New in Louisiana - Trans Am

[sjgrimsley]

Hi all,

Figured it was time to sign on and introduce myself. Been lurking here for a while getting ideas for my daily driver.

1982 Trans Am with the typical go-fast parts (heads, cam, intake, exhaust, etc.)
No aero mods yet, but ideas are taking shape. Looking at a more aggressive front air dam, adding tire spats, LeMans style side skirts, full belly pan, and rear diffuser.

I'm not sure what else to add so if you have questions, please feel free to ask.

[mcrews]

Welcome !
Raise the psi in the tires to 40plus.
Get a gauge ( see link in my signature)
Adjust the nut behind the wheel

[redneck]

Welcome,

If you haven't read these, do so.

100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com

65+ Vehicle modifications for better fuel economy - EcoModder.com


If your car is carbureted, a vacuum gauge would be helpful. If injected a MPGuino.

Like mcrews said "Adjusting the nut behind the wheel" will give the best results.



>

[UltArc]

If you're going to do an underbody, don't bother with an air dam. Air dam increases frontal area so the mess underneath experiences less air- if the bottom is totally smooth, then there is no point in increasing frontal area.

[sarguy01]

Welcome!

What is your baseline MPG? What are your goals?

[elhigh]

Wow. Reading your rig's data is more a stat sheet for a weekend strip fighter, not an ecomodder.

406 SBC under the hood, blimey. If you have something smaller lying around and a free weekend, you might want to screw in a mill that's got perhaps a few less cylinders? But that's probably not a viable option.

You could consider reflashing the ECU to something more economy-minded. Your stat sheet indicates you installed the tune that's in there, so coming up with something thriftier should be well within your skill set.

That generation of Firebird was one of the most aero products GM was making at the time, right at .3 CDa if I recall. I don't doubt there are improvements to be made though. Why, for instance, do no manufacturers offer rear wheel skirts even as an option? It's so simple, so obvious.

For my own part, whatever Ultarc says I would second. He's got over 300hp on tap and still knocks out over 40mpg. I don't know precisely what the heck he's doing but he's seriously dialed in on that Mustang.

[JRMichler]

What's the RPM at 60 MPH? Big engine in a small car needs low RPM for MPG. Think down around 1400 RPM and tuned for efficiency at that RPM. And one of those wide ratio six speeds so the first gear is low enough to get it rolling without burning out the clutch.

[sjgrimsley]

Thanks for the warm welcome. I didn't expect replies this soon. Lol

I run the front tires at 36, rears at 32. If I go any higher the ride is hell and the rears wear in the middle of the tread.

I can use a scan gauge it will show as a 2003 Corvette 5.7. But until I upgrade to LS3 injectors with known injector data for the PCM it will show mileage about 4mpg high. For now I check by the odometer. I have verified it with gps.

Point taken on the air dam vs. belly pan. If doing only one, which would make the most improvement?

My baseline average is 21 mpg about 75% highway. Goal is 28. Our '03 corvette coupe frequently knocks down 30-32 mpg in the same conditions. New Z06's frequently do 28 hwy.

The .70 OD and 3.23 rear end have me at 1600 rpm at 55 and 2100 rpm at 70. Planned is a 6L80 auto with .67 OD and 2.56 rear end. More fun and more fuel efficient.

I feel pretty confident with my hypermiling techniques. I took a 2011 Suburban 5.3L from Alexandria to Shreveport and averaged 28.8 mpg. It could have been better I'm sure but this was a bone stock vehicle.

Thanks again for the warm welcome, everyone.

[2000mc]

89 Iroc I had would overheat / make the fans run going 55mph or higher without an air dam. Also the air dam from my the iroc and other later 3rd gens w/ lower ground affects might be larger than the earlier 3rd gens

[sjgrimsley]

Originally Posted by 2000mc

89 Iroc I had would overheat / make the fans run going 55mph or higher without an air dam. Also the air dam from my the iroc and other later 3rd gens w/ lower ground affects might be larger than the earlier 3rd gens

Correct, these cars are bottom feeders. Also GM had two designs for the air dams, a two piece like I have and a revised, more aggressive three piece. If a belly pan is more effective than an aggressive air dam, I will be replacing the one I have with a new one since this one is warped from age.