Anyone Build 302's for MPG? And General Wagon Economy

[Brown_Muscle]

my 351 2bbl with 3.27's gets 18-19 on the highway if i baby it

[knucklehead0202]

Just did a little trip(225 miles or so) and got a little over 20 with 3.08s. I ran 75-80 most of the way, and maybe a little faster in a few spots. My '98 did much better but wasn't nearly as pleasant a road car as the '90. Around town I usually get between 10-15, which is DEFINITELY influenced by my driving habits.

[DerekTheGreat]

Ash & I just wrapped up a 300+ mile trip in my party barge, averaged 18.xxmpg both ways. Got stuck in traffic multiple times both ways that ended up putting us at a crawl. Target speed was >80mph but top speed was about 104 if the GPS is correct, speedo needle was all the way aimed at OD

[gadget73]

Oddly enough, last tank calculated out to 18.7. This tank I can tell you already will be much lower. Differences in top-off habits and pumps. On a super-full tank its about 70-80 miles before it finally drops down to F. This tank I was under F at 65 miles. If I were to average out my fuel tank to tank, its probably closer to 17-17.5 overall. Local driving is about 14-15, straight highway it might see 18. I used to have an electric fan, it didn't help any. I've tried it with and without the AC, not much difference other than how much I sweat. Drive it like I stole it, drive like I'm dead, it just doesn't matter very much. When I got it, it did 11 mpg with the stock motor. Just before I blew it up, it was up to about 14. With the original HO swap and the cam off a tooth it did mid 16's. The last engine config with the Explorer cam it was around 17 once it went mass air. With the cam swap I picked up a tiny bit of economy, but a fair bit of power. I'll consider it a win.

[ootdega]

I'm no expert, but I'll share my thoughts on the subject.

The thing about the 302 Windsor is, for a V8, it's actually very efficient and has a lot of potential. There's a lot you can do to make it run more efficiently.

A mass air conversion will increase MPG by about 3. A camshaft built for mileage can increase it by as much as 8. A supercharger will increase it by about 6 with normal driving. An underdrive pulley will get you 3 or so. Other things such as a high energy ignition distributor, oil cooler, and an engine rebuild with better parts will help as well. Reducing the rotating mass of the crankshaft and serpentine by using a lighter engine fan and pulleys will reduce the parasitic effect they have on the engine.

There are also things you can do outside of the engine to help get the wheels moving more efficiently. Upgrade the transmission with a better overdrive servo and valve body, with wide ratio gears and a more effective transmission cooler, and it'll really bring out the best in the engine. An aluminum driveshaft, aluminum wheels, and limited slip differential will also help. A good fuel pump and exhaust system are solid investments too.

Doing just one of these won't help much if there are shortcomings in other areas that counteract it. It has to be treated as a whole system, not a sum of individual parts. With a thorough build and a good ECU tune, approaching the realm of 30mpg isn't much of a stretch for the 302.

Will it be expensive? All things considered, not really. It's a durable engine with widely-available parts and good aftermarket support, and fully-built AODs are very affordable for performance transmissions. It's very doable.

[jaywish]

I am a novice in this arena but one thing you said ootdega caught my eye. You mentioned a supercharger could improve mileage. I know the unit itself is a parasite requiring engine power to run and for many years i had been told superchargers make power but cost economy and turbos make power but don't cost economy as they run off exhaust pressure.

It would be great if you could get both from a supercharger. Do you know how this can be achieved?

Thanks,
Jay

[ootdega]

I am a novice in this arena but one thing you said ootdega caught my eye. You mentioned a supercharger could improve mileage. I know the unit itself is a parasite requiring engine power to run and for many years i had been told superchargers make power but cost economy and turbos make power but don't cost economy as they run off exhaust pressure.

It would be great if you could get both from a supercharger. Do you know how this can be achieved?

Thanks,
Jay

With a turbo, it depends on how it's tuned. Since they require the engine to reach a certain rpm before they spool up, and then give a surge of power, it's difficult to achieve. Not impossible, as the Ford Eco-Boost demonstrates, but difficult.

A supercharger is belt-driven, so it's always on. How much of a parasitic effect it has depends on the size of it. A simple centrifugal supercharger won't cost the engine much of anything, those can be turned by hand easily. If you go with a roots or twin screw supercharger, it's a bit different, especially since they weigh more. For example, the Hellcat's supercharger requires 80 horsepower to run, because the thing is absolutely gigantic and the engine as a whole makes over 707 horsepower.

If you want massive power, you have to make some sacrifices. But with a modest ~300hp 302, you're not at that level.

[gadget73]

When I went mass air, it gave me about 1 mpg. Better power, but no amazing fuel gains. Folks that have done stock Mustangs and Mark VII's report about the same 1-2 mpg, and usually no power increase. Mine came from the fact that it ran horribly lean when it was speed-density and the mass air helped fix the fuel mix.

Manual transmissions help more than AOD upgrades ever could. Less weight, less internal loss. I know a guy who reported 32 mpg from a 5 speed Mark VII, and the remainder of his fleet did no better than 25. He had a dozen of them and had owned one since 1986, when he bought his first one brand new so there was reasonable sample size there. Just depends if you want a manual in your car. For me, not in the Townie. Maybe the Mark VII at some point.

[jaywish]

I guess my question is how do you set up to get better mpg with a supercharger? A bit of extra power would be nice.

A stick might be a nice idea in the future, as I have always thought the wagon would be more fun that way but I don't think right now. Someday may come though.

[ootdega]

I guess my question is how do you set up to get better mpg with a supercharger? A bit of extra power would be nice.

A stick might be a nice idea in the future, as I have always thought the wagon would be more fun that way but I don't think right now. Someday may come though.

It basically just does it on its own. You could tune it to optimize the torque curve but just installing one makes the engine have to work less to make power. It just makes combustion more efficient overall. If you don't drive like a hooligan, anyway. If you do, mpg will drop significantly.

I couldn't use a stick, it's not a good idea in terms of mental fatigue for me. Putting a manual in a luxury sedan is kind of silly anyway. But yeah, there are also aftermarket overdrive kits for manual transmissions.

As for the mass air thing, I was just going by what I remember from Google research. But like I said, any one thing on its own is unlikely to have a huge effect. Changing the transmission is one thing, yes, but it changes the very nature of the car itself, so that's a different thing.

[His Royal Ghostliness]

I couldn't use a stick, it's not a good idea in terms of mental fatigue for me. Putting a manual in a luxury sedan is kind of silly anyway. But yeah, there are also aftermarket overdrive kits for manual transmissions.

Yeah they make add-on ODs, but why bother? They are expensive, bulky, and overall not needed for a light-duty application like a passenger car. You're much better off with a light truck transmission, like the Mazda 5-speed (M5OD-R2) - they're typically found in halfton trucks (and some lower-GVW 3/4-tons) and thus are reasonably strong yet fairly compact (unlike a ZF5), plus I honestly think the soft way their shifter moves is more suited for a heavy car than the notchy/scratchy feel of a T5. As far as gearing goes they fall between the 4-cyl and the V8 versions of the T5, bonus points for having a synchronized reverse instead of having to do the neutral-3rd-reverse shuffle to stop the countershaft so she goes into gear without grinding... About the only possible issue I foresee is the location of the shift tower, but luckily Rangers/Exploders have a different top plate with the tower at the rear so mix and match should produce a unit that puts the shifter where it needs to be to clear a car dash.

[MrMarquis]

I'd love to get a 5 or 6 speed stick and put it in the whale. That way I could truly play with hypermiling, engine-off-coasting and the like. It's hard to really hypermile with an auto of any sorts.

[His Royal Ghostliness]

I'd love to get a 5 or 6 speed stick and put it in the whale. That way I could truly play with hypermiling, engine-off-coasting and the like. It's hard to really hypermile with an auto of any sorts.

You have a good 5-speed already tho... Too bad it's the wrong bolt pattern for a 4.6 engine. Then again I wouldn't go hacking and slashing into a nice whale just for hypermiling purposes - now if the slushbox went poof then all bets are off

[pantera77]

I never noticed any increase in MPG's when I did my 5sp swap. Then again, I was having too much fun driving the car.
If fuel economy is your goal, I'd recommend you start with a car half the size and half the cylinders.


I still want to swap a 2.3T/T5 into a box some day. I think a 88-91 with slight weight reduction, or a stripper tudor, lowered, and some aerodynamic mods would have no problem getting 30+ on the highway and still run 15/14's.

[His Royal Ghostliness]

But with a wide-ratio 5-speed you can run stupid-high rear gears and practically idle on the interstate, while still having reasonable takeoff ability from stand-still.