Joined: Sun Dec 16 2012, 01:56AM
Location: Calgary, AB
Posts: 2
This is an interesting thread - no matter how big an engine is, no matter how much power it makes, it will benefit from headers over cast iron manifolds 100% of the time.
There are also benefits of reduction of sprung weight, being over the front end especially.
I personally have never seen a power drop by use of headers over a factory manifold. EVER.
If there is a power reduction, then there are other major issues in the selection of the combination. For those whom exceed 500 hp on cast iron manifolds, that's great -though trust me, you've left power on the table. If your thing is stealth, and you need an iron manifold, there are ways to prep them for more power - though no mater what they will never flow like a tube header and will still be a heavy iron material. <span class='smallblacktext'>[ Edited Wed Apr 24 2013, 07:16AM ]</span>
Joined: Fri Aug 05 2011, 08:06PM
Location: Brisbane Australia
Posts: 132
never seen a header worse than stock manifolds? look at more headers lol
the $900-1k for tti's is an awful lot for not much better than stock?, that may and may not fit, you are significantly better off finding a -Reputable- local exhaust co and getting a custom set done with equal length primaries, if it costs you a bit more, its money well spent provided the fabricator knows what they are doing - for example if it costs $300 more but you get an extra 30 hp = $10 a hp, not much else on your motor will achieve that for the same money
google headers by ed, they seem to have a good take on things
If you like the DIY route ed recommends, but lack skills/equipment, consider getting the flange plates (40-50 at summit etc) and dummy up a set that fits with some right size flexible tubing, if you run a thick bit of fencing wire through each tube they will retain shape pretty well, when it looks good, fill each tube with expanding foam (makes it pretty sturdy) and then take it to a shop to copy in steel
This should be one of the last things you do on the car after the engine is fully built and ratios etc are set in stone, any "major" work on an engine in theory requires a change to the exhaust too
Joined: Sun Dec 16 2012, 01:56AM
Location: Calgary, AB
Posts: 2
Alchemi wrote ... never seen a header worse than stock manifolds? look at more headers lol
the $900-1k for tti's is an awful lot for not much better than stock?, that may and may not fit, you are significantly better off finding a -Reputable- local exhaust co and getting a custom set done with equal length primaries, if it costs you a bit more, its money well spent provided the fabricator knows what they are doing - for example if it costs $300 more but you get an extra 30 hp = $10 a hp, not much else on your motor will achieve that for the same money
This should be one of the last things you do on the car after the engine is fully built and ratios etc are set in stone, any "major" work on an engine in theory requires a change to the exhaust too
I was thinking there was something odd with that statement, though since I've never been to Australia before, maybe there is areas in the world where physics do not apply?
Do tube headers weigh more than cast iron manifolds in Australia?
Do pulse rates for exhaust timing change there?
If you think the only solution is custom fabbed equal length long tubes, then the sky is the limit - for a 500-600 horse application big block in a C-Body, why not go to a stepped 42" primary header with 180 degree consideration to take into account exhaust pulse in a specific targeted RPM range.........
Joined: Fri Aug 05 2011, 08:06PM
Location: Brisbane Australia
Posts: 132
"Do tube headers weigh more than cast iron manifolds in Australia? " Dunno i have never weighed them, i doubt there would be much in it - a lb or two, three? any one compared this??? and when your sending them from there to here, then yeah they may as well be made of lead as far as cost of freight is concerned....
"I was thinking there was something odd with that statement" probably the person making it !clown
"maybe there is areas in the world where physics do not apply? " Sometimes i wonder... our toilets do swirl the other direction though....
"Do pulse rates for exhaust timing change there? " No, but i doubt if even 1 in 20 exhaust "specialists" any where would apply the knowledge to a customers system without charging a crap load for it
"If you think the only solution is custom fabbed equal length long tubes, then the sky is the limit - for a 500-600 horse application big block in a C-Body, why not go to a stepped 42" primary header with 180 degree consideration to take into account exhaust pulse in a specific targeted RPM range......... " Sounds awesome - might have to change the length to suit his rev range though
The reason i replied how i did was so that cancritter can go and have a look at a few more ideas other than "what is every one else using" and possibly making a more informed decision - either "stock" hp mani's, some tti's or equiv, or heaven forbid go and spend the money locally and support jobs where you live - yes there is some hypocrisy in that statement, due to where i live, what im driving and bits im importing, but you get the drift yeah? - Open a book before your wallet, knowledge is power
If you read most of the headers by ed site (did you top heavy?) the main gist (apart from buy their stuff) is that most production headers out there are crap and you can do better yourself, and i happen to agree
Joined: Tue Oct 16 2012, 12:15PM
Location: calgary
Posts: 1269
just wondering if the manifold 3418351 shown on page 2 with heat riser is a hp manifold ?.....l need a drivers side hp exhaust manifold with heat riser..thanx
Joined: Wed Dec 21 2005, 07:34AM
Location: indiana
Posts: 791
Yes, the -351 is an HP and takes a heat stove that funnels warm air into the air cleaner snorkel. The manifold in that picture doesn't have the stove on it. EDIT - you can ID these manifolds by the extra ridges on them, they help with heat transfer to the air.
'Heat riser' generally refers to the flap inside the passenger manifold.