1 3/4 or 1 7/8 whats better?

**Camaro69Mac** · 05-05-2010, 12:09 PM

I got some hooker lt 1 3/4 headers and now I'm wondering if they are too much for a basically stock car you guys know way more than I do so let me know what you think differences in the two besides size of course...thanks for the help

**sixpack_2_go** · 05-05-2010, 12:37 PM

1 3/4 are perfect for a stock or even a head/cam/intake car. 1 7/8 are for when you get into bigger cubic inch motors like 402ci/408ci. i would stick with the 1 3/4 or you will loose a lot of low end and midrange power. hope this helps man

**Camaro69Mac** · 05-05-2010, 01:11 PM

Originally Posted by sixpack_2_go

1 3/4 are perfect for a stock or even a head/cam/intake car. 1 7/8 are for when you get into bigger cubic inch motors like 402ci/408ci. i would stick with the 1 3/4 or you will loose a lot of low end and midrange power. hope this helps man

it sure does...thanks alot! I got the hooker 1 3/4's and the hooker y i hope it sounds good. I just was curious cause this y pipe is huge and i figured i wouldnt have any back pressure with a 3" y and borla 3" cat back

**blackbird0230** · 05-05-2010, 01:27 PM

1 7/8 works fine too just stay 3" max on the exhaust unless your goin lots more hp

**Camaro69Mac** · 05-05-2010, 04:43 PM

Originally Posted by blackbird0230

1 7/8 works fine too just stay 3" max on the exhaust unless your goin lots more hp

Ya i'm not going to do anything else with the exhaust its costing me enough this far haha. I just hope it all works out doing these headers and y pipe. I dont see how i'll have clearance with the size of that y its a beast compared to stock

**Hi-Po** · 05-05-2010, 05:31 PM

Go with 1 7/8's. I would love to see someone post up a good informative, non biased, back to back dyno run comparing the two. Your not going to lose any power/torque down low with 1 7/8's, but there is a better chance you gain power up top with the 1 7/8".

1 7/8's.

**blackbird0230** · 05-05-2010, 05:41 PM

I got 1 7/8 headers and a dyno vid in the firebirdsection under "got her on the dyno" but I also have an ory and catback. Not sure what route op is taking

**Camaro69Mac** · 05-06-2010, 05:19 AM

So basically this topic goes either way it seems

**blackbird0230** · 05-06-2010, 09:20 AM

Not necessarily, I think 1 7/8" are better all around. They can be used fine on stock motor and you'll be set for future mods. You might lose a little on the bottom but up top will make up for it.

There are more 1 3/4" options for you so either way it will add power. Up to u man

**NavyTATwo** · 05-06-2010, 10:17 AM

I asked the samething when I was buying headers for my GTO. I went with 1 7/8 since I was planning to do a H/C change in the future. Right now I just have the headers and a Corsa Touring catback (

) and the car runs fine. If you race the car at the track you might be able to feel the loss of torque down low but most people probably can't tell the difference. If I buy a set for my T/A it will be the 1 3/4 because I don't see much more happening with the car. I would go for the bigger set if you plan on modding the car a bunch. Just my .02.

Scott

**pajeff02** · 05-06-2010, 11:18 AM

I went with 1-7/8" Kooks on our car. No serious plans for a head or cam upgrade as of yet. But I am running a catted Y and felt it best to have a little extra volume since my exhaust is more restrictive compared to an ORY. Does that make sense?

**Camaro69Mac** · 05-06-2010, 12:46 PM

Originally Posted by pajeff02

I went with 1-7/8" Kooks on our car. No serious plans for a head or cam upgrade as of yet. But I am running a catted Y and felt it best to have a little extra volume since my exhaust is more restrictive compared to an ORY. Does that make sense?

Sure does...basically stock motor no cats go smaller 1 3/4 I appreciate it now the fun part of installing it haha doing eibach pro kit with bilsteins this weekend then tackle the headers next weekend oh boy

**Klug23** · 05-06-2010, 02:01 PM

Go 1 7/8.
Dynoed my numbers in sig, with 1 7/8s kooks, filter, tune on a mustang dyno.

**Mr. Luos** · 05-06-2010, 09:36 PM

Originally Posted by Hi-Po

Your not going to lose any power/torque down low with 1 7/8's

I do believe it will suffer a LITTLE bit in the lower RPM's....when compared to the 1 3/4 primaries.
Nothing noticeable though.

Regardless, you will gain power across the board when compared to the factory manifolds.

**Camaro69Mac** · 05-07-2010, 04:08 AM

Originally Posted by Mr. Luos

I do believe it will suffer a LITTLE bit in the lower RPM's....when compared to the 1 3/4 primaries.
Nothing noticeable though.

Regardless, you will gain power across the board when compared to the factory manifolds.

That's all I need haha I just want to get it in the 12's ill be happy with that for now till winter

**BrntWS6** · 05-07-2010, 04:56 AM

Dyno results with 1 3/4 Kooks headers.

- Lid / Filter
- catted y with GMMG cat -back
- Ported stock TB

341.6hp 350tq tuned w/ Mustang dyno

**Hi-Po** · 05-07-2010, 05:25 AM

Originally Posted by Mr. Luos

I do believe it will suffer a LITTLE bit in the lower RPM's....when compared to the 1 3/4 primaries.
Nothing noticeable though.

Regardless, you will gain power across the board when compared to the factory manifolds.

I'll agree, the velocity is obviously going to be slightly slower with the larger pipe... it will be completely unnoticeable as you said.

This is a pretty dang good 1 3/4 vs 1 7/8 header dyno graph overlay. Car's in question are both 08 vettes with the LS3 engine. Trying to decide which header is which on the lower RPM's would be near impossible. Besides exhuast, they are completely stock. Both have a catted X pipe as well of the same brand.

Really a moot point in then end, but I will stay with my 1 7/8's

**Firebirdjones** · 05-07-2010, 05:57 AM

You are right HiPo.

There was a back to back dyno comparison on this a few years back on a stock LS1 that a magazine test ran. I'm sure if you google, it can be found. I just suck at that. I know it's out there, since someone here asked to see it.

But I do remember the LS1 performed better accross the board with the 1 7/8 headers, and didn't show any loss down low, but only a slight gain up top.
Showed the LS1 really liked the larger headers, even in stock form.

An even better approach would be a stepped header (1 3/4 to 1 7/8) and I'm willing to bet those are out there made by someone too.

**blackSS01** · 05-07-2010, 11:58 PM

Originally Posted by Hi-Po

I'll agree, the velocity is obviously going to be slightly slower with the larger pipe... it will be completely unnoticeable as you said.

This is a pretty dang good 1 3/4 vs 1 7/8 header dyno graph overlay. Car's in question are both 08 vettes with the LS3 engine. Trying to decide which header is which on the lower RPM's would be near impossible. Besides exhuast, they are completely stock. Both have a catted X pipe as well of the same brand.

Really a moot point in then end, but I will stay with my 1 7/8's

EXCELLENT POST

To OP, go 1 7/8's.....I wish I would have the first time

**sixpack_2_go** · 05-11-2010, 02:13 PM

this comparison does not relate to a stock 346ci ls1. It was done on a larger cube motor(ls3 376ci)..thats why this motor did not lose any low end! You guys need to understand that bigger is not always better! motor building is a science...you don't just throw the biggest stuff you can find on a stock cube motor... if that was the case we would all run 5" primaries

Originally Posted by hi-po

i'll agree, the velocity is obviously going to be slightly slower with the larger pipe... It will be completely unnoticeable as you said.

This is a pretty dang good 1 3/4 vs 1 7/8 header dyno graph overlay. Car's in question are both 08 vettes with the ls3 engine. Trying to decide which header is which on the lower rpm's would be near impossible. Besides exhuast, they are completely stock. Both have a catted x pipe as well of the same brand.

really a moot point in then end, but i will stay with my 1 7/8's