Headers- 1 3/4", 1 7/8", or 2"... why??
Thread Starter
Drifting
Joined: Jul 2012
Posts: 1,325
Likes: 239
From: Missi'ppi... no mo' MO for me!!
Headers- 1 3/4", 1 7/8", or 2"... why??
From what I've read, these three sizes seem to be the (only?) most common sizes for headers. It seems to me that larger would be better, allowing exhaust gases to be evacuated faster. (I thought keeping some "back pressure" to enhance engine performance was a myth.)
1) What determines which size you purchased for your own use?
2) Why 3 sizes?
3) What's the GM OEM diameter on a c5 z06?
Thank you.
1) What determines which size you purchased for your own use?
2) Why 3 sizes?
3) What's the GM OEM diameter on a c5 z06?
Thank you.
Burning Brakes
Joined: Jan 2013
Posts: 1,091
Likes: 1
From: Hercules CA
From what I've read, these three sizes seem to be the (only?) most common sizes for headers. It seems to me that larger would be better, allowing exhaust gases to be evacuated faster. (I thought keeping some "back pressure" to enhance engine performance was a myth.)
1) What determines which size you purchased for your own use?
2) Why 3 sizes?
3) What's the GM OEM diameter on a c5 z06?
Thank you.
1) What determines which size you purchased for your own use?
2) Why 3 sizes?
3) What's the GM OEM diameter on a c5 z06?
Thank you.
Drifting
Joined: Jul 2010
Posts: 1,400
Likes: 39
From: Atlanta Georgia
Here's how I see it.
- 1-3/4" if you keep your engine stock
- 1-7/8" if you plan to add heads/cam or supercharger/turbo
- 2" if you plan on making 800hp+
Just my 2 cents......I personally have 1-7/8" (2006 C6 w/LS2) and my engine is stock. Someday I might put on heads/cam that's why I didn't get 1-3/4, so I only have to buy one set of headers in my life. It ain't cheap!
- 1-3/4" if you keep your engine stock
- 1-7/8" if you plan to add heads/cam or supercharger/turbo
- 2" if you plan on making 800hp+
Just my 2 cents......I personally have 1-7/8" (2006 C6 w/LS2) and my engine is stock. Someday I might put on heads/cam that's why I didn't get 1-3/4, so I only have to buy one set of headers in my life. It ain't cheap!
Drifting
Joined: Sep 2007
Posts: 1,649
Likes: 50
From: Goldsboro NC
There are guys here running both 1 7/8 and of course the 1 3/4 headers with just basic boltons and a cam. You will get great numbers with both. Its been said however, that with stock cubes (especially 5.7) and use of the 1 7/8, that there is a slight torque to hp trade off in the rpm band. That being said, im pretty sure LG posted the numbers years ago and there wasn't a difference in low end tq. Hp was better by 10+. Really just purely preference. Now, IMO would NOT go near a 2" unless you have 400+ ci as I can really see your tq just falling on its face. That's A LOT of air to move out of a 346ci, even with FI. Its just simply not needed. The smaller sizes are tried and proven
Le Mans Master
Joined: Apr 2005
Posts: 8,077
Likes: 4
From: Scarborough ONTARIO
#3 post nailed it, i would go 1 7/8 ARH headers catted, and wont turn back. I have SW 1 3/4....wont recommend, Kooks you had to be above average mechanically inclined, OBx.....all so so. ARH hands down literally.
Edit: i have installed all the above mentioned headers.....personal experience. ARH was the best and in fact i did install 2" ARH as well....fit like glove.
Edit: i have installed all the above mentioned headers.....personal experience. ARH was the best and in fact i did install 2" ARH as well....fit like glove.
Le Mans Master
Joined: Apr 2012
Posts: 7,818
Likes: 2,267
From: Brighton MI
There's a fair amount of science that goes into it, but generally you want to size the primary tubes in order to maintain a certain flow rate. This allows the headers to actually promote scavenging the cylinders - which helps pull out ALL of the spent gases and, depending upon cam overlap, it can help draw in the fresh air/fuel mixture too.
That is why, when a header is sized too big for an engine, you lose the low end torque...there is no scavenging happening due to the low flow rate of the exhaust gases.
Hope that helps...
That is why, when a header is sized too big for an engine, you lose the low end torque...there is no scavenging happening due to the low flow rate of the exhaust gases.
Hope that helps...
Melting Slicks
Joined: Nov 2007
Posts: 3,475
Likes: 10
From: Wake Forest NC
Here's something to consider as well. Two inch headers put heat closer to other engine components than smaller headers. And if that becomes a problem, you have even less space to wrap heat insulation around the headers.
They also make it that much more difficult to access the components. If you don't mind moving headers around to get to other engine parts, go for it.
As counter-intuitive as it sounds, it almost makes sense to buy the smallest headers that will do the job for your particular application. Too much header creates headaches elsewhere.
.
They also make it that much more difficult to access the components. If you don't mind moving headers around to get to other engine parts, go for it.
As counter-intuitive as it sounds, it almost makes sense to buy the smallest headers that will do the job for your particular application. Too much header creates headaches elsewhere.
.
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Tech Contributor
Joined: Jan 2004
Posts: 20,030
Likes: 289
From: Wylie TX --> Less is More, except under the hood !
LG's did tests on 1 3/4" and 1 7/8" headers on our 346ci motors.
They determined that the larger 1 7/8" headers lost low end torque compared to the 1 3/4".
Anthony told me that the 1 3/4" headers are best for stock 346ci, or full heads cam setups.
Supercharged cars or larger displacement motors will benefit from the larger 1 7/8" headers.
Contact Anthony at LG's and he can fill you in.
Toque
They determined that the larger 1 7/8" headers lost low end torque compared to the 1 3/4".
Anthony told me that the 1 3/4" headers are best for stock 346ci, or full heads cam setups.
Supercharged cars or larger displacement motors will benefit from the larger 1 7/8" headers.
Contact Anthony at LG's and he can fill you in.
Toque
Race Director
Joined: Dec 2006
Posts: 12,392
Likes: 2,911
From: Fort Worth, Texas
Depends on where you want to make the most power and how much you plan to make, here's a comparison I did...
http://forums.corvetteforum.com/perf...s-results.html
http://forums.corvetteforum.com/perf...s-results.html
Racer
Joined: Jan 2009
Posts: 352
Likes: 0
From: Wichita Kansas
Here's how I see it.
- 1-3/4" if you keep your engine stock
- 1-7/8" if you plan to add heads/cam or supercharger/turbo
- 2" if you plan on making 800hp+
Just my 2 cents......I personally have 1-7/8" (2006 C6 w/LS2) and my engine is stock. Someday I might put on heads/cam that's why I didn't get 1-3/4, so I only have to buy one set of headers in my life. It ain't cheap!
- 1-3/4" if you keep your engine stock
- 1-7/8" if you plan to add heads/cam or supercharger/turbo
- 2" if you plan on making 800hp+
Just my 2 cents......I personally have 1-7/8" (2006 C6 w/LS2) and my engine is stock. Someday I might put on heads/cam that's why I didn't get 1-3/4, so I only have to buy one set of headers in my life. It ain't cheap!
If you ever plan on doing a blower just get the 2" and be done, wouldn't want to do headers multiple times. And if you did the blower you don't have to worry too much about torque problems, more like traction problems
Drifting
Joined: Sep 2007
Posts: 1,649
Likes: 50
From: Goldsboro NC
LG's did tests on 1 3/4" and 1 7/8" headers on our 346ci motors.
They determined that the larger 1 7/8" headers lost low end torque compared to the 1 3/4".
Anthony told me that the 1 3/4" headers are best for stock 346ci, or full heads cam setups.
Supercharged cars or larger displacement motors will benefit from the larger 1 7/8" headers.
Contact Anthony at LG's and he can fill you in.
Toque
They determined that the larger 1 7/8" headers lost low end torque compared to the 1 3/4".
Anthony told me that the 1 3/4" headers are best for stock 346ci, or full heads cam setups.
Supercharged cars or larger displacement motors will benefit from the larger 1 7/8" headers.
Contact Anthony at LG's and he can fill you in.
Toque
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
True, but unless you RACE all the time, you will spend FAR more time out of boost than in. The smaller tube (1 3/4 isn't really small) promote low end torque better than a 2" does, and will still make some crazy HP #s.