Question for ppl that have done an LS3/Similar swap (1 Viewer)

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Depending on my skinny pedal usage, I have seen as low as 12 mpg and as high as 16.

My 62 is running a 5.3 and 4L60 from a 2003 Tahoe. 4.10 diffs, front and rear bumpers, 35’s
 
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Would probably be a good idea to note whether these swapped power plant vehicles are running the same configuration that they were with a 2F and what the 2F or 3FE engines were getting for mileage. Point being a stock vehicle will turn in one set of numbers but a lifted truck riding on 33's or even 35's and loaded up with racks and bumpers and winches etc will have an impact. So a heavily modded truck might only be getting 15 with the V8 swap but that same truck in the 2F might have seen 8 or 10 mpg. So it would still be an improvement.
 
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That’s a tune up problem, and not normal for the 2F. I always got 15mpg on the highway and 12mpg around town on a stock 2F.


Tried both the lean drop and the aussie FSM idle mix procedure and got similar results for both. My distributor was DUI and and it was fully desmogged. timing was advanced so it was just above pinging. Always ran rich no matter what i did to it I was definitely just wasting gas out of the tailpipe. Had a new aisin carb too, that being said, it had oem jets in it so you might be right on the tuning stuff, I just didnt want to sink any more money into the 2f when i was planning on taking it out anyways. I think a lot of it was the 33x12.5 tires, roof rack, 3.73 gears and extra weight from bumper and sliders. Thankfully all of that stuff is gone like the dodo bird. My 5.3 should be running within the month thankfully. Tuning it to run on 93 octane pump gas expecting about 16 or maybe a little better mpg even with all of the stuff on the cruiser. Dyno tuning is pretty key to these LS swaps. Its kind of crazy that people load a base tune on the ECM and call it good.
 
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WSOPgold2012

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Im at 12-16 highway depending on the incline with my 2F. City is always 12.
see...thats 3/4s my issue...i live at 9500' I cant leave my driveway without an "incline" :rofl: :rofl: :rofl: :rofl: :rofl:


Im also thinkin a NEW, outta the crate LS3 will perform better than a used 2003 Tahoe motor...but, maybe im wrong
 
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see...thats 3/4s my issue...i live at 9500' I cant leave my driveway without an "incline" :rofl: :rofl: :rofl: :rofl: :rofl:


Im also thinkin a NEW, outta the crate LS3 will perform better than a used 2003 Tahoe motor...but, maybe im wrong

You are probably right, but it's all about $$$ and it does add up with a V8 swap. I got lucky and found a drivetrain from a local in Nashville that had engine, transmission, motor mounts, transmission mount, wiring harness, etc... for a great deal. I then used a local hot rod shop to do the install. If I did it again and money was no object I would ship my truck to one of the known cruiser swap gurus and bring a blank check.

My 5.3 has a torque cam and short headers and it blows my old 3FE out of the water, but it definitely drives now like a cop car mixed with a 60 series, LOL. I do sometimes miss the old iron, but it's also nice doing 80 on the interstate purring at 2,100 RPM.
 
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You are probably right, but it's all about $$$ and it does add up with a V8 swap. I got lucky and found a drivetrain from a local in Nashville that had engine, transmission, motor mounts, transmission mount, wiring harness, etc... for a great deal. I then used a local hot rod shop to do the install. If I did it again and money was no object I would ship my truck to one of the known cruiser swap gurus and bring a blank check.

My 5.3 has a torque cam and short headers and it blows my old 3FE out of the water, but it definitely drives now like a cop car mixed with a 60 series, LOL. I do sometimes miss the old iron, but it's also nice doing 80 on the interstate purring at 2,100 RPM.
Man, dont sell yourself short! My LS swap is the first motor swap ive ever done and its actually not as bad as people make it out to be on the internet. Next time if you have the time you should give it a stab! Always pretty fun to push your limits a little bit. Thankfully due to covid i have a ton of time, which was really my main reason i wasnt going to do it myself in the first place. Im over here in memphis but ride mtb out in nashville all the time. Ive got another buddy named Isaac that lives your way with a reallynice 60 as well
 
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Man, dont sell yourself short! My LS swap is the first motor swap ive ever done and its actually not as bad as people make it out to be on the internet. Next time if you have the time you should give it a stab! Always pretty fun to push your limits a little bit. Thankfully due to covid i have a ton of time, which was really my main reason i wasnt going to do it myself in the first place. Im over here in memphis but ride mtb out in nashville all the time. Ive got another buddy named Isaac that lives your way with a reallynice 60 as well

Awesome man. My rig is done and back on the road! Put me in touch with your buddy Isaac…!
 

WSOPgold2012

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You are probably right, but it's all about $$$ and it does add up with a V8 swap. I got lucky and found a drivetrain from a local in Nashville that had engine, transmission, motor mounts, transmission mount, wiring harness, etc... for a great deal. I then used a local hot rod shop to do the install. If I did it again and money was no object I would ship my truck to one of the known cruiser swap gurus and bring a blank check.

My 5.3 has a torque cam and short headers and it blows my old 3FE out of the water, but it definitely drives now like a cop car mixed with a 60 series, LOL. I do sometimes miss the old iron, but it's also nice doing 80 on the interstate purring at 2,100 RPM.
That certainly wasn't a knock on your swap...jus a statement of fact that a NEW LS has to be more efficient than an older unit....just natural for tech to get better. I have ZERO wrenching skills, This is smthn i cldn't ever do, nor trust that it would be done right. I'm fortunate to be able to source it out.
 
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see...thats 3/4s my issue...i live at 9500' I cant leave my driveway without an "incline" :rofl: :rofl: :rofl: :rofl: :rofl:


Im also thinkin a NEW, outta the crate LS3 will perform better than a used 2003 Tahoe motor...but, maybe im wrong
Of course an LS3 will have better performance, goes without saying, but that doesn't always translate into fuel economy. You can have an LS "built" WAY cheaper than you can buy a crate LS3 though. Get a 5.3 and bore it to a 5.7, cam appropriately, find a GOOD tuner, and you'll be super happy. I've done several LS swaps and love them
 
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A LS3 is a car engine. It has a car camshaft. So you really want a engine more ideally built for a truck or SUV. There is a truck version of the 6.2. Unless you need the 6.2 LS3 erod designation for emissions I would look to other LS motors such as the truck version 6.2 or the 6.0. Even the 8.1 if you want monster torque is a option. 5.3 is fine too but skip the 4.8. My opinion anyway
 
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A LS3 is a car engine. It has a car camshaft. So you really want a engine more ideally built for a truck or SUV. There is a truck version of the 6.2. Unless you need the 6.2 LS3 erod designation for emissions I would look to other LS motors such as the truck version 6.2 or the 6.0. Even the 8.1 if you want monster torque is a option. 5.3 is fine too but skip the 4.8. My opinion anyway

But the Car intake looks so much cooler!!
 
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But the Car intake looks so much cooler!!
I have the "car intake" on my LS1, and yes it looks much cleaner. Buy a car intake and put it on a "truck" engine if thats what you like. I did it on the 6.0 I put in an S10 also
 
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I have the "car intake" on my LS1, and yes it looks much cleaner. Buy a car intake and put it on a "truck" engine if thats what you like. I did it on the 6.0 I put in an S10 also
Ive got the truck intake on mine, but plan on running the LS6 intake. The car vs truck intakes are a trade off like you said, they increase HP at the expense of torque. My torque is already double what it was with the 2f so i dont think losing a bit will hurt much. Down the road when i do cam/heads/injectors etc i do plan on running the car intake for sure
 
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Ive got the truck intake on mine, but plan on running the LS6 intake. The car vs truck intakes are a trade off like you said, they increase HP at the expense of torque. My torque is already double what it was with the 2f so i dont think losing a bit will hurt much. Down the road when i do cam/heads/injectors etc i do plan on running the car intake for sure
I GUARANTEE you'll never know the difference in any "lost" torque.
 

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