Headers for an L99 Automatic.....17/8 or 1 3/4 ?

[Jekyll-N-Hyde]

So what do yall think Headers for an L99 Automatic.....1 7/8 or 1 3/4 ?

I have always been told that on a heavily modded car go with 1 7/8 otherwise especially on an automatic go with 1 3/4 thats mainly stock go with 1 3/4.
Because the 1 7/8 will hurt you in the low end on a basically stock car.
meaning a car with exhaust , headers , cai and a tune.

We have seen ARH's #'s for the LS3 with 1 7/8 has anyone put on some longtubes on a Automatic and what #'s did they get and what size headers did they get?

I was going with kooks however the only way for me to use my borla axle back would be for me to go wtih ARH there xpipe bolts on to the axle back from borla.
Kooks Xpipe only bolts on to there mufflers so with using there headers i would be forced to have bought there headers , connection tubes and there mufflers I couldnt use there set up with borla.

kooks said go with 1 3/4 for an automatic ARH says 1 7/8
kooks said 1 3/4 would be perfect for my car 1 7/8 would hurt it in the low end.
ARH says on a LS3 go with 1 7/8 and the same would work for a L99
however I dont see any numbers for a L99 yet from ARH.

What are yalls thoughts and info??????

Is there anyone who has put a set of 1 3/4 longtubes on a L99 with a 3inch xpipe and a tune and if so what are you #'s now ?
What were they before and after the tune ?

[ZZcamaro]

I have installed two sets of ARH on L99 cars....They were awesome. Once tuned you will get the full benefit of the system.

In my experience you did not lose any TQ at teh bottom end by using the bigger tube...but the smaller tube may gain a little more on the bottom end.

That being said...in my experience, both were gains across the board, and I would use the larger tube so that if you do anything in the future you are not going to hav to buy new headers again.

Even just adding a Cold Air Intake will help with the bigger tubes....that is just my thoughts....If you need pricing or have any questions feel free to get in touch.

[FTI-EDC]

Originally Posted by MellowYellow

So what do yall think Headers for an L99 Automatic.....1 7/8 or 1 3/4 ?

I have always been told that on a heavily modded car go with 1 7/8 otherwise especially on an automatic go with 1 3/4 thats mainly stock go with 1 3/4.
Because the 1 7/8 will hurt you in the low end on a basically stock car.
meaning a car with exhaust , headers , cai and a tune.

We have seen ARH's #'s for the LS3 with 1 7/8 has anyone put on some longtubes on a Automatic and what #'s did they get and what size headers did they get?

I was going with kooks however the only way for me to use my borla axle back would be for me to go wtih ARH there xpipe bolts on to the axle back from borla.
Kooks Xpipe only bolts on to there mufflers so with using there headers i would be forced to have bought there headers , connection tubes and there mufflers I couldnt use there set up with borla.

kooks said go with 1 3/4 for an automatic ARH says 1 7/8
kooks said 1 3/4 would be perfect for my car 1 7/8 would hurt it in the low end.
ARH says on a LS3 go with 1 7/8 and the same would work for a L99
however I dont see any numbers for a L99 yet from ARH.

What are yalls thoughts and info??????

Is there anyone who has put a set of 1 3/4 longtubes on a L99 with a 3inch xpipe and a tune and if so what are you #'s now ?
What were they before and after the tune ?

Some pretty good header discussions

[radz28]

Those are good discussions for sure. Call me the pessimist, but I prefer actual testing vs. theory. I work in a laboratory, and see calculations (admittedly - most I know understand, lol) and there constantly different results based off of what was expected and calculated. Sure, I can calculate what a pipe should flow and all that stuff, however, there are so many variables that I've seen affect actual results.

My point is, is though I think this too is a great article, there are no tests in it; just calculations. Yes - I've seen the author in that article in many publications and many of his associations; I'm not questioning him one bit. He'll forgot more than I will ever know. I want dyno' testing. I want data where all variables eliminated and hard numbers to support these calculations. Too many times, I've read other articles and seem other information where results were not the same as what this article states. Maybe in a perfect world, under perfect circumstances, but that's not real-world. How many times has anyone seen a dyno' graph when shorties out-performed long tubes? I haven't seen any - but I'll admit I certainly haven't seen all of them. Why don't NASCAR and other motorsports use shorties instead of LTs? They spend thousands of dollars optimizing size, length, bends, collectors, etc. Cost is no object, yet they still run LTs; what does that say?

I'm not arguing one bit I'm no expert. I just want data I can put my foot on, ya' know?

[FTI-EDC]

Originally Posted by radz282003

Those are good discussions for sure. Call me the pessimist, but I prefer actual testing vs. theory. I work in a laboratory, and see calculations (admittedly - most I know understand, lol) and there constantly different results based off of what was expected and calculated. Sure, I can calculate what a pipe should flow and all that stuff, however, there are so many variables that I've seen affect actual results.

My point is, is though I think this too is a great article, there are no tests in it; just calculations. Yes - I've seen the author in that article in many publications and many of his associations; I'm not questioning him one bit. He'll forgot more than I will ever know. I want dyno' testing. I want data where all variables eliminated and hard numbers to support these calculations. Too many times, I've read other articles and seem other information where results were not the same as what this article states. Maybe in a perfect world, under perfect circumstances, but that's not real-world. How many times has anyone seen a dyno' graph when shorties out-performed long tubes? I haven't seen any - but I'll admit I certainly haven't seen all of them. Why don't NASCAR and other motorsports use shorties instead of LTs? They spend thousands of dollars optimizing size, length, bends, collectors, etc. Cost is no object, yet they still run LTs; what does that say?

I'm not arguing one bit I'm no expert. I just want data I can put my foot on, ya' know?

Most NASCAR headers are TriY.. How's that for a curve ball?

[Jekyll-N-Hyde]

I got the automatic for first gear !!! I dont want to lose my first gear by going with to much of a primary.

now if i were for sure going to supercharge my car then yes i would go 1 7/8 but can i tell the future right now ? No


I just want to see what a L99 with a tune , exhaust did with 1 3/4 and compare the 1 7/8 and go from there.

we have seen 41 hp from the ls3 now lets see the l99's numbers with this stuff done to it.

ARH says we use 1 7/8 on the manual ls3 and got this.....then what do you use for an automatic L99? the same as the LS3 they say.

well from what I have heard in the past a car that isnt heavily modded needs a 1 3/4 but if you are one who is going with forced induction and cams and etc then you need to jump to the 1 7/8 for the future.

[BLT4SPD]

L99/a6 tuned,1 7/8 ARH headers and exhaust.NO CAI yet went 12.98@107 in 90 degree heat Saturday. dynoed Friday evening

[FTI-EDC]

Originally Posted by MellowYellow

I got the automatic for first gear !!! I dont want to lose my first gear by going with to much of a primary.

now if i were for sure going to supercharge my car then yes i would go 1 7/8 but can i tell the future right now ? No


I just want to see what a L99 with a tune , exhaust did with 1 3/4 and compare the 1 7/8 and go from there.

we have seen 41 hp from the ls3 now lets see the l99's numbers with this stuff done to it.

ARH says we use 1 7/8 on the manual ls3 and got this.....then what do you use for an automatic L99? the same as the LS3 they say.

well from what I have heard in the past a car that isnt heavily modded needs a 1 3/4 but if you are one who is going with forced induction and cams and etc then you need to jump to the 1 7/8 for the future.

Don't fear the 1-7/8" primary headers on these engines. They do not loose any low end power when the combination is done right. Besides, who runs a stock torque converter when you mod a car with an automatic?

Ed

[Jekyll-N-Hyde]

I have always been a Kooks guy however since there Xpipe doesnt bolt up to aftermarket companies like borla and corsa exhaust im affraid ARH just took my busniess.I just hope the quality and craftmanship equal the same if not better.

[_GTO_]

As far as I know and as I tested on the dyno on my friends cars , if your engine got bolts on or a cam the 1 3/4 will give you the best result , but if you got forced induction the 1 7/8 is absolutely the best for you .

[toehead93]

Why doesn't a shop install each on one car so we can see the dyno results. I remember seeing a comarison like this between AR and LM headers a while back. It'd be nice to see some comparisons for the LS3. There is talk of doing this for the CAI kits, obviously header installtion is way way way more time consuming than poppong on and off CAIs.

I'd also like to see how different merge collectors affect torque and HP also. I understand a longer collector with more volume gives a broader torque curve.

[ZZcamaro]

I have a customer whom just dynoed his L99...He has a New Era intake, and the ARH system...He gained 56 RWHP with a tune.

Not bad!! and they are the 1 7/8.

If you are looking to order something please give me a chance to earn your business.

[radz28]

Originally Posted by FTI-EDC

Most NASCAR headers are TriY.. How's that for a curve ball?

SEE!? WTF is that?! A header like that goes against some of what that article is saying. I totally see where the article is coming from, and the information, but I want to see dyno's, not numbers and theory.

[FTI-EDC]

Originally Posted by radz282003

SEE!? WTF is that?! A header like that goes against some of what that article is saying. I totally see where the article is coming from, and the information, but I want to see dyno's, not numbers and theory.

That's all great except that 99% of the cars modded are not at the caliber of a NASCAR engine or even an NMCA "heads up" class car so if there is a delta, where is it? Is it a benefit? Personal choice for most.

What if the smaller tube headers use a baffled muffler and the bigger tube header utilizes a straight through? Maybe one combination uses an "X-pipe" and the other does not? Too many variables for a "test" to be valid on a vehicle but ... I'm sure some magazine will make an attempt so they can sell an advertiser's piece. This is not a GEN1 engine and these LSx platforms respond really well to the bigger pipes. At least from the data we've collected.

Take what's said with a grain of salt because I'm sure some "marketing guru" will justify their product just like Splitfire plugs and those magic fuel line ionizers.

Ed