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The Nostalgic 265 Engine Build

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denverflatheader:
bfalfa55 – you know either x or h-pipe is termed a balance pipe as it provides a crossover point to equalize flow side-to-side in a V8.  Engines create exhaust pulses due to firing order and to smooth out these low and high pressure pulses, a balance pipe maybe used to address the backpressure created.  Backpressure simply slows down exhaust flow.

Most agree about x and h pipes and they both relate to sound and power.  X-pipe is higher pitch noise and the h-pipe a deeper tone.  Slight hp gain from x-pipe due to the venturi effect which allows exhaust gasses to exit combustion chamber faster (i.e. scavenging); the more cam duration, the more effective according to the experts.  The 90 degree bend in the h-pipe provides more back pressure which increases low-end torque and maybe important in some cases.

My own experience 18 years ago in 1998, I bought a new Ford f150 and after a year, I had dual exhaust installed with an h-pipe.  Prior to installing the dual exhaust, it ran 15.30-50s around 90mph on test night for fun.  After the new exhaust, it still ran the same et/speed just over 5,500rpm.  Whether you chose x or h or neither, my guess is your ’55 265ci results might be similar.  Although no improvement on the track, it sounded faster.  Alan

bfalfa55:
The bore isn't even that big it is 3.81. Standard bore of a 265 is 3.75.  It would neat to see what numbers would come from a dyno run. If I don't get just the engine on a dyno, we have a place local here that has a chassis dyno, so that will be the real tell all.

bfalfa55:

--- Quote from: denverflatheader on November 02, 2016, 11:38:18 AM ---bfalfa55 – you know either x or h-pipe is termed a balance pipe as it provides a crossover point to equalize flow side-to-side in a V8.  Engines create exhaust pulses due to firing order and to smooth out these low and high pressure pulses, a balance pipe maybe used to address the backpressure created.  Backpressure simply slows down exhaust flow.

Most agree about x and h pipes and they both relate to sound and power.  X-pipe is higher pitch noise and the h-pipe a deeper tone.  Slight hp gain from x-pipe due to the venturi effect which allows exhaust gasses to exit combustion chamber faster (i.e. scavenging); the more cam duration, the more effective according to the experts.  The 90 degree bend in the h-pipe provides more back pressure which increases low-end torque and maybe important in some cases.

My own experience 18 years ago in 1998, I bought a new Ford f150 and after a year, I had dual exhaust installed with an h-pipe.  Prior to installing the dual exhaust, it ran 15.30-50s around 90mph on test night for fun.  After the new exhaust, it still ran the same et/speed just over 5,500rpm.  Whether you chose x or h or neither, my guess is your ’55 265ci results might be similar.  Although no improvement on the track, it sounded faster.  Alan

--- End quote ---

Low end torque is always an issue with a 3 stroke engine, so if any balance pipe will help, I will certainly try it. I have extra exhust pipe the same size as what is on it now so it won't cost anything but time.

denverflatheader:
Positively I agree to install balance pipe since it’s an enhancer, no negatives.  Plus two items which might change your conclusion, no catalytic convertors and performance cam with more duration than oem.

Frontenginedragsters:
I was thinking 283 bore.

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