Recommendations for Dual Exhaust on a 318

[moparmike71]

Hi Everyone,

Looking to punch up the sound and fun with the 318 in my 71 Charger. I was told it is out of a 1974 Duster, so from what I understand the HP is way down from what it would have been if it was the original, 1971 318. It currently has stock manifolds and a single exit exhaust. The exhaust is more holes than actual pipe at this point...

The car is generally a daily driver for the summer months and I do plan to take it on longer trips, highway or otherwise. I'm after something that has a deep/low rumble and does not drone for the longer trips. I'm not trying to be the bane of the neighborhood either when I start it up every morning. 

Looking for some opinions on whether or not I should use the stock manifold or do headers. If I go the route of headers, what are folks using out there and are happy with? The Hooker Headers (link here) seem like a reasonably priced option and I've always been a fan of the company. I'm also thinking of a 2.5 inch system over the 3 inch so it isn't ungodly loud or droning, currently looking at the 19303 Magnaflow set up (link here). 

Anything anyone can offer (including sound clips) for what setups they think may do the trick would be most appreciated. Thanks!

[DynoDave]

Headers will gain you a little performance (better flow, better torque with long tubes, less weight), but are noisier, and radiate more heat. You will also have to tune for them (fuel mixture, timing), so be prepared for that extra work as well.

For mellow cruising and a healthy sounds at wide open throttle (WOT), I think you would be happy with the Magnaflow. Stainless is nice too. If you have some drone, you can always add some resonators at the tailpipes as the factory did.

The factory would have used Hemi mufflers on a performance B-body, and have a reputation as being very quiet to live with, but have a nice growl at WOT. There are reproductions available, or you can use Walker Super Turbos, which are a similar design to the Hemi.

I think part of the answer is where you plan to go long term. If a better performing engine is in the plans down the road (or a rebuild/enhancement of the current engine), then headers (particularly ceramic coated ones) and the stainless Magnaflow system will help a little now, sound nice, and still be around later when you build that new engine.

If it's just for right now, you could go with something less expensive (no coating, some super turbos, and a fabbed system from a local shop).

I'm not sure about the 2.5" system. I think theory would say that with a 150-ish horse 318, 2.25" pipes would preserve more of your low end torque, which is already in limited supply. But I'm going to guess that at this point, it won't make too much difference either way. And again, for a future build, 2.5 might make more sense then.

[Tom]

May 15, 2018 11:50:59 GMT -5 moparmike71 said:

 from what I understand the HP is way down from what it would have been if it was the original, 1971 318.

Not really true.

71 318 was rated at 155 HP , 72-75 was rated at 150.

www.allpar.com/mopar/318.html

I would not bother putting headers on a anemic/stock 318.

If ya build a 300 HP 318...sure, why not.

The many negative points of header ownership will outweigh the (temporary) cool sound

Temporary I say, because once the flange gaskets start blowing......... the headers don't sound so good.

One of my 318 cars. (Yes, it was anemic too. LOL)  had dual exhaust with a a pair of glass pack mufflers on it.

That's the way it was when I bought it. It sounded pretty good, most people assumed I had a big block in it. 

I would just visit an exhaust shop and see what they could do as far as mufflers and pipes. On a budget of course.

[moparmike71]

Thanks guys! All solid advice and I'll take it to heart.

I'm not planning to build the 318, it is a future replacement engine (hopefully). My dream build would be to dump a modern 392 Hemi into it, but for the time being I'll be rocking the 318.

Don't want to pump too much into it as a result, but I want to make due with what've I've got since the build would be years off. Plus I want it to stay reasonably solid in the interim so don't want to make it too crazy. I have heard similar stories about doing headers. I think it would make sense just to skip them since they sound like more of a pain than a benefit. My uncle (long time wrencher) suggested the same thing about checking out a local shop to see what they would run for a new system.

[dodgecharger4404]

318 ratings: Note the 150/155 hp is the "Net" rating of '72 and following years. At the crank is 230. Hedders (or headers): Such will improve performance of the 318, and with the limited cubes, you need all you get. My '71 Dart received HTC units last summer (replacing black painted), and the underhood heat difference is noticeable.

Should you build a 360 or 360 stroker, you can use the same hedders, though 1 5/8 inch primaries might hold it back on the top-end. A Hughes supplied kit (360 to 426) would be a fun drive. If I had it to do over, that is what I should have done last summer. My 318 stock heads had begun to sink exhaust valves, so updated to Edelbrock aluminum heads, more squeeze pistons, Edelbrock 2176 intake. All those $$$ + would've made a 360 stroker with bunches more power.