As I research Mopar engines more and more, I find myself questioning the 4.7HO for my 56 Dodge pickup build, and considering a tuned 360 with EFI, headers, Magnaflo exhaust, electronic ignition, some form of tunable engine management, and hopefully connected to a 545RFE trans with my 3:55 limited slip 9.25" rear axle. The 360 makes a lot more torque down lower in the revs where I prefer to drive, and the tuning options are far greater than the 4.7HO. What about daily driving, year round, what is reasonable for fuel mileage? With the 545RFE or perhaps even the 66RFE, the overdrive is either .67 for the 545RFE or .62 for the 66RFE, on highway speed at 75 would be spinning the engine around 2,000 rpm. At that speed a tuned 360 makes around 375 ft-lb of torque, about 100 ft-lb MORE than the 4.7HO can hope to make.

That kind of difference, to me, says the tuned 360 would be better at those highway speeds/engine RPM and better on fuel. Plus with that kind of torque available from 2,000 rpm up to and past 3,500 rpm the engine could easily take the load and not have the tranny hunting for lower gears. Am I right? Does the 545RFE maout up tot he 360? Oh, and the 360 under hood is a much better looking engine, especially with MOPAR MAGNUM valve covers.

I sure wouldn't want to discourage you from dumping the 4.7, and a 360 might actually get better mpg then a 4.7. If you are seeking mpg, a 318 is about the best SBM for gas mileage, and a magnum is better then an LA was. Might want to look into the 5.2 Magnum numbers.

My 318 with a 46RE and 3:55 gears with 235 75 15 tires turns 2,000 @ 70 mph.

545RFE uses the small block bolt pattern, truck transmissions have the starter on the driver side, don't know about the car transmission. My '93 Ramcharger had the 230 HP 360 Magnum with the 518 lockup trans, w/ 3.55 gears. Highway mileage was ~ 16-16.5 MPG with heavy crosswinds @ 75 MPH average. Low end torque was much better with the 360 than the 2007 5.7 I swapped in. Torque throughout the range was relentless and impressive. The 5.7 was soggy torque wise on the low end by comparison.

I'm told you can get 5.7 Hemi power out of the 360, but at what cost, financial and fuel economy wise?

FWIW, our other '93 Ramcharger was a 318 Magnum, not as much torque but not a bad choice in any event. I drove the 318 Ramcharger back to back with an '04 Durango 4.7 235 HP w/ 3.55 gears, base model, no options, so nice and light. At one point in the RPM range you could feel the extra 5 HP, but the 318 has more power under the curve and would have handily outrun the Durango. No replacement for displacement.

Mileage, at it's peak the 318 Ramcharger would exceed 20MPG, 20.7 or 21.7, can't recall; the 360 Ramcharger never got 18 MPG, if memory serves.

A late 5.7 Hemi w/ the 8 speed blows them all away. Our 2015 Durango will slightly exceed 24 MPG, without heavy crosswinds, my 300 will knock down 25 MPG, highway numbers. And they're fast, 0-60 6.6 in the Durango, 0-60 5.2 in the 300.

Thanks for the replies all. I wonder too, are those numbers on engines with carbs or with EFI?

Some things about the newer engines is port fuel injection, individual coil packs, electronic fuel management, and coordinated engine and trans management.

I'll have to think hard about this, I do like the lower rpm torque.

if you're building a 360 for 'low rpm' work, IMO you won't need headers - good ole exhaust manifolds would be just fine in every way. I'm breaking in a freshly restored magnum 360, with a 2bbl Sniper and 70's era pre-smog 318/360 truck manifolds, and I love it. About the only thing I upgraded was a Comp 20-745-9 truck cam 9and springs), and it runs smooth with no lope (might need longer pushrods tho - TBD). Don't have any numbers yet but it sure 'feels' good. It was the original engine for my 02 Dakota so that's what I'm running, but a 318 would likely have be fine for how I'm using the truck. I started the build with a 440 with a 4bbl Sniper but eventually decided to go back to the 360 - here's the thread - might glean some ideas - https://board.moparts.org/ubbthread...-rocklander-440x4x4x40s.html#Post3099065

I'm also preparing to drop a warm magnum 318 in our 71 Demon, and it will have an Eddy 7577 intake, Demon 625 4bbl carb, and 318 manifolds.

And if you haven't seen it here's a good thread about manifolds (vs headers), especially the chart at the bottom with the results - https://board.moparts.org/ubbthreads/ubbthreads.php/topics/3149775/340-manifolds-or-magnums.html

- Sam

All the '93 engines, to my knowledge were port fuel injected Magnums with 2bbl throttle bodies.

What kind of daily driving are you doing? 360s have horrible city mileage. 318 is the better choice.

Thats what I'm hearing from everyone, and why I'm glad I asked about it being a potential engine. My 56 will be my common everyday driver, running errands (like trips to Home Depot/Menards etc), short trips to car shows and longer vacation trips. I want a vehicle at least equal to my current 2001 Dakota.for daily driving. In fact the Dakota will be the donor chassis going under my 56, but I'm likely not using a 4.7 in the 56. The 360 may be the torque leader, but the fuel mileage is not something I can accept, especially long term. I have found numerous articles about building a 318 Magnum to make really good usable power and still be much more fuel efficient than the 360 could be. A built 318 can provide satisfying power when standing on the go pedal, so I'm leaking strongly toward a built 318.

if your '56 is decently heavy (north of 5000 lbs), you'll appreciate the bottom end torque of a 360 around town...and once up to speed you may also appreciate the 42 more cubic inches on the highway. To put it simply...IMO...318's are for cars, and 360's are for trucks. Both have their pros and cons, and really you may not notice much of a difference between the two.

I have an '01 Ram with a 5.2, 1500, 4X4, 3.55 gears that's right around 5,000 lbs. It's a bit of a slouch, and only gets 12 MPG. I'd much rather it had a 5.9.

I have a 96 5.2 magnum out of a Dakota on a 93 Dakota 4x4 chassis under 49 Dodge pickup sheet metal. Years ago I owned a 54 Dodge pickup, I suspect the weight of the street ready sheet metal between the 56 and the 49 are about the same weight. Andy is using an 01 2 wd Dakota chassis under his 56, I suspect it is at least a couple hundred pounds lighter then my 93 4x4 chassis (with the transfer case, front diff, front driveshaft, and both 1/2 shafts).

My truck is on the road, and was driven 100 miles this afternoon. The factory stock, 54K miles, 5.2 Magnum drive train, with the 46RE trans with 3:55 gears, 235 x 75 x 15 tires on the 4x4 chassis in 2wd, moves the truck nicely down the road. It will reach 60 mph plenty quickly enough to run as fast as most traffic, with power left over, When it drops into passing gear, I'm not concerned about passing anyone. It is not a slouch. I'm not going drag racing with it, but it feels on par with the performance of a 318 in a late 60s or early 70s well tuned Duster or 2 door Dart.

His current (and chassis donor) 01 Dakota has a 4.7 in it, the 5.2 Magnum is a pretty big step up, and he is talking about building the 5.2 Magnum up a bit. Should be a fun truck.

True, the [/b]stock[b] 5.2 in a truck that size is likely a bit of a slouch. My 56 will weigh less, and the 5.2 magnum I plan to use will be updated to make much more power/torque. I had planned to budget over $4500 to put a remanned 4.7HO in my 56 since my 2001 Dak donor chassis already has a 4.7 in it. But everything I researched about the 4.7HO versus the 5.2 Magnum clearly shows the 5.2 as a better choice. Its not enough to just compare the HP/Torque peak numbers. For instance comparing a 4.7HO and a 5.2 Magnum, both produce around 330 ft-lb of torque, at near the same RPM. But that is not enough, you have to look at the "shape" of the torque curve. The 4.7HO torque curve is concave, actually flat briefly, before curving quickly up to a sharp peak with quick drop off. The 5.2 Magnum, especially a built 5.2 has a convex broad curve up to the peak and slowiy tapering off to the HP peak. Just the kind of curve for good driveability. And you have to consider "where" the torque curve relates to your driving style.

The torque curve for a built 5.2 is similar to the 5.9 for how early in the RPM range it ramps up. Again, good for driving, and that early ramping torque curve of the 5.9 is what makes it feel powerful and responsive. But the built 5.2 can get better fuel mileage, making it easier to live with in a daily driver. For the money I had budgeted for the 4.7HO engine, I can build a stronger more satisfying 5.2 Magnum.

My 5.9 in my 01 Ram Van gets 12-13 mpg. Kinda peppy but likes gas!

That was my point. For roughly the same MPG's you can have more power (torque and HP).
But as the OP said, he can (intends to) do some slight modifications to a 318 and get the performance he's looking for.

Sounds like a plan.

I was always interested in doing that swap, these days like everyone else I'm looking more at a hemi. Then again I don't have a parts magnum truck and they're hard to come by around here now.

Since the latest post I bought a 2010 vintage factory rebuilt 5.2 Magnum that was in a RAM 1500. Only 25,000 miles on the engine when the RAM was wrecked. I got the engine, complete, for $600. That leaves a lot of budget for Keith Black pistons, Hughes cam, kegger mods, long tube headers, Progression Ignition distributor, so I hope to be nearing 400hp/390 ft-lbs when in my 56 build.

Then I also bought a 2016 8HP-70 8-speed trans out of a Challenger with only 50,000 miles on it, for $400 with the complete draveshaft. I've read many good results of that trans behind a 5.2 Magnum for a lively daily driver that still makes 22mpg possible on the highway.

Nice deal you got and much better choice over 4.7 with it's overhead cams

For whatever it is worth, from 1997 to 2006 I did a large number of MPG tests on highway runs with a 1995 Ram 5.9 V8 Magnum 46RH 2wd, originally with a 3.55 and later with a 3.21.

I later bought an Australian Oztrip aftermarket trip computer that could accurately give fuel consumption, distance travelled, quartermile and 1 mile acceleration timing, etc.

I also borrowed or rented 2wd and 4wd Rams with the 5.2, and later with the 4.7.

Some thoughts:
Pay attention to 2wd versus 4wd on Rams.
The CAD (central axle disconnect) system on Rams was very inefficient.
4wd CAD Rams got 3 to 4 MPG worse for me over the exact same highways at the same speeds than my 2wd.
When Chrysler finally did away with their CAD they admitted it was costing 1 to 2 MPG compared to competitor systems.
The older hub disconnects 4wd were far less friction.

I later bought the PerformanceTrends computer programs “Fuel Economy Calculator” and “Engine Analyzer 2.0” by Kevin Gertgen, an ex-Ford engineer.
I found both programs made excellent predictions.
The Fuel Economy Calculator “coast down hill” ability allowed me to calculate the aerodynamics and tire rolling resistance coefficients of my Ram.
It also predicted how wind directions and speeds heavily influenced MPG on trips.

Many times after trips I would use the computer programs to calculate how much better the MPG would have been with a 5.2 than my 5.9 V8.
It was almost always 0.7 to 0.4 MPG better - not much.
Most gain for the 5.2 vs 5.9 was when the speed was lower like 55 to 60 MPH
At 75 to 80 mph there was very little benefit.

This interested me back then because I was interested in the rod/stroke ratio of an engine affecting mechanical efficiency.

“Long Rod” engine combinations were supposed to be measurably more efficient transferring power to the crankshaft and the piston “dwelled longer” at top dead center allowing less ignition advance.
5.2 and 340 V8 have better rod/stroke ratio than 5.9 Magnum V8s - or many other make engines.

Honda engineers disputed this, and even joked that
“the rod only needs to be long enough to connect the piston to the crankshaft without binding.”

When Chrysler built the new 5.7 Hemi V8 they did not go “long rod” spec like the 340 V8.

I guess Honda was right.

Interesting. I have read similar articles saying much the same. In fact that Honda quote is in the book I bought about building Mopar engines for performance. The book details everything from the crankshaft up to the intake on how to build a good performing Mopar small block engine.

When all is said, engines come down to breathing. Comparable engines like the 5.2 and 5.9 breathe similarly up to some point, and then one is better than the other. Comment made above how the 4.7 is not as good as a 5.2 because of the overhead cam design. When actually, had Chrysler developed the breathing of the 4.7 heads like was done for the 5.2/5.9, it may have developed the power possible in the block. The 4.7 is a stout, solid block design from the crank up, with some oiling and cooling issues that Chrysler eventually addressed. But perhaps the valve train architecture/head porting of the 5.2/5.9 can't be as easily designed into an overhead cam head, to capture the breathing capabilites of the Magnums. Honda knows how to make an overhead cam engine make power.

Eventually it comes down to packaging. Ford made the SOHC engine, a really good looking engine, but had some issues with cam chains as it was developed for drag racing since NASCAR was not going to allow a "non stock" engine on the big tracks: https://www.motortrend.com/news/90-day-wonder-sohc-427-cammer/

https://www.autoevolution.com/news/...the-infamous-sohc-427-cammer-199758.html

Had Chrysler learned from Ford, perhaps a stronger 4.7 OHC could have been developed. But the success and legend of the Hemi far out shown the possible Chrysler Cammer engine.