17.8 calculated MPG on last tank...Meh

[454GrandPrix]

Ironically (?) both of my big blocks get virtually the exact same economy, which is 11-12 in typical day-to-day driving.

Vehicle 1: 1980 Grand Prix, 454, FiTech EFI, 4L80E, 3.55 axle ratio, 26.1" tire, 3700 lbs
Vehicle 2: 2001 Suburban 2500 4x4, 496 (Vortec 8.1L), 4L80E, 4.10 axle ratio, 30.5" tire, 6500 lbs

 

[81cutlass]

My 2+2 gets like 22 mpg highway.

6.0 LS, cam, long tubes, blower, t56, 3.73

Less in town.

 

[pontiacgp]

My 2+2 gets like 22 mpg highway.

6.0 LS, cam, long tubes, blower, t56, 3.73

Less in town.

just wondering with your second OD at .50 what are you reving at around 60-65 with the 3.73 rear end?

 

[Wageslave]

350 Vortec heads, TBI, and a cam with a TH200 with no lockup and 2.41's- 15mpg

17.5 with an overdrive 5-speed.

At least it goes fast...

 

[81cutlass]

just wondering with your second OD at .50 what are you reving at around 60-65 with the 3.73 rear end?

It went 80 at 2k with 275/40/18's, I went down to 275/40/17 and it's a bit higher now.

I think about 1750 at 65 if I remember right. Honestly it lugs too much at 55 in 6th and hills so I run it in 5th.

 

[AZRegal]

I took the cutlass on a 500 mile road trip this past weekend. This was the first long haul since the LS1 swap. 75 to 80 mph for the most part. Using the googlator to measure distance and filling the tank until it puked out the filler hole i was getting 22 mpg. Stock tuned ls1, 4l60e, 3.42 gears and a 25 inch tall tire. 22mpg and enough torque to climb hills and pass people effortlessly when needed. I like it.