77blue said:After going back and forth many time I have decided to go with the OEM exhaust manifolds that came on my LS376 /480 crate engine. It's documented in multiple tests/articles that they flow exceptionally well for a mass produced OEM exhaust. Anyway, since I have a new MIG welder, chop saw, and time to practice my technique welding pipe, I've decided to do my own exhaust. Planning to do 2.5" aluminized steel unless you guys convince me I'm on the wrong track. I Like low-end torque and am not concerned with horsepower especially, so I was thinking the 2.5" was sufficient (versus 3.0"). Regarding not going stainless - I was thinking the care to car will receive will help eliminate the concern with the elements - although you guys with more experience could easily change my mind (2x price penalty).
I know it's always dangerous to ask for opinions but that's the great part about this forum is that they are worth something. Thanks in advance.
I've gone through this dozens of times so Ill point out a few things and let you think it though,
first you can ACCURATELY calculate the size of the exhaust pipe that will be required to allow the cars engine to perform well.
next, welding stainless REQUIRED back filling the pipe with shield gas , and temporary seal it while welding and TIG, is the preferred , method, and generally you'll find use of an (X) pipe helpful.
twin 2.5" should work reasonably well below about 5500 rpm, but it will become restrictive as the rpm's increase to higher rpm's, yet from what you've stated , I doubt you'll spend enough higher rpm engine time to worry about the minimal restriction.
grumpy, who makes a really good quality header for my car?
my dad always stated..
"A couple hours , well spent in doing carefully documented &,detailed research,
before.... jumping head first off the dock,
into any project,....can prevent you from wasting month's of non-productive work and a wheel barrow full of cash!!"
I get similar questions all the time, and there ARE certain brands that do have a reputation for better fit and finish on headers,
but your results are totally dependent on you doing accurate ,prior research, your asking the correct questions,
knowing exactly what cylinder heads your using,and yes better quality tends to cost more than bargain basement prices!
knowing exactly what car it will be installed into and if your dealing with a better quality manufacturer helps.
http://garage.grumpysperformance.com/index.php?threads/header-dimension-calculator.15013/
keep in mind installing an (X) almost increases the effective cross sectional area, of the dual exhaust ,or collector cross sectional area to double what it had been behind a single header collector, by doubling the area that the exhaust flow sees, dropping the restriction to flow almost in half
http://www.superchevy.com/how-to/148-0404-best-headers-shootout/
http://www.lemonsheaders.com/
http://www.stahlheaders.com/
http://www.stainlessheaders.com/
http://stainlessworks.net/products/performance-systems/headers
http://www.burnsstainless.com/
https://www.carid.com/performance-headers.html
the links and sub-links should help
http://garage.grumpysperformance.com/index.php?threads/building-an-exhaust-system-for-your-car.1166/
http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/
http://garage.grumpysperformance.com/index.php?threads/x-or-h-pipe.1503/#post-24096
http://garage.grumpysperformance.co...eld-gas-selection-for-welding.1108/#post-2185
more related links and info
http://garage.grumpysperformance.com/index.php?threads/building-custom-headers.961/
http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/
http://garage.grumpysperformance.com/index.php?threads/what-diam-headers-do-i-need.7017/
http://garage.grumpysperformance.com/index.php?threads/exhaust-components.361/
http://garage.grumpysperformance.co...-guys-that-just-slap-on-factory-headers.3155/
http://garage.grumpysperformance.co...arder-too-find-exhaust-system-components.496/
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