Fuel millage

[L31MaxExpress]

Hmmm I thought GM switched to Vortec in 96 or is this a Canadian thing?

Mexico had the 350 TBI until atleast 98. They also had a port fuel injected 250 I6 dubbed the 4100 down there. US market had a Vortec head TBI in 96 as well. Vortec boats were TBI into the 2000s as well. When Mexico switched to the GMT800s they also kept the 350 Vortec. I have driven a factory built GMT800 based 2002 Tahoe with a L31 5.7/5spd. I also have a Blue/Green 1 meg GM tune file for a 2006 350. The only emissions system enabled was canister purge and vent. No EGR, no Cats, and no rear 02s.

I know Canada also had standard 4bbl Q-Jets all the way through our dreaded feedback carb years.

 

[sbnova]

1988 RCSB, 350/ 5-speed and 3.08's. Rear tires are 275-30-20's. I got 19mpg at the highest from central Florida to Houston Texas, the worst was like 17mpg, all highway. Stock engine, K&N in the stock filter housing, stock exhaust manifolds with a modified factory Y-pipe that exits to 3", no cat, and 3" mandrel bent full exhaust with a 2 chamber flowmaster.

 

[kennythewelder]

Im glad to see all of the responces this thread is getting. Thanks guys, and keep them coming.

 

[DerekTheGreat]

Mexico had the 350 TBI until atleast 98. They also had a port fuel injected 250 I6 dubbed the 4100 down there. US market had a Vortec head TBI in 96 as well...

That straight six sounds nifty. Where could find Vortec headed TBI stuff in the US, vans?

 

[7thdarkangel]

1988 K1500 RCLB. 406ci engine, 700r4, 3.73 gearing 3 inch body lift, 35x12r15 Micky Thomson MTZ tires. Getting an impressive 7.9 MPG highway, and 6.5 MPG local driving.

 

[fancyTBI]

That straight six sounds nifty. Where could find Vortec headed TBI stuff in the US, vans?

I believe the G vans had vortec heads with a TBI intake.

 

[Jglew82]

1990 ECSB C1500

LQ9 .020 bore
TSP 216/220 .550/.550 112 LSA
Gen 4 intake and Flex Fuel injectors
Long Tubes with high flow cats, custom Y-pipe into 3" Flowmaster 70 series
Built 4L65e
stock 3.08 10 bolt
Stock ride height
265/70/15

Still working out kinks, with a lot of in town test/tune and commute mixed with driveway idling - 12.5mpg so far (slightly lower than actual due to uncorrected speedo). Hopefully I'll get some good highway data soon!

 

[Gibson]

'97 Sub K2500, 265x75x16s, 4.10, 350 Vortec.
One time only; a 300 mile trip, flat/level/no wind, set the CC at 58, got 16.4,, increase speed to 65 and mileage drops to ~15 for a steady cruise.
Normal mixed driving runs ~11>13 ,, it's the stop-an-go that kills mileage on a heavy vehicle.

 

[evilunclegrimace]

1998 K1500 Suburban 3.73 gears 4l60E. 15.7 MPG all in town

 

[Trenton]

'97 K1500 4x4, 350 cubic inch TBI, 87 octane, everything stock just like it came from the factory in Canada. I like a quiet truck, so it's staying that way, at least for now. (I'm of the "If it ain't broke, don't fix it" school of thought.) Also has 17 inch rims and tires in place of the original 16 inch items.

City driving at 5,200 feet elevation = 13.1 mph.
Combined highway/city at 5,200 to 7,200 feet = 15.3.
I'll know the highway mileage after a vacation trip in October from Albuquerque to Estes Park, Colorado and back.

Where at in Colorado? I live here too.