5.3 LS, 4L60e, 3.73 gears. Enough power to rip the tires off, mellow enough to be a dead reliable daily driver, should easily hit 25+ mpg on the highway. Cheap and plentiful. The only con is it will not look period correct when you lift the hood.

57 Pathfinder wrote:

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5.3 LS, 4L60e, 3.73 gears. Enough power to rip the tires off, mellow enough to be a dead reliable daily driver, should easily hit 25+ mpg on the highway. Cheap and plentiful. The only con is it will not look period correct when you lift the hood.

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 x3  My setup,410 hp and 25.7 mpg 

My 2¢

Modern fuel injection cannot be beat for mileage, performance and driveability. But swapping them into our old cars is not trivial.

I agree with Taylor55 that the cheapest way to do it is buy a running vehicle and steal the engine, transmission, plus all the wiring, fuel pumps, sensors, computer etc from it.

Small things can still cause you grief. Such as: The newer transmissions (like the 4L60E) do not have mechanical speedometer gears, so connecting your speedo becomes another obstacle.

I've owned several cars with respectable power and, driven conservatively, managed over 24 mpg. That's with carburetor and a non-overdrive transmission (but rear end ratios in the 3.08 to 3.23:1 range). I had a '65 GTO years ago with a '69 Pontiac 400, 4 bbl, muncie. I was always surprised when I checked fuel mileage. Always averaged mid-20's mpg, even with some "energetic" driving. I had a '64 Olds Cutlass with 330 CID, 4 bbl, T400 and got about 25 mpg. My Beaumont, with 330 HP 350 CID, 700R4, 3.73:1 gears does over 20 mpg in combined driving. Around town, my mileage varies depending on how often the secondaries are opening up. The gears and engine combination should allow you to cruise along at highway speed without the secondaries opening. If the engine is under-powered, or if the RPM's are too high, causing the secondaries to be open all the time, your mileage will be dismal (at least that's been my experience).

Your Acadian is pretty light. As an alternative to the V8 swap, you could look at swapping a v-6 out of a Buick GN, or possibly a mid-'80's Monte Carlo. Personally, I'd go for the V8 options. More power, likely mileage would be just as good, resale would be better, and the parts will be easier to find (and likely cheaper).

If you are electronically inclined, like testing wiring harnesses and tweaking ECU's, then fuel injection is the way to go, and the 5.3 LS is perfect. If you're like me and prefer mechanical linkages and carburetors, get a mild 350, gear it so you're doing about 1800 to 2000 RPM at highway speed.

Cost wise...if you have to rebuild a sb,buy all the add on's headers/carb/intake etc and then buy a od trans think it would come out close to the same as an LS if you can buy a complete vehicle and do some of the work youself. Just a matter of what you really want old school or new? Rough idea of what it cost (motor/trans) and a sh$t load of work! If keeping the stock front end you'll need the GTO pan kit to clear stock steering linkage.

1000- complete 2000 GMC truck
200- rad
150- fuse panel,relays,wire
500- GTO pan kit
900- CBR headers
80- air box setup (astrovan and truck)
0- throtle linkcage (Stock truck and car)
20- trans cross member material ( made)
100- engine mounts
80- new waterpump
450- cam
120- Intake cover
45- rad/heater hoses
250- fuel pump/filter/lines
240- trans cooler/lines/pan/filter
0- Cooling (stock truck fan)
20- shifter linkage and detent (made)
140- ecm program
180- plugs/wires
60- paint/clear
40- drive shaft (wreckers)
60- u joints
200-fluids/clamps etc
130- gauges
260-shift kit/fluids
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