Engine Tuning & Chassis Upgrades

Engine Tuning & Chassis Upgrades

When car manufacturers come out with a new engine design, some car enthusiasts eye the new technology from a perspective of how to squeeze more performance out of it. The smaller displacement engines that are turbocharged or supercharged tend to be the most likely chosen because of their power-to-weight ratio.

When Saab introduced a turbocharged 4-cylinder fuel-injected engine in 1978, it was very successful as it was offered only in the hatchback version of the 99 model. The turbocharger was air-cooled and no intercooler was offered at that time. Like any new model, it had some drawbacks from the oil coking and plugging up the lubrication passages, as the life of the turbo was short lived. The chassis was a proven design that was carried over from the EMS model that had good looks as well as handling. This was a great stepping-stone for Saab from a performance perspective.

When Saab came out with the 16-valve DOHC fuel-injected intercooled version in 1985, it represented a hallmark design. That year, the APC system (automatic performance control) that made its debut in 1982 was updated with the latest BOSCH LH fuel system. This made the intake system incorporate a fairly decent-sized intercooler, which produced lower combustion chamber temperatures so the boost pressures could run at a higher level without the damaging knock and the help of the APC control for automatic adjustable boost pressures.

The APC is the control system for the turbo boost system. It uses a knock sensor mounted in the center of the engine block to detect knock or ping when under boost. When the knock or pinging is detected, the charged boost is dropped down to basic boost…like 3 to 4 lbs. This is controlled by the solenoid mounted close to the turbo; the pressure bleeds off to the suction side of the turbo. When high-grade octane fuel was used on a cool day for lower intercooler temperatures, the boost was retained to a higher level. When the Trionic 5.2 fuel system came out in 1993, it was the start of a whole new future. The Trionic 5.2 was out for only one year, and then Saab updated it to the Trionic 5. In 1994, a new engine, called the B234R, and the Trionic 5 were introduced for the performance that was needed. The crankshaft sensor was relocated in the block to be more precise in measuring crankshaft revolutions.

The Saab 9000 that uses the 2.3L linked to the 5-speed tranny was the way to go. This combination was not only compact, but it delivered great performance — especially the 1994 9000 aero. The 9000 used the Mitsubishi TD04 turbocharger with a 6cm exhaust housing that withstood the higher boost levels and abuse that went along with tuning these cars. Saab really made the B234R engine durable. This engine is capable of withstanding power greater than 500hp without even removing the valve cover!

In 1994, Saab introduced the new-generation 900. In the turbo form, this car also used the Trionic 5 fuel system. It was available with the 2.0L turbocharged engine, that used the same block as the 9000 B234R, but it had a shorter stroke. With the reduced stroke, the engine made less torque and horsepower, but since the 900 was also much smaller and lighter, less power was needed. The 2.0L also withstands 500hp in stock form.

The Trionic 5 fuel system is actually three computers in one — 1st is the fuel, 2nd controls spark and 3rd is the turbo pressure. With such a great fuel system, it only makes sense to use it to make more power safely. This is done by changing the files in the ECU, which is something that’s done by different tuners. I have Sweden’s SQR as my tuner and we’re their U.S. distributor.

The ECU files can be changed to meet customer requirements, from basic stage tuning to full custom tuning that’s required with larger turbochargers and so forth. Stage tuning is available from stage 1 to a stage 5, where power goes from 230hp to 360hp depending on the car. Any stage after 5 requires a custom tune that has to be done in person on a dyno.

A stage 1 upgrade, for example, is only an ECU upgrade and everything else remains stock. A stage 2 upgrade requires a large, open-air filter. A stage 3 requires an open-air filter as well as a 3” downpipe. Stage 4 is both the open-air filter, a full 3” exhaust system and the TD04 turbocharger. A stage 5 is the air filter, full exhaust system injector upgrade and the TD04 6cm turbocharger refitted with a larger 18t compressor wheel.

In 1999, Saab introduced the Saab 9-3 and 9-5. Both of these cars used the new T7 fuel system, except for the base 1999 9-3s that still used the T5 system. The T7 fuel system used both a map sensor and a mass air flow meter. This system still used the engine speed sensor in the side of the block and controls the three different systems — fuel, spark and boost.

Saab also updated the engines. The block is almost the same with few changes. As for the rotating assembly in the engine, Saab lightened up everything to increase fuel economy. But doing this also weakened the strength of the engines. As for a safe max power, I would not go over stage 5, 360hp. Piston cracking may occur as well as other issues.

One benefit did occur with the engine now being lighter — it revs quicker and makes power smoother in the powerband. The cylinder head also flows better. Tuning the T7 Saab is basically the same as tuning the T5 engine. Stage 1 is ECU only; stage 2, open-air filter; and stage 3 is air filter and downpipe. Stage 4 is an open-air filter, full exhaust and the TD04 6cm Mitsubishi turbo. Custom tuning is also available on the T7 fuel systems.

With increased horsepower, upgraded braking is a necessary addition. Braided brake lines and a high boiling point brake fluid are a great start. A more aggressive pad also works well. I have good luck with an autocross compound pad for street use. A full competition pad isn’t a good idea for this application. The compounds used for high-performance driving are formulated to withstand the high temperatures generated on the track from constant severe braking. Some drivers use their cars for street use and change the fluid along with the street pads. The reason for the pad shuffle is because they aren’t very effective when cold and will need some hard braking to work effectively.

Now back to the brake fluid. After every race event or severe street braking, the fluid must be changed! When the fluid runs at a very high temperature and starts to boil, it will draw in moisture and that’s a real problem in creating corrosion. Brake components start to fail in early life because of this. Standard 900s, 9-3s and 9-5s can be upgraded to larger vented rotors and special caliper brackets from the 9-3 Viggen and 9-5 Aeros. This will help in upgrading 4- or 6-piston calipers, which are an option but usually do not directly bolt on and can be very costly.

The brakes hoses are one of the safest performance enhancements. The standard rubber hoses get replaced with tough braided, stainless steel-covered lines resulting in a more solid pedal. It also alleviates fear for the driver of the lines coming apart under hard braking. Some of the Fords that run in our car club must have replacement lines and they tend to fail under harsh conditions on the track. So when tech inspections are performed before each event, the brakes are looked at closely.

With more horsepower and upgraded braking comes the need for suspension upgrades. The new generation 900 and the 9-3 have a flexible chassis. Upgraded urethane bushings are recommended to replace the factory rubber. Torque steer is also a problem. One way to help this condition is to stiffen up the steering rack on the passenger side by bracing the rack to the chassis. There are a few kits available for this modification.

A larger rear sway bar is a very noticeable upgrade that can easily be installed and purchased at a reasonable price. Lowering sport springs with shocks and struts are a common upgrade in all Saab models. Some customers ask about roll cages and bars. This request depends on how the car will be used. When using the car for the street, the roll cage or bars tend to get in the way and it’s not easy to get in and out of the vehicle. However, it will stiffen up the chassis under hard cornering and braking. Adding just a small support between the rear shock towers provides a noticeable difference as the body has less flex and keeps the rear from having too much body roll.

We’ve installed a stiffener X bar in some 9-5 and 9-3s, as it’s located over the front subframe. This tends to help in body flex under hard cornering as well as in giving some strength to the driveline. The bolt-in versions can be removed with ease when servicing the driveline; the weld-in versions tend to get in the way and are time consuming to remove and re-weld in place.

After making any changes to the springs and struts, you will need to realign the suspension. When you’re performing an alignment on a custom suspension system, you set the camber to the far side of the negative spec. Some negative camber will give the tire a real good contact surface on the road for going around tight corners. Just charge the customer a little more for the alignment, as it’s time consuming to get the correct angles that you need when major components have been changed.

When increasing positive boost in a small-displacement engine, the air has to escape the engine as well as it was put in. The headpipe that is bolted to the turbocharger in the 9-3 and other Saab models had a real sharp bend and runs down the center of the chassis, then there’s a cat converter that links to the center muffler. This restrictive system must be changed to accept the high pressures.

To modify it, we build the headpipe with a 3-inch diameter, that goes down to a free-flow cat converter. The center muffler is a free-flow unit that is quite long (42-inches) and runs into a large, free-flow muffler. Some customers just use the 3-inch headpipe with the free-flow cat converter.

The O2 sensors will have to be relocated when any exhaust system is changed in any way. This can present a problem with installation at times. There is just no room to work with. The larger diameter will require that extra care be taken in mounting the system to prevent any rattles or vibrations and heat damage to the chassis. There is very little in the way of exhaust performance systems offered for the Saab car line. Most systems are specially designed and handcrafted to fit the general application.

Following is a step-by-step procedure to install the Aero turbocharger on a low-pressure 9-5, resulting in higher performance (See Photo 1). As you can tell, the inlet and exhaust ports are larger on the Mitsubishi unit than the standard Garrett turbocharger.

  1. Raise the car on a lift and drain the coolant out of the radiator. The drain plug is located on the lower right side, close to the subframe.

  2. Drop the car down and remove the turbo bypass valve and tube, then pull off the heat shield covering the turbo.

  3. Remove both coolant hoses and the oil pressure feed tube, then discard.

  4. Remove the intake pipe and hoses, and boost control valve with all three hoses.

  5. use a torch to heat them up for removal. Try not to snap off the studs, as you will have a tough time drilling them out and tapping, as it’s hard steel.

  6. Remove the turbo drain to the block and stay bracket.

  7. Take off the four lock nuts securing the turbo to the exhaust manifold.

  8. Drop the turbo down from under the chassis.

  9. Remove the exhaust manifold from the head as the end of the gasket blows out because of loose or broken long studs.

  10. When reinstalling the manifold, just use the same studs as those used in the center. The long studs tend to break off with heat and will be necessary to drill and tap (See Photo 2).

  11. In order to install the Mitsubishi, four tubes must be purchased from Saab. They’re reasonably priced and will help you make the swap with ease.

    – Cooling pipe, P/N 91 82 460

    – 2nd cooling pipe, P/N 91 74 947

    – Oil drain tube, P/N 91 74 939

    – Oil feed tube, P/N 91 79 458

  12. Install the Mitsubishi turbo in reverse procedure.

  13. Change the oil and filter, then just before you start the engine, disconnect the Direct Ignition cassette cable and crank the engine over for a minute or so to lubricate the new turbo.

  14. Now that the higher-output turbo is installed, the ECM will need to be reprogrammed.

The reflashed ECM will be more aggressive than the stock Aero version using the stock headpipe. By installing a free-flow air filter, this will help in gaining 50 more horsepower at the wheels. The Trionic 7 system needs some adaptive test runs to learn after any changes or even when the power has been disconnected. This is professionally done on the open road or safely done on a chassis dyno. Many other modifications could be done if the customer wants to go in higher stages. Larger injectors, a higher capacity intercooler and 3-inch exhaust system are just a few examples. But when these components are changed, the program must be tailored to run effectively.

Now that power is delivered to the transmission, some changes could be done to accept the higher torque and horsepower. There are not many high-performance aftermarket parts available in this area, as the factory clutches and transmissions are quite strong to accept 350hp. Some wheel spin and lots of hard pulling from right-to-left acceleration could be eliminated. The use of a limited slip differential could be installed with a lower final drive ratio that would improve driveability.

In our race cars, we use an external oil pump linked with a small oil cooler resting next to the intercooler while using special synthetic lubricant. When the car is run on the track, heat buildup from the limited slip differential causes the cast aluminum case to expand and distort. While this happens, the gears do not mesh correctly — this could be catastrophic.

The use of Viggen drive axles and spindles will solve most of the outer CV joint problems in the 900 series. We recommend replacing the outer CV joint boots with some type of rubber compound as the heat buildup from the brakes melts the factory plastic boots.

Much can be gained by changing the parameters for the fuel curve, ignition timing and boost pressures. As professional techs, there are some legal issues that have to be considered. In our shop we are careful with what we install so as not to break the emission laws. In general, most exhaust system and intake mods meet the approval of the California Air Resources Board.

When your shop builds a reputation for performance work, it will be “the” place to go in your area. This will help keep the bays full and the techs busy with the enjoyment that performance tuning brings.

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