1 7/8 vs. 1 3/4 headers
08-17-2006, 09:57 PM
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1 7/8 vs. 1 3/4 headers Anyone have comparing dyno graphs? Looking for combos based on stock cubes. I don't want to hear "you'll lose torque with the big headers." I want to see the graphs to see proof.
08-17-2006, 10:03 PM
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I'll try to get a graph up tomorrow of two cars. One is a Z06, LG 1 3/4, cold air, G5X3, stock catback and the other is a Z06, LG 1 7/8ths, cold air, G5X3, stock catback. Same EXACT mods other than the headers. The 1 3/4 car was 15 hp and 24 rwtq up down low on the larger primary header. It held the edge till 5K where they were identical all the way to 7K. Both setups tuned by me on the same dyno.
08-17-2006, 10:16 PM
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Just found this post on ls1gto. It seems to be a 50/50 mix of people saying you'll lose power compared to the smaller primaries, everyone else says it's not a noticeable difference.
So damn confused.
So damn confused.
08-18-2006, 08:48 AM
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Originally Posted by John02SS
I'll try to get a graph up tomorrow of two cars. One is a Z06, LG 1 3/4, cold air, G5X3, stock catback and the other is a Z06, LG 1 7/8ths, cold air, G5X3, stock catback. Same EXACT mods other than the headers. The 1 3/4 car was 15 hp and 24 rwtq up down low on the larger primary header. It held the edge till 5K where they were identical all the way to 7K. Both setups tuned by me on the same dyno.
08-18-2006, 09:31 AM
#6
On the TFS engine dyno with swapping from Hooker 1 3/4" headers to Kooks 1 7/8" on several different sets of PORTED heads, I saw the following results. The TEA Stg 1.5 5.3 heads with STOCK 1.55" exhaust valves made MORE POWER everywhere with the bigger headers. The TFS heads with their 1 .57" valves didn't care, and the AFR 205's with 1.60 made LESS power everywhere with the bigger headers. With stock heads I think the results would be like the TEA heads since they share the same exhaust valve diameter.
BTW, we saw the same thing on our chassis dyno in the past, with ported heads and stock valves the Kooks 1 7/8" headers made more power everywhere, most all of these cars had conservative cams, less then 232 @ .050" Hope this helps.
BTW, we saw the same thing on our chassis dyno in the past, with ported heads and stock valves the Kooks 1 7/8" headers made more power everywhere, most all of these cars had conservative cams, less then 232 @ .050" Hope this helps.
08-18-2006, 10:23 AM
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Originally Posted by Brian Tooley
On the TFS engine dyno with swapping from Hooker 1 3/4" headers to Kooks 1 7/8" on several different sets of PORTED heads, I saw the following results. The TEA Stg 1.5 5.3 heads with STOCK 1.55" exhaust valves made MORE POWER everywhere with the bigger headers. The TFS heads with their 1 .57" valves didn't care, and the AFR 205's with 1.60 made LESS power everywhere with the bigger headers. With stock heads I think the results would be like the TEA heads since they share the same exhaust valve diameter.
BTW, we saw the same thing on our chassis dyno in the past, with ported heads and stock valves the Kooks 1 7/8" headers made more power everywhere, most all of these cars had conservative cams, less then 232 @ .050" Hope this helps.
BTW, we saw the same thing on our chassis dyno in the past, with ported heads and stock valves the Kooks 1 7/8" headers made more power everywhere, most all of these cars had conservative cams, less then 232 @ .050" Hope this helps.
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I was told on 5hp difference between kooks 1-7/8's vs 1 3/4 new edelbrock stepped headers
08-18-2006, 11:18 AM
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Originally Posted by Brian Tooley
On the TFS engine dyno with swapping from Hooker 1 3/4" headers to Kooks 1 7/8" on several different sets of PORTED heads, I saw the following results. The TEA Stg 1.5 5.3 heads with STOCK 1.55" exhaust valves made MORE POWER everywhere with the bigger headers. The TFS heads with their 1 .57" valves didn't care, and the AFR 205's with 1.60 made LESS power everywhere with the bigger headers. With stock heads I think the results would be like the TEA heads since they share the same exhaust valve diameter.
BTW, we saw the same thing on our chassis dyno in the past, with ported heads and stock valves the Kooks 1 7/8" headers made more power everywhere, most all of these cars had conservative cams, less then 232 @ .050" Hope this helps.
BTW, we saw the same thing on our chassis dyno in the past, with ported heads and stock valves the Kooks 1 7/8" headers made more power everywhere, most all of these cars had conservative cams, less then 232 @ .050" Hope this helps.
Over the winter I may be installing the torque cam that Patrick G uses. I will be on stock heads for probably a year after that. When i do heads i'll be doing something with a small runner (AFR 205's, ETP 215's, etc.) and at that time i'll not longer be using stock sized valves.
08-18-2006, 12:59 PM
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I assume the discussion is about 1 7/8" headers on a stock cubed motor.
What about a larger size motor such as a 408. Is there any significant gains going from 1 3/4" to 1 7/8"? Sorry if I hijacked, but I was wanting to know the same thing, but for a larger motor.
What about a larger size motor such as a 408. Is there any significant gains going from 1 3/4" to 1 7/8"? Sorry if I hijacked, but I was wanting to know the same thing, but for a larger motor.
08-18-2006, 02:41 PM
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Originally Posted by 11SECDWS6
I assume the discussion is about 1 7/8" headers on a stock cubed motor.
What about a larger size motor such as a 408. Is there any significant gains going from 1 3/4" to 1 7/8"? Sorry if I hijacked, but I was wanting to know the same thing, but for a larger motor.
What about a larger size motor such as a 408. Is there any significant gains going from 1 3/4" to 1 7/8"? Sorry if I hijacked, but I was wanting to know the same thing, but for a larger motor.
08-18-2006, 02:50 PM
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Originally Posted by 383ss
no significant gains. 1 7/8 on my 408 lost a lot of tq and gained nothing till 5000rpm. they then gained 5rwhp and carried the curve out about 500rpm.
I would like to have the 1 7/8, but since I already have the
1 3/4 I'll just stick with those. I hear the 1 7/8 sound great though. But I gotta spend that $1k in other places...
What about 1 7/8 vs 1 3/4 on a stock internal car with bolt ons?
04-16-2007, 01:22 PM
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There is an interesting article here http://www.popularhotrodding.com/eng...exh/index.html
Basically saying you should choose the primary diameter based on exhaust port flow and expected application. There is a nice little graph you can use and select your sizing.
Basically saying you should choose the primary diameter based on exhaust port flow and expected application. There is a nice little graph you can use and select your sizing.
