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Wondering if anyone has had factory exhaust manifolds extrude honed & how much flow capacity was gained & compared to a set of headers. Trying to figure out if that is the way to go on a 340 that will be stoked to 416 cu/in. Am trying to retain the stock look & want to get the most performance out of it that I can. thanks

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I asked the same question a while back, and the general consensus was that the gains were minimal, and that the cost relative to the gains wasn't worth it.

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...and don't let anyone tell you that you need headers to have good performance from your stroker; lots of FAST guys running them with manifolds and having incredible results.


Dave

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...and don't let anyone tell you that you need headers to have good performance from your stroker;

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100% correct

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...and don't let anyone tell you that you need headers to have good performance from your stroker;

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100% correct

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Define "good" performance. I go by ET..Loosing 50hp out of a small block is not what I would typically call "good" performance when it is there to be had.

Like I said, we have built them with nearly stock parts, and we have built them with with slightly better parts that can look stock, and there is a big gap between the two. 11:50-12.0 in a heavy street car is the norm with a 416 and stock parts. 10.50's are what we see out of well thought out combo that can still look deceivingly stock for a small block.

The runs good crowd loves the extra cubes and seemingly instant throttle response, and those of us with street/strip cars are not so happy because an unstroked 360 with good heads runs the same ET as our stroker with stock intake/heads and exhaust! We have guys running 9.90's with unstroked W2 engines and just a single 4 carb!

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I asked the same question a while back, and the general consensus was that the gains were minimal, and that the cost relative to the gains wasn't worth it.

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...and don't let anyone tell you that you need headers to have good performance from your stroker; lots of FAST guys running them with manifolds and having incredible results.




Dave

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a FAST build and your basic 416 build are 2 different animals. I'd wager 100% of the fast guys would love to be able to run headers. Even a cheap small tube header is going to give you 15-20hp over a monifold. can you car run good with logs? sureit can but it will ALWAYS run better w/ headers.

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I asked the same question a while back, and the general consensus was that the gains were minimal, and that the cost relative to the gains wasn't worth it.

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...and don't let anyone tell you that you need headers to have good performance from your stroker; lots of FAST guys running them with manifolds and having incredible results.




Dave

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a FAST build and your basic 416 build are 2 different animals. I'd wager 100% of the fast guys would love to be able to run headers. Even a cheap small tube header is going to give you 15-20hp over a monifold. can you car run good with logs? sureit can but it will ALWAYS run better w/ headers.

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This "discussion" has raged on here forever. Basically, it depends how you are looking at the question;

- Do headers typically provide a hp increase over stock exhaust manifolds? Yes.

- Can I build my engine to X horsepower using manifolds? Yes.


The LA stroker is a great combo that provides a welcome boost in torque over what's available in similar smaller displacement packages. Some people prefer the use of stock manifolds and are happy at the performance level that can be had using them.

Purestock and FAST have shown that you don't need headers to knock down some truly epic horsepower numbers.

....AND lastly, I've always said that you need to look at the ENTIRE exhaust system as a whole. I'd be willing to bet that my HP manifold, 2.5" mandrel bent TTI exhaust and dynomax ultraflows performs better on my car than a set of cheapie headers, stock compression bent 2.25" exhaust and crappy mufflers.


Dave

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Purestock and FAST have shown that you don't need headers to knock down some truly epic horsepower numbers.

....AND lastly, I've always said that you need to look at the ENTIRE exhaust system as a whole. I'd be willing to bet that my HP manifold, 2.5" mandrel bent TTI exhaust and dynomax ultraflows performs better on my car than a set of cheapie headers, stock compression bent 2.25" exhaust and crappy mufflers.


Dave

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It is naive to think those times are coming with totally stock equipment.

R.

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Purestock and FAST have shown that you don't need headers to knock down some truly epic horsepower numbers.

....AND lastly, I've always said that you need to look at the ENTIRE exhaust system as a whole. I'd be willing to bet that my HP manifold, 2.5" mandrel bent TTI exhaust and dynomax ultraflows performs better on my car than a set of cheapie headers, stock compression bent 2.25" exhaust and crappy mufflers.


Dave

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Well FAST and Pure Stock is a whole different level all its own and I really wouldn't compare those to this. Those guys look at everything for Hp...As I have said, we have built the small block strokers both ways, and it depends how you want to approach it.

I will say this. Build it with all stock parts, and then upgrade things later if you so desire. I would not spend the time or the money to extrude hone stock parts, when at half the cost, there are basic performance parts available that bolt right on.

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Extrude honing is the LAST resort method to increase performance. It is really costly, probably in the order of $50 per horsepower.
I maintain DPelletier is half right. A free-flowing exhaust system is a much better use of your money. And that must include an H- or X- pipe.

What I maintain he is not right about is the true advantage of long tube headers where the exhaust pulses are separated from each other for the right amount of time. You can't do that with stock exhaust manifolds, HP or not. It's physics. In an exhaust system flow is not everything.

AndyF's dyno work found the MP .528 cam worked better than most other off-the-shelf cams in bigblocks.

And, FAST is appearance based. Except for the really low-buck racers, about every racer forced by the rules to use cast iron manifolds, either intake or exhaust, has them ported by professionals. Brzezinski comes to mind. It is naive to think those times are coming with totally stock equipment.

R.

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It is naive to think those times are coming with totally stock equipment.

R.

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Nobody said that AFAIK.
The important part and the point that is relative to this converation is that they are doing those time with manifolds.....and in the case of Purestock, with non-extrude honed ones. It simply proves you don't need headers to achieve most reasonable horsepower goals.

I guess I'll put it another way; if one person builds a 450hp motor with headers and another builds a 450hp motor with manifolds, which is "better"? ...it doesn't take too much effort to see that this question has more than one correct answer depending on how you measure "better".....and that is my point.




Dave

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Am trying to retain the stock look & want to get the most performance out of it that I can.

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i've never had a set done but imho for the most performance/dollar value there would be a LOT of other places i'd be spending money before i did that.