Almost_There_1

How’s it going guys, so I tried searching but couldn’t find a specific answer. About how much power would I be leaving on the table by staying with 1 7/8” headers vs 2” on a basic HCI car?

build details:
2006 z06
Ported/ milled heads
Hi Ram
NW 102
RPM B3
10% ud
E85

Thanks in advance!

Last 1

I would say about 6 to 10hp on the top end

drewz06

whichever you decide on.... make sure its American Racing Headers (ARH) their quality is uncompromising.... its more expensive but the cost is 100% worth it...

-drew

VetteWanted

AZDave has a before/after dyno graph when switching from 1 7/8" to 2". He picked up quite a bit of midrange power (30+). Maybe he will chime in.

AzDave47

I went from Pfadt Tri-Y 1 7/8" headers to ARH 2", both with catted x-pipe in the dyno runs below, headers the only difference. If it had been ARH to ARH it would have been a better comparison if you are a first time header buyer on your build. The pickup in torque at 2500 RPM was very noticeable in daily street driving and made it much easier from startup to traffic speed on my McLeod RXT 1000 trwin disk clutch and billet steel flywheel. Pretty much full HCI build with Katech K501 cam:

Turbo6TA

Jeeeze ... I feel bad now

I have a set of Pfadt 1 3/4" headers on my GS . .

AzDave47

6.2L vs 7.0L with full HCI are different animals.

Turbo6TA

Well, my GS is supercharged.

When I had the 1 3/4" headers installed, I never thought I would boost the car sometime later on.

Had I of known that, I would have installed 1 7/8" headers in the first place (2" pipe headers were not available back in 2013 when I had the headers put in).

.

JMB

Unless you have have a good exhaust system with merge collectors it's really not going to matter, BUT if you did, the 2" headers would lose power over the 1-7/8". How can I say this with such certainty? Let me give you a couple of real life examples.....on my full tilt SBE LS7 I had 1-3/4" to 1-7/8" equal-lengty headers with 3-1/2" merge collectors making 660 RWHP NA. I built a set of "engineered" equal-length 1-7/8" to 2" to 2- 1/8" triple stepped headers with 4" merge collectors (and 4" exhaust vs the previous 3-1/2") and the power only went up 20 RWHP to 680!

My point is, I had Roman at Burns Stainless create the design for my headers.....he could have obviously used any size but he didn't!

Almost_There_1

I guess I should have specified that I already have a set of LG 1 7/8 headers on the car currently. Just seeing if the cost to get a new set is justified. Thanks for the replies!

JMB

Yes, that was my whole point, you'd be spending money for not....my point also was that some people might swap from an "existing" 1-7/8" header that did not have a merge collector to a 2" header that did have a merge collector and they still have a less than adequate exhaust system down stream and they report a slight gain.....this is possible because the "whole exhaust system" has not been optimized. If you have a minimum of 3" to 3-1/2" exhaust all the way back, 1-7/8" headers with merge collector will outperform the 2" header on an NA application.

Apocolipse

Long tubes are tuned for down low torque gains. They typically do not show much improvement up top...other than sound.

18JamesS

I just bought some 1 7/8" ARH long tubes for my c6z (536whp/484lbft) after weeks of trying to decide between 1 7/8" and 2". I'm swapping out my AHP 116 cam and just ordered an RPM B3, hoping to hit 600whp. After speaking extensively with Sal at ARH, he convinced me that 2" was absolutely unnecessary until 800+whp. He said 1 7/8" would actually make more power on an NA 600whp build. With that said, however, I wonder if I should've just said "screw it" and ordered the 2" headers. Any thoughts?

AzDave47

My builder, Cordes Performance Racing, down in the Valley of the Sun, almost exclusively uses ARH 2" on any build at 550 rwhp or above. While not a comparison of ARH 1 7/8" to ARH 2", see my post #5 above. I am running Billy Boat Fusion Extreme mufflers. The dyno run was one day to the next with just the headers changed. As far as I know this is the closest back to back header dyno comparison posted on this forum

JMB

The only problem with this comparison is that we are comparing apples to oranges when you are comparing tri-y to standard headers.

SPDKLZ1

I wouldn't worry about it. I have 2" with 558whp and if I had to do it again might do 1 7/8. A lot of old school shops and the one that did my car prefer 1 7/8 for better scavenging.

Nowanker

OK, that's some worthwhile info!
I'm in the same boat as the OP. Already have H/C/I and LG 1 7/8 headers. Planning to up the cam and intake, and add some compression. At 505 now, expecting ~550.
If ARH says 1 7/8" is good at that level, I won't swap them out.

Apocolipse

Matt0144

I just put 2 inch arh’s on my zo6. Plan to add a heads cam package next summer

AzDave47

What other mods do you have now? Are you tuned for the headers?