Splitting the exhaust on the eight.

keithfullmeryahoocom

So, sometime after I had my original, stock manifold porcelain coated with aluminum (I love the way it looks), I bought a great-looking home made, split exhaust from Park W that I was thinking of using.  I know how good these make these engines sound as I once had a Terraplane with this setup, and maybe it was just my imagination, but it really seemed to actually run better.   I would like to keep the stock manifold for the way it looks, but I'm entertaining splitting the exhaust in some other way.   

If I was to split the exhaust pipe right behind the manifold, keeping the manifold single but running two exhaust pipes back, side by side, would this mod give the exhaust a better sound?   Is there anyway that it would help relieve the back pressure on the exhaust, and in your respective opinions would this help or hinder sound and performance.

I am assuming that I would never be able to find the "two into one" that is more common for the six.

Thanks for any discussion along these lines...k

Ol racer

Keith,
I probably shouldnt reply since never had an 8, but if your after tone just install a glasspack muffler. If your in a warm climate remove the heat baffle inside the manifold will help flow slightly. You could have a muffler Shop make you a 2 in 1 adapter pipe to bolt onto your 8 Cyl Exh Flange. I made one for a Hornet by welding onto a flared  truck 3 '/2"" pipe then wrapped the opposite end around two 2" pipes exiting to the rear, but the gain vs expense was minimal at best....
However, If you had an old Manifold it could be split in the middle by a compentent Weld Shop then you would experience a slight gain..

Park_W

Keith, the sound usually sought by folks is created when the front half of the engine feeds one pipe, and the rear cylinders feed a separate pipe.  Most folks who heard mine thought it sounded great.  The "dual effect" could be increased by further isolating the front and rear halves of the manifold, i.e., put a more close-fitting blockage in the center (the heat riser butterfly area), and better blocking off the heat path that goes under the carburetor.

The one I had back in the fifties was totally separated into three pieces . . . front manifold section, rear manifold section, and the remaining piece that supports and mounts the carburetor.  Now that one really sounded good!  And the performance compared to the original single manifold was definitely improved.

keithfullmeryahoocom

So, there's not much real advantage to keeping the single manifold and splitting just the exhaust pipe?   

Park, did you have a "triple exhaust"?   Lol...k

Park_W

That's correct, Keith.  The good sound comes primarily from the greater spacing of exhaust pulses from the individual pipes, and the alternating pulses from one side to the other.

keithfullmeryahoocom

Thanks, Park.  Decision making time...k