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Of course it's fast
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Discussion Starter · #1 ·
I've been planning my ls swap for my car but I'm having second thougbts because of costs, plus I need to get the car drivable before summer. So I had the idea of swapping the heads and intake from a vortec or tbi engine onto my current short block. It runs fine but I really want efi for the reliability and mpg's. Will I gain any significant fuel economy from this? I'm hoping for at around 18mpg in the city. Is that number acheivable. It will be backed my a muncie 4speed and I haven't chosen the rear gears or tire size yet so I can pick whatever will be best.
 

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Lt4 is the easy swap lt1 is ok as well. Still cost a pile but will not as much as ls. I fought with this when i was building my 89 vette. I ended up with dumping the efi since it was crap and couldnt be fixed for less than full on replacement of intake injectors and computer and since my car has 300k miles on it the wiring was shot as well. But you may be able to source and lt swap alot cheaper. I would cruise all the local junk yards and ask if the have swaps with engine trans and computer/wiring harnes sensors and all assesories. It is not un common to find these now a days since engine vary so much from model to model its not always a guratee it will work without the computer it was born with, so some mechanics insist on a a full setup just in case even for customer work since even a different injector can killl the engine replacement. And have the mech working for hours extra hes not getting paid for. Ask for a good price what ever they say offer half. Then tell hard luck story and hope for the best.

Its a carbed 360 with older style intake and heads. With the th700r4 it still gets ok milage. Not the same as the ld tpi but it is a lot faster as well. So it was worth dropping to between 15 and 22 mpg. Highway is ok but stomping around town eats up gas unless you baby it.

I would suggest the same thing for you as well. First off the muncie is not going to get good milage. With high gears it will load in low gears and need to be pushed harder to reach normal speeds. With low gears it will always be eating fuel on the highway and not much better in the city but fast.

Th700r4 with most older cars will improve milage. By a few mpg along with a shorter first gear the over drive is really good with 3:55 or 3:73 on the street also works ok with talller gears gm commonly sold then matted to 2 something engine. Shorter first gear makes it roll away smooth with little push of the pedal. Which also helps on the fuel milage.

Also same holds true for the six speed. But the auto is a little faster at the strip.

Sorry for the long post hope it helps.
From all I've seen 5.3L's go a lot cheaper than 5.7 lt1's. And there's a lot more to mpg's than EFI, though it helps.
 

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In my area i just looked and found a few but nothing that was really cheap a stripped out engine is not really a good deal since the sensors cost more than the block a long block build up is big bucks. Also lt will not have too many newer systems that will hold up the build like tpms and traction control or at least they are easy to deal with in lt. Speedo is alos cheaper to get right with lt since you can buy cheaper speedo. Lots of other little stuff.
or just ditch the factory ECM and run it with $5 worth of junkyard sensors...
 

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So you are willing to spend a G note or more to upgrade your engine so you can save $25.00 dollars a month on fuel costs?
My thoughts exactly. Unless you're driving 10K miles a year, it doesn't matter if the car gets 10 mpg, or 20 mpg. I've done several LS swaps, and an LT1. They're great if you're starting from scratch, but if you've got a carb'd engine that runs fine, it's not worth it unless you just WANT to have the LS.
 

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Of course it's fast
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Discussion Starter · #6 ·
So you are willing to spend a G note or more to upgrade your engine so you can save $25.00 dollars a month on fuel costs?
The car will be my daily driver. I put a lot of miles on my car. At least 12k per year. It gets 9mpg as it sits. If i could just grab the top end off a tbi motor with the ecu and harness and get that mileage up to 16mpg that's a huge increase and well worth the maybe $300 + whatever it costs to get the ecu tuned. I'd get it set up to run off the least amount of sensors as possible. I can't see it costing much more than $600 total.
The muncie is staying, ditching it is out of the question.
I could get the 5.3 with harness for around $600, but there's no way I'm gonna find an lt1 for that price.
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What kind of mpg could i expect with tbi, 4 speed, and whatever gears would be best?

If i could squeeze 16mpg out of the car it would save me over $1300 a year.
 

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I had a 67 Camaro with two 750 carters and 4.10 gears and I got 13 mpg when I drove it like a car.If your car is getting 9 MPG now then something is way wrong with the car or more likely,its the way you drive!
The Corvette I drive now gets about $20.00 per hour when I drive it and I enjoy every single second Im driving it. What is the real problem? how much horse power does your car produce? 1 pound of fuel will make close to 3 HP for an hour,do some math?If your car is making a lot of HP and you are using it,then fuel consumption is a mathematical formula based on all these parameters.
after you figure out where the fuel is going and why,then you can make "all" the corrections or most important corrections for the goal you desire
 

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Of course it's fast
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Discussion Starter · #8 ·
I had a 67 Camaro with two 750 carters and 4.10 gears and I got 13 mpg when I drove it like a car.If your car is getting 9 MPG now then something is way wrong with the car or more likely,its the way you drive!
The Corvette I drive now gets about $20.00 per hour when I drive it and I enjoy every single second Im driving it. What is the real problem? how much horse power does your car produce? 1 pound of fuel will make close to 3 HP for an hour,do some math?If your car is making a lot of HP and you are using it,then fuel consumption is a mathematical formula based on all these parameters.
after you figure out where the fuel is going and why,then you can make "all" the corrections or most important corrections for the goal you desire
It's slightly out of tune. But I'm so tired of messing with it. I need new heads and intake anyway so i figured i would just go efi white i'm at it
 
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