Recently my motor ate one of the crankshaft bearings and messed up one the crankshaft. With some of the other issues i've been having with it I have decided to do a engine swap on it. I had a few questions that I was hoping to get answered, this is DD and mainly sees highway city driving. I don't do any aggressive wheeling just dirt and gravel roads. First question is which would be better the 6.0 or a 5.3 LS, mainly would a 6.0 swap get better MPG than the 5.3. I know it would get more power but it doesn't really seem like the extra power would make a massive difference compared to the 2f. Second question is would there be any benefit in doing the 6l80 over the 4l60, I know it gets two extra gears but the final overdrive is only around .04 ratio difference. How I see it is that the 6l80 requires alot of extra work and effort for very minimal payback. Lastly would be what is the realistic expectation for MPG, assuming only a front bumper and 33's?
LS swap question (1 Viewer)
- Thread starter mrtullis
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let ya know in 6-8 months....
First question is which would be better the 6.0 or a 5.3 LS, mainly would a 6.0 swap get better MPG than the 5.3. I know it would get more power but it doesn't really seem like the extra power would make a massive difference compared to the 2f.
The 5.3 would get better mpg. However a large part of fuel economy is determined by who you have tune it. If your going to tow more at higher elevations here n there a 6.0 may be the way to go. Best mpg I typically get on the highway with my 6.0 is 14mpg with my 80 series. A 5.3 should get better mpg than a 6.0 by 1 or 2 mpg. A 6.0 will be more fun.
Second question is would there be any benefit in doing the 6l80 over the 4l60, I know it gets two extra gears but the final overdrive is only around .04 ratio difference. How I see it is that the 6l80 requires alot of extra work and effort for very minimal payback.
The LS motors make their power from 3krpm and higher. The more you can keep the rpms in the power band the less the motor will have to lug. With a 6L80 you will get better take off acceleration and keep it in the power band as gears are shifted. If you can afford the 6l80 go for it. If you can't than go with a 4l60 or 4l80. The 4l80e does create a bit more power loss AFAIK and will reduce fuel mileage slightly, maybe less than 1mpg. 6l80 should increase fuel mileage slightly by like 1mpg I'm guessing.
Lastly would be what is the realistic expectation for MPG, assuming only a front bumper and 33's? 11-15mpg
- Thread starter
- #5
Thank you all for the responses and helping set some realistic expectations for me. I was reading some threads where people were claiming high teens to low 20's and I think that was getting my hopes up to much. I will probably just look into rebuilding the motor since it seems like that is going to be the more cost effective method, and also get the rig running sooner. Again I would just like to thank you all for the responses I really appreciate everyone taking the time.
tmxmotorsports
SILVER Star
I've seen 12 to 18 mpg in 60 series ls swaps with nv4500 6.0 cam swapped 4l80e lq9 no cam swap
I'm in almost the same situation as you, will be following
I went with the 5.3 4L60 combo for a few reasons.
1. 6.0 engines are getting harder to find and more expensive, same with a 4L80, fuel economy difference is negligible
2. In a Cruiser you are doubling the power doing the swap so either one is a blast
3. The 6l80 is hard to source and more expensive
As a side note I'm swapping a true LS1 (aluminum 5.7) and 4l80 into my wifes '85 60 series as we speak.
Fuel economy wise these things are a brick flying down the road, so don't expect miracles, likely to be around 15mpg. The drivability you gain is priceless, being able to go 80mph like its nothing
1. 6.0 engines are getting harder to find and more expensive, same with a 4L80, fuel economy difference is negligible
2. In a Cruiser you are doubling the power doing the swap so either one is a blast
3. The 6l80 is hard to source and more expensive
As a side note I'm swapping a true LS1 (aluminum 5.7) and 4l80 into my wifes '85 60 series as we speak.
Fuel economy wise these things are a brick flying down the road, so don't expect miracles, likely to be around 15mpg. The drivability you gain is priceless, being able to go 80mph like its nothing
The ways to optimize mpg:
1 5 speed
2 Fj60 diff ratio
3 low rolling resistance tires….skinny and tall
4 keep speeds below 60
5 use the tallest gear possible for cruising and keep revs down.
6 doing all these steps will insure the best mpg while also insuring the least exciting driving experience.
1 5 speed
2 Fj60 diff ratio
3 low rolling resistance tires….skinny and tall
4 keep speeds below 60
5 use the tallest gear possible for cruising and keep revs down.
6 doing all these steps will insure the best mpg while also insuring the least exciting driving experience.
You forgot to mention.....buy a Prius instead
That’s another way to say #6
my scangauge says 15.5 mpg average with my lm7 swapped 60 with 4l60e. And i have a really heavy right foot. This is with a base tune from my tuner too. When i get it on the dyno, i am going to tune the first 70% of my pedal stroke for economy and the last 30% to be full Wide open tune to maximize power and not conserve fuel. After doing this swap, youll be fine with a 5.3 or 4.8. It is way way way way more power than anything you are used to in your 60. Im getting 15.5 mpg with 33x12.5 MT tires with 3.73 gearing in the diffs all in city. I just got the swap done so i am still very heavy footed
That being said, i went with a LM7 gen 3 just because it was cheap. I am planning on buying an iron 6.0 block to build up from scratch over the next few years. Going to bore it out to 4.065 to build a Iron block 6.2 LS3. Same stroke, bigger bore with lighter weight pistons. This way i can do cam/ported heads/rectangle port intake/fuel rail and injectors/etc all while still driving my truck. The LM7 definitely is enough for the fj60 though. I have just always wanted to build a LS from the ground up. Looking for like 550-600 HP NA. Will probably switch up to the 6l80e and use a standalone harness for it to work with the Gen3 motor and pcm. This is all years away but thats the plan at least
That being said, i went with a LM7 gen 3 just because it was cheap. I am planning on buying an iron 6.0 block to build up from scratch over the next few years. Going to bore it out to 4.065 to build a Iron block 6.2 LS3. Same stroke, bigger bore with lighter weight pistons. This way i can do cam/ported heads/rectangle port intake/fuel rail and injectors/etc all while still driving my truck. The LM7 definitely is enough for the fj60 though. I have just always wanted to build a LS from the ground up. Looking for like 550-600 HP NA. Will probably switch up to the 6l80e and use a standalone harness for it to work with the Gen3 motor and pcm. This is all years away but thats the plan at least
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Just turbo your 5.3 and make that power with 1/3 the cost
Yeah was looking at the vortech belt drive sc kit. They run low boost with out an IC. I would lose my fancy fj62/fzj80 airbox though
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or you could do a $400 turbo
Not really much room in there for the IC is the main thing
NCFJ
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Sounds like a very solid plan. Sometimes it is far more about the doing, like building a motor from the ground up, than it is about doing it on the cheap. I have not built a motor from the ground up since my Austin Healy days, sold my last Healy in 1983
Once I have a clean room that I can leave things sit in building a motor becomes more of a reality. Perhaps for my wife's Mercedes build. 500-600 HP and a Tremec 6 speed in a 3600lb Merc 360SL would certainly be entertaining.Building a motor is the dream, then I see I can get the same power out of mine with a turbo hahahSounds like a very solid plan. Sometimes it is far more about the doing, like building a motor from the ground up, than it is about doing it on the cheap. I have not built a motor from the ground up since my Austin Healy days, sold my last Healy in 1983
You could build a 408 out of a 6.0 rather than turn it into a 6.2. Would have quite a bit more torque. Just an idea anyway. Probably would be similar in cost too.
Nice! I’ll have to research that. I’ve always wanted to build up a LS motor my dad and I built a 383 stroker SBC for his firstgen Cameron back when I was in high school and it would be cool to do it with a modern fuel injected motor. The more I look into this turbo though the more tempting it is. I’ve got plenty of room now that I’m running EFans, but the intercooler is the big hurdle. Turbine noise would sound pretty cool! Haha
