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Old 12-25-2013, 06:04 AM   #1 (permalink)
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Suzuki Swift Aeromodding - my thoughts

Hey guys, I just bought this brand new




Facebook Picture of my baby bonus points, identify my other car with the Dominos Cartop on it

It's a 2013 Suzuki Swift. You can see the mileage in my signature, but its first three fills are averaging 7.1l/100km (33mpg us). That's around town doing pizza deliveries with the a/c blasting and only the most basic of eco driving (in gear coasting with injector cut-out, changing up at first opportunity). However this tank was done almost entirely without a/c except where it was for safety or sanity reasons (i.e. forced to park in sun, driving in full sun with little ambient breeze. Or raining when you need it for defog in the tropics) and I'm looking at getting 5.5l/100km

But on to the point, the clued on of this list are going to think the same things I did...

Oh my what big wheel arches you have... (the better to suck fuel with)
Oh my what bumpy wheels you have (the better to pull air with)
Oh my what a short spoiler you run (you get the point)

Plus there are those fake fog light/intakes which are in fact neither, so could be smooth.

Not shown in the photos due to angles is that the rear wheel arches are almost vertical (so the cover can be nearly flat), and also due to the hatch metalwork (you can't see it because of the wrap around black glass on the hatch hiding the true size of the vision opening) I can actually extend the c-pillar airflow surface back about a foot without affecting rear visibility at all. So between that and the roof extension I can probably drop the area at the rear cutoff by 10% or so.

I haven't properly inspected the underside of the car but given that it's a cheap car ($15500 drive away when a mirage is $12000) it's likely that I can do a small amount of improving.

So:
Rear skirts
Fill in front arch gap
Flat hubcaps
Smooth out fog light holes
Partial boat tail/kammback (rear area reduction)
Undertrays front and rear

The first four are going to be easy to build and easy to test. The last two will require a bit more effort and will be tested separately.

Any guesses on what results I'll get in terms of drag reduction and fuel economy?

Note that fuel economy testing will be difficult, the highway design and landscape in my area kills my chances to just set cruise and let go for 5 minutes. Coast down testing though, I have a place for.

Of course if the damn things work it means I have build them properly out of decent materials. Damned if I leave real estate sign that's been used as a paint testing platform on my wheels for more than I have to...

Thanks
Ben

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Old 12-25-2013, 11:19 AM   #2 (permalink)
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Originally Posted by BLSTIC View Post
Facebook Picture of my baby bonus points, identify my other car with the Dominos Cartop on it
I just Googled "tiny ute". Too easy. (I won't spoil it for anyone who wants to make a genuine effort.) . Funny, I'd heard of them before, but hadn't seen one.

Quote:
So:
Rear skirts
Fill in front arch gap
Flat hubcaps
Smooth out fog light holes
Partial boat tail/kammback (rear area reduction)
Undertrays front and rear
I'd also add: air dam. May be more effective depending on how smooth you're able to get the underside, plus it's far easier to make/fit than undertrays.

Quote:
Any guesses on what results I'll get in terms of drag reduction and fuel economy?
If you did all of that, my W.A.G. is 4-6% better economy at 90 km/h.
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Old 12-25-2013, 07:07 PM   #3 (permalink)
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Well if it gives enough of a drag reduction at 100kph to make up for running the a/c, I'll be happy...

I just wish the highways in Australia weren't so speed limited. If the roads were limited to 140kph as opposed to 100 I could probably sell a product like this. I mean who wouldn't want to use less fuel and have higher top-end acceleration? And on a car like the swift with a mere 70kw at its disposal I would expect that the difference in performance would be pretty big (although the standard car can make 180kph apparently... I'm gonna go consult our charts to see what cdA that relates to)
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Old 12-25-2013, 07:38 PM   #4 (permalink)
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I just ran some 'stuff it I'll guess until I get the right economy' numbers in our charts. If I work with a drag co-efficient of .32 and put in vehicle weight of 1008kg (factory kerb weight) it pumps out 5.8l/100km at 105kph and 10.02 @ 145. Total hp required at 145 is 36hp.

Dropping drag to .288 (10% reduction) gives me 5.33l/100 @ 105, 9.14 @ 145 and hp at 145 as 32.9.

If I were to market it as a 'performance increase' that gives me a 3hp gain at 145kh. Or from 57hp remaining to 60. A gain of 5% at that speed, which would not be enough to feel.

Trying to market it as a performance increase would require a reduction in drag of 20%. That would bring road hp at 145kph down to 29.7 for a 6hp gain. But dropping drag by 20% is no mean feat with ad-ons that don't aesthetically alter the car dramatically.

Anyway I'm going to run those numbers again when I get home and have a chance to hunt down the cars actual aero data
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Old 12-26-2013, 06:24 PM   #5 (permalink)
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Swift

Primarily,what kind of driving will you be doing? Drag reductions will show very low returns in an urban setting.
If, however,you'll do a significant amount of constant-speed highway cruising,then the aero mods will definitely be in their element.
Also,you need an accurate mpg baseline created at the highway velocity you'll be driving or else we'll never be able to predict a thing,nor have anything to compare to after mods are in place.
--------------------------------------------------------------------------
Some parametrics which are of interest:
*Coefficient of aerodynamic drag (if published)
*Projected frontal area (if published)
*Length
*Width
*Height
*Ground clearance
*Highest point on roof when there's 300-pounds of weight in the car
*Widest point of body when looking down from above.
*Degree of underbody 'roughness' compared to a smooth belly
-------------------------------------------------------------------------
Any meaningful drag reduction will come from the aft-body of the car.Thule makes a 1-inch receiver hitch for bicycle carriers which could form the anchoring point of a removable tail section,snugged by tension straps.
If you're looking to really cut drag you'll need to think in this direction.
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Old 12-26-2013, 06:31 PM   #6 (permalink)
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How much of your driving is on the highway, rather than deliveries around town ?

Around town, the benefits of aeromodding won't be huge.
The effect of using AC full tilt in city driving can be massive.
I've seen it as bad as 50% extra fuel consumption - and we get nowhere near Ozzie temps in summer.
When you're doing 100kph, the effect of AC on fuel consumption is quite limited.
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Old 12-27-2013, 08:07 AM   #7 (permalink)
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I'm aware that, unfortunately, aeromodding won't actually do me much good on my car (if I make a bicycle faring however...). My main purpose isn't to save money though, the main purpose is to prove to myself that I can, and to properly document the process for others.

It kind of sucks that I don't do much highway driving (in fact in this car I simply haven't been outside the city limits). But as I said before, this is a 'just coz' thing.

But anyway I looked under the car. There's clear evidence of aero development. A rubber lip hangs down under the car across the full with of the radiator. The bumper comes all the way back to meet this panel and the wheel spats (deflectors, whatever you call them). The front grill opening is more or less sealed to the radiator/condenser, and as you can see, that's some huge-ass openings in the grill.

The rear leaves more to be desired though... As does the mid section, but it looks decidedly easy to panel over. No Tailshaft, exhaust down the trans tunnel. Panel each side of the exhaust. Wham Bam Thankyou Maam. I suppose according to the volvo paper the front wheels are the largest contributor on the underside, so at least they sorted that one...

I would like to modify to increase fuel economy around town, but without majorly intrusive driving style changes and obviously-piss-off-the-dealer mods I'm limited to what I can do.
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Old 12-27-2013, 08:17 AM   #8 (permalink)
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About the only thing I could think of for around town mods are lightweight wheels, a free flowing exhuast, and computer tuning to keep the injector cut-off operating down to 1000rpm with the a/c on.

Other than that... It's already got a fairly small engine (1.4 litre, dual vct), manual, electric power steering, kerb weight of around 1000kg. Ambient temperature up here is 30-40 degrees centigrade above the road anyway, so even 'cold' air induction is warm.
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Old 12-27-2013, 06:15 PM   #9 (permalink)
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prove

The information which exists in the public domain suggests that if the Swift is like the Chevy Spark (Cd 0.326) that if you fully tricked out the car,aerodynamically,that you could see in the range of 49.4 mph HWY if your actual highway mpg turned out to be the EPA rated 38 mpg as your starting point.
You'd do better than this in the city if it weren't for the cold-starts,cold restarts, yields,stops,traffic lights and congestion.
A hybrid would recover some of the lost energy as you know,at roughly twice the selling price of the Swift.
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Old 12-27-2013, 06:25 PM   #10 (permalink)
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The swift is the next size up in cars. Not by much, but in Australia the spark is seen as a competitor to the Mirage, which is decidedly smaller and more economical than the swift.

Although one nifty trick up the sleeve of the swift is that it warms up really fast. I mean it lets me do the injector cut thing within a minute of starting, it's showing full temperature within a 4 minute drive (my daily commute). And it retains temperature for just as excessively long. It makes stop start driving that much more economical I suppose...

But Hyundai i20 vs Suzuki Swift | Auto Express points at the drag coefficient being 0.32...

Anyway time to be off and go visit lakes full of bikini clad ladies. Or maybe they aren't clad with bikinis...

I can only hope

Catch you guys later

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