what combo = decent mileage+ power/torque

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WONTGETDUSTED

CRACKED-OUT MOPAR TECH JUNKY
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ok what do you guys think? 318,349,360,408+ cid? what heads? lets keep under $2500 bucks or so? something that will idle well enough to run power brakes and doesnt need a lot of converter and let say a gear range of 2.94 to 3.55 .......i have thought about the 349 stroker but then whats the point when you can build a 360 + for the same money ......but then i dont want to get 10mpg on the interstate either....
 
360, but it still might cost more than $2500. Should be able to get 14-18mpg with 3.23 in an A body. Nothing else is in the price range really. 'cept a 318
 
Gas mileage is all relative to hp. If you want more hp then your mpg goes down. A well built 360 can get good gas mileage. If it's a daily driver then reuse the crank and rods, and try to get a piston that can get you 9.7 to 10 compression if you want to run 92 but since you said you want mpg I take it that you want to run 87. If so then aim for 9 even. If it were mine I'd reuse the heads even if they have 1.88 valves and if you can port I would open up the bowls and pushrod pinch, profile the valve guide boss and smooth the short turn abit...nothing fancy just help it breath. Some people think that porting will lower gas mileage but I haven't seen, heard or showed any difference on my motors. Porting is free and you can grab some real hp with the exact same combo if you know how to do it.

Sorry this is long but the is alot to it. As for manifold a good dual plane is your best choice and bottom end power is were your gas mileage is at. Cam.. I would use a set of 273 rockers and put a solid cam in it. Something small say in the 230-233 range at .050. Again most will say you will get bad mpg but look at the slant 6. Try to get the most advance you can without pinging. Probably one of the most over looked is the carb. I like the holley or demon because they are easier to tune in my books. Try to get the air fuel ratio in low 15 at cruise and mid 12's for WOT. Hope this helps. Oh before I forget go with 2.76 gears, they are a blast on the interstate.
 
How much power are you looking for and whats good mileage for you.

A basicly stock 360 and a overdriven tranny can do very well with simple bolt on's. No cam change at this point in my thinking.

Let me ramble a second here;

I had a '79 Dodge Magnum, heavy late model B body with a 360 and a 904 tranny that got 20 mpg's, mostly stock, upgraded the ignition, dual exhaust off the manifolds and a Carter 625 AFB. Gear ratio was a 2.76 and 26 inch tires.

IF you go a similar route like;

360 with exterior bolt ons,; Smallish carb (600 for example) aluminum dual plane intake, headers into a nice exhaust, (well preped heads would be a plus) bolted to an overdrive 904 version, the 500 will give an overdriven ratio of 2.70 with a 3.91 rear ratio, 2.83 with 4.10's.

The simple bolt ons to a stock 360 and the rear combo will make an excellent daily driver with some guts. Once you start thinking cam, stay small.
You could get the same, if not more mileage out of a set up like this. (Minus the cam change. Still thinking with a stock cam here.) The car is lighter with less of a profile than the big B body.

A stock 360 will produce an easy 240 HP as per how it was rated back then. Freeing up the power of the engine by just simple breathing enhancments should net you a decent amount more.

The mello MoPar create engines, 9.0-1 with a dead cam made 300 HP with exhaust manifolds and a decent exhaust pipe size. Food for thought.
 
I agree with Moper, but it will depend on what type of car this engine will be going in. Big car 360 small car 318. IMHO
 
WONTGETDUSTED said:
ok what do you guys think? 318,349,360,408+ cid? what heads? lets keep under $2500 bucks or so? something that will idle well enough to run power brakes and doesnt need a lot of converter and let say a gear range of 2.94 to 3.55 .......i have thought about the 349 stroker but then whats the point when you can build a 360 + for the same money ......but then i dont want to get 10mpg on the interstate either....
Click to expand...

Build a late model roller magnum 318, get a core from the junk yard. Use the stock cam, a performer rpm intake, and a Jet performance quadrajet. I know, I know but they cannot be beat for performance & fuel mileage...we use them alot in our builds, and they work great.
The 360 will get worse mileage with the same gear ratio so you'll need to figure in your vehicle's weight to determine if the 360 can work with a taller gear.
Brian
 
The smaller the displacement, the less fuel it will use and the less torque it will produce all else being equal.

Use cast iron heads, as they will not dissipate as much heat which makes them more efficient. Use closed chamber heads and set your quench to about .040. This will allow higher compression ratios on crappy gas and compression is free power. In other words, use magnum heads. Don't increase
your valve size as you want to keep intake velocity high. Porting won't hurt if it's done by someone who is knowledegeable and may help increase velocity, but just hogging them out won't help either. Good port work cost money.

Your cam duration should be 218 degrees or less @ .050 lift for a good steady idle with high vacuum. A hydraulic roller would be more efficient than a solid or hydraulic flat tappet, as well as broaden your power band, but they are EXPENSIVE.

A small runner dual plane like an old LD4B would work well up to about 5000 rpm, but I don't think I would go as small as a performer unless MPG is your only goal.

Fuel injection would be great for mileage, but your going to spend some money again. Next on the list would be a Holley street avenger.

You might be best off getting a 5.9 magnum out of the boneyard complete with fuel injection and rebuilding it with a hotter cam and MP computer.
 
the motor will be going in a swb 2wd d-100 truck that weighs 3800lbs. dosent have to win alot of drag races just needs to make decent power and perform on par with a late model hemi truck
 
My 360 is getting 17-18 mpg around town and 21-22 on the hiway. Filled up yesterday and it was 21.5.

This is a 10.6:1 engine with a comp XE268H cam, dual plane intake, magnum heads, headers, 670 Holley Street Avenger. It's in a 68 Barracuda with an A833OD tranny and 3.55 gears. Turns just a little over 2000 rpm at 70 mph.
 
2500.00 ??? i know its on the cheap but he doesnt want to spend a ton of cash....
 
Budget will be your limiting factor. Parts alone will run you up to $2500. Do you plan on doing all the manual work yourself? Any type of stroker would probably overrun your budget. Cost to build 349 vs a 360, may be cheaper to go with a 360 with reuseable internals.

Otherwise a used magnum engine with some bolt-ons (cam, headers) might get you there.

2.94-3.55 is a wide range. 3.21 or 3.23 may be good performance/economy balance.
 
My first hot rod dart had a 318 with 360 heads (8.5:1 CR), headers, a TQ, weiand dual plane intake, fast recurved electronic ignition, a crane econo power HMV 278 cam, 4 spd, 323 gears and short 24 or 25 inch tall tires, it regularly pulled 17-18 mpg on the highway, and ran like a raped ape.

If I were you I'd consider picking up a remanned 360 on the cheap and throw some hot rod parts in it. Cam, timing chain, valve springs, lifters. Look in ebag for a deal !
 
what mpg is acceptable?
what type of driving do you mostly do? city, highway?
will you tow or haul regularly?
does it need to pass an emissions test?
have you thought about smaller cid with a turbocharger?
bigger cid with a turbo or supercharger really rock
and are a bolt on in that price range.
 
he drives normal most of the time 20 miles of intersate a day and tolls around town some ...tows a 22 boat almost every weekend during the summer .....he is trying to justify not buying a new hemi truck to his wife....he likes the truck he's had it for years ......btw he owns a junkyard here in town......so finding a 318 360 400 or 440 is not a problem....
 
wontgetdusted

thats an easy desision, tell her she can buy the new truck if she payes for it,
and he can drive it to work, to save money to build his old truck he loves.
both get something they want. WIN -WIN
turbo diesels don't do to bad on fuel! =P~
 
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