I had a 2" system with cherry bombs on a 289. I ran a best time of 12.83 with nothing more than a solid cam, 650 Holley and headers. The car ran within a tenth with open headers as it did with the full exhaust.
Anything short of a full on rece motor does not need 2.5".
Most of the power gains in a 2.5" system are in your head and not real. Just my 2 cents
I had a 2" system with cherry bombs on a 289. I ran a best time of 12.83 with nothing more than a solid cam, 650 Holley and headers. The car ran within a tenth with open headers as it did with the full exhaust. Anything short of a full on rece motor does not need 2.5". This is the same as the guy who has a stock 289 with a 480 cfm autolite, bolts on a holley 600 and says wow what a different's that made! And it actually lost power and slowed down. Most of the power gains in a 2.5" system are in your head and not real. Just my 2 cents
What about an 800hp 351w?
tx65coupe,
You said:
"Oh. Its too bad it doesn't have an H pipe instead." Please explain. Is an "H" pipe better than an "X" pipe and why? From what I can tell it seems a topic of spirited debate with only minimal differences. I could be wrong. But if you click on the exhaust link near the top of the page, scroll down to the setup for your car and click the part number, it will link you to the Magnaflow site with an expandable pic that shows all the parts that appear to be quite well made with many good reviews throughout the internet.
Gene
Undoubetedly 2.5". Do not crutch a V8 with any less.
There's gains on even my motor with 3" duals at its little 347 cu inch. 2 1/2 would be too small.
That magnaflow chart seems pretty good to me if you go by HP of the engine. I'm sure most 2 1/2 is more than sufficient on this site.
Are you saying that even a bone stock 289 2V needs 2.5 inch exhaust?
I just don't see how 3 inch duals is necessary on a small block V8. I don't think that 2.5 inch duals are too small for a 347.
I just don't see how 3 inch duals is necessary on a small block V8. I don't think that 2.5 inch duals are too small for a 347.
His motor makes over 600hp. The chart in the link above does not even go that high. Blown65, did you dyno your motor with your exhaust?
I just don't see how 3 inch duals is necessary on a small block V8. I don't think that 2.5 inch duals are too small for a 347.
So in your line of thinking, a Nascar motor at 358" should just run 2 1/2 inch? Or does that 11 more cubic inches need 3" now? What size do you think they run. LOL
Well seems how they cruise down the road at a constant 8Krpm’s and most of us here don’t, I think your analogy is poor at best.
after owning many V8’s over the years and few small blocks, I would say that pipe diameter is more a matter of what the car is being used for and less about displacement. Most street cars make their usable power at lower rpm’s and smaller pipes aren’t a performance issue. I realize this is a stupid blanket statement (it should be right at home inside this thread), but in general small pipes hurt a race engine and big pipes hurt a street engine. Personally, I like bigger pipes for their acoustical purposes.
BTW, 351 at 800hp would be 3 1/2", 3" would be too small IMO.
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