Daily Driver.. LA318 vs 360 Magnum

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For comparison my 60,000 mile 1973 318 in a 3700 pound Satellite with 2.73 gear and factory carb gets right at 14 MPG average.

Only mods are open air filter and 2" dual exhaust.

I'm not convinced that one is completely dialed in yet, though.

Both vehicles run the AC regularly although not all the time.
 
...and as I've posted before, my family and close friends have owned quite a few Dakotas and Durangos.

We've found the 5.2 with 3.55 gears (and OD of course) gets 16 MPG average and the 5.9 with 3.92 gears gets 13.5.

How much of that is the gear, how much is the cam and how much is the displacement is up for debate.
 
I'd build one of the 318's. you already have them. Good machining, don't cheap out. Get a street demon or TQ Carb. You should be able to get around 20 mpg or better on the highway.
 
My 5.9 jeep got 12.5 mpg when I drive. When my dad borrowed it got about 14 mpg.

My 318 5th Ave got around 15 mpg.

Can’t see a similar performing 318 or 360 get that difference in mpg.
 
YY1 said:
For comparison my 60,000 mile 1973 318 in a 3700 pound Satellite with 2.73 gear and factory carb gets right at 14 MPG average.

Only mods are open air filter and 2" dual exhaust.

I'm not convinced that one is completely dialed in yet, though.

Both vehicles run the AC regularly although not all the time.
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"In the day" friend of mine had a 318 Charger. Used to regularly bang on the 18 -19 door. He was, however, a careful driver. I don't know just how much you need to discount modern alky fuel from that figure. His car at the time would have had about that same mileage, and factory single exhaust
 
YY1 said:
...and as I've posted before, my family and close friends have owned quite a few Dakotas and Durangos.

We've found the 5.2 with 3.55 gears (and OD of course) gets 16 MPG average and the 5.9 with 3.92 gears gets 13.5.

How much of that is the gear, how much is the cam and how much is the displacement is up for debate.
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Bear in mind those are fairly heavy vehicles, and have a lot of operational friction---4x4, transfer case, etc and no locking hubs
 
None of ours were 4WD.

Most were extended cab, though and I've posted the weight of those I know.

I did that so the OP could compare his weight.
 
Another issue is clarifying situational MPG.

I am very careful to state average MPG.

Highway mileage can be somewhat conditional (although so can average).

My 5.9 can get 23 on an open stretch of 50 MPH road, but only 16-17 at 70 MPH.
 
Gears trump CID every time, provided the air going into the engine is all going in the same direction._____________

In 2004, my 367/6liter was at 10.7/1 Scr (alloy heads) with pressure around 180psi. It was running a [email protected] cam.I combo'd it up with a .71odA833, and the .78GVod behind it, so that's double overdrive.The FinalDrive ratio was 1.97; The cruise rpm maths to
65=1590/75=1835/85=2080
The 223* cam vacuum-peaked at or around 1900. That means, finally at 1900, reversion was done, and I had a clean, controllable, intake mixture.
So I planned a trip down to the CarCraft Nationals in Shakopee Minnesota, a good long daytrip. I had previously dialed in my speedo . I gassed up the tank and filled the trunk with Jerry-cans of Canadian 87E10 gas, I knew exactly how much gas I had on board.
Early next morning, we headed out, and drove and drove and drove. On the Canadian side, the speed limit is 100kph/62mph. On the US side the Interstate is 75. Somewhere in N.Dakota, we noticed that they like to drive 85 MPH, so we kept up for most of the rest of the trip.
Ok now, when we arrived near our destination and exited the interstate, we found a spot, pulled in, and from the Jerry cans I gassed up one last time. Then I calculated the mpgs. My calculator spit out 40 mpgC , which converts to 32 USg. _______________________

How I did it;
I used an old Holley 1850, which is a 600cfm; for it's small primaries. I had removed the plugs at the top of the idle wells to access the IFRs and had prepared a selection of wires to insert into them, and I had installed tiny MJs into it. And my secret weapon was the dash-mounted, dial-back, timing delay box. And my super-secret weapon was the cranking cylinder pressure. But the biggest deal of all was the low cruising rpm, that was just high enough to be out of reversion.
Now, with 1.6 rockers, the lift on this Hughes HE2430AL cam is advertised to be .538/.549.. That same combo except with a 750DP, went 106 in the quarter on it's one and only pass, which, at 3650 pounds/930 ft elevation, translates to 335hp, so... this is no slouch of an engine.
I do not own an AFR gauge, and I did not spend any time prior in tuning this combo. The only changes were stopping on the side of the hiway to swap wires or jets. And each time I did that, I then re-optimized the timing, from the cab.
So anyone of you can do the exact same thing.
Imagine how much MORE mpgs a similarly built, hi-Scr/smaller cam, 273/318 spread-bore, triple-booster carb, could get.

Listen fellas; I keep telling you that the world is lying to you, and that the government is not your friend, and.........
Have you not noticed that the cars of today, after 75 long years of evolution since the 265 came out (1955), are still only doing relatively the same fuel economy, size for size? Oh they have worked so hard on complicating thechit outta them, and brainwashing the masses that their wonderful next-gen whatever will do wonderful things for us; which they never do.
>I tell you what; the 273 is a 4.47liter engine. Install a 4bbl and headers on it, but Combo it up like your favorite modern tricked out direct-injected VVT, whatever; with the same 8-speed auto, and 200/220psi cylinder pressure, and stick it in your lightweight 65 Barracuda, and see what happens.
Every modern car you climb into, is a rolling tax collector, from the the first mile to the last mile; it is not actually designed for fuel-economy; rather, it is designed to generate revenue for someone way up the food chain, to spend on stupidchit to brainwash you with.
But I digress,lol._________________

When the factory installed 2.45s into the super low-pressure early-80s 318FAs, they were on to something. My Dad had one and kept a log-book. It rarely got less than 25mpgC/20 USg. My Dad had 6 sisters and 6 brothers, scattered across the Prairies, and he loved to go visit them in his retirement years. He had that car long enough to install two timing chains. I did the second for him, and put a dual-row in it.
But the factory could have done so much more.
In 2010 when Dad died, I inherited that 1984 FA.
 
AJ/FormS said:

Listen fellas; I keep telling you that the world is lying to you, and that the government is not your friend, and.........
Have you not noticed that the cars of today, after 75 long years of evolution since the 265 came out (1955), are still only doing relatively the same fuel economy, size for size? Oh they have worked so hard on complicating thechit outta them, and brainwashing the masses that their wonderful next-gen whatever will do wonderful things for us; which they never do.
>I tell you what; the 273 is a 4.47liter engine. Install a 4bbl and headers on it, but Combo it up like your favorite modern tricked out direct-injected VVT, whatever; with the same 8-speed auto, and 200/220psi cylinder pressure, and stick it in your lightweight 65 Barracuda, and see what happens.
Every modern car you climb into, is a rolling tax collector, from the the first mile to the last mile; it is not actually designed for fuel-economy; rather, it is designed to generate revenue for someone way up the food chain, to spend on stupidchit to brainwash you with.
But I digress,lol._________________

When the factory installed 2.45s into the super low-pressure early-80s 318FAs, they were on to something. My Dad had one and kept a log-book. It rarely got less than 25mpgC/20 USg. My Dad had 6 sisters and 6 brothers, scattered across the Prairies, and he loved to go visit them in his retirement years. He had that car long enough to install two timing chains. I did the second for him, and put a dual-row in it.
But the factory could have done so much more.
In 2010 when Dad died, I inherited that 1984 FA.
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First part, emissions. There's no way in heck you're going to get less than 10x the emissions of a modern car out of a mildly hopped-up 273 designed in 1964 especially when the tune is optimized for fuel economy (or power). And if you think throwing cats on it will fix it it might help but then you have to tune your cruising mixture to be 14.7:1 and there goes a few MPG, can't lean it out or you'll "wear out" the cats. I agree regarding the modern transmissions though that's where most of the MPG comes from. Less frictional losses and way more gears to keep the engine at the optimal RPM for the situation. I don't buy into emissions being a conspiracy either I learned a lot about it in my Internal Combustion Engines classes in engineering school, it's very real and the effects are quite bad for the environment. Heck we have ozone problems on the Front Range in summer time due to the high temps and sun and part of it is due to pollution from cars; sometimes it's bad enough there are days when people are told not to go outside unless it's absolutely necessary. Doesn't mean I'm about to throw cats on my Duster it's just something to think about.

Regarding the 2.45 gears, maybe they're acceptable at sea level but the 1988 5th Avenue I had came with 2.21 gears; acceleration was sooo bad it was literally the slowest car on the road and just trying to merge onto the freeway was scary. After switching to 3.07 gears in an 8 1/4" I got out of a Jeep Cherokee the acceleration vastly improved and my AVERAGE gas mileage stayed the same. I'm sure highway mileage went down and city mileage went up which was OK because I didn't only use it for long highway trips. I also averaged around 20 MPG btw.
 
@MopaR&D
My post was irrespective of emissions equipment. I'll wager not one in a hundred of us consider it when we hop our cars.
My post was comparing a well-built, alloy-headed, hi-compression, small displacement, V8 of yesteryear, to a similar displacement, highly regulated, over complicated, engine of today, in the fuel-economy arena only, and at about the same weight; sorry if that was unclear.
If I, a common uneducated country-boy hick, can get 32mpg out of a 6 liter 1960s tech engine; and modern cars are doing that but with 2.5liter 4-bangers, and it's 55 years that have elapsed, you gotta suspect something. And when you consider that this 6 liter makes 335 NA hp with just a carb swap, com'on; Somebody is holding back.
 
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AJ/FormS said:
@MopaR&D
My post was irrespective of emissions equipment. I'll wager not one in a hundred of us consider it when we hop our cars.
My post was comparing a well-built, alloy-headed, hi-compression, small displacement, V8 of yesteryear, to a similar displacement, highly regulated, over complicated, engine of today, in the fuel-economy arena only, and at about the same weight; sorry if that was unclear.
If I, a common uneducated country-boy hick, can get 32mpg out of a 6 liter 1960s tech engine; and modern cars are doing that but with 2.5liter 4-bangers, and it's 55 years that have elapsed, you gotta suspect something. And when you consider that this 6 liter makes 335 NA hp with just a carb swap, com'on; Somebody is holding back.
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Ya I was getting 20 or better in my 68 Barracuda 340 4speed car in the city back about 70-71ish and other than a tune it was all stock. 3.23 gears. It did everything well. And as far as mpg goes I purchased a 78? Torismo about 84 it had the 1.6 VW engine 4 speed manual, no o.d. any kind of driving it got 42mpg.
 
If mpg is the deal breaker build the 318, personally I like 360's better, but both are great engines.
 
AJ/FormS said:
@MopaR&D
My post was irrespective of emissions equipment. I'll wager not one in a hundred of us consider it when we hop our cars.
My post was comparing a well-built, alloy-headed, hi-compression, small displacement, V8 of yesteryear, to a similar displacement, highly regulated, over complicated, engine of today, in the fuel-economy arena only, and at about the same weight; sorry if that was unclear.
If I, a common uneducated country-boy hick, can get 32mpg out of a 6 liter 1960s tech engine; and modern cars are doing that but with 2.5liter 4-bangers, and it's 55 years that have elapsed, you gotta suspect something. And when you consider that this 6 liter makes 335 NA hp with just a carb swap, com'on; Somebody is holding back.
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I understand your point but I still don't believe something is being "held back", you can de-cat a modern car and tune it to cruise at 17:1 AFR and pick up a bunch of fuel economy. I also know modern Corvettes are rated for almost 30 MPG highway so there's something with similar weight and engine size to your car getting that good of fuel economy. Your 32 MPG claim is pretty lofty as well, I don't think you're lying more just a miscalculation or something. Hard for me to believe but even if it is true nobody else has ever come close to that without a LOT of work. I'd almost say some of it was luck with your overall combo, not many others getting anywhere near that even in old Mopars that are purpose-built for gas mileage especially not with a 360. I remember a while back on Mofarts there was a guy with an A-body Barracuda who built a 318 purely for maximum gas mileage (with OD manual trans and well-matched gearing) and I think he just about broke 30 MPG.
 
@AJ/FormS Your biggest weapon in getting mileage is the GV/OD unit coupled with your well tuned engine combo.

The second part most here can do if there serious enough to chase the tune to the 9’s!
The first part, expensive! Very!

Have you ever thought about Rhoades lifters on that cam ... if it is Hyd.? Just wondering....
 
I don’t believe 32 MPG’s ether.
I’d like to try it out one day myself just to see what I can do. No GV/OD expense will be done, to danm much $$$$!!!!
MopaR&D said:
I understand your point but I still don't believe something is being "held back", you can de-cat a modern car and tune it to cruise at 17:1 AFR and pick up a bunch of fuel economy. I also know modern Corvettes are rated for almost 30 MPG highway so there's something with similar weight and engine size to your car getting that good of fuel economy. Your 32 MPG claim is pretty lofty as well, I don't think you're lying more just a miscalculation or something. Hard for me to believe but even if it is true nobody else has ever come close to that without a LOT of work. I'd almost say some of it was luck with your overall combo, not many others getting anywhere near that even in old Mopars that are purpose-built for gas mileage especially not with a 360. I remember a while back on Mofarts there was a guy with an A-body Barracuda who built a 318 purely for maximum gas mileage (with OD manual trans and well-matched gearing) and I think he just about broke 30 MPG.
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The best "non modern" MPG I've gotten in a small block was about 22 average with a light almost no option 67 Coronet (no AC, manual steering) and it's bone stock (but carefully tuned) 68,000 mile 9.2:1 318-2 single exhaust automatic. It combusted so efficiently, it actually dripped clean water from the tail pipe, and idled so smoothly, you could balance a pen upright on the air cleaner. I believe it had 2.94 gears.
 
AJ/FormS said:
@MopaR&D
My post was irrespective of emissions equipment. I'll wager not one in a hundred of us consider it when we hop our cars.
My post was comparing a well-built, alloy-headed, hi-compression, small displacement, V8 of yesteryear, to a similar displacement, highly regulated, over complicated, engine of today, in the fuel-economy arena only, and at about the same weight; sorry if that was unclear.
If I, a common uneducated country-boy hick, can get 32mpg out of a 6 liter 1960s tech engine; and modern cars are doing that but with 2.5liter 4-bangers, and it's 55 years that have elapsed, you gotta suspect something. And when you consider that this 6 liter makes 335 NA hp with just a carb swap, com'on; Somebody is holding back.
Click to expand...

I too consider myself a "country-boy hick" with an engineering degree. As a young man living in South Dakota, I tried all kinds of combinations with a 273 Commando in a 1964 Barracuda. The best combination would get high 20's on the highway. That was with 273 commando short block machined like a Stock Class car, 72 J Heads, 71 340 intake and Carb, a used 340 cam, and 75 manual OD trans. I can't remember the rear ratio. When gas went bad I pulled the 273 and replaced it with a 170 /6 that would get 30+ mpg. No sense in talking average mpg since it is heavily dependent on location and drivers ability. I believe AJ's 32 mpg. He was trying, I was not, it just happened. My odometer was calibrated so it was accurate by mile markers after 200 miles of steady cruising. mpg was calculated using multiple fill ups and was consistent. My 2009 6 speed manual Challenger will get 28 mpg. My 1996 ACR Neon would get high 30's with 3.91 gears and 23" OD tires. My 1998 5 speed SOHC Neon would get over 40 mpg.
 
As for the conspiracy theory, My cousin bought a used 71 Ford Pinto. German 1.6 engine with a manual transmission. It did not run right, so he brought it to me. I figured the carb was messed up, so I told him to go to Ford and buy a new one. He comes back with an "export only" carb. We put it on and the Pinto runs great, more power and his mpg goes from mid 20's to around 40. You figure it out...
 
My (long gone) Hyundai Excel (last year made model) was a 5 spd manual with a Jacobs ignition added that got 42 mpg’s.
 
66fs said:
As for the conspiracy theory, My cousin bought a used 71 Ford Pinto. German 1.6 engine with a manual transmission. It did not run right, so he brought it to me. I figured the carb was messed up, so I told him to go to Ford and buy a new one. He comes back with an "export only" carb. We put it on and the Pinto runs great, more power and his mpg goes from mid 20's to around 40. You figure it out...
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The "export" carb probably had a non-emissions tune, back then the U.S. was ahead of the rest of the world with emissions regulations. Euro-spec (or JDM-spec) imports to this day always have more power and get better MPG than U.S.-spec cars. If you lived outside the U.S. you could still get some pretty peppy cars in the 70s and 80s with no emissions crap, I've heard a lot of them went to the Middle East.

Some day I'll use the original 318 block out of my Duster and build it into a mild cruiser engine with an AX-15 5-speed and 2.76-2.94 gears (that trans has super deep 1st gear and not very tall 5th, only 0.79:1) in an A-body. See if I can break 32 MPG, it's a challenge for me now lol.
 
for mpg you need good gears, a good tune, light weight and aerodynamics! but theres more mpg in how it driven than anything else! drive it like it ant got brakes and ya got an egg for a throttle peddle! we tried it all searching for better mpg in trucking. we were averaging 4.5 mpg in the 80s and theres trucks getting 7.5 average now but thay dont run as fast or pull near as hard on a hill...
 
The best tool is a vacuum gage. The higher the vacuum at a certain speed the more mpg. Aerodynamics surely helped the 64 Barracuda and the Neon. Timing lights so you don't have to come to a full stop and then accelerate from a stop helps non highway mpg.
 
66fs said:
. The higher the vacuum at a certain speed the more mpg.
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better yet is a dash-mounted, dial-back, timing retard box, so you can adjust your timing on the fly, searching for the highest mpH at a specific throttle opening. This goes along with what @66fs is saying.

To do this, you will need an adjustable, repeatably consistent, throttle stop. You set the stop to achieve the ~mph you want to cruise at, and go. Once the combo has warmed up, I retard the timing 3* and watch the mph drop, to prove the last test is still valid, then I add the 3 back in, and let it stabilize, then add 3 more, and so on until the MPH no longer picks up. When I get home, I put the timing light on it and record it, together with the mph/rpm.
Next time out, I will cruise at plus 3mph or minus 3mph, and again record the timing and rpm, for the new MPH. Eventually I have enough data points to plot a cruise timing curve, and then go make it happen.
To get it right, I use the same flat level hard stretch of hiway.
Then I change a different parameter; like tire pressure, engine temperature, or rake; and start all over. I might even change the rear gear.
Before I start, I make sure the cruise rpm is not too low, for the cam.
What I do is, with a decent PowerTiming curve already worked out; in Neutral, rev it up to the lowest rpm that achieves the highest vacuum, indicating the lowest rpm that all the air that is going into the engine is finally all going in the same direction, and not being pushed back up into the intake, past the late-closing intake valve. Usually, the bigger the cam is, the later the Ica and the higher the minimum cruise rpm will have to be.
Then I advance/retard the timing at that rpm to achieve the highest rpm. Now she's ready for road-testing.
My engine has had three cams;
a 223/230/110, a 230/237/110, and a 292/292/108, which IITC is about [email protected]..
The smallest liked~1900, The current likes 2200, and the 292 liked 2500. Your results may/most likely will, vary.
The cranking cylinder pressure was adjusted for each, to maintain about 177 to 185 psi.
 
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