Horsepower with mileage options
- Thread starter Penstarpurist
- Start date
-
Penstarpurist
Well-Known Member
Yeah, I need to sit down with my son and try and get him to loosely nail down an end goal. With what he really wants, is willing to change or sacrifice to achieve his end result. Then he can really plan it out for a build beyond just the bench.
BigBlockMopar
BigBlockMember
Besides power and mileage, there's another aspect that can be very satisfying to have in an old car, and that's good handling.
Especially for a young guy he might like a good handling car that can take corners and have it handle like a more modern car.
Especially for a young guy he might like a good handling car that can take corners and have it handle like a more modern car.
ir3333
Well-Known Member
Start a new thread..."what are your build specs, mileage and performance"
..i'm betting there are small cam,14 " tire combinations out there that will get lots of rubber and 20 mpg!
This ^^^^ is where it’s at.
Nothing more, nothing less.
If anybody is worried about the return on dollar spent vs mileage gained they should sell the vehicle and roll the money over into the highest mileage BRAND NEW CAR they can find that gets the highest mileage available.
If your building to get mileage, then enjoy the hunt and science behind discovering what works and what doesn’t.
That! Is where that joy should be. Not cost worry. Because if there is worry, your in the wrong hobby.
I got the best of 20 mpg’s with a 4bbl equipped 360/904/2.76 gear with 235/60/15’s, in a ‘79 Dodge Magnum.
Working A/C, P/S, P/B, etc...
IMO, the 3.55’s are pretty good. With the Chrysler .69 OD it will equal 2.4495 or just 2.45.
I didn’t mind 3.23’s but with an OD, it would equal 2.22. (Eeeek!) with stock sized diameter tires, it should scoot well IMO.
I didn’t mind 3.23’s but with an OD, it would equal 2.22. (Eeeek!) with stock sized diameter tires, it should scoot well IMO.
Penstarpurist
Well-Known Member
I would agree with the 3.55 gear ratio being a good balance for getting the best of low end off the line with a balance of it drinking fuel. Provided of course a lighter foot on the pedal, accompanied with a 4bbl carb and intake combo, 258-268ish cam, dual exhaust, and an od transmission would get it in the range of a semi economical rompity car.
I definitely think handling should be on the list of improvements.
He's not going to get 20 mpg in the type of driving mentioned - not even with a slant 6. The new goal is now not getting worse than it has witrh more pep, and that's doable.
Yes. With more pep, good stopping and turning are a great idea. Factory front sway bar is a minimum.
There's a lot of threads about 318 cams here on FABO. For mileage and efficiency you should keep the duration at 220° or below. Much more than that and you may need a higher stall torque converter to make it work. Here's a couple threads I saved. Within this thread are links to other 318/cam threads. 318 Build on a small budget
Here's another: 318 build with XE268 AND 302 heads
Slantsix64
Well-Known Member
For Gas mileage and more torque a 318 with sp2p intake 302 heads 500 cfm carbuerator fan clutch And a four speed. Should get you in the 18mpg . I had a early dart with a 318 two barrel and a four speed got decent mileage and could roast the tires.
Slantsix64
Well-Known Member
if you keep it auto go with a trans go shift kits work well
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,688
- Reaction score
- 12,968
I have a David Vizard book, called Performance with Economy.
In that book is a nice little chart comparing compression increases to power increases and to economy increases.
That chart shows that a compression increase from 8.0 to 11.0 is worth 5.2% power increase, and "the mileage gains (percentage) will be about double"
Now the last time I quoted that here on FABO, I was told that the power increase would be waaay more than just 5.2%; probably 100% more! or 10.4%. I can't argue that point, cuz I have no data of my own. But I have to wonder; if Mr.Vizard was off by such a huge factor in compression, was he also that far off in the economy prediction?
_______________________________________________________
In any case; to put a 318 into the performance arena,with bolt-ons, is gonna throw economy right out the window. You're looking at gears,a TC, and a 4bbl set-up, at the minimum, plus maybe a lil cam. What's that come to in Dollars? I'll guess $2500
Now, what would it cost to find an LA 360 core and pump the compression up, and a quickie valve job? And now, you can keep the gears and TC you now have, and stick your 318 cam into the 360, and keep it as a 2bbl. I'm guessing a lot less than $2500.
More torque, More power, and probably less fuel consumption.
Or you can leave that Lo-Po 252 cam in there for a ton-O-fun,and not including all the horsing around you're gonna be doing, I bet it still makes better mpgs on the hiway.
I tell ya, I wouldn't spend a nickle on a stock long-block-318-automatic, beyond what I had to to keep it running .
In that book is a nice little chart comparing compression increases to power increases and to economy increases.
That chart shows that a compression increase from 8.0 to 11.0 is worth 5.2% power increase, and "the mileage gains (percentage) will be about double"
Now the last time I quoted that here on FABO, I was told that the power increase would be waaay more than just 5.2%; probably 100% more! or 10.4%. I can't argue that point, cuz I have no data of my own. But I have to wonder; if Mr.Vizard was off by such a huge factor in compression, was he also that far off in the economy prediction?
_______________________________________________________
In any case; to put a 318 into the performance arena,with bolt-ons, is gonna throw economy right out the window. You're looking at gears,a TC, and a 4bbl set-up, at the minimum, plus maybe a lil cam. What's that come to in Dollars? I'll guess $2500
Now, what would it cost to find an LA 360 core and pump the compression up, and a quickie valve job? And now, you can keep the gears and TC you now have, and stick your 318 cam into the 360, and keep it as a 2bbl. I'm guessing a lot less than $2500.
More torque, More power, and probably less fuel consumption.
Or you can leave that Lo-Po 252 cam in there for a ton-O-fun,and not including all the horsing around you're gonna be doing, I bet it still makes better mpgs on the hiway.
I tell ya, I wouldn't spend a nickle on a stock long-block-318-automatic, beyond what I had to to keep it running .
Last edited:
Cope
Fusing with fire
I had a 318 in my 71 dart.
Bolted on aluminum intake, a 4150 and headers.
It was fun enough and got decent MPG and looked great to the untrained eye with the hood open.
it probaby had 300,000 miles on it when the float got stuck and washed 5 gallons of raw fuel into the oil killing the mains.
I drove that car every day for 10 years with almost ZERO maintanince, just gas in the rear and oil in the front.
The 14" tires were dirt cheep, I would white smoke the one to the cord then slap it on the other side and drive more. Total cost about 1,000.00 bucks.
Bolted on aluminum intake, a 4150 and headers.
It was fun enough and got decent MPG and looked great to the untrained eye with the hood open.
it probaby had 300,000 miles on it when the float got stuck and washed 5 gallons of raw fuel into the oil killing the mains.
I drove that car every day for 10 years with almost ZERO maintanince, just gas in the rear and oil in the front.
The 14" tires were dirt cheep, I would white smoke the one to the cord then slap it on the other side and drive more. Total cost about 1,000.00 bucks.
Penstarpurist
Well-Known Member
I've got a 1970 low mile j headed la360 sitting on an engine stand in our spare room. Lol. It's a concrete floor. Has a 4bbl aluminum intake and edelbrock 600 cam carb. It's ready to install, has a 727 trans sitting with it. So cost to find is zero. My son is welcome to use it in any project he wants. He has just been saving it for either the resurrection of his 68 fury or our 74 amc javelin. He just likes the idea of using the original engine in the valiant. Which is why he has been basing all the plans on the 318.
Matts440
Well-Known Member
Horse power and mileage says turbo to me, out of boost to low boost good gas mileage, in boost horsepower.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,688
- Reaction score
- 12,968
Whatever you do; do not put 74 plus cc heads on that 318 with a 340 cam, and 3.23 gears or less, with the stock TC. I did that once back in about 1980,and it was a total waste of time. The Dcr was so low that, (I didn't know about Dcr/VP back then), that 73 Swinger felt like it weighed 5000 pounds. But it had pretty good passing power at 75mph.......... in second gear!Eventually I put a 2800TC on it and it was still doggy down low. Finally I put 3.91s in the back, and that sorta woke her up. But gas mileage? Fugedabowdit!
I still have that engine, now returned to stock, but with a TQ on top. That was my winter engine for 5 in a row. It goes really good with 4.30s and double overdrive, and studded tires.
Last edited:
Penstarpurist
Well-Known Member
Good advice. I can't imagine 75mph I'm 2nd gear, that's Bonneville salt flats right there!
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,688
- Reaction score
- 12,968
That wasn't even 5000rpm yet. The math says 4500rpm right about where the 340 cam begins to come alive, snuggled into about a 6/1Dcr 318 . That was my all-time worst combo. I was about 25, and dumb as a brick. But hey,I had just found me a wife in 77, and the plumbing was working. I had my first baby, a daughter in 1980. So there's proof right there, that even a DA kid ......................... can find someone to love.
Criminy, I got an anniversary coming up in 6 weeks!
Last edited:
I’d vote turbo except of tubing concerns and cost and headache and....
I admit I’m not up in it enough to argue against it since it is the same idea I was saying about a super charger.
OH! No you’ve done it!!!!!
TrailBeast
AKA Mopars4us on Youtube
Not necessarily, but kinda yea
I run 80mph at 2,100 rpm's on the hiway getting a hair over 25mpg and can still light tires just fine.
1996 5.9 Magnum 9:1 carbed
214/224 cam
A500OD with lockup
15" 60's on the back
There's no way I can get into the cam power range in anything higher than 3rd.
In OD I would have to be doing in excess of 140 before the cam even starts building.
Penstarpurist
Well-Known Member
That is impressive without a doubt.Not necessarily, but kinda yea
I run 80mph at 2,100 rpm's on the hiway getting a hair over 25mpg and can still light tires just fine.
1996 5.9 Magnum 9:1 carbed
214/224 cam
A500OD with lockup
15" 60's on the back
There's no way I can get into the cam power range in anything higher than 3rd.
In OD I would have to be doing in excess of 140 before the cam even starts building.
Matts440
Well-Known Member
Well you can simplify the tubing and run from turbo to carb hat, you don't have to have a intercooler. Plus supercharger are on all the time where turbos are only on when spooling.
It exactly true. It alswould depends on the type of super charger & Pulley ratio used.
Matts440
Well-Known Member
Very true
-
