#63263, "Anyone port and polish their 420A Exhaust manifold?"
Just wondering... I'm pretty new to this and was wondering if anyone had done this...or knew anyone who has, and what the pro's and cons are/were. I'm getting a new one to replace my cracked one, and thought I'd run it by everyone first. If its not worth the trouble then I won't bother. Thanks for any info
#63264, "RE: Anyone port and polish their 420A Exhaust manifold?" In response to Reply # 0
no. bad idea. not worth it. save money and get headers. looks better and maybe gives you a few extra ponies.
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#63270, "RE: Anyone port and polish their 420A Exhaust manifold?" In response to Reply # 1
Now maybe if you had the money, get the aftermarket header ExtrudeHoned to help keep the gas velocities up, but you'll really only see gains from that if you have a lot of headwork done imo.
#63271, "RE: Anyone port and polish their 420A Exhaust manifold?" In response to Reply # 2
Originally posted by DR1665 Now maybe if you had the money, get the aftermarket header ExtrudeHoned to help keep the gas velocities up, but you'll really only see gains from that if you have a lot of headwork done imo. Keep thinking outside the box though!
Uh, no. Don't extrude hone a header. Headers should be tubular, extrude honing them will thin and weaken them, they are not cast. If it's a bad weld job you could clean up the inside, but welded up properly, don't touch the header. If you want to keep exhaust velocities up ceramic coat the header and lkeep the heat in.
#63302, "RE: Anyone port and polish their 420A Exhaust manifold?" In response to Reply # 2
Here's the deal..."BTW..keep up the fire! I like alotta responses!" I just got a brand new OEM exhaust manifold for $20+$20 shipping, and Advanced Racing Dynamics quoted me $140 for the porting work. I asked them: "How much would it cost to make the inside of my exhaust manifold look like a mirror?" I always do alot of research before I pop up questions, and this seemed to be any easy way to free up the exhaust flow as it exits the engine..therefore improving the engines efficiency.(will be better when I get new exhaust) My car is being dialed in right now before I put it on the road...HEY! How bout I get it DYNOed before and after???? Anyone wanna see results? C'mon...dare me! Oh wait...I just put a new clutch in...uhhh..I gotta wait a couple hundred easy miles first huh. I would like to see more dyno results on this board for EVERYTHING that can be bolted on. I'm sure everyone else would!
#63325, "RE: Anyone port and polish their 420A Exhaust manifold?" In response to Reply # 7 Nov-18-03 06:15 PM by 95dsmrsproj
What about the heat build up under the hood. Pointless to wrap a header. Then you couldn't see it...thus eliminating the purchase-for-looks half of the deal.(HP gains being the other half)Stainless steel headers get HOTTTT. Do they improve the flow enough that the heat isn't radiating?...I would think that w/SS headers the heat has no where to go, but to heat up the head where it mounts to the header(warpage?)...the cast iron does a better job insulating the heat, and thats why they don't come w/SS headers from the factory...maybe? .....I just thought: "hmmmm....cast iron to insulate the heat(maybe ceramic coated inside and out)... after it was mirror polished internally for super-improved flow over stock. The best of both worlds? Just a thought...please comment on this.
#63336, "RE: Anyone port and polish their 420A Exhaust manifold?" In response to Reply # 8
Exhaust manifold comes cast from he factory for one reason, cost. They are cheap and easy to make. The engineers know an equal legnth tube header will outflow and outperform it's unequal length cast counterpart. The cast manifold gets plenty hot, remove the heat shielding and put your hand near it when the car is warmed up.
The best bet to counteract this ambient heat inside the engine bay is to use a ceramic coated header, or to send your header for ceramic coating. This keeps the heat of the exhaust gasses in the exhaust and promoted better flow and reduced underhood temps. There are other factors getting into header design, but that's another discussion.
#63344, "RE: Anyone port and polish their 420A Exhaust manifold?" In response to Reply # 9
Plus you can get a decent header for a good price (mine = Pacesetter 4-2-1 used @ $60). Then you get the copper Spray-A-Gasket and paint the sucker. Turns a sort of GM color once it bakes in. Then you can wrap it. Header wrap says "performance" imo.
#63390, "It's Decided..." In response to Reply # 11
Well From what you guys are saying...It appears I'll be saving for a new header after Christmas..Thanks for all of your input. I'll put the new exhaust manifold on for now until after Christmas spending is over. Thanks!
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Thanks man!