Vitals: This is a street driven low and slow vehicle, very mild (only about 200hp) 1971 350 cid sbc engine, has block hugger headers with a 2-1/2" collector diameter (at the header discharge). What size exhaust pipe/mufflers should be used? The exhaust system will be relatively short, terminating just forward of the rear tires. Want to order a set of Porter mufflers. Are 2" ins/outs too small? 2.25" better?
Ran 2" on my 318 Dodge for years and they were great - noise was acceptable and the droning is all controlled by the muffler so the overal effect can come from your muffler choice more than pipe size. With a Lo-Po engine you are not squeezing huge amounts of spent gas down the pipes compared to the higher performance engines even in the upper rev range
Wish I wasn't poor. I want a set of 2 1/4 " Porters for my Shoebox. Mild Ford 302 with stock Mustang manifolds. I guess Cherry Bonbs are gonna gave to work.
2" should be good. I have 2.25" from the headers straight into a 2.25" gl***pack on each side and exiting just before the rear tires on my F100, so it's about 4 or 4.5 feet on each side. A supposed 350 HP 350 is breathing through them and I feel kind of guilty if I leave the house before 9am on the weekend because it's so loud.
I think I would just go with the 2.25 for the simplicity. Plus that's the size of the mufflers. I can't see going with anything bigger since the mufflers would be pinch down point. With what you stated that you are gonna run they will be fine. Small pipes seem to make a lot of brap brap instead of a clean deep tone. If that is the sound you want
I went with 2.25' on my 58, with the porters mounted just before the rear axle. Sounds nice and quiet when their new, but once their broken in, sound even better. I have a little bit of a drone though, so you might want to plan a x or h pipe into your setup. -dd
I agree as well, 2.25 should treat you very well. But if you wanted to go bigger, just take your muffs to the local muff shop and have them step them up to 2.5. I'm sure they'll do it for free. Mine did. I put 2" exhaust on our '53 with Brockman Mellowtones and had them stepped from 1.75 to 2. Another tip regarding the "droning" thing...I read somewhere recently that it depends on where you actually put the gl***packs...they should be placed more towards one end or the other to reduce the droning effect, not be placed right in the middle of the exhaust pipe between the header collecter and the tip of the tail pipe(don't want to break the sound wave lenth directly in half). Find out where the middle of your exhaust system is and move them back from there a bit maybe...
big pipe is a little higher in price but large pipe is harder to bend in tight places 2 in is easiest to work with in tight places , been bending pipe since 1972 its still fun .go for the big if u have room .
2" is pretty much perfect for a mild SBC or most v8's that size, anything bigger and it sacrifices low end torque. People really like to put a larger exhaust than they need on cars all the time.
if you want gas milage and your not going racing i would go with 2"and a set of smittys and a cross over pipe.
2" Is just fine for normal street performance. I usually go with 2 1/4". 2 1/2 is over kill and can actually reduce the sounds by reducing the velocity and pulsations at idle, especially on a garden variety street engine. 2 1/4" is a great compromise between performance and sound quality. Bigger isn't always better.
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