Aero mods to VT Commodore (with pics)

[Phantom]

I would love to get a rear end form a VT or VX and mate it to my GrandPrix but that will not happen.

If I had that car I would go to www.delcohacking.com and find someone that has the equipment to burn the ECU or start doing it myself. Checkout the address and see if anyone can help program the computer if so you should be able to modify the turn on points for lean cruse and the running duration of it along with shift points. I'm not sure what all is available on the ECU to be edited since it is a OBDI setup.

[Phantom]

Also I did not catch the year of the car but if it is over 7yrs it is probably a good time to replace the O2 sensor they tend to get lazy as they get older and richen the mixture thinking that it is ok. Although the O2 could last longer than the US version since the Aussie version of the 3800 use one O2 per bank and the US gets exposed to both banks for one O2 (I disregarded the post cat O2 since that one does not matter).

[davidgrey50]

ShadeTreeMech - I believe the Holden is a platform-mate to the late Cadillac Catera.

[BLSTIC]

Ahh the benifits of having literally the most sold car in Australia... The computer is known inside and out. Hell, I even know that it takes 150 seconds of 60-120km/h cruising to enter lean cruise mode. I just wish that was more like 10 seconds... The slightest hill knocks it out (according to my fuel consumption display anyway)

It's possible that reducing drag slightly will help it stay in lean cruise longer. That should affect my fuel consumption a lot...

[BLSTIC]

Front Undertray

Centre piece



Side Piece



"Complete" (taped and tied) front piece.



Yes it has a downwards slope. If I was to retain the function of that plate, there had to be. However I don't think that will cause lift, as the air coming through the front is now trapped, airflow should be a lot higher on the bottom of that piece, sucking it downwards enough to cover the slope... It would have been better if I was starting with an 'S Pack' front bar, as they are lower to start with.

Rear to follow...

[BLSTIC]

Rear





I'll have to do something about that lip. The rear section is fine but the transition to the fuel tank is a step. And the RH side needs some kind of cover, it's acting as a scoop.

Preliminary testing (i.e. I couldn't wait and wanted a number) indicates 6.5-7.5l/100km for the short flat sections we have around warwick, and it seems a little quieter. So it's *slightly* better than last time I went on a trip. However more to the point, nothing fell off at 130...

[lunarhighway]

nice job! now you can use this as a mounting point for wheel dams. if you can find some L shaped plastic you can use this to screw the dams to the undertray.. i find that wood screws in coroplast work pretty well.

my tray is at an angle too and i have yet to discover any sign lift with the wheeldams i feel the car has actually become more stable.

my biggest reason fro being enthousiastic about an undertray is when i took it of once, and noticed more roadnoise, and a less stable feel. it also makes for a cleaner engine

[BLSTIC]

I'm not sure how easy it's going to be making front wheel blocks. The track is quite wide compared to the size of the body, and there really isn't much room for them at the front (unless I want them to be painfully obvious).

I'm thinking about how to make them though, and I think expanda-foam might prove to be my best bet. Or at least polystyrene blocks...

[BLSTIC]

Much revised right-rear section





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[galahs]

I read this thread with great interest. I own a VX Commodore and have considered coming up with a way of blocking my upper grill. I think the lower bumper opening on the VT and VX would easily be big enough for effective cooling except if the car is being driven hard (street racing) or towing heavy loads in summer.

I blocked the upper grill of my Corolla and even when driving in the middle of summer with the car fully loaded the water temp didn't increase any noticable amount.

I have contributed to a thread on Aero Drag for Holden Commodores on the "Street Commodores" online forum you might find interesting
http://forum.streetcommodores.com.au....php?t=8554029