Any advice re high mileage Saab 9-5 2.3 Hot Aero?

I have a 2002 9-5 Aero Wagon. My experience (which some here disagree with, but I'm not sure they've driven the US version of the Aero) is that the Aero is a pretty disappointing car.

The HOT engine can crank out an amazing amount of power. The trouble is that it very seldom delivers it when I need or want it.

I've been told by 3 different Saab mechanics that the Aero's turbo is a very large turbo with a lot of inertia. Because it is large, it can pump a lot of air through the engine and deliver a lot of power. But because it has a lot of inertia, it takes a very long time for it to spin up to the point where it gets into that power stage.

In my car, there is a lag of 1.5-2.0 seconds from "hit the gas" to "full turbo power." I've driven 2 other Aeros and they were similar. Doesn't matter how fast you're going -- you can be cruising at 4000 RPM and hit the gas, and the power doesn't fully kick in for over 1.5 seconds. That's a long time to wait for power if you're trying to pass on the highway. It's an eternity when you're trying to dart out of a side road onto a busy street.

Furthermore (again according to the 3 mechanics), because of emission controls, the turbo apparently somehow spins down EXTREMELY rapidly when you let off the gas -- faster than I can shift. (I don't see how this high-inertia turbo can spin down that fast, but it does.) This means that you face the same turbo lag on EVERY shift. Because the car does have some power before it maxes the turbo, and because you accellerate VERY rapidly once you finally spin up the turbo, and because you have to go through the same cycle on every gear, you end up spending VERY little time in the "full power" mode. You spend a lot more time in the "geeze when will this tank finally start moving" mode. It's maddening.

(My car has a 5-speed. I believe the engine may be better matched with an automatic transmission, which would allow the engine to keep torquing more steadily than a manual, but that's a guess.)

You'll also find the Aero has (comparatively) very little power off the line -- the turbo isn't spun up. In 3 years of pretty aggressive driving, I have NEVER ONCE "burned rubber" in my car. It CAN'T. There isn't enough power there, from a standing start, to do it. There's barely enough to get the car moving quickly without choking. Pretty pathetic for a "sporty" car that was advertised to have a ruler-flat torque curve all the way down to 1400rpm. (I test drove a 2003 9-3 once and ACCIDENTALLY chirped the tires several times. After driving my Aero I just wasn't used to that much torque off the line.)

If you spend all your time on a dynamometer -- like the ones they used to generate those torque curves -- then the Aero's engine is a monster. The steady-state power delivery is amazing. It would be terrific if you climb a lot of mountain roads. It's pretty good for highway driving. But if you spend a lot of time driving in town, frankly I think it sucks.

If I'd understood this before I bought the car, I wouldn't have gotten the Aero. I would have gotten the regular turbo 9-5 and probably would have been a lot happier.

Gary

Hmm. Perhaps it's not such a bad idea that Saab/GM has now come up with a new turbo charged 2.8/6 engine with the same power 250bhp.

I was looking at the secs for the HOT engine about a wek ago.

I was surprised to see that although it produces more power than say the 9000 Aero, it's way down on torque.

Not a good configuration imho.

Graham

This is very different from my experience with the HOT engine in a 9-3. The spool-up was rapid enough. It would spin its wheels in gears 1-3 at the drop of a hat. And while it does dump boost whenever the clutch pedal is depressed, it was not too bad coming back up on boost after a shift.

I have a 1998 9-5SE automatic transmission regular turbo (2.3L 4 cyl) and yes, I have spun the tyres with that, accidentally too, and there is virtually no noticeable turbo lag either. You would have been happy with one of those instead of the Aero, I am! (Don't think there was a 1998 9-5 model in the USA - think the first one there was 1999)

--=20 Regards, Peter Wilkins Profanity is the crutch of inarticulate @ssholes

Ok, mine's a 9000 Aero so apples and oranges maybe but I have no problem whatsoever with NOT burning rubber, in fact, if I bury the throttle in

1st even when moving, there's a huge tendency for the tyres to break away and these are Bridgestone S03's so hardly a cheapo high mileage aka. hard slippy tyre.

David.

Any other 9-5 Aero owners want to comment because this doesn't sound right to me?

Agreed. I can understand the "big" turbo on a 9-5 Aero being smaller than similar on say an old C900, but that should make it easier to get off the line.

I know that European C900's got a lot higher compression than US models, which made them a lot more "driveable" off boost, and my new convertible seems perkier than my old '84, so I guess it has the Mistu rather than the Garrett turbo. I wonder if the US 9-5 Aero was a lower compression beasty too, which made it more sluggish

I just recently test drove my friend's 2004 9-5 Aero sedan, but he has the automatic. It did appear that the programmed sport shift mode kept the engine running at RPMs that were more conducive to keeping the turbo spooled up when you got on the accelerator. This also seems consistent with Edmund's recommendation of purchasing the automatic to be able to better take advantage of the 2.3 HOT's peculiar performance characteristics.

Alas, the 2005s are all but pretty much blown out due to the GM fire sale.

-Clint