A.R. Shale Targa

iTrader: (2)

Almost a year ago I also switched from these shorties mated to the 4 cat pipe
http://www.corvetteguys.com/ceramic-...t-headers.html
To this set-up also marketed as a 1 3/4 but dial calipers showed 1.90" OD,
It has merge collectors w/spike, full 3" w/cats, and the X pipe is now off the
headers instead of the pre axle Corsa 2.5" X pipe.
http://forums.corvetteforum.com/c5-p...e-headers.html
I have yet to retune since but the before trap speed was 116.7 and the post
mph is 119.85...both @ 1800-2000 DA
I realize that my change of exhaust was much more than the OP but does
verify that his results are impressive and indicative that the LS engines LOVE
to breath.

TXZ28LS1

iTrader: (5)

Damn!!!

Blackpanther99

iTrader: (8)

Wow! great change in numbers!

RonSSNova

iTrader: (3)

So I'm not the only C5 owner who noticed that the XS power headers are 1.90" OD....on some of the tubes. They actually vary. Some are 1.84" as well.
Interesting huh? I actually got up inside the collectors and cleaned up the welds around th emerge cone.. Still nice headers...I got mine used and had them coated to boot.

Ron

WKMCD

iTrader: (2)

Nice to see yet more proof that 1 7/8 LT's don't loose power anywhere in the curve contrary to internet mythology. Ed Hutchings ran the same test on his dyno a few years ago and got similar results.

1989GTA

"So I'm not the only C5 owner who noticed that the XS power headers are 1.90" OD....on some of the tubes. They actually vary. Some are 1.84" as well."

Interesting as we all know that 1 7/8" equals 1.875" in decimals. Looks like the XS power headers are favoring the 1 7/8" number but apparently being sold as 1 3/4".

screaminz847

Ron, were the different sizes on different primaries on your set of headers, or different sets? Did you happen to measure the ID on them by chance? I wonder if they may have used different gauge pipe at different points or depending on which primary it was.

RonSSNova

iTrader: (3)

Different tubes in the same set. I didn't measure the ID.
They just looked bigger than 1 3/4 pipes to me.
I didn't measure the thickness either.

Who knows, maybe just build with the material they source at the time? Luck of the draw? They are a copy of the AR header for our cars. My bud has his out, and virtually identical. I didn't measure his.

I have another set of Bassani Try-Y 1 3/4 headers. The tubes are 1.75" od on the nose. They look little!

Ron

jmilz28

iTrader: (13)

Those of us who have put the bigger primaries on bolt on cars are 100% UNsurprised by this. These cars love to breathe and the touch up tune was the right thing to do. There is no downside to this. The loss of torque is a result of archaic SBC thinking and people not doing a follow up tune. There is a reason most good shops no longer install the 1 3/4 primaries if larger is available. That's the only reason I'd ever go smaller than 1 7/8. Nice gain, definitely loving the TDs, they helped you for sure.

dhctss

iTrader: (3)

Yeah im glad tsp is out of 1 3/4 headers so i had to get 1 7/8 with there ory. I put down 322hp and 323 tq on a mustang dyno. My clutch was slipping. I only have a lid and i have stock echaust . I bet on dynojet would of been 335 or so

Bolt-OnM3

I might of missed it but do you run a catted y?

Dynospeed

iTrader: (3)

We haven't installed 1.75" headers on any lsx powered vehicles in over 5 years unless it was a swap car that only offered the smaller header.

427LS7HCI

In a C5 and C6, LG Super Pros 1 3/4s made more power and torque than Kooks 1 7/8ths.

JakeFusion

iTrader: (7)

That's because the LG's are 32" primaries vs 23 or whatever the Kooks are. And it also depends on the shop. I've seen a couple of different shops show no difference between the LG and Kooks - but that's a whole different can of worms over brand allegiance and what have you. Lou is a VERY polarizing figure in the Corvette world.

On the F-Body, they are all limited to pretty much the same length header due to the design of the car. With that variable out of the way, the only differences are primary diameter and collector length. For the LS1 in the F-Body platform, it makes no sense to go with a 1-3/4" header over a 1-7/8". Other platforms may be different as evidenced by the Corvette discrepancy.

low2001gmc

iTrader: (148)

gonna have to get me some 1 7/8s....

Rise of the Phoenix

iTrader: (27)

BrntWS6, I dug up your old thread and read through it again. I'm hoping I'll see similar results. Switching my setup from Stainless Works headers (1 3/4" w/ 2.5" collectors) to Speed Engineering (1 7/8" headers w/ 3" collectors). I would really love to pick up as much as you did, but given I still have the LS6 intake and stock/unported TB, I assume it will be a little less.