more power out of 318?

[abernard161]

does anyone know how to get more power of a 318 its in my 1973 d20. what headers will fit on this?

[RedneckExpress]

Bout the only way I know how to get more power out of a 318 is to swap it for a 360 . 

[abernard161]

lol  yeah thats what i'm finding out

[RedneckExpress]

Well, the nice thing about 360s is Dodge made alot of them, the trick is finding a 360-3, which is the style used in motorhomes vs a 360-1, the style used in Pickups and Autos.   As I recall, there's a difference in the cam shaft and intake going between a 1 and a 3 model. 

[Oz]

You didn't mention if the 318 has the stock, 2bbl carb?  The only way to get more power is to install a bigger motor?  The 318 is a widely used motor that's been around like... forever.  Just like the Chevy 350. Upgrade parts are plentiful and there's no shortage of them at the street rod/hot rod shows so I would reasonably assume they must be able to be tweaked... just like every other motor.

Start with an Edelbrock, economizer 650cfm, 4 bbl carb? or Install a TBI?
Install an upgrade HEI ignition and Tweak your timing?
Install a mild performance cam?

You can put in headers if you absolutely feel that you must but, the gain is nearly nothing, especially compared to the cost and the complications... meaning... you're going to need to re-route wiring, maybe the fuel lines... and you WILL have to install heat shielding.  Or, you can add your story to the ones already out there about how the headers melted the fuel and brake lines and started a fire.

Instead, add dual exhaust.  That will do far more than headers.

There's plenty you can do to add power.  The key is NOT to sacrifice gas mileage.  Personally, I'd go with the dual exhaust and, if affordable... TBI - or, the 650 cfm carb.  Swapping to and electrirc fan would be a plus too. 

I'm sure others have very specific info on what to choose.

[RedneckExpress]

Mark, I had a D150 a while back with the 318 and the TBI, it was still a gutless wonder by comparison to the 360 that I have in my W250/350. 

[Oz]

You can get more power out of the 318, regardless if you put a TBI in it or not.  And, I'm doubtful that a TBI system gives it any more power, it should just make it more efficient.  Again, it wasn't stated if it had the OEM 2bbl.  Whch I'm fairly certain that, if replaced with a 4bbl, would give it more power?  Is that correct?.  The same with adding dual exhaust and tweaking the timing.  Correct? 

How do you get more power from a 360?  Put in a 440 instead.  How do you get more power from a 440?  Put in a bigger carb, add dual exhaust, tweak the timing & fuel/air mixture.... etc... or put in a bigger, diesel motor.

The question was how to get more power from a 318, which, if I read right on the mopar performance sites, IS something which can definitely be accomplished.  And, there were plenty of 318s made, just like the 360.  Swapping to bigger motor.... yeah, that's always a way to get more power and is an option but, it doesn't answer the original question.  How to get more power from a 318. 

[abernard161]

thanks.. i'll look into the 4bbl. it does have the stock 2 bbl.. to put the carb on will i have to change the intake? and which intake is a good one? what is a TBI? thanks for the help again

[Oz]

TBI - Throttle Body Injection.  You shouldn't have to change the intake but... you can.  I did on my 440.  Edelbrock is a good choice.  You can go to JEGS or Summit Racing websites and see what they have.  They sell new and rebuilds.  Other brands too, like Holley.  Over the years, I've read that the Edelbrocks seem to be the easiest to work with and are good quality.  I had one in mine.  You can also call their tech support.  They've always been good for me.  If you want power... the Thunder series (previously the Performer series) is the choice.  They have the carbs and intakes.  WARNING:  There is a price for that kind of power which is paid for at the gas pump! 

The most sensible thing to go with is simply an Economizer.  When I bought my last Winnie, it had a 600 cfm Edelbrock Economizer on it.  This was on a 440 which is really too small.  However, it fared ok on the road, except for steeper hills.  The rig would drop to no more than 40 mph.  But, my rig was also a 24'.  The upside... I got 8 mpg, which is about tops for a 440.  With the Performer carb... I got 5 - 6 mpg.  But, I could blow up any mountain at whatever speed I felt like.  This still with a single exhaust.

Oh yes, some people tried the MSD full ingintion system upgrade (on their 318s).  It's expensive, many people reported problems with it, most didn't notice any or minimal improvements.

What you choose to do is really based on what you want for the end result.  Most people want to be able to not have to crawl up hills but not have to own a bank to pay for the gas either.  And, most people don't have a lot of money to dump into parts... much less to pay a mechanic to do the work.  Replacing the carb with an Edelbrock is really simple... I can tell you that.  Add a dual exhaust system (which you can make yourself with off-the-shelf parts), and you'll have a good balance between power and economy without having to sell your body parts to pay for.

[polarman]

 It seems to me that just changing to a 4 Bbl carb and intake won't do any good without a cam swap. It will only move so much air and fuel with the stock cam, regardless of how big a carb is on it. You can, and likely will, actually lose performance if the parts arent matched to work together. On the regular 318 engine, 340 heads with the big valves will bolt right on, but I'm not sure about the 318-3.

[LJ-TJ]

Well I have a little experience with this and here's what I would suggest. Swap it out for a 440. You'll be like a dog chasing it's tail, you'll spend more money trying to get more poop out of a 318 than if you just swapped it out for the 440. Your not going to realistically beat 8 to 10 miles to the gallon which you will get with a tuned 440 and in a 21'er she'll go like stink and pass everything on the road. I had a souped up 318 in my 21'er and now have the 440 wouldn't even consider going back to a 318.  :)ThmbUp

[RedneckExpress]

Search for a 1983 or older copy of "Trailer Life's Rx for RV Performance & Mileage", By John Geraghty & Bill Estes ISBN 0-934798-06-0

Follow instructions from Chapter 29 - Modifying Dodge 360 and 318 V8s.

[Oz]

Search for a 1983 or older copy of "Trailer Life's Rx for RV Performance & Mileage", By John Geraghty & Bill Estes ISBN 0-934798-06-0

Follow instructions from Chapter 29 - Modifying Dodge 360 and 318 V8s.

You don't have to search far to find it.  We've had it here, in the store for quite a while.

[ibdilbert01]

Its actually very common to see the mopar guys at the track getting 400+ HP out of a little ol' 318.      You just have to know how to build one right, and be willing to spend the money.

[greggholmes]

"How fast do you want to go?"

"How much money you got?"
.
Engines are like rubber bands, the more you stretch it the sooner it will snap.

A bigger engine can be had for the price of a new TBI system.

[Oz]

Anyone who has one of these smaller RVs (D19 - D21) and has a 440-3, as stated, knows that's the best option, if it is an option to you.

If it's not then, just seek outside sources for info.  There's nothing here which actually answers the question in detail other than read the aforementioned book and some general suggestions.  It most certainly is possible and not exhorbitantly expensive to get more power from a 318 without stretching it like a rubber band until it breaks.  It's simply that, those who have had them here, apparently have all had the resources to go with a bigger motor.... which has all the "stretch" and then some to handle anything you want to do with a smaller rig.

[LJ-TJ]

  Hm? Shoot I don't quit know how to explain this as I started out with a 21ft 318 which I loved and thought was the cats bum. If you have a good running 318 my suggestion is don't mess with it. It's a great little engine and will get you from one end of the States to the other trouble free and at about 8 to 10 miles to the gallon.  But as most know you can spend a fortune chasing power on a little 318 and when your all done you could have bought a decent used low mileage 440 out of one of these rigs for half if not the same money you would spend trying to get more power out of the 318 and you'll get around the same mileage 8 to 10 with the 440. If the 318 is soft then just swap it out. My observations and experience tells me 440's are available for a few hundred to several hundreds of dollars. I've see 440's for the price of a good four barrel and intake manifold for the 318.
http://motors.shop.ebay.com/i.html?_nkw=Dodge+440&_sacat=33612&_dmpt=Motors_Car_Truck_Parts_Accessories&_odkw=&_osacat=33612&bkBtn=&_trksid=p4506.m270.l1313

[JDxeper]

For that kinda money I will sell you a good running 440-3  78,000 miles, trans mission, water heater, AC, working refrig and a genset.. , along with new 16 inch rims and tires.

[greggholmes]

http://www.allpar.com/mopar/4bbl.html

http://www.popularhotrodding.com/enginemasters/articles/mopar/0667em_mopar_318_engine/viewall.html

http://www.squidoo.com/Mopar318

http://www.dippy.org/forum2/index.php?topic=242.0

http://www.hotrod.com/howto/113_0304_318_small_block_build/viewall.html

[Thomas Budzowski]

I put Heddman headers, 4 barrel Edlebrock carb, Edlebrock manifold, large air filter and free flowing dual exhaust already had dual exhaust previously on my 318-3 and it definately made a difference (should of for what it cost).  On its maiden voyage I was like "this thing will probably go 100 now!"  Shortly thereafter I see giant smoke in mirror.  Limped it home and found broken piston ring.  I guess the tired old engine didn't care to be hurried along.  I swapped it out with a 360  ( not a -3) but was able to use all the goodies I had put on the 318 plus the distributor, timing chain set, and the water pump.  It really goes now.  I towed a 7,000 pound trailer cross country and back.