318 LA hp and torque question

-
okiemike

okiemike

Active Member
Joined
Dec 13, 2014
Messages
39
Reaction score
1
Location
walters Oklahoma
Im new to the mopar world so I would like to ask a question regarding my 69 notchback barracuda w/318 La. The book states this engine is 230 hp @ 4400 rpm and 340 lb torque @ 2400 rpm. It is bone stock with the orig. intake and 2 barrel carb and single stock exhaust. If I install a SP2P 318 edlebrock alum. intake and 600 cfm carb. along with dual exhaust what kind of hp and torque increase would I be looking at? Thanks
 
Not as much as you're thinking but you are moving in the right direction. Install a new cam and lifters would help as well (don't forget a double roller timing chain, the factory 318 ones suck).
 
okiemike said:
Im new to the mopar world so I would like to ask a question regarding my 69 notchback barracuda w/318 La. The book states this engine is 230 hp @ 4400 rpm and 340 lb torque @ 2400 rpm. It is bone stock with the orig. intake and 2 barrel carb and single stock exhaust. If I install a SP2P 318 edlebrock alum. intake and 600 cfm carb. along with dual exhaust what kind of hp and torque increase would I be looking at? Thanks
Click to expand...



Okie Mike

That 230 HP rating @ 4400 RPM's was way over-stated by Mopar.

As per the NHRA Horsepower Ratings, the 1969 '318' put out 195 HP.

* First Step > Dual-Exhaust will help immensely.

On the Edelbrock #SP2P, it was designed for Low-End Torque and Economy,
as it has small runner-ports to go along with a dual-plane style.

Many call it, the 'Motorhome Intake'.

The carburetor base is designed for a Thermoquad or Spead-Bore style
carburetor.

You won't gain much in Horsepower with this Intake, but the Low-End
Torque will get a 'bump'.
 
Not meaning to Hijack but I've always wondered. I'm building a 318 with a stock 73 bottom end, late 80's closed chamber swirl port #302 heads, Edelbrock LD4B and 600 cfm carb, 340 cam, dual exhaust, maybe headers but probably stock exhaust manifolds. How much Hp and Tq do you guys think it will make.
 
I'd say with intake, carb and headers/dual exhaust you'll be lucky to get close to what the factory rated it at. In addition to those things -ported, closed chamber heads, thinner head gaskets and a decent cam (a lot of guys including me did the xe268 from Comp) is probably the best recipe for success given a stock 318 short block with it's lame pistons.
 
I would personally not use that intake. It is primarily designed to improve bottom end torque with its small ports to increase velocity like for instance in truck and towing applications. The Weiand Action Plus or similar would be a better choice.
 
CultClassik said:
I'd say with intake, carb and headers/dual exhaust you'll be lucky to get close to what the factory rated it at. In addition to those things -ported, closed chamber heads, thinner head gaskets and a decent cam (a lot of guys including me did the xe268 from Comp) is probably the best recipe for success given a stock 318 short block with it's lame pistons.
Click to expand...
Yup, the thinner head gaskets and closed chamber heads hopefully raise the cr to somewhere around the 9's. It was a toss up with me between the 340 cam and the xe268.
 
okiemike said:
Im new to the mopar world so I would like to ask a question regarding my 69 notchback barracuda w/318 La. The book states this engine is 230 hp @ 4400 rpm and 340 lb torque @ 2400 rpm. It is bone stock with the orig. intake and 2 barrel carb and single stock exhaust. If I install a SP2P 318 edlebrock alum. intake and 600 cfm carb. along with dual exhaust what kind of hp and torque increase would I be looking at? Thanks
Click to expand...

The NHRA's way of rating power is for there racing issues.

The intake should not be used. Look for a LD4B, Performer or Weiand Action Plus.
You'll need a small adapter plate that you can get from Edelbrock.
The 600 is fine.
With the dual exhaust, your probably looking at 250/260HP.
Adding a new cam can add 20HP. Depending on the cam.
I would suggest headers into a 2-1/2 exhaust to help the cam work better and add additional HP and torque.
Over all, with a modest cam, you could make 270/280 HP without changing heads or pistons.
 
Dustert73 said:
Not meaning to Hijack but I've always wondered. I'm building a 318 with a stock 73 bottom end, late 80's closed chamber swirl port #302 heads, Edelbrock LD4B and 600 cfm carb, 340 cam, dual exhaust, maybe headers but probably stock exhaust manifolds. How much Hp and Tq do you guys think it will make.
Click to expand...


Well, Hi-Jack you did and I'll answer the question, but first, stock head gaskets are the thin head gaskets. I would not use the stock 302 head unless it has seen some work done to it.
The bump in compression will be modest at best.

With the 340 cam, see above for power out put guess'.
With the upgraded performance 340 from MoPar, you can crest 300 easy.
On the 302 head, install 360 valves, intake and exhaust, bowl port and open the ports to match the intake.
That combo is worth about 340/350 hp. (With headers)
 
Dustert73 said:
Yup, the thinner head gaskets and closed chamber heads hopefully raise the cr to somewhere around the 9's. It was a toss up with me between the 340 cam and the xe268.
Click to expand...

From what I've seen you won't see 9:1. If memory serves I had my 273 closed chamber heads milled 15 and used the Mr Gasket thin head gaskets, mine came out to about 8.6, but good enough for what it is :) I think the 302 heads might have a tiny bit smaller combustion chamber but I'd use whichever was found at the right price.
 
CultClassik said:
From what I've seen you won't see 9:1. If memory serves I had my 273 closed chamber heads milled 15 and used the Mr Gasket thin head gaskets, mine came out to about 8.6, but good enough for what it is :) I think the 302 heads might have a tiny bit smaller combustion chamber but I'd use whichever was found at the right price.
Click to expand...
As long as it wins against the occasional import, makes v8 noises, and roasts my radials I'm fine with it :burnout:
 
okiemike said:
Im new to the mopar world so I would like to ask a question regarding my 69 notchback barracuda w/318 La. The book states this engine is 230 hp @ 4400 rpm and 340 lb torque @ 2400 rpm. It is bone stock with the orig. intake and 2 barrel carb and single stock exhaust. If I install a SP2P 318 edlebrock alum. intake and 600 cfm carb. along with dual exhaust what kind of hp and torque increase would I be looking at? Thanks
Click to expand...

Going by your 'original question'.

The 318/230 HP puts out closer to 195 Gross Horsepower @ 4100 RPM's.
Torque read outs are around 305 Ft/Lbs. @ 2500 RPM's.

By adding a decent Dual-Exhaust system {Exhaust Manifolds, 2.25" Exhaust Pipes, and Low-Restriction Mufflers} {ie; Mopar 340} you should increase Horsepower by a minimum of 12% {or 23 HP}.

The 1969 318/230 HP came thru with a Carter BBD {285 CFM} Carburetor.

If your replacing the Intake and Carburetor with an Edelbrock S2P2, and
a 600 CFM Carburetor, you will probably gain another {12 to 15 HP}.

The Edelbrock S2P2 is really designed for low-end Torque, and is not
effective over 4000 RPM's for horsepower increase.
 
If the 69 318 uses the 920 head casting, it's a wash on compression using the 302 head.
They both have the same volume. The book lists '69 318 with 9.2:1 compression.
That's the same spec as the roller cam, 302 head motors.
The gain would be hardened exhaust seats, but the size of the valves IIRC is the same.
...and perhaps the "swirl".

That 268 cam is kinda peaky for a street build.
One or more steps "down" is more tq earlier and not much HP sacrifice.
I think the 340 cam is right on target.

I agree with duals being the best first mod.
That's what the factory did on 318 Roadrunners, and said it was good for 20HP.
Headers are a double edged sword. Esp small block headers.
 
CultClassik said:
I love V8 noises, haha!
Click to expand...

Then I suggest yall get one of these and leave the real cars to us.

[ame="https://www.youtube.com/watch?v=kkf8mj_bzpo&x-yt-ts=1421914688&x-yt-cl=84503534"]SoundRacerV8 - YouTube[/ame]
 
YY1 said:
If the 69 318 uses the 920 head casting, it's a wash on compression using the 302 head.
They both have the same volume. The book lists '69 318 with 9.2:1 compression.
That's the same spec as the roller cam, 302 head motors.
The gain would be hardened exhaust seats, but the size of the valves IIRC is the same.
...and perhaps the "swirl".

That 268 cam is kinda peaky for a street build.
One or more steps "down" is more tq earlier and not much HP sacrifice.
I think the 340 cam is right on target.

I agree with duals being the best first mod.
That's what the factory did on 318 Roadrunners, and said it was good for 20HP.
Headers are a double edged sword. Esp small block headers.
Click to expand...

YY1 is correct. My 69 318 Barracuda came from the factory with 9.2:1 CR (by the factory manual). When I swapped out the stock heads for 302 castings I found that the original heads were 69CCs, when I checked the swirl port heads they were also 69CCs. The pistons were .039 down in the hole (the tallest piston they put in a 318). I was hoping to get a little more power from the swirl ports but the main reason was for the larger exhaust sealing surface for the 340 driver and 360 magnum passenger exhaust manifolds. The old original 318 heads have almost no sealing surface on the bottom edge of the exhaust port relative to the large 340/360 manifold ports as shown by the big difference between the stock 318 exhaust manifold gasket and the 360 magnum gasket. I've read that you can get the stock heads to seal but why take any chances when you have a set of swirl port heads sitting on the shelf saying, "use me...use me!!"

Treblig
 

Attachments

  • DSC01769.jpg
    66.4 KB · Views: 441
  • DSC01770.jpg
    66.1 KB · Views: 513
Treblig said:
YY1 is correct. My 69 318 Barracuda came from the factory with 9.2:1 CR (by the factory manual). When I swapped out the stock heads for 302 castings I found that the original heads were 69CCs, when I checked the swirl port heads they were also 69CCs. The pistons were .039 down in the hole (the tallest piston they put in a 318). I was hoping to get a little more power from the swirl ports but the main reason was for the larger exhaust sealing surface for the 340 driver and 360 magnum passenger exhaust manifolds. The old original 318 heads have almost no sealing surface on the bottom edge of the exhaust port relative to the large 340/360 manifold ports as shown by the big difference between the stock 318 exhaust manifold gasket and the 360 magnum gasket. I've read that you can get the stock heads to seal but why take any chances when you have a set of swirl port heads sitting on the shelf saying, "use me...use me!!"

Treblig
Click to expand...

Wish I had a set of #302's sitting around! I'm still waiting on CMengines to find another uncracked core to machine. I've been waiting around a month for them.
 
Dustert73 said:
Wish I had a set of #302's sitting around! I'm still waiting on CMengines to find another uncracked core to machine. I've been waiting around a month for them.
Click to expand...

302s aren't that hard to find?? At least I didn't have any trouble finding any. I guess it depends on where you live or where you look.


PS - Just for fun I threw in a pic of one of my "machined" magnum manifolds next to a stock 318 manifold. The difference is DAY and NIGHT!!! That's why the exhaust sealing surface has to be so large on the 340 driver and the 360 passenger.....more FLOW!!!!
Treblig
 

Attachments

  • DSC01752.jpg
    27.3 KB · Views: 441
  • DSC01753.jpg
    37.2 KB · Views: 374
  • DSC04221.jpg
    36 KB · Views: 440
You must log in or register to reply here.
-

Back
Top