[Z06] 2" vs 1 7/8 header difference w/ full boltons and H/C
#21
Yes, the 591 with arh 1 7/8" run was july and the 608 with kooks 2" run was in october of the same year. I am sure the temp in october was not accurate at 102.5. It was toasty warm in MI that weekend in october though. I am sure the tune was a bit different than the previous too. Dan Millen was awesome to deal with, I drove down to detroit and he dropped me off at the airport then picked me up sunday to delivered the car before he took off to Texas to win another big race.
Last edited by MBR44; 05-12-2011 at 01:17 PM.
#22
Melting Slicks
I doubt you will see any substantial gains in horsepower switching from 1 7/8" primary headers to 2" primaries in a normally aspirated LS7 427CI engine, especially through the mufflers.
If you have over 450CI and large aftermarket heads/valves, you may benefit from the Kooks/ARH 1 7/8" to 2" step primary headers. But even then, the gains will be small.
If you have over 450CI and large aftermarket heads/valves, you may benefit from the Kooks/ARH 1 7/8" to 2" step primary headers. But even then, the gains will be small.
#23
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Its not an ls7 but will be pertinent. Had a 370cu lq4 with 225cc trick flows with all the bells and whistles - 2" kooks picked up an average of 12 hp and 8 ft of torque across the board vs 1 3/4 kooks. Thats with 370 cu
#24
Safety Car
No problem, I will. Right now I'm running the lg 1 3/4". I wanted my car built to pull all the way to redline. That's what it does. Makes peak hp at 7k. So with the 2" you will get more up top, that's also what I was looking for. I know it will be hard to compare going from 1 3/4" to 2" but my friend who is a vendor on here and has a shop that built my car, has a z06 with the same setup as me. He is running the 1 7/8" so I'll post the difference. Should be nice!!
I'll also post up the dyno, it's pretty impressive
I'll also post up the dyno, it's pretty impressive
#25
#26
Melting Slicks
I found this info to be very useful. Thanks to the MBR44 for posting up dyno charts, we all know that can be time-consuming and costly, but it helps everyone to know what works and what doesn't.
Last edited by Josh B.; 10-08-2016 at 12:04 PM.
#27
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Great question!!
I noticed a big push towards the 2" while working at ARH over the past few years.
I was surprised myself to see the bigger tubes used on 580whp NA builds.
Never did any testing personally.
I noticed a big push towards the 2" while working at ARH over the past few years.
I was surprised myself to see the bigger tubes used on 580whp NA builds.
Never did any testing personally.
#28
Drifting
I remember this thread. Yes it does contain some good info.
#29
Any results? Im getting my first set of headers along with everything for a cam upgrade including the MS4 cam. Some guys are saying the 2" ARH longtubes are overkill and will hurt low end...
Any info on this?
Any info on this?
#30
Team Owner
Wrong...at least on an LS7. Gains across the board by going with 2" ARH LT's over 1 7/8".
#31
People who say bigger headers lose low end have no experience with them
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#33
Supporting Vendor
here is a graph i posted awhile back showing the lack of zero low end loss doing a 2''. These two cars are absolutely identical,
Same heads, same cpr cam (alpha), same msd intake, same cold air, same state, same dyno, both done by us, etc, etc. The only difference is the lower powered one had ARH 1 7/8 and the higher powered one had ARH 2''. That's it!
Same heads, same cpr cam (alpha), same msd intake, same cold air, same state, same dyno, both done by us, etc, etc. The only difference is the lower powered one had ARH 1 7/8 and the higher powered one had ARH 2''. That's it!
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Cordes Performance Racing aka "CPR"
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Cordes Performance Racing aka "CPR"
Owner of AZ's premier LSX/LTX motorsports shop
http://cordesperformanceracing.com/
www.facebook.com/cordesperformanceracing.com
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480-359-5914
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#34
Drifting
While this may not be a direct apples-apples comparison, HotRod tested a big block Chevy 427 and found that the 2-1/8" headers actually had better low end torque/hp than the smaller tube headers, and slightly *less* peak horsepower. More or less contrary to all conventional "wisdom" posted on the forums.
http://www.hotrod.com/articles/headers-dyno-test/
http://www.hotrod.com/articles/headers-dyno-test/
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HC Mechanic (12-28-2017)
#36
Melting Slicks
here is a graph i posted awhile back showing the lack of zero low end loss doing a 2''. These two cars are absolutely identical,
Same heads, same cpr cam (alpha), same msd intake, same cold air, same state, same dyno, both done by us, etc, etc. The only difference is the lower powered one had ARH 1 7/8 and the higher powered one had ARH 2''. That's it!
Same heads, same cpr cam (alpha), same msd intake, same cold air, same state, same dyno, both done by us, etc, etc. The only difference is the lower powered one had ARH 1 7/8 and the higher powered one had ARH 2''. That's it!
I have a question Joe. What's the difference then between the AMERICAN RACING 2" X 2-1/8" X 3-1/2" HEADERS & 3-1/2" H-PIPE and the 2" ARH C6 Z06 CORVETTE 2006-2013 LONG SYSTEM.
The proof is that 2" headers make more power than 1 7/8" but the 1st picture above has a cross connecting tube whereas the 2nd looks like it has two elbows that join together. The first is more expensive than the second. I just want to make sure I get what makes the most power. NA 600-650 rwhp for road course is the application.
#37
Team Owner
The 2 1/8" are stepped headers with 3.5" collector and pipe. Would need custom exhaust from their back, and is for bat **** crazy full race stuff.
Unless you are planning a 1500+hp blower build, I would do the 2" as they bolt on and work. More than enough for 600-650rwhp.
Unless you are planning a 1500+hp blower build, I would do the 2" as they bolt on and work. More than enough for 600-650rwhp.
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Racingswh (04-29-2017)
#38
Melting Slicks
The 2 1/8" are stepped headers with 3.5" collector and pipe. Would need custom exhaust from their back, and is for bat **** crazy full race stuff.
Unless you are planning a 1500+hp blower build, I would do the 2" as they bolt on and work. More than enough for 600-650rwhp.
Unless you are planning a 1500+hp blower build, I would do the 2" as they bolt on and work. More than enough for 600-650rwhp.
Maybe someday I will have a road race twin turbo engine built that makes power like you are used to but until then I am excited for this build to be completed and get the car on the track.
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HC Mechanic (12-28-2017)
#40
Instructor
here is a graph i posted awhile back showing the lack of zero low end loss doing a 2''. These two cars are absolutely identical,
Same heads, same cpr cam (alpha), same msd intake, same cold air, same state, same dyno, both done by us, etc, etc. The only difference is the lower powered one had ARH 1 7/8 and the higher powered one had ARH 2''. That's it!
Same heads, same cpr cam (alpha), same msd intake, same cold air, same state, same dyno, both done by us, etc, etc. The only difference is the lower powered one had ARH 1 7/8 and the higher powered one had ARH 2''. That's it!