How do I get the absolute best MPG

[mcmullinauctions]

Hi.
I am an insurance agent and I drive ALOT. Sometimes 2000 miles a month. I want to replace my 2005 chevy 2wd extended cab (5.3 /auto) with my 1963 when it is finished. I want to get the 18-19 mpg I currently get or even better....HOW? I am not worried about taking off fast or performance (within reason). I just want to use the 63 factor body, frame, and upgrade the drivetrain and suspension. I would love to stick with a 4 or 5 speed and have a v8. I am not opposed to a 700r4 though. Whats the best way to do it. TPI? 5.3 swap (can I run a t-5 with that?), TBI injection? I just want to run 70 on the highway at around 1800-1900 rpm. What's you opinion? I'm trying to do the drivetrain without spending a rediculous amount of money too. Thanks

[jonathan-m]

Don't drive it

I'm planning to switch to TPI for fuel mileage. Right now with a 350 sb I get about 10 MPG and I'm happy for that. 18-20 would be a dream

[Turkey]

Put a diesel in it

[70 Suburban]

I'm doing a 08 5.3 with the variable displacement.

[TwoFiftyShifter]

If you want to get that mileage. copy the drivetrain.... 5.3l and automatic 700r4 or 4l60e. your old truck is boxier but lighter, so long as your gearing is right you should be able to get that mileage. I don't reccomend a T5, it's not that strong, and a 5.3 is kinda strong.....

[ampsyco]

never EVER step on the gas.

or else suffer with the rest of us.

seriously, fuel economy is all about how you drive.

[mcmullinauctions]

You're all right! They dont burn gas in the garage. They also aren't any fun! I thought about a diesel but want to keep a gas motor. Keep the opinions coming!

[70 Suburban]

well have in trailer queen is like have a trophy wife.. what good is it if you dont get to ride it.....

[protrash64]

My .02 cents. The 1800rpm may be too low and lug the engine causing worse mileage, possibly. I would be careful about the combo of parts and shoot for 2000-2200rpm. I tend to notice that most GM vehicles run at 70mph in this range due to the efficiency of the powerband, usually about 2000-4000rpm.

You will defeat the purpose of your mission if the engine runs too slowly.

[Captainfab]

I agree with protrash. You need to have the rpm's in the engine's 'sweet spot' for best mpg.

With that said I would recommend going with the 5.3 and a 4L60E as others recommended as well. You will likely need to have the PCM reflashed in doing a conversion, at which time the tuner can tweek things a bit to try and maximize efficiency.

Originally Posted by protrash64

My .02 cents. The 1800rpm may be too low and lug the engine causing worse mileage, possibly. I would be careful about the combo of parts and shoot for 2000-2200rpm. I tend to notice that most GM vehicles run at 70mph in this range due to the efficiency of the powerband, usually about 2000-4000rpm.

You will defeat the purpose of your mission if the engine runs too slowly.

[Fred T]

It all depends on how much money you have to spend. The best bang for your buck will be new gears in the rear. 1800 rpm at 60 is a good goal if the hills aren't too bad. Go to one of the rpm calculators to figure out what gears you want.

If you are in the hills and overdrive tranny will be a big help.

For an engine go with the SBC with minimal upgrades. A mild cam, performer intake and cast iron exhaust manifolds will be your best bet. The cast manifolds help by maintaining the exhaust temperature, keeping the engine compartment cool. Also a tuned electronic ignition makes a big difference in mileage.

On top of the intake use a quadrajet carburetor. The small primaries make a huge difference on mileage, provided you keep your foot out of it. If I were going fuel injection I would go EFI. It costs more, but Chevy got about a 20% increase in mileage with it.

With a properly outfitted SBC, q-jet, OD tranny and the right gears 18-20 mpg should be a good goal.

I had an 80 1/2 ton van that was bare bones. It had the 250 six, 3 speed, decent gears and a progressive Rochester 2 barrel carb (like half a q-jet). Highway mileage ran 16 to 20.

[mcmullinauctions]

Thanks for all of the responses. I would love to be cheap and semi-original and keep it carbed with a 700 or a t5 for simplicity, nostalgia, and price but we do have alot of hills in my area. It's not prarie country. What would a 2 barrel do? I don't need tons of pep. What different would a 283 or 327 instead of a 350 make in MPG as well? That way it stays semi-original.

[LEEVON]

Best mileage I've ever gotten in a truck was my '92 with 4.3TBI / 5-speed. It regularly got 18mpg around town and up to 22mpg on the highway. I'm just not sure how to get there with a carb?

I've had several newer vehicles with 4.8's, 5.3's and a 6.0 and have never gotten better than 15-16 mpg in any of them. Probably has alot to do with my foot but in my opinion a V8 is what it is and they will always need fuel.

But for simplicity sake a stock sbc with a 2bbl carb, HEI and 5 speed would be a good start.

[SCOTI]

A 4.8 or 5.3 LS swap will get you near your goal (same drive train as a newer truck w/less weight & worse aero). The 4.8 would move the truck; the 5.3 will move it better & I believe is available in the DOD set-up which will definitely help on the open road. Precise tuning will reap benefits as well.

As for a 'traditional' small block, a 350 w/Vortec heads, hyd roller cam, OD tranny w/some 3.42's would be the standard. Feeding the fuel will require a Q-jet (set-up for efficiency over performance). Other options would be one of the 'new' carb based/throttle body fuel injection set-ups (air cleaner hides the updated fuel meter so it still maintains a traditional look); or the mid 80's TPI set-ups (not very traditional looking). As was suggested, the 4.3 6cyl w/OD could get the job done as well.

[roofingbloke]

My 63 has a 350 with the standard 2 barrell carb, 4 speed manual, this is the most economical small block i have ever had. 70mph at 2200 rpm. im getting 18 to 20 mpg. but she aint that fast, At £4.70 a gallon.

In the uk you are born free taxed till death.

[astrochimp]

I have about the same plan, the best highway MPG with my truck.

IF you have the ability to dyno your truck,you can base gearing from that.
(IIRC highway speed at peak torque?)

I am trying to do modifications to increase low rpm power, and plan a overdrive swap.

Normally, a q- jet gets better MPG than a 2 barrel. I have one about ready to install, with a old GM factory performance intake, and will add aluminum heat shield/spacers under the carb, (that worked well in my 77 T/A).

If I were to swap engines, for carb SBC I would go 383 or 400cid built for torque.

Injected I would go early 90's drivetrain from a Buick Roadmaster (& other GM's) as my father got 29 mpg highway in his, and my 93 1 ton van got 18 with about the same set up. Van weighed just under 8000 lbs loaded. These are cheap to buy running now.



Good automotive calculators here-
http://www.bgsoflex.com/auto.html

Edit- dont forget effect of tire's! not just size, but tread, weight, ..........
David