Blacksix

OK it's 2022 and fuel prices everywhere are horrible, probably here to stay for awhile. I've searched for fuel economy, mpg, mileage threads and most of them are really old. I know most of this crowd historically is not concerned about gas mileage but that will probably change. I can't help thinking that in 20+ years of building LS motors someone has struck upon a great formula for fuel economy. And cam technology has probably advanced also ... I remember the Crane "Econopower" cams of the 70's, no idea what their tech was or if it actually worked, or how it would apply to LS architecture (better heads etc.)

I'm dropping an LM7/4L60e in a 97 Chevy shortbox for running around town, not too concerned about power cause even stock it will be probly be double that of the worn-out V6. The stock V6 setup is clearly tuned for low-end operation as the trans shift points are REALLY low, it's always pretty much lugging around. What cam and intake suggestions do you all have for the 5.3 to maximize MPG in this little 4000lb truck? Or just use the stock cam? My gears are 3.42, could change to 3.08 if that would make much difference? Might hurt with the 5.3 lack of low-end torque.

Discuss.

99 Black Bird T/A

iTrader: (4)

#1 Tip for gas mileage, don't build a full size truck. Heavy plus relatively poor aerodynamics. If one must do a truck a small truck like an S10 is a more MPG friendly candidate.

#2 If MPG matters enough its part of the build criteria, pick something small and light that can have an excellent power to weight ration and be geared accordingly, like a Miata with a 5.3

#3 Limit mods to basic bolt ons like cold air, 85mm MAF, ported 92mm/102mm Fast intake manifold, long tune headers and free flowing dual exhaust, crank scrapper, 25% underdrive pulley, etc get it tuned professionally.

01CamaroSSTx

iTrader: (3)

Best advice I can give you would be to keep it as GM designed it. Getting about 12MPG cruising around in the 01 with the A/C on and the occasional step off into its *** to run someone down or toy with them.

My factor is high though.

theunderlord

Build the lightest vehicle you can find, it's all about tradeoffs. You could build a Turbo'd 4.8L and put it in a S10 or a similar smaller truck and get great MPG's and still have the power on tap to have some fun.

RPM WS6

iTrader: (3)

I'm not really sure it will change all that much. As these cars are 20+ years old now, most are no longer primary daily transportation - as such, MPG isn't a concern on the same level as it might be for a daily driver (which was more typical fare for these cars when they were new/newer). When I think of how few miles I drive my toys annually, even with gas at double the price of last year it still only amounts to maybe $200-300 more per year. That's just not enough to make me rethink anything about a build or an established setup.

But, if you plan to drive it regularly/semi-daily then I can certainly understand the concern, and in that case these are some good recommendations mentioned above:

99 Black Bird T/A

iTrader: (4)

FWIW - on MPG, back in the day my 99 T/A did some daily driver duty and now my 02 Z28 is a good weather daily driver.

99 T/A M6, 3.42 gears, 3500 pound car
Stock to basic bolt on's
323whp 335 wtq
~23.5 mpg my normal driving during the week
~32.5 mpg highway interstate

99 T/A M6, 4.10 gears, 3500 pound car
224/224 cam, TEA 5.3 S2 heads, LS6 intake, 1 3/4 headers, 10%UD ATI, mail order tune
418 whp 404 wtq
~20 mpg my normal driving during the week
~27 mpg highway interstate

99 T/A M6, 4.10 gears, 3550 pound car
416 LS, Magnum, 8.8 rear end, 1 7/8 headers, true dual, 10%UD ATI
517whp 471 wtq
~14 mpg my normal driving during the week
~21 mpg highway interstate

02 Z28 A4, 2.73 gears, 3400 pound car
Stock to basic bolt on's
326whp
~21 mpg my normal driving during the week
~27.5 mpg highway interstate

91 RS M6, 4.10 gears, 3200 pound car
383 LS1, 90mm LS6 intake, TEA S2.5 LS6 heads, T56, 8.8 rear end, 1 7/8 headers, 25%UD ATI
465whp 442wtq
~20 mpg my normal driving during the week
~25.5 mpg highway interstate

Getting the weight down, getting the compression up, keeping the cam small to medium helps with making decent hp and keeping fairly good mpg.

A turbo 4.8 would probably be the best of both the high hp world and good mpg.