from a passenger door or a trunk/hatch.  Just pull off the door panel, and swap the hardware!  Once it's all mounted up, you will need to get power to the new motor - to do this, you'll want Pins #7 and #8 at the door lock relay.  Giving +12v to pin #7 will lock the doors, reversing the polarity (+12v to pin #8) will unlock them.  Simple!  Note #1:  If you are adventurous, you can actually dismantle the door lock motors and switches, and combine two units into one.  I have personally seen this done, though never bothered to do it myself - cracking open those cases is tough work, and like I said above, central locking at the driver's door isn't that important to me.  Note #2:  One thing I always make a point of doing is using window switch and locating it with the other window switches - With a little work, you can wire the switch into the door lock relay and use it to un/lock all the doors from the center console.  It's a lot less obvious that reaching for the door, and is convenient for those times when you use the key to unlock the driver's door, then need to unlock the trunk or a rear door.  If you need help doing this, let me know and I'll email you simple instructions on what to do.

Other little bits of information:

Siren Location:  The best place to mount a siren, in my experience, is on the passenger side fender, just behind the washer fluid reservoir.  

Hood Pin Location:  Most alarms will allow you to mount a switch to detect if someone is tampering with the hood.  There is a hole on all 1985 and later Saabs on the radiator crossmember, passenger side, designed for just this.  I can provide pictures of the location for those of you with earlier cars, or those having trouble finding it.

Trunk Open Detection:  If your alarm has an input for trunk open detection, it will work exactly like the passenger door detection.  Locate the switch in the trunk area (under the striker plate on hatchbacks, near the left rear speaker on trunked models) and tap in here.

As with alarm systems, Saabs are extremely normal when it comes to their stereos.  In the very early days of the 900 (and the later days of the 99), Saabs did not come to the States with any sort of audio.  Such luxuries were exclusively dealer-installed options.  With that in mind, Saab designed the cars to accept industry standard sizes of everything; that design stayed with us until the very end of production.  On 9000s, Saab continued their use of industry standard sizes, and provided a very flexible platform for audio installation.

On 900s, Saab provides at least one DIN-sized position for an audio head unit.  Certain 900s are also fitted with a center console, located just in front of the shift tower, which provides a second DIN-sized slot.  On 9000s, there are actually three DIN positions - two are in use by the factory stereo system, and the third is in use by the ashtray.  It can quite easily be removed and used as an alternate position.

On both cars, installing any DIN-sized head unit is done from the front.  There are no rear brackets or supports which require attention from the installer.  This setup is sometimes called, appropriately, front-mount.  Installation will usually consist of inserting a metal sleeve or bracket, and bending several tabs to retain the bracket in the dash or other slot with a screwdriver.  Any stereo should come with basic instructions as to how this should be done.

When doing the wiring, use the following guide to help you connect things to the right places - all Saabs use standard wire colors and should be the same across the board assuming your car has (or once had) a factory stereo and not a dealer-installed stereo:

Harness #1 - Power

Grey (Pin 1) - Battery +12v
Red (Pin 4) - Switched +12v
Black (Pins 5, 9, 10) - Ground
Green (or Blue) (Pin 6) - Antenna/Remote Trigger
Brown&White (Pin 8)- Dash Illumination:

Harness #2 - Speaker Output

Green (Pin 1) - Left Front (-)
Brown (Pin 2) - Left Front (+)
Blue (Pin 4) - Right Front (-)
Red (Pin 3) - Right Front (+)
Green&White (Pin 5) - Left Rear (-)
Brown&White (Pin 6) - Left Rear (+)
Blue&White (Pin 8) - Right Rear (-)
Red&White Pin 7) - Right Rear (+)

Additionally, there may be three more connectors you find floating in the dashboard.  One will be a 2-pin T-shaped connector with two black wires - this is a ground loop which connects the top DIN slot (stereo) to the lower DIN slot (equalizer).  The second and third will both be 6-pin round DIN-sized connectors.  On those models with an equalizer, these connector form the bus between the two units.  All of these cables may be removed if you like, or left in place in the event you decide to reinstall the original stereo.