How much fuel should I save ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1984 t type · 08-20-2013, 02:12 PM

I have a 91 jimmy with a tbi 350 and it threw a rod. Thinking about doing a 5.3 swap instead of putting in another used 350 but curious as to how much fuel I will actually save by doing the swap. Will be a daily drive that will not be going off road or doing much if any towing. Looks like I can pick up a good 350 for about 500 bucks, and the 5.3's are running about 600-800 complete with all the accessories but I would still have at least another grand tied up in a harness and all of the other supporting mods. Guess I'm kinda at a lost on if it would be worth it for a truck I may only keep a few years. Also this won't be my first LS swap so I'm aware of what's all involved and capable of doing all work but the harness and PCM flash myself. Just looking for you guys thoughts and input on this one. Thanks
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Billett · 08-20-2013, 05:36 PM

If you won't keep it, it isn't worth the work. Just buy the 350 and use a light foot. Most of these trucks see around 18 mpg avg. Some more, some less, but I still wouldnt do it.
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68GMCCustom · 08-20-2013, 06:52 PM

its not just the motor that makes all those mpg's...it's also with the help of an overdrive transmission. drop in a new 350 and add a 700r4 (200-4r may even fit w/d-shaft) more easily.... with only slightly less economical results.

swapping to efi and adding an od trans isn't something to do on a $500-$1000 budget...as you'll spend that much in extras after you've bought your engine/trans combo.

1984 t type · 08-21-2013, 05:49 PM

Already have a 700r4 in it so it was just gonna be a straight motor swap.
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1984 t type · 08-21-2013, 05:54 PM

Guess I'm leaning more towards the LS swap just trying to convince myself.
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BR3W CITY · 08-21-2013, 06:44 PM

Hahah happens all the time in this section. 99% of the people asking about the "Benefits" already know they want one lol.

Pretty much every "is it worth it", "should I", "might be going/doing" or "help me decide" thread ends up with the self-actualization that you want one....we could save people psychologist bills if everything worked that way.

mooseknuckles · 08-21-2013, 07:33 PM

don't do it!......you'll never want to get rid of it.....

08-20-2013, 02:12 PM	#1
1984 t type Registered User Join Date: Nov 2010 Location: MICHIGAN Posts: 196	How much fuel should I save ? I have a 91 jimmy with a tbi 350 and it threw a rod. Thinking about doing a 5.3 swap instead of putting in another used 350 but curious as to how much fuel I will actually save by doing the swap. Will be a daily drive that will not be going off road or doing much if any towing. Looks like I can pick up a good 350 for about 500 bucks, and the 5.3's are running about 600-800 complete with all the accessories but I would still have at least another grand tied up in a harness and all of the other supporting mods. Guess I'm kinda at a lost on if it would be worth it for a truck I may only keep a few years. Also this won't be my first LS swap so I'm aware of what's all involved and capable of doing all work but the harness and PCM flash myself. Just looking for you guys thoughts and input on this one. Thanks Posted via Mobile Device __________________ 1987 Buick Grand National 2018 Road Glide Special

08-20-2013, 05:36 PM	#2
Billett Registered User Join Date: Jun 2012 Location: Pittsgrove, NJ Posts: 1,502	Re: How much fuel should I save ? If you won't keep it, it isn't worth the work. Just buy the 350 and use a light foot. Most of these trucks see around 18 mpg avg. Some more, some less, but I still wouldnt do it. Posted via Mobile Device __________________ Will 1968 C10 - Project Texa Go 6.0/4L80e 2003 Mitsubishi Lancer Evolution 2002 Ford Excursion 7.3L 2024 Toyota Sienna

08-20-2013, 06:52 PM	#3
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: How much fuel should I save ? its not just the motor that makes all those mpg's...it's also with the help of an overdrive transmission. drop in a new 350 and add a 700r4 (200-4r may even fit w/d-shaft) more easily.... with only slightly less economical results. swapping to efi and adding an od trans isn't something to do on a $500-$1000 budget...as you'll spend that much in extras after you've bought your engine/trans combo. __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

08-21-2013, 05:49 PM	#4
1984 t type Registered User Join Date: Nov 2010 Location: MICHIGAN Posts: 196	Re: How much fuel should I save ? Already have a 700r4 in it so it was just gonna be a straight motor swap. Posted via Mobile Device __________________ 1987 Buick Grand National 2018 Road Glide Special

08-21-2013, 05:54 PM	#5
1984 t type Registered User Join Date: Nov 2010 Location: MICHIGAN Posts: 196	Re: How much fuel should I save ? Guess I'm leaning more towards the LS swap just trying to convince myself. Posted via Mobile Device __________________ 1987 Buick Grand National 2018 Road Glide Special

08-21-2013, 06:44 PM	#6
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: How much fuel should I save ? Hahah happens all the time in this section. 99% of the people asking about the "Benefits" already know they want one lol. Pretty much every "is it worth it", "should I", "might be going/doing" or "help me decide" thread ends up with the self-actualization that you want one....we could save people psychologist bills if everything worked that way. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

08-21-2013, 07:33 PM	#7
mooseknuckles Registered User Join Date: Sep 2009 Location: ottawa,canada Posts: 4,550	Re: How much fuel should I save ? don't do it!......you'll never want to get rid of it..... __________________ my build threads '86 C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415628 '67 C10 http://67-72chevytrucks.com/vboard/s...d.php?t=635078 '63 GMC http://67-72chevytrucks.com/vboard/s...d.php?t=674682



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