Hipo 318 exhaust manifolds?

[Wakko]

My '78 Fury 318 needs new exhaust and I'd rather not do headers (don't want the look, the heat or the volume) but I would like to bump up some horsepower if there's some to be had.  Were there any hipo 318 manifolds?   360 manifolds work and be better?   

[Chryco Psycho]

late 60s & early 70 318 had better exhuast manifolds

[Skull-1]

late 60s & early 70 318 had better exhuast manifolds

How do these compare to similar 360 manifolds?  My factory 1969 318 exhaust manifolds are in the attic.  Maybe I should ditch my headers and put these back on....

[Ghoste]

The headers will breathe better than the manifolds but if the car is mostly stock then there isn't much advantage to running headers anyway.  The 340 ones are better than the 318 manifolds and so are some of the 360 ones.  I'm not sure if all the 360 ones are the same but I'd be surprised if they were.

[Kern Dog]

Years ago Mopar Muscle magazine did a dyno comparison on a 300 HP 360. They tested several manifolds and headers to see what effects there would be on a fairly mild engine.
The testing began with the basic econo-318 manifolds followed by larger passage 360 manifolds, then the famous 340 manifolds. Sadly, there wasn't a huge difference! The 360 manifolds only showed a 4 HP gain over the 318 ones and the 340 manifolds only made S E V E N HP more! Their opinion was that on a mild engine, the manifolds don't help much. The headers they used DID add 20 HP though.

[Ghoste]

Thats interesting. 

[ACUDANUT]

If it is a 78 318, your engine is already a no performance engine.  Yuck.

[Skull-1]

The headers will breathe better than the manifolds but if the car is mostly stock then there isn't much advantage to running headers anyway.  The 340 ones are better than the 318 manifolds and so are some of the 360 ones.  I'm not sure if all the 360 ones are the same but I'd be surprised if they were.

I have a cam and 4bbl with EI.   If the headers are overkill I wanna go back to manifolds.   I wonder if my 1969 stock mans would be just fine....

[A383Wing]

I would think you would have to open up the exhaust ports on the head to see any real big gains from adding the 340-360 cast iron manifolds. The ports are bigger on the manifolds than the head

[Kern Dog]

A chain is only as strong as its weakest link.
The outlet of the manifold to the exhaust pipe is where the flow gains are found in a cast iron small block manifold. Most 318 and 360 manifolds have a 2" outlet. The 68-71 340 had 2 3/8" outlets.

[Skull-1]

A chain is only as strong as its weakest link.
The outlet of the manifold to the exhaust pipe is where the flow gains are found in a cast iron small block manifold. Most 318 and 360 manifolds have a 2" outlet. The 68-71 340 had 2 3/8" outlets.

Hmmmmm.   That explains why I still have 2" pipes.....

So my headers are for show pretty much....

[Kern Dog]

Not entirely. Even with 2 inch exhaust pipes, you're flowing better than an engine with iron manifolds and a single exhaust pipe.

[Cooter]

I'll say it again......headers (tubular exhaust manifolds) are ALWAYS better than standard exhaust manifolds.
more power, torque, fuel mileage, AND noise.

Barring the stupid money the FAST guys have in extruded honing manifolds, asking for more performance from stock cast iron manifolds is like installing screen doors on a submarine. They even have the stupid "shortly" headers that bolt in where manifolds were.

[Skull-1]

Sounds fair to me.