Dont know HOW many times i've heard this. Never once has someone not knocked the inefficiency ov the 360... whether old style LA, or the newer Magnums (except ME... i thought my 78 Volare 360-2bbl was great on gas). Looking at ratings, the math makes the 318 far better for its size than the 360. I've rarely heard anyone rag on the 318 for its piggishness, or really, even for its sluggishness. Most 318 owners were happy with it for what it was, a far rarer sentiment with 360 guys, especially Magnum guys.

Personally... i cant see how one relatively similar engine (360) can suck at efficiency when such a close relative (318) doesn't (lets say both are Magnums). It seems to me more an issue ov installation, tune, accessories. I know they pooched the factory tune on the 360 Magnums. Maybe the exhaust/intake is already too small for the 318, and dumping it on the 360 further chokes it up?


I have a very light car (will be 3000lbs), with a stick, and it'd be nice to be as fast as a 12 second car from a roll (its not a drag car). I found a really nice 318 Magnum ('95 Ram), and i am really trying to find a reason why i need a 360? What i DONT want... is a pig. If i wanna suck gas i'll stick with the 400 lowdeck. Quite honestly... my 96 4.6L Mustang (3400lbs, 215HP) goes almost fast enough for what i need... a 318 Magnum as installed (Dougs headers, full race exhaust, RPM air-gap, Holley, cam, etc.) should make far more power, and in a lighter car.


Do i keep looking for a 360? Instinct tells me the 318 Magnum (with my mods) should be plenty fast and efficient in a 3000lb stick car.

Sorry but I stopped reading again until the first 'ov'.

360 is a "stroker motor" compared to a 318, will make a lot more torque than a 318 will all being equal.

I have a 5.9 in my Duster, I'm very happy with it. I'll take any you want to get rid of.

I think people tend to compare the 340 to the 360 (which replaced it) and the 360 did have a poor power/tune compared to the 340 despite the 20 extra cubes. I'm thinking the 360 (like the 400) was built with emissions in mind and less for performance.

If you are satisfied with the 'Stang and have the 318 already, I'm sure you would be more than happy just building it and skip trying to find a 360. Of course, if you are looking for the most power, the 360 is the way to go.

If I were building a motor (and had both engines to choose from), I'd take the bigger displacement of the 360 over the 318. I think you will have an advantage with the extra cubes if you are willing to build it with performance parts as opposed to leaving it bone stock.

You ought to clarify what you mean by "inefficient".

Do you mean less capable of turning a pound of fuel into an hour of horsepower,
or do you mean less capable of making of making high horsepower at high rpm?

The 360 has relatively large main bearings,
which may be good for low rpm heavy torque towing duties.

This beefed up lower end also makes it about 57 lbs heavier than a 318,
but race shops like Petty Enterprises found plenty of places on the stock block to machine away unnecessary and non-load bearing weight.

Nearly all the American V8 manufacturers found that Honda's redesign of main bearing were both smaller, less friction and capable of higher rpm.

The internally balanced 318 has one of the highest rod/stroke ratios which has inherent low friction advantages,
and can allow slightly higher dynamic compression rations. The 360 is only slightly less.

For high rpm horsepower production,
cylinder head breathing mostly dominates,
and valve size (and number) in turn is very important.

Canted and opposed (Hemi) valve arrangements
allow larger diameter valves
and straighter runners
than side by side valve Wedge designs
in cylinders of the same diameter,
so a 5.7 Hemi has a high rpm breathing advantage
over a Magnum 5.9 Wedge.

When comparing pickup truck duty
Magnum 5.2 to Magnum 5.9
the dominant thing is the beer barrel intake manifold,
which was designed for the 5.2
and when this 15.5 runner length intake manifold is bolted unmodified on a 5.9
brings peak torque and horsepower in at lower rpms.

Drag racers consider this as choking off performance above 4000 rpm.

For working pickup truck use
available low rpm torque is a good thing.

If you want to fault a particular feature of both 5.2 and 5.9 V8s,
one very questionable area is:
why are the
Quench clearances of piston to head
so much larger than 0.026 inches,
(0.047 plus 0.055)
and why are the factory dynamic compression ratios so relatively low?

The probable answer is that
cylinder to cylinder quality control at the factory
was so variable
that a large average Quench clearance was necessary
to keep "statistical outlier"
tight cylinder piston fits
from hitting the cylinder head
and generating a costly to Chrysler warranty claim.

And push rod angles a bit on the extreme side for performance applications

Take advantage of the addit'l 42 cubes. adequate SCR. matched bolt on components for the short block. 040" quench.

generally, all gasoline engines are "inefficient". an engine that uses 70-75% of it's energy creating heat, and not power, would be considered inefficient. this covers most gasoline engines.

Honestly I'm not a 318 fan unless it is a Magnum. They run for a long time but they really don't set the world on fire.
My son swapped out the 125HP 318 out of his 88 Shortbox 4X4 for a Magnum 360 and it was like night and day. The 360 Magnum is a pretty stout package for 93 technology, they get decent power and pretty good fuel economy. The stock intake/injection setup is the one thing that holds them back.
Back in 1974 I would venture to say the 4 bbl 360 was the best all around smallblock available from any manufacturer. Lots of big blocks got their tailpipes handed to them by a 4 bbl 360. Remember the SS454 Chevy pickup truck that was slower than the Lil Red 360's?
I bought a new 318 magnum in my 92 pickup and that thing hauled butt, So I made the mistake of getting another 318 Magnum in my new 96 pickup, that truck was a dogg, I always wished I had sprung for the 360 Maggy in the 96 and I would recommend only a 360 magnum for a swap. Sure the topend HP will be limited by the intake setup but you'll get more lowend grunt and you could run a bit higher rearend ratio to take advantage of the torque for better fuel mileage with the 360.

Sheldon

RR: No I've never measured one, I suspect a true 9-1 but that's strictly guessing. The 92 318 is a way better package stock. Better camshaft, better exhaust manifolds and I suspect better computer settings than the later versions. My 92 D150 always ran 16.0 to 16.1 at 2300 feet totally, factory stock with 3.55's, pretty good for a dead stock 318 pickup. For comparison my 86 318 D150 ran 19.20's at the same track (when my racecar was broke). My kid just took the hurt 318 out of his 87 RC, I told him to keep the valvecovers and throw the rest of it away.

Sheldon

RR, the 5.2 has a nominal deck height of 9.577 - 9.578.
The largest piston compression height was in the early 5.2Mags and that was 1.755. The 1986 318 used 1.745, I measured my piston as 0.055 down in the hole on my 86 block.

R.

Alright, thank you

I used to plow with an 89 Dodge 3/4 360, A 90 Dodge 3/4 360 and a 90 Dodge 1/2 Sno Commander with a 318.

I really didn't expect to see to much difference between them since the gearing was about the same and the 90 3/4 truck had overdrive.

But the difference in fuel comsumption between the 318 and 360's was staggering. Power was about the same. The 318 seemed like it got double the fuel economy of the others. I'm sure the other trucks were heavier but that's why they had the 360's. The 1/2 ton truck probably felt heavy to the 318 engine.

Hard to check fuel economy with a plow truck as they don't hardly put any miles on them plowing. But you could go two full days on a tank with the 318 as compared to the one tank a day with the 360's.

Low compression on the 360 when compared to the 340's is the culprit.

I have a 360 with 9.5:1 and a 750 3310 Holley. It's as efficent as you're gonna get in a 5,600 lbs. Powerwagon with full time 4wd. It does get better mileage than the 318 2 bbl. it replaced.

11 mpg average for the 360 and 9 mpg average for the 318 with LOTS more grunt and towing capability.

If the 360 would have been the engine built with the same type of pre emission specs in '68 rather than the 340 the 340 would be the engine in question in this post. It is not very hard or spendy to build some power into the 360.

I had some friends who were driving government fleet vehicles, Dodge Durangos, it was widely known and they confirmed that the 5.9 Mag got better mileage than the 5.2.

Going back to the 1974 Duster, the 360 most always was a gas hog. Now I don't know why, but stock it had a bigger cam and bigger ports than a 318, for most of the production run. Many also had a four barrel carb while the 318 never had a 4-barrel until the very late cop cars.
We had a mid'70s Dodge W250 on the site with full-time 4wd. That would knock down 6mpg, no improvement no matter how you drove it.

Now there is no earthly reason why a 360 would have different economy characteristics than a 350 chevy, but they seemed to. During the '70s, neither one had much compression and neither had a cylinder head with squish.

If you have a 5.2 Mag on a stand I say build it. The reports on them from Board members is that with proper tuning and a few hotrod parts they will make power equal to an LA 360 but with quite better mileage. That's for street engines.

If you really want more power stick a 4" crank in the 5.2 and go to town.

Before I'd put a 5.2 on the shelf for a 5.9, I'd find a G3 Hemi. That's significantly lighter and stronger, also more efficient.

R.

In my 87 Diplomat I ran both a 318 and a 360. Both with 4bbl setups and similar cams.

The 318 got maybe 3-5 more mpg highway vs the 360, but the 360 was quicker and faster, probably 20 mph more top speed.

Best combo for my setup was the 360 with the 87 318 heads, Comp XE262 cam. Lots of torque, good mileage and good passing abilities. 20-22 mpg highway was common with that setup.

I've been around a few well-built 360s. They have no problem making power...

The 360's in trucks that i have seen always had lower gears in them. 3/4 and 1 tons had 4:10 and lower gears. If it was a half ton it had 3:91... The 318's I have seen in 1/2 tons in the 70/80's had 3:23 gears and in the 90's and up had 3:55's Those low gears realy hurt MPG.