Best 2 inch header for supercharged application
Drifting
Joined: Jan 2011
Posts: 1,442
Likes: 226
From: Atlanta Ga
This is the first post I have seen that shows a loss with a 2" header on a FI C7. Of course the conditions could have been different also, temps, diff dyno, tuning, ect. I have actually seen posts with gains from 2" vs 1 7/8" on lightly modified C7's. So on goes the 1 7/8 vs 2" debate.
Racer
Joined: Nov 2008
Posts: 495
Likes: 50
I am with you on the low end loss. I am sure it does move the curve. I am at 800rwhp so any more low end is pretty much useless in my application. What I was questioning was the loss of top end power.
Drifting
Joined: Oct 2014
Posts: 1,802
Likes: 69
Should I go 1/34 stepped 1/78 long tube headers from Lg
Or full 1/78 Longtubes
They say straight 1/78 will be better for s/c and the stepped will lose only a bout 8hp up top but gain more down low the stepped turns in to a long tube 1/78 I don't see any reason to not go with the stepped
While still havin top end from the 1/78
If it turns into a long tube
My goal is 700 to 750+
Last edited by Seannyc; Apr 22, 2016 at 01:28 AM.
Team Owner
Joined: Mar 2005
Posts: 20,933
Likes: 905
From: salem OR
I would use 2 inch before 1 3/4 which is better for an Ls1.
I used 1 3/4 and they ran friggin hot and I gained power and cooler going to 1 7/8's .
The Blown 6.2 is best with 1 7/8's or 2 inch.
Safety Car
Joined: Aug 2007
Posts: 3,562
Likes: 233
2
How u figure..?
I went 135 on 8lbs..
Try this
1 3/4 up to 700 rwhp
1 7/8 up to 900 rwhp
2" 900 and above
Horsepower addicts diid testing to with lt1 and made no gain w 1 7/8 over 1 3/4 700 or less and dont even use headers on z06s
Also i had an ls3 22lbs boost 900 rw w 1 3/4..went to 2 and no gain
Theres not much power in header size period!..nothing ur gonna notice on a drag strip
I went 135 on 8lbs..
Try this
1 3/4 up to 700 rwhp
1 7/8 up to 900 rwhp
2" 900 and above
Horsepower addicts diid testing to with lt1 and made no gain w 1 7/8 over 1 3/4 700 or less and dont even use headers on z06s
Also i had an ls3 22lbs boost 900 rw w 1 3/4..went to 2 and no gain
Theres not much power in header size period!..nothing ur gonna notice on a drag strip
Last edited by blown81bu; Apr 24, 2016 at 04:45 PM.
Melting Slicks
Joined: Jun 2004
Posts: 2,836
Likes: 110
From: El Paso TX.
2
How u figure..?
I went 135 on 8lbs..
Try this
1 3/4 up to 700 rwhp
1 7/8 up to 900 rwhp
2" 900 and above
Horsepower addicts diid testing to with lt1 and made no gain w 1 7/8 over 1 3/4 700 or less and dont even use headers on z06s
Also i had an ls3 22lbs boost 900 rw w 1 3/4..went to 2 and no gain
Theres not much power in header size period!..nothing ur gonna notice on a drag strip
How u figure..?
I went 135 on 8lbs..
Try this
1 3/4 up to 700 rwhp
1 7/8 up to 900 rwhp
2" 900 and above
Horsepower addicts diid testing to with lt1 and made no gain w 1 7/8 over 1 3/4 700 or less and dont even use headers on z06s
Also i had an ls3 22lbs boost 900 rw w 1 3/4..went to 2 and no gain
Theres not much power in header size period!..nothing ur gonna notice on a drag strip
Safety Car
Joined: Aug 2007
Posts: 3,562
Likes: 233
true no clean passes either was an issue with trans that i figured out while i was parting car out..u would never believe what i found....
Last edited by blown81bu; Apr 24, 2016 at 07:44 PM.
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Drifting
Joined: Oct 2014
Posts: 1,802
Likes: 69
So from your information should I go stepped header from Lg full 1/78
Team Owner
Joined: Mar 2005
Posts: 20,933
Likes: 905
From: salem OR
2
How u figure..?
I went 135 on 8lbs..
Try this
1 3/4 up to 700 rwhp
1 7/8 up to 900 rwhp
2" 900 and above
Horsepower addicts diid testing to with lt1 and made no gain w 1 7/8 over 1 3/4 700 or less and dont even use headers on z06s
Also i had an ls3 22lbs boost 900 rw w 1 3/4..went to 2 and no gain
Theres not much power in header size period!..nothing ur gonna notice on a drag strip
How u figure..?
I went 135 on 8lbs..
Try this
1 3/4 up to 700 rwhp
1 7/8 up to 900 rwhp
2" 900 and above
Horsepower addicts diid testing to with lt1 and made no gain w 1 7/8 over 1 3/4 700 or less and dont even use headers on z06s
Also i had an ls3 22lbs boost 900 rw w 1 3/4..went to 2 and no gain
Theres not much power in header size period!..nothing ur gonna notice on a drag strip
I would dig out my old dyno's where I swapped out 1 3/4 KOOKS with ARH 1 7/8ths and had a size able gain on the same tune at just under the 600 rwhp level.
ARH does use a much better flowing cat than Kooks as well.
My tuner had a hard time with it as well. But not it's worth it. You run what ever you want.
I do wish I would have went 1 7/8's
instead of the 2 inch I have in my office on the floor.
But I'm sure it will work well since I'm going with a pulley.
And a intake filter that flows 680 cfm.
Last edited by 3 Z06ZR1; Apr 25, 2016 at 12:05 AM.
Drifting
Joined: Oct 2014
Posts: 1,802
Likes: 69
I have used both sizes that's how.
I would dig out my old dyno's where I swapped out 1 3/4 KOOKS with ARH 1 7/8ths and had a size able gain on the same tune at just under the 600 rwhp level.
ARH does use a much better flowing cat than Kooks as well.
My tuner had a hard time with it as well. But not it's worth it. You run what ever you want.
I do wish I would have went 1 7/8's
instead of the 2 inch I have in my office on the floor.
But I'm sure it will work well since I'm going with a pulley.
And a intake filter that flows 680 cfm.
I would dig out my old dyno's where I swapped out 1 3/4 KOOKS with ARH 1 7/8ths and had a size able gain on the same tune at just under the 600 rwhp level.
ARH does use a much better flowing cat than Kooks as well.
My tuner had a hard time with it as well. But not it's worth it. You run what ever you want.
I do wish I would have went 1 7/8's
instead of the 2 inch I have in my office on the floor.
But I'm sure it will work well since I'm going with a pulley.
And a intake filter that flows 680 cfm.
Last edited by Seannyc; Apr 25, 2016 at 01:22 AM.
Racer
Joined: Nov 2008
Posts: 495
Likes: 50
I gained 30 rwhp at 3500 rpms switching from the stock manifolds to 2" headers and a pulley change with the tune untouched. It carried that gain through the power band to 36 rwhp at 5800 rpms. I did gain 1lb of boost with the pulley change so it's hard to tell what just the headers did by themselves. The 2" headers seemed to do fine even in the lower rpm range. Could I have made more power down low with 1 7/8? Maybe. Would it have been significantly more? I doubt it. Again this was with the tune untouched. I was at 715 rwhp at the time.
Last edited by Silverboost; Apr 25, 2016 at 08:58 AM.
Team Owner
Joined: Mar 2005
Posts: 20,933
Likes: 905
From: salem OR
I have the dyno sheets but not on this laptop.
I went from 513 to 572 same engine, same car, same dyno, same tune. I changed from Kooks 1 3/4 to 1 7/8's ARH
I also removed the rubber corner boots and hard piped the charge tubes the whole air path. that helped some of it.
I still remember my tuner's own disbelief.
I went from 513 to 572 same engine, same car, same dyno, same tune. I changed from Kooks 1 3/4 to 1 7/8's ARH
I also removed the rubber corner boots and hard piped the charge tubes the whole air path. that helped some of it.
I still remember my tuner's own disbelief.
Drifting
Joined: Oct 2014
Posts: 1,802
Likes: 69
I have the dyno sheets but not on this laptop.
I went from 513 to 572 same engine, same car, same dyno, same tune. I changed from Kooks 1 3/4 to 1 7/8's ARH
I also removed the rubber corner boots and hard piped the charge tubes the whole air path. that helped some of it.
I still remember my tuner's own disbelief.
I went from 513 to 572 same engine, same car, same dyno, same tune. I changed from Kooks 1 3/4 to 1 7/8's ARH
I also removed the rubber corner boots and hard piped the charge tubes the whole air path. that helped some of it.
I still remember my tuner's own disbelief.
That's a pretty big improvement
Would u go with a stepped header 1/34 turns in to 1/78 or full 1/78
On a. S/c
Last edited by Seannyc; May 1, 2016 at 03:29 AM.
Team Owner
Joined: May 1999
Posts: 34,551
Likes: 505
From: Auburn Hills MI
I gained 30 rwhp at 3500 rpms switching from the stock manifolds to 2" headers and a pulley change with the tune untouched. It carried that gain through the power band to 36 rwhp at 5800 rpms. I did gain 1lb of boost with the pulley change so it's hard to tell what just the headers did by themselves. The 2" headers seemed to do fine even in the lower rpm range. Could I have made more power down low with 1 7/8? Maybe. Would it have been significantly more? I doubt it. Again this was with the tune untouched. I was at 715 rwhp at the time.
I am not the person to do the math but I'm sure others could.
If you changed the pulley, how much did mass air flow change? If you did not retune then aren't you just running leaner?
My question is based on the airflow change does that calculate out to 36hp on the pulley change alone without considering the header at all?
Racer
Joined: Nov 2008
Posts: 495
Likes: 50
I am not the person to do the math but I'm sure others could.
If you changed the pulley, how much did mass air flow change? If you did not retune then aren't you just running leaner?
My question is based on the airflow change does that calculate out to 36hp on the pulley change alone without considering the header at all?
If you changed the pulley, how much did mass air flow change? If you did not retune then aren't you just running leaner?
My question is based on the airflow change does that calculate out to 36hp on the pulley change alone without considering the header at all?