saab 9-3 turbo aerodynamic mods-help and suggestions needed!

[320touring]

hi,

I've recently aquired a saab 9-3 like this: Saab 9-3 Aero (2001) with pictures and wallpapers
And i'm looking to modify it to maximise mpg on mainly motorway commutes.
I currently p&g, and have the tyres at 34psi.
However i'm interested in grill blocks/floor pans/aero hubcaps etc. The grill blocks may be difficult as the intercooler is positioned in the middle of the bottom grill-i dont want to block flow to it.

Can anyone give me an indication of the 'top 10' aero mods i can make? Ideally i'd like to get the car to 50 mpg uk (42mpg US) as my daily commute will be that.

The car has a Cd of 0.3 as standard. I hope the pics above let you see areas where improvements could be made.
Thanks in advance for your help
Neil

[Piwoslaw]

I understand it is a turbodiesel? If so, the best combination is to keep the engine hot and the intake air cool.

Block the upper grille first. This will keep the engine warm and help the aerodynamics up front. Maybe put openable blocks on both grilles, like I did?

Next, rear wheel skirts.

If the rear spoiler can be easily detached/attached, then I'd do some testing with and without. If it hurts FE, then use the mounting points to attach a Kammback .

[320touring]

Originally Posted by Piwoslaw

I understand it is a turbodiesel? If so, the best combination is to keep the engine hot and the intake air cool.

Block the upper grille first. This will keep the engine warm and help the aerodynamics up front. Maybe put openable blocks on both grilles, like I did?

Next, rear wheel skirts.

If the rear spoiler can be easily detached/attached, then I'd do some testing with and without. If it hurts FE, then use the mounting points to attach a Kammback .

Hi Piwoslaw,

Sorry- the car is a 2.0 PETROL turbo

[Piwoslaw]

Originally Posted by 320touring

Sorry- the car is a 2.0 PETROL turbo

Well then that's easy: For good fuel economy you want a warm air intake. That means:

• The air intake should be moved into the engine bay, behind the radiator is best,
• You can block your intercooler, or
• Take it off, thereby freeing up the intake flow.

In any case the upper grille can be blocked, while lower should be used to regulate the coolant temperature.

[320touring]

Originally Posted by Piwoslaw

Well then that's easy: For good fuel economy you want a warm air intake. That means:

• The air intake should be moved into the engine bay, behind the radiator is best,
• You can block your intercooler, or
• Take it off, thereby freeing up the intake flow.

In any case the upper grille can be blocked, while lower should be used to regulate the coolant temperature.

thanks for that suggestion!i'd been considering the wai, but dont particulaly want to lose the punch of the turbo-its ideal for low rpm high load pulses..

I'm hoping to have some time to look at the car this weekend- so i can see where to mount rear wheel covers and to see about a grill block.

What sort of gains in mpg would you expect from a grill block?

[Piwoslaw]

Originally Posted by 320touring

What sort of gains in mpg would you expect from a grill block?

About 2%, according to the wiki: Grill block partial or full.

Originally Posted by 320touring

thanks for that suggestion!i'd been considering the wai, but dont particulaly want to lose the punch of the turbo-its ideal for low rpm high load pulses.

If you still want cool air for performance every now and then, then maybe a dual air intake? One warm, one cold, and you choose which is open with a switch. Fuel efficiency: WAI with blocked IC. Performance: CAI plus open IC block. Also helps when the engine starts to overheat.

[320touring]

Originally Posted by Piwoslaw

About 2%, according to the wiki: Grill block partial or full.


If you still want cool air for performance every now and then, then maybe a dual air intake? One warm, one cold, and you choose which is open with a switch. Fuel efficiency: WAI with blocked IC. Performance: CAI plus open IC block. Also helps when the engine starts to overheat.

thanks very much for the info.

I was thinkin gof blocking the grill by both the foglights and leaving the IC intake clear..

However, what you're suggesting could be possible.

I vould make a vent flap that opened automatically when I switched to the Cold Air intake. this would give me more power and allow me to switch back to WAI when needed.

Do we think anythng could be done Air dam or sideskirt wise?

I'm hoping to identify mount points when I get a look under the car at the weekend- any design tips would be great!

Neil

[lunarhighway]

according tot wikipedia your version has a bodykit that lowered drag over stock... i think the Cd for that car was 0.28 but i could be mistaken. and some winder tires and a bigger engine with slightly less grillblock could send you back a little...all in all the aerodynamics of most details are pretty well sorted. so i'd be carefull with to extreme mods.

what you could do is a grill block, i'd keep it simple, see how hard it is to get the grill unbolted and put something behind it, make a vertical slot in it if more cooling is needed... keep in mind that something you could get away with in winter might not work in summer, but if you make it so it can be pulled out quickly no need for fancy mechanisms. (always cool if it does work, but sometimes simple less perfect things get actually done while perfection remains a dream)

next i'd recomend an undertray if there isn't one. try covering the area before the front tires and perhaps between then over the engine bay... the underside should be realatively smooth . than i'd do tire dams, front and rear wheels. (if you make them light you can glue them onto metal bits with construction glue, no drilling required) look at oem setups and don't make them to big dams that are to small will still reduce drag, dams that are to big will add drag

warm air intake is a real good thing... if you have a cold/warm air intake valve in the airbox you can make an incert that prevents the wai from closing fully... you'll get warm air all the time.. you'll se FE go up and power go down! it's a trade of but you have a big engine so the car should remain more than drivable with a few horses left!, plus a good drivestyle will make up for them. i'm flirting with 40 since i have it but i think the post holliday traffic and winter well put an end to me FE rise... i will keep an eye on how the wai affects my winter milage wich is traditionally bad.

[Piwoslaw]

One more thing came to mind: Unless it's already OEM, put a piece of plastic or aluminum between the lower and upper grilles in such a way that the intercooler is isolated from the radiator. That way you can block the rad without it getting spoiled by the cool air from the open IC block.

[320touring]

Piwoslaw thanks for the idea regarding the intercooler-i hadnt figured on airflow there but you make a valid point.

lunarhighway- interesting info you gave there! Most of my research suggests Cd as 0.3, but the car appeaars to roll as well as the Cd 0.28 Avensis I was using previously.

The underbody panels are something I'm definately interested in- the WAI will need investigation to figure out where it could be routed.

Thanks!