Technical CALLING ALL EXHAUST GURUS

I am about to replace the exhaust system on my 65 Buick 300. I will be keeping my factory manifolds and going to dual exhausts. Has exhaust theory changed in the last 50-60 years? Way back then the hot ticket was 2 1/4" pipes, an H or crossover pipe and late model Cadillac mufflers with resonators. Has anything changed?
This car is my daily driver, around town and frequent 4-6 hour interstate cruises. I would like a throaty sound around town without an annoying drone on the interstate. Please chime in with your pros and cons about pipe size, location of crossover pipe and mufflers and the need or not for the resonators. Thanks

 

Bump on this topic.

 

I have the Pypes 2-1/2" system coming off the exhaust manifolds on my 454 with a pair of Dynomax Super Turbos #17749 It sounds excellent!

 

Thinking 2 or 2.25 should be more than enough for a stock LA 318 with stock exhaust manifolds.
Duals of course to replace my cobbled botched dual exhaust I created with pieces layin around...lol

 

I revived a no response older thread.
Not sure why OP intended to have an H or X pipe.
Im not but tru duals dumping out 1 side at rear of running boards.

 

On my Fargo it’s dual 2.5” the left side crosses over under the bellhousing area and crosses back over after the differential.

It has thrush welded mufflers on it

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Yup sounds bout how mine will be routed. 2.5 inch, yup too big for my 80s 318 Im thinkin

 

Engine Masters just did a video on that and it does not work the way we thought it did a 3-inch pipe actually makes more horsepower than to two and a half look it up

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Yup bet it does. Once were talkin over 400 hp im guessin. My lowly 175 hp 318 might do better with smaller pipes I figure.

 

I highly doubt you will notice any difference regardless of the size of pipe you put on it besides the sound. Smaller will be a little rappier, bigger will be a little deeper.


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Yup gotta agree, unless my 318 gets 4bbl carb intake and more cam not gonna be much more outta of her.
1 plus is my 318 has the cast "302" heart shaped CC heads. Decent flowing heads but valves a little on small side.

 

I wouldn't go any larger than 2" or 2 1/4" pipes. No H pipe or crossover.
When you go to really large diameter pipes you will decrease your low end torque and for a driver I would rather have low end torque than high RPM HP.

 

You betcha Northern Bro? Spend mosta the time 1500 to 3000 rpm

 

The idea of needing small pipes and/or back pressure is just dried up antiquated bovine scat.

Step up to 2.50" pipe right off the manifolds. If you aren't revving high a lot forget a X-pipe and do a full 2.50" H-pipe. Mufflers. Do NOT select chambered mufflers. They don't call Flowmasters "drone masters" for no reason. You'll want something like Magnaflow mufflers that aren't their race mufflers. If you do experience drone, you can add a properly sized hemholz chamber for the rpm where it occurs or a variable J tube and tune it out.

If you just don't want to run 2.50", then run 2.25" but no smaller. The 2.50" pipe is super crazy common. So popular. Assuming you are somewhere around stock power levels (200-250hp) Either would work well. The 2.50" will never be a restriction at that power lever. The 2.25" will get the job done too with little issue and cost very little power. Stock off-topic 5.0 Mustangs had 2.25" from the factory and arrived with 225hp and 300 ft-lbs. same ballpark as your 300. When stepped up to a full 2.50" system they picked up 15-30 hp. So at that power level 2.50" is really the right size.

 

The bigger pipes move your torque band up. That engine wouldn't like bigger than 2" pipes on it, and like they said above no "H" pipe.

 

Pass on the H-pipe and the X-pipe and step up to the O-pipe exhaust. Absolutely no droning at all.
..
Clickie >>>>> https://etel-tuning.com/engine-parts/41-o-pipe
..

 

I have a 4.3 v6 with headers and smithys The drone is bad! Any thoughts?

 

2 inch, 2-1/4 inch, 2-1/2 inch...too much to think about, I'm exhausted

 

Timing will effect the drone.Timing is everything,does it have a carb?

 

No need for anything larger than 2 1/4" actually 2" would be fine but I don't like the look of a 2" exhaust system. The smaller system helps with scavenging by increasing air speed of exhaust.

It might be the V6 itself or how the exhaust is hung under the vehicle, too many hangers or hangers that are not flexible enough and transmit vibration.

 

Run a decent sized single exhaust.
Road Racers have used this method for years now [most sanctioning bodies have a noise limit]

With the correct setup you can remove the mufflers and still stay under the Db limit.
The idea is to increase the number of pulses down the pipe to smooth out the sound. [an X pipe attempts this]
The worst car is a BB Corvette with side pipes [you only hear 1/2 the engine so it sounds like a tractor]

 

Where is the fun in single zost Bro?...lol
Seriously, on my application mostly stock LA 318 would any type of single exhaust be advantageous?

 

Running off factory manifolds should’nt notice a difference I think, even in the butt dyno. I’ve heard the “ move the tq rang up/ down” talk before, but no one I’ve spoke to has actually said it will move it “xxx RPMs “ nor have I see dyno sheets with back to back runs with mild engines
So say it move the RPMs range up 250 , would noticeable?

 

Mimilan, worse sound than the Corvette is the five cylinder Viper sound on each side. It sounds like sort of sick tractor.

 

Trust me, you won’t notice a damn bit of difference no matter what you put on it, except the sound


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Yup gotta agree but this 1986 318 with the "302" swirl heads minus all emissions, non lean burn carb, ,non lean burn electronic distributor has a lot more snap then I ever figured. Gonna be interesting once I do cam swap and go 4bbl and intake.

 

This is what Chevy told their SAE buddies happened when adding a 4 bbl and (small Ø pipe I bet) duals.
Full throttle yes.

I rescaled the graphs so the HP and torqueage Y axises are the same.

 

I see a 2 bbl vs 4bbl with duals, how is that a comparison with exhaust pipe size, or did I miss something?

It doesn't mention the 2 bbls exhaust, then there is the difference in carbs to look at as well.

 

I don't know about that ^^^^ it might sound like a 5 cyl Audi Quattro

We had a C3 Road Racer with 5" side pipes [designed on a flowbench], it sounded really nice inside the car [with a helmet on] but to spectators it sounded like a Plow Tractor, even at 100+mph

Unless you are running open headers, a single "Big Bore" will make more power. That's why Trans-Am series cars run them.[Aussie V8 supercars have been running them since the 90's]
They make the engine sound like it is revving a lot higher ["On Song"]

Duel exhausts with glass-packs on a low revving street car is as annoying as pulling up beside some rice rocket with a "Boom Box" sound system.

We actually removed the factory duel exhaust off our 57 Chevy and ran a cross-over "Y" pipe behind the bellhousing over to a single 2-1/2 in exhaust system.
It now has that nice burble sound that a Y block Ford makes.