What kind of MPG's are you guys getting?

[Jolseen]

I want to do the LS1 swap in my 71 c10, and just want to get an idea of the MPG's, cost and power that comes with the ls1 swap.

[69sinker]

I've just driven 1000+ miles (95% highway) in the last 3 days and have averaged 18 mpg.
I have a stock 5.7LS1, 4l60e and 3:73 gears. Average highway speed was 70-80 mph. The best fuel mileage I have ever got is 20 and worst is 16. The old 350 4bbl/ 350 turbo I swapped out averaged 11 and probably had half the hp. I've never met anyone who has regretted an LS swap. Go for it! Dave

[Andy4639]

Mine is a 6.0LS 4L80e with 4:10 gears. I got 16-18MPG last year on the power tour. Depending on if I had the AC on and how much traffic we sat in!

[TwinsSpeedShop]

5.3/4l60e 228r cam and 3k stall converter. I get 16 in town driving and havent really checked hwy. About to do my T56 swap and hope to get closer to 20. Like stated above, i have never met anyone that regretted the swap. If you have to put money into your current setup, put it towards an LS swap of any sorts and you will thank yourself as soon as you take that first test drive.

Good luck with it

[Angryman117]

stock 5.3 in 89 chevy 4x4 with nv4500 and I get 18-20 highway and city driving.

[BR3W CITY]

about 19 hwy through a heavy drivetrain. 14-16 city. Within 1-2mpg as my dd Blazer (s15 style)

[TwinsSpeedShop]

as always, its obvious that manual trans really helps with the MPG's

[Wasted Income]

I never calculate it.

[solidaxel]

I am using Torque Pro and the speed and tach are accurate, so I believe the fuel mileage to be also, and it says I am getting 20 to 22 mpg 5.3/4L60E and 3;42

[BR3W CITY]

Originally Posted by solidaxel

I am using Torque Pro and the speed and tach are accurate, so I believe the fuel mileage to be also, and it says I am getting 20 to 22 mpg 5.3/4L60E and 3;42

Make sure its actually calculating based on the mileage. Lots of the scanners and apps use the injector pulse and guestimate. While in theory it could be accurate, mine never was.

[ls1nova71]

I check my mileage on just about every fill up, I'm kind of OCD like that! Over the last 15k miles ive had the swap done on my truck, I almost always get 17mpg. Thats with a 2004 5.3/4l60e in my 71 swb with stock size tires and 3.08 gears. I was hoping it would get closer to 20 since I hear people say they get that, but mine never does. Even on long highway trips with the cruise set it only does slightly better.

[Marty68]

ls1nova71, do you think your mpg would be better if you had a lower rear gear? say 3.73 or 3.42 is your truck at too low an rpm at 70 and not up in its power range?
i have read that 3.08s with od arent the best. i also have 3.08s and am curious what to expect.

[A1971Blazer]

I've been kicking this around as well. I will be running a stock LS1/4L60E going in my '71 K5.
From the research I've done and advise from other members here......I concluded the same thing, the MPG will be the best if the engine is operating close to it's power range.
By observing various speed/RPM ranges on different vehicles, most seem to be geared to run at around 1700-1900 RPM at 65 MPH.
So by using a gear ratio calculator, I have determined that if I run a 33" tire with the 4L60E overdrive ratio of .7:1........ I will run 4.11 gears. That should give it a lot of low end grunt as well?

go here and plug in your parameters.
http://www.4lo.com/calc/gearratio.php

[ls1nova71]

Originally Posted by Marty68

ls1nova71, do you think your mpg would be better if you had a lower rear gear? say 3.73 or 3.42 is your truck at too low an rpm at 70 and not up in its power range?
i have read that 3.08s with od arent the best. i also have 3.08s and am curious what to expect.

I have thought about it, and think it might help some but not sure how much. . All the other trucks ive built have had 3:73's, but I didnt check the mileage on them as much since I didn't drive them as much either. I would have already swapped it out if my truck didnt have a nice factory installed posi!(There's a problem to have, right? LOL) But on the highway I figured it would do really well, but it just doesnt do as good as I had hoped. It runs down the highway great and doesnt feel like its being bogged down by the tall gear.

[lynnfield]

Just got mine on the road, licensed, taged, and inspected with about 200 miles so far. I haven't figured the gas mileage, but holy crap what a difference. It's a lot of work and well worth it. Greg

You can check out what I did here: http://67-72chevytrucks.com/vboard/s...d.php?t=585899

[cableguy0]

Originally Posted by ls1nova71

I have thought about it, and think it might help some but not sure how much. . All the other trucks ive built have had 3:73's, but I didnt check the mileage on them as much since I didn't drive them as much either. I would have already swapped it out if my truck didnt have a nice factory installed posi!(There's a problem to have, right? LOL) But on the highway I figured it would do really well, but it just doesnt do as good as I had hoped. It runs down the highway great and doesnt feel like its being bogged down by the tall gear.

Just as a test leave the transmission in 3rd gear instead of overdrive on the next trip or turn off overdrive if you have the ability. I bet you get better mileage. Your rpms are super low on the highway with that rear gear and an overdrive. These Ls engines seem to do best with 3.73's and overdrive.

[joeydurango]

'72 4x4, 2.5" lift, 33" tires, 5.3 LM7, 4L60E, 3.73 diff. I get 17-18 everywhere, in town, highway, 50mph or 75mph. Best of all, way fun!

[OneOffStroker]

I got between 17-18 in my '69 Suburban with a 5.3/4L60E and 3.08 gears and 31x9.5-15 tires. I initially figured I'd be in the low 20's, but it was lower due to the high gears. At 55-60 mph it only ran at about 1300-1400 RPM. That was too low to make any reasonable torque, so the engine was working too hard and using too much fuel. With 3.73 gears, you can run 60-65 at 1700-1800 RPM, which would be perfect for cruising power and could probably get into the low 20's on the highway.

Either way, I didn't regret the swap. I actually kept the motor when I sold the Burb so that I can use it in my '57!!

[85burb]

I have a 85 4x4 burb with 4.10 gears 33 inch bfg mud terrain 6.0 with cam, headers, tune with a 700r4 and I do not drive it nice. 2400 stall converter also does not help. I get around 12-13 mpg with mixed city highway. I am very happy with that. My tuner said I have about 425 at flywheel. It was a junk yard motor and for the total cost I have no idea. Worth every penny. Drive it to work every day.

[Clyde65]

I have a 4.8\4l60e with 3.73's in my 12 bolt. I do not drive mine daily, currently have the bed off for rebuild. But, I took it to Abilene a few months ago ( October I think) and went over 300 miles and got 21.3 MPG average. I probably got 23 on the way back, it seems Abilene is up hill to and down hill back. local driving I get around 17/18, mixed.

[Jolseen]

I plan on using my truck as a daily driver.