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21 September 2012 #1
- Join Date
- 30 Jul 2010
- NW Michigan, USA
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Saab 900 Enduro: Steroid Poppin' Swede
Article from AutoSpeed.com reproduced here for archival purpose.
By Michael Knowling
Pix by Julian Edgar
13 October, 1998
It's got a swollen body and a fiery temperature ....
Not many people choose to hot up a Saab turbo. They're too expensive and unreliable, plus you can't make them fast, people usually say. Wrong! Unfazed by tuning 'experts' declaring the Saab a performance basket case, Canberra's Mark Kostyrko has built his rare 1980 Enduro 900 into a real surprise packet.
Only twelve examples of the Enduro pack were sold in Australia in 1980. The package - which was fitted by Saab Australia - includes massive boxed guards along with upgraded instruments, improved suspension and big wheels and tyres. Under the bonnet the wastegate was set at a huge 17psi (1.2 Bar), making the standard water injection system an engineering necessity, not just a marketing ploy!
Now don't sit back in your chair thinking it's just a grenade engine; 'cos it ain't. Over 350,000kms have been racked up on the standard engine, which has had its head off only once. While the single cam 8-valve head was detached for a gasket replacement, Mark decided to tackle it with an air-grinder and give it some effective flow gains - but this is the only internal modification.
The standard static compression ratio of 7.2:1 is retained to allow for the big turbo-rush. Incidentally, many of the early Saab turbos were maligned for their 'on/off' power band which was probably caused by this combination of a low CR ratio and high boost - great for max power, but wanting on the road.
The turbo on Mark's car is a high flow T03 using an unknown spec compressor housing around a bigger wheel. The exhaust housing has a 0.48 A/R. A large 42mm Garrett external wastegate now bypasses the turbine as the original internal 'gate couldn't flow enough gas - leading to problematic over-boosting. The separate wastegate exhaust pipe re-unites with the main engine pipe about mid-way down the length of the car, ensuring there is no flow-impeding turbulence directly after the turbo. Gasses roar out through a 3-inch mandrel bent system with two Lukey straight though mufflers. What, a 3 inch exhaust on a Saab?!
On the intake side, a large oiled foam Unifilter draws in air though a cold-air duct in the front guard. The filter performs well in its intended role, but Mark says that it needs to be cleaned fairly frequently. After being filtered, the air gets compressed by the turbo and swirls around inside a modified air-to-air intercooler mounted behind the headlight. This core was actually pulled from an aftermarket kit fitted to a Holden VL Commodore Turbo.
Putting an even greater chill into the induction air is a 'Patent Pending' water injection system which Mark has devised. Understandably, Mark wasn't too keen to give its full specs away, but tells us it consumes around 200 ml/minute while in operation and that he usually throws in a 25 per cent metho/water cocktail.
So with all this cool air forcing its way into the combustion chamber, how is the fuel delivery spiked?
Ahh, this area always humbles non-believers! To give you an insight into how this K-Jetronic mechanical injection system works, an electric pump pressurises fuel at up to 82psi and sends it to an injector head, which distributes the fuel to the continuous flow injectors. A measuring plate moves in proportion to airflow (ie it's a mechanical airflow meter), determining the exact amount of fuel delivered. Mark has added a solenoid that is tripped at 4 or 5psi boost to drop 'control pressure' thus increasing mixture richness. But more ingeniously, he's also fitted a V6 Volvo injector head in place of the original, a conversion that literally bolts in - but needs extensive tuning.
Since the Volvo head has six metered ports instead of the four of the standard 4-cylinder engine, extra injector(s) can be easily run. In this case, only a single extra injector is fitted, being brought into action once the engine reaches 10psi boost and is over three-quarter throttle. Mark found the ideal injector position by testing it in different locations on the intake. In this way he found the spot where the engine didn't stumble when the injector was activated - the injector G-spot!
Unless Mark is tuning, the car always has its tank filled with leaded fuel. During tuning sessions he uses premium unleaded - enabling him to fit an exhaust gas oxygen sensor and an air/fuel ratio meter.
Unfortunately, the original gearbox hasn't proved as reliable as the engine. In spectacular style, the standard Saab 900 'box stripped all the teeth off a cluster when the engine came on boost. A replacement came from a later model Saab 16-valve turbo Aero and bolted in with the original Saab 900 clutch plate. According to Mark, the drivetrain is a bit delicate and he so doesn't recommend doing too many crazy launches.
The 3.89:1 ratio open-centre diff has a tough job. Mark would like to replace it with a good front LSD - probably a Quaife unit - but the prices being demanded are currently too high. In the lower gears, only 13psi boost is dialled up which then inflates to around 21psi as the car gets mobile. There isn't much point in pumping in a truck-load of boost when the car is just going to turn the extra torque into tyre smoke....
The Enduro suspension is still in place and uses 386 pound/inch front springs and 484 pound/inch rears together with quality Bilstein dampers at each corner. Mark is considering stiffening the rear suspension to limit some of the alarming wheelspin off the line. Mark told us stories of massive wheelspin exiting corners at (get this!) around 160km/h in 4th gear - yeah!!! This happens despite the substantial factory-fitted 225/50 width tyres mounted on Simmons 15x7¾ rims.
After we photographed the car, Mark tied the car onto a chassis dyno for a power run and to check mixtures. With boost set at the minimum 13psi, traction was still a problem as the car "walked off the dyno at around 3500 revs" making a full power run impossible. Still, a figure of 150hp was recorded at the wheels at these lowly revs...
One thing noticed on the dyno was that an intake hose was deforming under load, strangling flow. This was quickly swapped for a straight length of solid pipe that made a huge improvement. "Before, it felt like I was dragging a train along behind me" Mark comments.
Maybe Saab Enduros should have come equipped with a towbar...
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