Headers: 1 3/4 vs. 1 7/8

[RxApple]

You can see my mods below... What are the pros/cons of each size?? Do I need the larger size? Thanks for the input.

[SLA]

Are you going to be doing any other mods such as a cam, ect... in the future? If not 1-3/4 is fine

[99-LS1-SS]

Are you going to be doing any other mods such as a cam, ect... in the future? If not 1-3/4 is fine

This.

[pha|anx]

1 7/8" is huge, do these things really need LT's that size? lol

[todds87ss]

Since there is no downside to getting larger pipes, why not? Are the smaller ones less expensive?

[Slizzo]

When you're not looking to make big power, the 1 3/4" headers actually make more power than the 1 7/8" ones.


If you're looking at a big cam or lots of boost down the road, 1 7/8" headers have been recommended.

[bigwillys58]

i went 1 7/8 because i plan on doin a cam shortly

[pha|anx]

When you're not looking to make big power, the 1 3/4" headers actually make more power than the 1 7/8" ones.


If you're looking at a big cam or lots of boost down the road, 1 7/8" headers have been recommended.

exactly. I'm looking at a low-lift cam down the line, but I think I'm just going to stick with 1 3/4" ones for this reason. no crazy boost or cam for me.

:wazzup:

[It's A G8!]

I read somewhere that if you get the 1 7/8 you loose torque down low but gain power up top. And the 1 3/4 you gain torque down low but loose power up top. I dont know how true this is.

[The Commodore]

I plan on getting 7/8s because I highly doubt the difference is that huge and if I do plan on going all out, it's going to be N/A only so 7/8s would be wanted there. I'm thinking down the road.

['02 ws6]

I would stick with 1 3/4 unless your going all out H/C setup, then step up to a 1 7/8.

[todds87ss]

I read somewhere that if you get the 1 7/8 you loose torque down low but gain power up top. And the 1 3/4 you gain torque down low but loose power up top. I dont know how true this is.

This was true with smaller motors...we are still waiting proof that there is a loss with the 6.0l motors.
Vendors...?

[SLA]

This was true with smaller motors...we are still waiting proof that there is a loss with the 6.0l motors.
Vendors...?

When placing my order with ARH they asked what my plans for modding were, and since I don't plan on doing anything drastic such as H/C/I or a blower until the warranty is up they recommended 1 3/4". I've also seen Tom@ARH recommend, in their section, 1 3/4" to a member here if they were only doing basic mods. Thats all the "proof" I need.

[99-LS1-SS]

i went 1 7/8 because i plan on doin a cam shortly

Me too and don't call me shortly!!:)

[99-LS1-SS]

This was true with smaller motors...we are still waiting proof that there is a loss with the 6.0l motors.
Vendors...?

As well as the 6.2L. I could understand it if we had the 346 cid (5.7) engines but our engines are 366 cid (6.0) and 378 cid (6.2). These engine move more air by nature.

[G8GT594]

1 7/8 would be the best way to go if you plan on making some high numbers. Don't make the same mistake i did...

[jbradsh1]

If I remember correctly, Kooks recommends using 500 hp (not rwhp) as a point where you would want to go to 1 7/8". Below that they're not needed.

[todds87ss]

When placing my order with ARH they asked what my plans for modding were, and since I don't plan on doing anything drastic such as H/C/I or a blower until the warranty is up they recommended 1 3/4". I've also seen Tom@ARH recommend, in their section, 1 3/4" to a member here if they were only doing basic mods. Thats all the "proof" I need.

I guess I was hoping for someone to pipe in with dyno results. I do understand that back to back testing on the same platform would be very difficult. I would very much like to see at what point on the RPM scale the HP picks up from 1 7/8 to 1 3/4. Based on my wheel spin, I could certainly afford to drop off a few lower RPM TQ for some up top HP.

[jbradsh1]

1 7/8 would be the best way to go if you plan on making some high numbers. Don't make the same mistake i did...

Paul, you still feel like the 1 7/8" will give you a significant hp increase up top?

Todds87ss Quote: I guess I was hoping for someone to pipe in with dyno results. I do understand that back to back testing on the same platform would be very difficult. I would very much like to see at what point on the RPM scale the HP picks up from 1 7/8 to 1 3/4. Based on my wheel spin, I could certainly afford to drop off a few lower RPM TQ for some up top HP.

What mods have you done so far?

[kyllekkc]

quick question since the lt headers bold up to the stock exhaust they should fit on magna or borla right?

[The Commodore]

quick question since the lt headers bold up to the stock exhaust they should fit on magna or borla right?

Not Magna or Borla cat-back if you are going with ARH or Kooks. I think they work with the axle-backs though.

[todds87ss]

Paul, you still feel like the 1 7/8" will give you a significant hp increase up top?

Todds87ss Quote: I guess I was hoping for someone to pipe in with dyno results. I do understand that back to back testing on the same platform would be very difficult. I would very much like to see at what point on the RPM scale the HP picks up from 1 7/8 to 1 3/4. Based on my wheel spin, I could certainly afford to drop off a few lower RPM TQ for some up top HP.

What mods have you done so far?

RF Air intake, VMS tune and HSRK, UDP. Much like everyone else, future mods will only be limited by budget (I hope). I do understand the theory which says that as primary size increases, the torque curve gets more top heavy. I have never heard of anyone getting 1 7/8" primaries, and wishing they had 1 3/4" (on these motors).

[Ktlplxm]

Well I finally got back to the dyno to test the difference between the 2 sizes on my car.. Disappointment would be an understatement. Switching from 1 3/4 to 1 7/8 netted me a total of 4 ft lbs and 5hp. Thats it. I picked up better numbers from the HSRK than I did on a header swap.

[GeorgeInNePa]

Well I finally got back to the dyno to test the difference between the 2 sizes on my car.. Disappointment would be an understatement. Switching from 1 3/4 to 1 7/8 netted me a total of 4 ft lbs and 5hp. Thats it. I picked up better numbers from the HSRK than I did on a header swap.

Would you be willing to post the dyno sheets?

[MarylandSpeed]

We have sold headers for the 6.0L GTO and Vette for years now..and there never really has been a difference between 1 3/4 and 1 7/8"...at least not that you will feel SOTP. There is more difference between a good tune, and a great tune than the two sizes.

We just installed 1 7/8" on our G8 since it will get a Maggie sometime this year. The 1 7/8" Kooks headers and X-pipe with tune at Behe Performance left me with 45rwhp more on an otherwise stock car. When you make that much power from headers, you don't fret if your losing a few ft/lbs of TQ down low. I tell customers if you doing bolt on's, run 1 3/4". Anything beyond bolt on's 1 7/8".

[Ktlplxm]

Would you be willing to post the dyno sheets?

I don't mind sharing them with individuals but not everyone. Too many people would incorrectly assume that it is a tuning issue and "bad mouth" the tuner. I'll see about getting you a copy though

[99-LS1-SS]

Me too...please...:)

[GeorgeInNePa]

I don't mind sharing them with individuals but not everyone. Too many people would incorrectly assume that it is a tuning issue and "bad mouth" the tuner. I'll see about getting you a copy though

Thanks, I'd love to see them.

If there is that little difference on a 427, I won't worry about my little 6.0.

;)

[jbradsh1]

Well I finally got back to the dyno to test the difference between the 2 sizes on my car.. Disappointment would be an understatement. Switching from 1 3/4 to 1 7/8 netted me a total of 4 ft lbs and 5hp. Thats it. I picked up better numbers from the HSRK than I did on a header swap.

Well, that's exactly what Andy @Livernois mentioned to me, 5 hp gain.

[johnh]

So, it sounds like if you already have 1 3/4 unless you're going crazy don't swap.

If you don't have headers and plan some mods like a cam of FI, get the 1 7/8.

[The Commodore]

I'm going 1 7/8ths just so I can say I am bigger. :)

[G8-4-Speed]

The problem I see is bigger headers need bigger exhaust to work. 2 1/2" is never enough for 1 7/8" to work. 3" at least and maybe 3 1/2 before the x-pipe. Plan to put the boost, juice to it or turn some rpm to really see a good difference. Another thing with 1 7/8" is ARH uses a merge collector to help broader the torque/lower the torque curve which can help bridge the gap between small and big tubes but still you will need a larger exhaust for it to work. The heads flow good enough to warrant a bigger header, just have to match the right combination of parts together.

[todds87ss]

I don't mind sharing them with individuals but not everyone. Too many people would incorrectly assume that it is a tuning issue and "bad mouth" the tuner. I'll see about getting you a copy though

me also, please.

So in retrospect, with your mods, if you were making your first header purchase, you would go with 1 7/8?
Thanks.

[GeorgeInNePa]

me also, please.

So in retrospect, with your mods, if you were making your first header purchase, you would go with 1 7/8?
Thanks.

If you are going to go with FI, yes. Unless the FI is twin turbos, then headers aren't a good choice at all. ;)

The 1 3/4 vs. 1 7/8 debate rages on...

Remember, SS Enforcer is running mid-11s with 1 3/4 primaries. With a cam that's around the same size as the Stage 1 from Livernois.

[RxApple]

Just to put this out there several years later.... I went with 1 3/4" because I didn't invision every being able to get a blower, well I now have a Stage 1 cam and a TVS1900, car made 557rwhp, so the 1 3/4" seem to still do ok.....