What kind of MPG's are you guys getting? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jolseen · 02-11-2015, 08:14 PM

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 · 02-11-2015, 09:31 PM

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 · 02-11-2015, 09:51 PM

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 · 02-11-2015, 09:58 PM

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 · 02-11-2015, 11:07 PM

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

BR3W CITY · 02-12-2015, 01:06 AM

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

TwinsSpeedShop · 02-12-2015, 07:53 AM

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

Wasted Income · 02-12-2015, 11:07 AM

I never calculate it.

solidaxel · 02-12-2015, 06:53 PM

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 · 02-13-2015, 01:35 AM

Quote:

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 · 02-13-2015, 03:15 AM

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 · 02-13-2015, 08:00 AM

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** · 02-13-2015, 08:41 AM

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 · 02-13-2015, 10:10 AM

Quote:

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 · 02-14-2015, 02:07 PM

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 · 02-14-2015, 05:11 PM

Quote:

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 · 02-18-2015, 11:03 PM

'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 · 02-20-2015, 07:10 PM

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 · 02-21-2015, 10:54 PM

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** · 02-23-2015, 11:10 AM

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 · 02-23-2015, 02:23 PM

I plan on using my truck as a daily driver.

02-11-2015, 08:14 PM	#1
Jolseen Registered User Join Date: Jun 2007 Location: Texas Posts: 4	What kind of MPG's are you guys getting? 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.

02-11-2015, 09:31 PM	#2
69sinker Registered User Join Date: Nov 2012 Location: eldred,il Posts: 503	Re: What kind of MPG's are you guys getting? 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 __________________ My 69 cst lwb 2wd LS1 swap 5.7/4L60e build http://67-72chevytrucks.com/vboard/s...d.php?t=589869

02-11-2015, 09:51 PM	#3
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: What kind of MPG's are you guys getting? 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! __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-11-2015, 09:58 PM	#4
TwinsSpeedShop Registered User Join Date: Mar 2014 Location: Easley SC Posts: 150	Re: What kind of MPG's are you guys getting? 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

02-11-2015, 11:07 PM	#5
Angryman117 Registered User Join Date: Jul 2013 Location: VAFB, CA Posts: 227	Re: What kind of MPG's are you guys getting? stock 5.3 in 89 chevy 4x4 with nv4500 and I get 18-20 highway and city driving. __________________ Angryman117's 47 Chevy Build 89 Silverado Z71 LS Swap (sold)

02-12-2015, 01:06 AM	#6
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: What kind of MPG's are you guys getting? about 19 hwy through a heavy drivetrain. 14-16 city. Within 1-2mpg as my dd Blazer (s15 style) __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

02-12-2015, 07:53 AM	#7
TwinsSpeedShop Registered User Join Date: Mar 2014 Location: Easley SC Posts: 150	Re: What kind of MPG's are you guys getting? as always, its obvious that manual trans really helps with the MPG's

02-12-2015, 11:07 AM	#8
Wasted Income Boosted Member Join Date: May 2002 Location: Mackinaw, IL Posts: 2,200	Re: What kind of MPG's are you guys getting? I never calculate it. __________________ 1972 2wd K/5 Blazer Turbocharged 370 LSx - 941 rwhp / 1093 rwtq 1969 Chevy K-10 L33 5.3 / 4L80E / NP241 / 4" lift 1964 Buick Skylark Twin TURBO 383 LS pro-touring project 2014 VW Passat TDI - Daily Driver Turbo diesel 2015 Sierra Denali HD Duramax Turbo diesel 2016 Ford Explorer Sport - Twin Turbskis 2017 Polaris RZR Turbo 2014 Nor-Tech Center Console - Twin Supercharged Outboards *TURBO ALL THE THINGS!!*

02-12-2015, 06:53 PM	#9
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: What kind of MPG's are you guys getting? 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 __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42

02-13-2015, 03:15 AM	#11
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,118	Re: What kind of MPG's are you guys getting? 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. __________________ My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html

02-13-2015, 08:00 AM	#12
Marty68 Registered User Join Date: Nov 2014 Location: west coast, Wi Posts: 534	Re: What kind of MPG's are you guys getting? 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.

02-13-2015, 08:41 AM	#13
A1971Blazer Senior Member Join Date: Nov 2013 Location: East Tennessee Posts: 2,109	Re: What kind of MPG's are you guys getting? 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

02-14-2015, 02:07 PM	#15
lynnfield The Waco Kid Join Date: Oct 2009 Location: Waco, TX. Posts: 1,781	Re: What kind of MPG's are you guys getting? 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

02-18-2015, 11:03 PM	#17
joeydurango Registered User Join Date: Dec 2013 Location: Durango, CO Posts: 809	Re: What kind of MPG's are you guys getting? '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! __________________ 1972 K10 Cheyenne Super \| LWB, fleetside \| 350/350/205 \| KEEPER 1971 K10 Cheyenne \| SWB, fleetside \| LS Swap 5.3/4L60 \| SOLD 1976 Trans Am \| 400/4-spd \| SOLD 1976 Trans Am \| 455/4-spd \| TOTALED

02-20-2015, 07:10 PM	#18
OneOffStroker Registered User Join Date: Jan 2012 Location: Virginia Beach, VA Posts: 282	Re: What kind of MPG's are you guys getting? 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!! __________________ 1972 C10 "Shop Truck" Build - EFI, 5-speed, Posi, and Patina http://67-72chevytrucks.com/vboard/s...d.php?t=834292 1957 Chevy pickup - Twin Turbo 5.3/NV3500, Jag IFS & IRS, AirRide http://67-72chevytrucks.com/vboard/s...d.php?t=606987 Check me out on YouTube - "Tiny Garage Fabrication" http://www.youtube.com/oneoffstroker



Register or Log In To remove these advertisements.

02-21-2015, 10:54 PM	#19
85burb Registered User Join Date: Dec 2009 Location: lindale,tx Posts: 2,373	Re: What kind of MPG's are you guys getting? 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. __________________ 82 c10 5.3/4l60 84 c20 5.3/sm465 85 chevy k10 suburban LQ4/4l60 91 chevy c10 suburban Lsa 5.3/4l60 2017 Silverado whipple 5.3 1964 Vw beetle 1974 vw beetle

02-23-2015, 11:10 AM	#20
Clyde65 1965 Chevy C10, 2005 4.8L/4l60 Join Date: Aug 2004 Location: DFW Texas Posts: 8,539	Re: What kind of MPG's are you guys getting? 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. __________________ Clyde65 Rebuild of Clyde http://67-72chevytrucks.com/vboard/s...84#post8338184 69 Aristocrat Lo Liner build http://67-72chevytrucks.com/vboard/s...84#post7561684 *support our troops!*

02-23-2015, 02:23 PM	#21
Jolseen Registered User Join Date: Jun 2007 Location: Texas Posts: 4	Re: What kind of MPG's are you guys getting? I plan on using my truck as a daily driver.

Register or Log In To remove these advertisements.