1 5/8" vs 1 3/4" headers??
Thread Starter
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
1 5/8" vs 1 3/4" headers??
Hey guys I just ordered a set of Hedman headers that are 1 5/8" primaries. I currently have some OLD SCHOOL 1 3/4" square tube headers on my car that leak like crazy and blow gaskets all the time. I mainly wanted to change headers to fix the leaks but I am curious if the 1 5/8" will be big enough when I build my GOOD motor(500hp 383) or if I am gonna have to buy another set of 1 3/4".
The reason I bought the 1 5/8" now is because Hedman had a deal on their Elite series with the big 3/8" flanges, thick 14ga steel tubing and ceramic coating for $265 so I couldn't pass it up. They are going on my stocker now and I hope I can use them on the good motor without killing too much HP.
At what hp level is the 1 3/4" headers really needed? I have 1 3/4" headers on my LS1 that makes almost 400rwhp and thats what the minimum primary size available was so.... maybe 1 5/8" is too restrictive for anything over 450 crank HP.. What you guys think?
The reason I bought the 1 5/8" now is because Hedman had a deal on their Elite series with the big 3/8" flanges, thick 14ga steel tubing and ceramic coating for $265 so I couldn't pass it up. They are going on my stocker now and I hope I can use them on the good motor without killing too much HP.
At what hp level is the 1 3/4" headers really needed? I have 1 3/4" headers on my LS1 that makes almost 400rwhp and thats what the minimum primary size available was so.... maybe 1 5/8" is too restrictive for anything over 450 crank HP.. What you guys think?
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Z-Man posted this link to a good article. If you pull up the graph it's not so much HP as CFM of flow potential on the exhaust port.
to reach 500 hp it requires pretty big heads. The minumum I would go is 210 cc intakes with 286 CFM of flow. All heads have the gasket specs. Like my Dart Pro1 227 cc on my 383 have @ 230 cfm of exhaust flow. The port it's self is actually bigger than my 1 3/4 header pipe. So I had to hog out in the inside of every pipe to port match it.
Exhaust Science
http://www.popularhotrodding.com/eng...exh/index.html
to reach 500 hp it requires pretty big heads. The minumum I would go is 210 cc intakes with 286 CFM of flow. All heads have the gasket specs. Like my Dart Pro1 227 cc on my 383 have @ 230 cfm of exhaust flow. The port it's self is actually bigger than my 1 3/4 header pipe. So I had to hog out in the inside of every pipe to port match it.
Exhaust Science
http://www.popularhotrodding.com/eng...exh/index.html
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
280cfm+ flow is correct for a 500HP 383ci you need the big heads and big heads need big exuast, I would have liked to go with 1 7/8 in. on mine but no one makes them 
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
heads that use a FelPro 1404 (1.5 X 1.5) or FelPro 1405 exhaust gasket (1.55 X 1.55) could use 1 5/8th headers.
The Dart 215cc is what I originally installed on my 383 with the optional 2.08 /1.625 valves and factory porting. It was actually 221 cc as delivered. These head could use a 1 5/8th header if the exhaust ports are not ported out.
http://www.dartheads.com/manager/upl...PRO1%20SBC.pdf
The Dart 215cc is what I originally installed on my 383 with the optional 2.08 /1.625 valves and factory porting. It was actually 221 cc as delivered. These head could use a 1 5/8th header if the exhaust ports are not ported out.
http://www.dartheads.com/manager/upl...PRO1%20SBC.pdf
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Originally Posted by ajrothm
Hey guys I just ordered a set of Hedman headers that are 1 5/8" primaries. I currently have some OLD SCHOOL 1 3/4" square tube headers on my car that leak like crazy and blow gaskets all the time. I mainly wanted to change headers to fix the leaks but I am curious if the 1 5/8" will be big enough when I build my GOOD motor(500hp 383) or if I am gonna have to buy another set of 1 3/4".
The reason I bought the 1 5/8" now is because Hedman had a deal on their Elite series with the big 3/8" flanges, thick 14ga steel tubing and ceramic coating for $265 so I couldn't pass it up. They are going on my stocker now and I hope I can use them on the good motor without killing too much HP.
At what hp level is the 1 3/4" headers really needed? I have 1 3/4" headers on my LS1 that makes almost 400rwhp and thats what the minimum primary size available was so.... maybe 1 5/8" is too restrictive for anything over 450 crank HP.. What you guys think?
The reason I bought the 1 5/8" now is because Hedman had a deal on their Elite series with the big 3/8" flanges, thick 14ga steel tubing and ceramic coating for $265 so I couldn't pass it up. They are going on my stocker now and I hope I can use them on the good motor without killing too much HP.
At what hp level is the 1 3/4" headers really needed? I have 1 3/4" headers on my LS1 that makes almost 400rwhp and thats what the minimum primary size available was so.... maybe 1 5/8" is too restrictive for anything over 450 crank HP.. What you guys think?
coated for $269.
Thread Starter
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Also I am questioning the square tubes vs. the round tubes. My car has stock heads but they do have some port work(at least on the intake side, never saw the exhaust ports). I was just wondering how they can run a square port header on a round port head?
It looks like all the big HP SB heads use square exhaust ports so I guess i will have to buy another set of headers when I build the good motor, thats assuming I don't go BB. Right now I am just trying to get the most out of my stocker and have it run well with no exhaust leaks. I am hoping the smaller tubes will help the complete lack of low end tq below 3k. Thanks for the links guys, I am gonna read up on em.
It looks like all the big HP SB heads use square exhaust ports so I guess i will have to buy another set of headers when I build the good motor, thats assuming I don't go BB. Right now I am just trying to get the most out of my stocker and have it run well with no exhaust leaks. I am hoping the smaller tubes will help the complete lack of low end tq below 3k. Thanks for the links guys, I am gonna read up on em.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Originally Posted by ajrothm
Also I am questioning the square tubes vs. the round tubes. My car has stock heads but they do have some port work(at least on the intake side, never saw the exhaust ports). I was just wondering how they can run a square port header on a round port head?
It looks like all the big HP SB heads use square exhaust ports so I guess i will have to buy another set of headers when I build the good motor, thats assuming I don't go BB. Right now I am just trying to get the most out of my stocker and have it run well with no exhaust leaks. I am hoping the smaller tubes will help the complete lack of low end tq below 3k. Thanks for the links guys, I am gonna read up on em.
It looks like all the big HP SB heads use square exhaust ports so I guess i will have to buy another set of headers when I build the good motor, thats assuming I don't go BB. Right now I am just trying to get the most out of my stocker and have it run well with no exhaust leaks. I am hoping the smaller tubes will help the complete lack of low end tq below 3k. Thanks for the links guys, I am gonna read up on em.
Thread Starter
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
NO I didn't order the ac bracket but I am pretty sure its already on there. Like I mentioned, the car already has the old 1 3/4" headers on it and I am positive all the brackets are on there. I did notice they had to notch out the lower alternator bracket to fit around the big tube on #1 but....
The old headers actually have a 4 bolt, square flange on the collector. The collector gaskets are blown and I can't even find replacement gaskets. The headers are leaking where the primaries merge at the collect and at the flanges on the two center exhaust ports.
I will just stick the hedmans on for now and when I figure out what motor I am putting in it, I will buy another set. I did look at the Hooker Super comps with the 1 3/4" primaries but they were like $350 without coating so....They would have been over $500 and thats more then I wanted to spend right now. Especially since I may still put a BB in it and I would be selling them off anyway.
The old headers actually have a 4 bolt, square flange on the collector. The collector gaskets are blown and I can't even find replacement gaskets. The headers are leaking where the primaries merge at the collect and at the flanges on the two center exhaust ports.
I will just stick the hedmans on for now and when I figure out what motor I am putting in it, I will buy another set. I did look at the Hooker Super comps with the 1 3/4" primaries but they were like $350 without coating so....They would have been over $500 and thats more then I wanted to spend right now. Especially since I may still put a BB in it and I would be selling them off anyway.
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Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
You probably already have whats needed. When mdjice wanted to
go from manifolds to headers I looked up the headman elite on there
web site and it said for early style A/c compressor there was an
extra bracket needed, he had the later R/4 on his 77 so I looked
no further into it.
go from manifolds to headers I looked up the headman elite on there
web site and it said for early style A/c compressor there was an
extra bracket needed, he had the later R/4 on his 77 so I looked
no further into it.
Racer
Joined: Mar 2005
Posts: 393
Likes: 3
From: Dallas, TX
these are some of the best headers and they come in 1 7/8, http://www.stahlheaders.com/Frame%20New%20RR.htm the downside, the cost.
-alex
-alex
Thread Starter
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
I got my Hedman elites in today. The quality on them is outstanding but the ceramic coating is not as shiney as I thought it would be. Its more of a glossy silver with a little shine. My Pacesetter headers on my LS1 are also ceramic coated but they are very shiney/reflective.
Anyway I am taking the vette to the muffler shop tomorrow for the header install, new collectors etc. They have really nice welds and they are really damn heavy.. I guess that thick 14ga steel adds some weight but...should last well.
I guess when I build the good motor I will have to buy some 1 3/4". Oh well.
Anyway I am taking the vette to the muffler shop tomorrow for the header install, new collectors etc. They have really nice welds and they are really damn heavy.. I guess that thick 14ga steel adds some weight but...should last well.
I guess when I build the good motor I will have to buy some 1 3/4". Oh well.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
They probably need to be polished, some shops don't polish them after ceramic coating ( can you say cheap and lazy ) , take some Mothers to them, I bet they will shine
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Originally Posted by ajrothm
The old headers actually have a 4 bolt, square flange on the collector. The collector gaskets are blown and I can't even find replacement gaskets. The headers are leaking where the primaries merge at the collect and at the flanges on the two center exhaust ports.
