Aero mods to VT Commodore (with pics)

[comptiger5000]

Finally, somewhere in the world where people recognize that in pretty much all conditions (yes, including rain and snow), RWD > FWD. The only time I like FWD at all is when drifting on solid ice, where the ability to power up the front end is the easiest way to straighten out (4wd with the t-case locked works too).

[Big Dave]

For Yankees' consumption:

The Commodore was fitted for left-hand drive and got a LS2 engine and was marketed for three years as a Pontiac GTO.

[BLSTIC]

Hmmm... Having driven four interpretations of the same car (moderately powerful family hauler) in 3 configurations (FWD, AWD, and RWD) I would say AWD is best, followed by FWD then RWD. But then again, australian RWD's have an alarming tendency to swap ends at the scent of rain. Pretty unsafe really. But that doesn't change the fact that I'm still thinking of things to do to my alarmingly unsafe in the wet RWD to make it use less fuel.

GTO = Australian Monaro. Based on the VT Commodore platform, similar weights and body style, but superior 2-door body for extra sexiness. One of the few cars that a Straight Man can choose to buy in yellow and not be confused for Gay Man

[BLSTIC]

Just took some photos. There's good and bad news. The front of the car is "really easy to improve upon" and the rear slightly less so. Uploading photos now, I'll add them to the first post and this one when they are up. Oh, and thanks do the exhaust layout, a full undertray might not happen.

*Edit*

I looked under the car and was confronted with this.



Uploaded with ImageShack.us

Behind it is the radiator exit and sump. Like so.



Uploaded with ImageShack.us

In front of it is a hole below the entry to the radiator (this pic taken between the front bumper and that flat plate)



Uploaded with ImageShack.us

And finally the rear of the car. Could deal with improvement. Other side is the same, but less exhaust.



Uploaded with ImageShack.us

So now I need to think about the reason that front deflector is there. I think it's to cause a low pressure after the radiator and a slightly higher pressure in front. A flat cover between the front *should* give less resistance and have a similar effect through sealing the front of the radiator. It may also lower front lift (yay).

The rear, well that's just messy coz it's cheap, but the rough aero shape is there. Time for plastic sheet and duct tape. Oh zip ties. Can't forget zip ties...

[dcb]

one wheel drive is probably most efficient, no differential

[comptiger5000]

BLSTIC - The tendency to spin in the rain can be adjusted for with changes in driving technique and suspension setup on the car (as well as tires, etc). Consider yourselves lucky. Almost all cars sold in America, regardless of drivetrain, understeer terribly unless you either lift off suddenly at speed to induce oversteer, or if RWD, hammer it early in the corner.

[BLSTIC]

I can deal with it, but for the unwary, ham fisted use of the throttle can be deadly. Hell, even a delicate touch in the live axle cars is all that's needed.

Overall the cars handle well though. It's not unheard of for a good driver in one of these to go hunting WRX's up mountain ranges...

[BLSTIC]

Well now I have my materials. Free excess coroplast signage. $3.50 worth of cable ties and $2 worth of Nitto wide flexible tape. One rusty (but still fine) set of tin snips, borrowed. I also bought another pair of hubcaps for the front. These are also factory holden items, but they have an outer surface that is perfectly flat (but has holes. I'll soon fix that) for $10.

So I'm down $15.50 worth of materials so far. Now I just need some polystyrene for wheel blocks, and some really thin plastic for the rear cutoff point...

[saand]

I have the same problems BLSTIC I purchased my car some time ago and didn't even look at the efficiency so here are some things i have done and am thinking about which might work for you
- Wheel covers on your rims
- remove non driver side windscreen wipper, im in australia as well and the roadworth says only single wipper is required on driver side. the VT may have the wippers out of the open airflow so many not be worthwhile for you
- remove side mirrors, roadworthy says only require a rear vision mirror, i drive changing lanes with head checks so never used my side mirrors anyway
- front grill block, if you put one on that is easily removable or can be changed to let some air through you can change it on the fly if your car starts to get hot
- If i was you i would be tempted to remove your rear spoiler and block up the screw holes, gives a bit of down force at the back, not sure how important this is for you
- belly pan, i have not been able to find cheap large coroplast in australia so i am going to try stretching cheap tarpoline see if it holdes up alright
- reduce weight, carpeting, floor matting, and anything in the boot could go. I also removed my AC but if your in the outback probably worth keeping that
- I am thinking of doing a change to manual steering. your VT might have electric assist in which case this would do very little for you
- Can try taping up gaps in panels if you are really getting serious
- antenna remove, replacing with well placed wires in the cabin may give same reception without the drag of the antenna that is in the open air

- I have also seen suggested a general tune can be a good idea depending if your efficiency has gotten worse much since you first started driving the car

- I cant think of much more than that unless you are willing to start changing your engine since yours is particularly large

good luck, i look forward to seeing what works for you and to see if you have any other interesting things i can try as well

[BLSTIC]

It's not that I didn't consider economy, it's that I chose the car that best suited my needs. Which are (and remain) primarily highway driving. Large Australian sedans make large journeys feel like laps around the block. The commodore isn't too bad at fuel economy either, it could just stand to be better.

Cheap real estate sign is available in 2600x1200 for $25 a sheet. Any signwriter should be able to point you to it.

Unfortunately the Commodore has exposed wipers and full time power steering. But I'm not willing to remove either. What I am willing to do however is replace the wipers with low profile flex bladed items when they next need replacing.

Perhaps another thing to try would be a water injection setup. The vacuum operated system on my Legacy GT (while I was in NZ) got about 10km a tank through keeping the engine clean. The catch can probably got similar results for the same reason.