318 MAX fuel economy builds?

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gagembassett said:
So I'm looking into buying a long-distance capable daily driver. I have my eyes on a Dodge Diplomat and Chrysler 5th Avenue. Both have 318s and I thought it may be of my own interest to buy one as a daily as they are things I can work on instead of things I would need to take to a shop. In the case that I buy one or the other I would like to build the 318 for high fuel economy, I'm talking like 20+ mpg if possible. Anyone done this? Any input? Etc. Let's coffee-table talk daily stuff instead of high horsepower for once.
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I have some pieces to do an economy mileage build, a 69 318 block,

an Edelbrock 318 Streemaster, designed for mileage and tork, (idle to all done at 4500) on a stock 318, will be interesting to to see what happens with a custom cam.

A 400 cfm Old style AFB or tweaked Thermoquad

273 closed chamber heads, haven't calculated the compression increase yet,

Thinking of Howard's Cams for a custom grind.

76 A833 aluminum overdrive transmission 4 speed with .79 final ratio

2.76 gears 27 tires

1 5/8 Doug's 453 headers


I don't see any reason that I can't get 25 mpg
 
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Thanks for the input regarding the 413 heads guys I am aware of what i have. All the 413 top end will be used including raised water pump. It is going in an RV so it was made for my intended purpose.

Not a horsepower build to be sure. It is all about low rpm torque for efficiency.

Small ports and valves help keep port velocity up at low rpm to help with gas mileage.
 
rumblefish360 said:
I had a coworker tell me it was a good help in his van. It is possible but more likely improbable to find a two barrel SP2P.
Crazy hard to find they are.
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Looky what I found in the town 15 minutes over from me. Snagged it for $75. Looks like this Max-Milage 318 is becoming very possible! :thumbsup:

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Oh wow! I’ve only have a picture of one but dang!
Presto and here we go! Nice!
 
mpgmike said:
As far as the heat chamber under the carb, Smokey Yunick did a rather elaborate design using a turbo back in the mid-80s. He was getting over 50 MPG with around 250 HP from a Fiero, Plymouth Horizon, and a European Fiat:

Smokey Yunick’s Hot Vapor Fiero; 51 mpg and 0-60 in less than 6 Seconds! See and hear it run in our exclusive VIDEO! - Information on collecting cars - Legendary Collector Cars
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The owner of Hill Country Performance in Spring Branch, TX owns the Plymouth Horizon, and has a 'micro museum' in the store to Smokey. Danny is fricking awesome in overall engine knowledge and machining. Does plenty of in shop 'how too' on YouTube. Here's a vid with the motor.
 
A little progress on my 360 mpg build. I got a .040 74 360. It's getting 318 rods and balancer and getting converted to internal balance, That's happening now. I used the factory style dish piston. I could not risk detonation issues. I picked up a performer egr manifold. My machinist is building me a block for the egr so I can tap into the egr before the valve and plumb it into a 1" 4 hole spacer. Running a tube from the passenger side heat crossover into the opposite side of the 4 hole spacer so the heat will circle inside the plate. Putting a 4 hole 1" air-aid spacer on top of that. milling the spacer the same as before but plumbing coolant through this spacer. Scoring the port walls of the intake and head. I just picked up a set of 302 heads that I will be massaging. Gasket match and mild porting in the pocket. polishing the chamber. Running a 216-220 @ .050 Hughes cam with Rhoads lifters and 273 adj rockers. avs2 carb with an Edelbrock distributer which has adjustable mechanical advance and adj vacuum advance for a nice fine tune. 67 cuda 2.94 gear but the a500 is going in shortly after the 360. 3.55 gear. Hoping for 20 plus.
 
You’ll do a lot better than 20.

I don’t like the heat plumbing your doing.
 
rumblefish360 said:
You’ll do a lot better than 20.

I don’t like the heat plumbing your doing.
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It's something I've been working on with another guy on here. If it does not work or it makes things worse, i can eliminate any and all of it pretty easy. But I have an idea. ;)
 
Dmopower said:
A little progress on my 360 mpg build. I got a .040 74 360. It's getting 318 rods and balancer and getting converted to internal balance, That's happening now. I used the factory style dish piston. I could not risk detonation issues. I picked up a performer egr manifold. My machinist is building me a block for the egr so I can tap into the egr before the valve and plumb it into a 1" 4 hole spacer. Running a tube from the passenger side heat crossover into the opposite side of the 4 hole spacer so the heat will circle inside the plate. Putting a 4 hole 1" air-aid spacer on top of that. milling the spacer the same as before but plumbing coolant through this spacer. Scoring the port walls of the intake and head. I just picked up a set of 302 heads that I will be massaging. Gasket match and mild porting in the pocket. polishing the chamber. Running a 216-220 @ .050 Hughes cam with Rhoads lifters and 273 adj rockers. avs2 carb with an Edelbrock distributer which has adjustable mechanical advance and adj vacuum advance for a nice fine tune. 67 cuda 2.94 gear but the a500 is going in shortly after the 360. 3.55 gear. Hoping for 20 plus.
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This is what I’m thinking for my 87 truck, 318 is wore out but I have a 92 360 in great shape that Ill use the 302 heads off the 318 with the S2P2 intake, does it need that cam for millage?
 
Ceedawg said:
This is what I’m thinking for my 87 truck, 318 is wore out but I have a 92 360 in great shape that Ill use the 302 heads off the 318 with the S2P2 intake, does it need that cam for millage?
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No. I'm being selfish and trying to have my cake and eat it also. If I use that cam AND Rhoads adj lifters I basically get a 2barrel cam at idle and the lift and duration will increase up to about 4000 rpm. Then it's approximately full lift from there. They build these lifters to help big cam engine have a little vacuum. I'm using them as a poor man's VVT timming. I'll get 3 cam profiles from one. If I didnt use these lifters I would drop one or two cam sizes to accomplish the same mileage goals. I think I'll be around 300 hp at the crank when done. But loads of torque.
 
gagembassett said:
So I'm looking into buying a long-distance capable daily driver. I have my eyes on a Dodge Diplomat and Chrysler 5th Avenue. Both have 318s and I thought it may be of my own interest to buy one as a daily as they are things I can work on instead of things I would need to take to a shop. In the case that I buy one or the other I would like to build the 318 for high fuel economy, I'm talking like 20+ mpg if possible. Anyone done this? Any input? Etc. Let's coffee-table talk daily stuff instead of high horsepower for once.
Click to expand...
Guess I'm in really late on this one. My wife had a 1985 Diplomat we bought used. Dead stock 318 (Lean Burn) with about 85,000 miles on it. Never touched the engine except for oil changes. Ran beautifully despite the Lean Burn and got 23-24 MPG (2.24 axle ratio) all day long on the interstate at 65-70 MPH. Beautiful riding and handling car. Not a stoplight sprinter but it was a solid car for the money.
 
Hysteric said:
He's right, liquids don't burn in the cylinder. The finer the droplets are the better the homogenization is and as a result the burn is better. SO if your engine requires a lot of timing what does that tell you?
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David Vizard covers fuel atomization where large droplets DO work with specific (some would label insufficient) combustion chambers. His experience with this subject came from Mini (Cooper?) racing in the 60's or 70's. One combustion chamber needed large droplets of fuel for the most power output of that particular engine.
 
mpgmike said:
Could you provide an example of doing it right, and another example of doing it wrong?

Could you explain the detriment caused by over atomizing fuel at the booster?

I'm open to learning new stuff.
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David Vizard covers fuel atomization where large droplets DO work with specific (some would label insufficient) combustion chambers. His experience with this subject came from Mini (Cooper?) racing in the 60's or 70's. One combustion chamber needed large droplets of fuel for the most power output of that particular engine. I would have to review hundreds of pages in his books or hours of his videos to find it. It was Carburetor and combustion chamber specific examples that provided him with the discovery. Later on he talks about an 80 horsepower increase in switching spark plugs, so take it with a grain of salt-but I have heard of others having tremendous gains from spark plug changes *** well.
 
So…. Like I always say….. it’s combination dependent…
One size does not fit all.

:lol:
 
greymouser7, if I recall correctly, you're referencing how it made more power with larger droplets from the carb. I don't remember any efficiency claims. My experience has been 100% that better vaporized and homogenized air/fuel delivers better part throttle power and economy -- haven't found an exception yet. As for making more power, when NASCAR mandated the restrictor plates, builders were trying to pour the fuel through those coffee straw holes for VE, then scrambling to get it vaporized and homogenized post plate.
 
greymouser7 said:
David Vizard covers fuel atomization where large droplets DO work with specific (some would label insufficient) combustion chambers. His experience with this subject came from Mini (Cooper?) racing in the 60's or 70's. One combustion chamber needed large droplets of fuel for the most power output of that particular engine. I would have to review hundreds of pages in his books or hours of his videos to find it. It was Carburetor and combustion chamber specific examples that provided him with the discovery. Later on he talks about an 80 horsepower increase in switching spark plugs, so take it with a grain of salt-but I have heard of others having tremendous gains from spark plug changes *** well.
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You are 100% correct. Use an exhaust heated intake and run the coolant temperatures at 195 or more for the guys who think the gain in thermal efficiency is more important than compression ratio and then atomize the fuel as fine as you can it will lose power and efficiency.

I‘d rather run my coolant temperature at 160 (just so I have heat/defrost), run a cold air intake and use the booster to get the fuel finely atomized and run my compression higher than all the boos and experts say you can.

The increased thermal and mechanical efficiency of the higher compression ratio makes far more power than hot coolant a heated intake.
 
greymouser7 said:
David Vizard covers fuel atomization where large droplets DO work with specific (some would label insufficient) combustion chambers. His experience with this subject came from Mini (Cooper?) racing in the 60's or 70's. One combustion chamber needed large droplets of fuel for the most power output of that particular engine.
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Guess that settles it then. David Vizard all the way back in 1960 or 1970 proved large droplets make the most power. :thumbsup:
 
Hysteric said:
Guess that settles it then. David Vizard all the way back in 1960 or 1970 proved large droplets make the most power. :thumbsup:
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That explains why all the fast cars are chasing injectors with a single orifice rather than getting the junk ones with 8 or 12 orifices.
 
I just swapped the original 1-hole injectors on my '95 Jeep GC for Ford 12-hole jobbies. I like them.
Inj1_12.png
 
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