I LOST 20ftlbs. And 5 hp!
The other possibility of course is that the previous
dyno result was "corrected" higher than realistic,
so any subsequent pull would read lower, and just an
exhaust change might not make up the difference....
Might be interesting to compare your original result
to similarly-set-up examples and see if your original
wasn't a bit "optimistic". You could be chasing a ghost.
There's too much after-the-fact fudgery applied to
make me trust anything besides relative readings on
the same strap-down.
dyno result was "corrected" higher than realistic,
so any subsequent pull would read lower, and just an
exhaust change might not make up the difference....
Might be interesting to compare your original result
to similarly-set-up examples and see if your original
wasn't a bit "optimistic". You could be chasing a ghost.
There's too much after-the-fact fudgery applied to
make me trust anything besides relative readings on
the same strap-down.
Where is the evidence that SE headers perform as well as a more expensive name brand header, that has the proof to back thier performance claims.
Last edited by dave04da; Apr 15, 2017 at 08:56 PM.
Interesting header test results...this might be a case of the engine not moving enough air for the longer header.
http://www.superchevy.com/how-to/148...ders-shootout/
http://www.superchevy.com/how-to/148...ders-shootout/
TECH Addict
Joined: Oct 2016
Posts: 2,513
Likes: 480
From: PDX-OR-USA
I've seen a small drop once just because of a new U-joint, LOL
We broke one on a pull, and swapped in a stronger one of the same size and lost about 4 HP .. We put the a lighter duty one in that matched the broken one and it came back, then broke the U-joint again. Don't believe it was weight, our theory at the time was the newer stronger one was not as straight as the original? Heck I could see losing 5 HP on a different tank of fuel..
We broke one on a pull, and swapped in a stronger one of the same size and lost about 4 HP .. We put the a lighter duty one in that matched the broken one and it came back, then broke the U-joint again. Don't believe it was weight, our theory at the time was the newer stronger one was not as straight as the original? Heck I could see losing 5 HP on a different tank of fuel..
11 Second Club
Joined: Mar 2012
Posts: 1,541
Likes: 15
From: South Florida
I've seen that test that wannafbody posted. The engines could be in the same power range. Although the differences between SBC & LS cylinder heads is substantial.
It's pretty much LS gospel to get long tubes for the best power. Although every once in awhile we see something odd happen.
One other thing I may ask is how does the car feel to perform? Same, little better or worse. A 20lb/ft loss may be quiet noticeable.
Maybe time to take it back to the track & see what she can do. Although switching the headers back will be interesting.
It's pretty much LS gospel to get long tubes for the best power. Although every once in awhile we see something odd happen.
One other thing I may ask is how does the car feel to perform? Same, little better or worse. A 20lb/ft loss may be quiet noticeable.
Maybe time to take it back to the track & see what she can do. Although switching the headers back will be interesting.
I agree, the Macs would hurt you at that power level. But you may have made 720 or 730 with a set of AR or Kooks. I highly doubt SE has invested much money into the R&D of their headers. Unlike the two brands I mentioned, who I'm sure have passed some of that R&D cost on to their customers to provide them with a high quality piece that has proven performance gains.
Where is the evidence that SE headers perform as well as a more expensive name brand header, that has the proof to back thier performance claims.
Where is the evidence that SE headers perform as well as a more expensive name brand header, that has the proof to back thier performance claims.
Exactly why I'm going back!
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Well I left the TSP cat back on because I cut up the flowmaster to get it off. The sound and quality of the TSP is soooo much better than the flowmaster. Yea, it only took me 3 hrs. start to turn key to swap back the headers.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Well I switched my complete exhaust from Mac Mids and a flowmaster, to Speed Engineering long tubes and the new Texas Speed cat back. So I decided to go for a retune, same outside temp. as the first tune, same tuner, same dyno. Well I LOST 20ftlbs and 5hp with this new setup. My tuner was baffled. The only thing he could think was a bad header design. So I am putting the Mac Mids back on and am going to go back sometime next week to see if there is any difference.
If you were right, the fastest LS1 cars on this sight would be running mid length headers. See how dumb that sounds. 
11 Second Club
Joined: Jan 2003
Posts: 1,000
Likes: 134
There are some long tube 1 7/8 headers for 4th gen LS cars that have a bit more equal in length primary pipes than the SE headers are. If this makes any difference to HP/torque or not on these engines I have no idea. It is just something I've noticed between the header brands.
There are some long tube 1 7/8 headers for 4th gen LS cars that have a bit more equal in length primary pipes than the SE headers are. If this makes any difference to HP/torque or not on these engines I have no idea. It is just something I've noticed between the header brands.
Last edited by dave04da; Apr 17, 2017 at 10:31 PM.
Interesting header test results...this might be a case of the engine not moving enough air for the longer header.
http://www.superchevy.com/how-to/148...ders-shootout/
http://www.superchevy.com/how-to/148...ders-shootout/
If I was the op I'd start looking for the headers contacting something. Check KR at WOT and ask the tuner if they had to pull any timing for KR. If not swap the other headers back on and retest.
Not an ls engine, different heads, intake manfiold etc. ON an ls1 its been shown time and time again bigger headers make more power.
If I was the op I'd start looking for the headers contacting something. Check KR at WOT and ask the tuner if they had to pull any timing for KR. If not swap the other headers back on and retest.
If I was the op I'd start looking for the headers contacting something. Check KR at WOT and ask the tuner if they had to pull any timing for KR. If not swap the other headers back on and retest.
I would really love to see what a set of American Racing headers would do on my car. I have a feeling they would be a big improvement. I may have to start shopping for a used set.
