This topic was started on 3rdgen.org. I own a saab 9000 and an 87' Monte Carlo. This is a quote from someone who claimed "they worked with saabs" and their turbos are out of date.
"You are correct in that Saabs use turbos on most everything they sell. However, for this very reason, Saabs do not sell very many cars.
Their turbo theory is quite out of date, and when people have problems with "turbo-lag" it is normally associated with Saabs.
Saab continues to design it's turbocharged engines in a way that most companies abandoned 20 years ago, putting a very large turbo on a motor that takes a good amount of time to spool up, making a motor that feels very, very peaky.
Modern turbo engines use much smaller turbos, which spool up faster and create a much smoother power curve with more availible power at lower rpms, as well as greater tourque and power across the whole band. The beauty of this system is that a smaller turbo can also provide similar power gains up high, however the turbo is spinning a good deal faster.
The difference between a Saab and a "modern" turbo design is immediately apparent. You floor the Saab, and nothing happens for several seconds, then the turbo finally spools up and the car suddenly lurches forward. A "modern" turbo gives you a smooth rush of power, starting at around 1500 rpm, and building as the revs increase.
Saab even goes further to compound the inherent problems with their design. Saabs use a computer controlled wastegate, that bleeds off boost under computer command.
Many turbo setups use a wastegate, but most are set up simply to limit boost to a level that will not damage the engine.
Saab takes this a step forward, and basically makes it IMPOSSIBLE to drive the car in a performance aspect.
Saabs bleed off boost under anything other than full throttle. Also, the wastegate opens fully whenever the clutch is depressed.
So lets break down what happens when you accellerate in a saab.
You floor it. The car goes nowhere, as the turbo has not spooled and the 4 cylinder is quite anemic without boost.
After about three seconds, the turbo comes up to speed, and the car shoots forward. In many cases, Saabs will actually lay rubber starting at 10 mph when the turbo hits. This IS a large turbo and it does produce power.
Then redline hits, and you push the clutch in to shift. The wastegate opens, and all the boost bleeds away in an instant. You shift to second, and floor it.
The car once again does not accellerate. For an interminable about of time, you putt in place. Then once again, the turbo hits, and puts you back, but just for a few seconds, as you now must shift to 3rd.
See the problem? This wastegate actuation makes what could be a 14 second car a 17 second one, and the turbo is unspooled more often or not.
Also, this makes the car a pain in the ass to drive daily for somebody not wanting to drive fast.
To the normal person, they accellerate off the light. The car does not accellerate well, so they give it more throttle input. Then the turbo suddenly spools, shooting the car unexpectedly forward, sometimes accompanied by squeling tires.
While working at a Saab dealership, I saw plenty of Saabs with front end damage from hitting somebody. THIS IS THAT EXTREME OF A PROBLEM, that people actually rearend people when the turbo hits.
So you get the best of both worlds. A car that goes slow when you want it to go fast, and a car that goes fast when you want it to go slow."
Opinions please. Though some good points are made I don't think that the lag is THAT noticalbe and will take off when drivin hard.
"You are correct in that Saabs use turbos on most everything they sell. However, for this very reason, Saabs do not sell very many cars.
Their turbo theory is quite out of date, and when people have problems with "turbo-lag" it is normally associated with Saabs.
Saab continues to design it's turbocharged engines in a way that most companies abandoned 20 years ago, putting a very large turbo on a motor that takes a good amount of time to spool up, making a motor that feels very, very peaky.
Modern turbo engines use much smaller turbos, which spool up faster and create a much smoother power curve with more availible power at lower rpms, as well as greater tourque and power across the whole band. The beauty of this system is that a smaller turbo can also provide similar power gains up high, however the turbo is spinning a good deal faster.
The difference between a Saab and a "modern" turbo design is immediately apparent. You floor the Saab, and nothing happens for several seconds, then the turbo finally spools up and the car suddenly lurches forward. A "modern" turbo gives you a smooth rush of power, starting at around 1500 rpm, and building as the revs increase.
Saab even goes further to compound the inherent problems with their design. Saabs use a computer controlled wastegate, that bleeds off boost under computer command.
Many turbo setups use a wastegate, but most are set up simply to limit boost to a level that will not damage the engine.
Saab takes this a step forward, and basically makes it IMPOSSIBLE to drive the car in a performance aspect.
Saabs bleed off boost under anything other than full throttle. Also, the wastegate opens fully whenever the clutch is depressed.
So lets break down what happens when you accellerate in a saab.
You floor it. The car goes nowhere, as the turbo has not spooled and the 4 cylinder is quite anemic without boost.
After about three seconds, the turbo comes up to speed, and the car shoots forward. In many cases, Saabs will actually lay rubber starting at 10 mph when the turbo hits. This IS a large turbo and it does produce power.
Then redline hits, and you push the clutch in to shift. The wastegate opens, and all the boost bleeds away in an instant. You shift to second, and floor it.
The car once again does not accellerate. For an interminable about of time, you putt in place. Then once again, the turbo hits, and puts you back, but just for a few seconds, as you now must shift to 3rd.
See the problem? This wastegate actuation makes what could be a 14 second car a 17 second one, and the turbo is unspooled more often or not.
Also, this makes the car a pain in the ass to drive daily for somebody not wanting to drive fast.
To the normal person, they accellerate off the light. The car does not accellerate well, so they give it more throttle input. Then the turbo suddenly spools, shooting the car unexpectedly forward, sometimes accompanied by squeling tires.
While working at a Saab dealership, I saw plenty of Saabs with front end damage from hitting somebody. THIS IS THAT EXTREME OF A PROBLEM, that people actually rearend people when the turbo hits.
So you get the best of both worlds. A car that goes slow when you want it to go fast, and a car that goes fast when you want it to go slow."
Opinions please. Though some good points are made I don't think that the lag is THAT noticalbe and will take off when drivin hard.
