scotty2000ss

iTrader: (2)

Just curious why 1 3/4 headers are an option if 1 7/8 are proven to make more power.

Correct me if I'm wrong

HCI2000SS

iTrader: (2)

Maybe price, clearance issues, etc...not sure

scotty2000ss

iTrader: (2)

I'm not sure either. I think the price difference is within 75$

CGSmith0524

Kooks is no longer making 1 3/4 Headers..... Which is why you see them on sale at Maryland Speed. With that being said, it wouldn't shock me if you see some of the other companies that make them in house, start to phase them out.

The companies that buy there headers overseas- well, they'll always sell them because people will always buy them. That, and they're made in bulk when shipped here to the US.

My two cents....

Toddoky

A lot of that does have to do with cost, but there are also now LS swaps being done on V6 and LT1 4th-gens using 4.8L and 5.3L Vortec truck engines. If you are doing a swap such as that and never planning to do further upgrades then the 1-3/4" are a good choice.

thunderstruck507

iTrader: (18)

Demand will still be there from people who hang on to disproven myths.

People still buy MSD coils, people still buy throttle body spacers, people still try to use 2.25" exhaust in performance applications, and people still say a 102mm Fast intake is "too big" for a mild ls1 car.

There are probably cases where clearance is too tight for larger tubes as well. And also they are usually a little cheaper.

dckmn52

1 7/8 headers are proven to make more power because crappy shelf cams are spec'd way off and therefore putting a larger tube on the primary makes more power.

http://www.exhausting101.com/?p=37

scotty2000ss

iTrader: (2)

What about on a stock cam application?

MuhThugga

1 7/8" headers make more power where and with what motor?

scotty2000ss

iTrader: (2)

The motors that are covered in this section. Gen III External

lemons12

iTrader: (71)

And who is this "expert" you linked us to?

Bull ****. They make more power with shelf, custom, and stock cams.

Just like a 102 VS 90.

Get outta here with that.

ULTIMATEORANGESS

iTrader: (4)

id have to say on bolt on mild setups 1 3/4s are adequate.

but on H/C OR FI applications 1 7/8th would be more optimal.


as with anything else people experiment to get more out of something its called progress.

1989GTA

I agree with that.

MuhThugga

4.8? 5.3? 5.7? 6.0? They are all Gen III engine sizes.

Different motors require different things. A blanket statement like 1 7/8" makes more power than 1 3/4" doesn't work because there are times where 1 7/8" doesn't make more power, or it only makes more peak power and loses out under the curve. Power is more than a single number.

scotty2000ss

iTrader: (2)

You're right. I should have states that. Lets keep this discussion to the LS1 and LS6 5.7 engine.

dckmn52

Guys that has been building NHRA ProStock headers and Cup motor headers and exhaust systems longer than LSx motors have existed. Road racing, ect ect.
Like you said, he's an expert.

There's more to it than just the cam timing thing. Exhaust ports are way too big, every cam has way too much exhaust duration in them, ect ect.
There is more than one piece to the puzzle.

This thread also drives me nuts.

https://ls1tech.com/forums/group-pur...y-headers.html

Like what the hell are we building here? 1100hp big blocks?
Apply some engine design theory to a build and actually think about it.

lemons12

iTrader: (71)

So you're telling me every GM engineer and every single person that has ever specd a cam for a LS style motor can't get the specs right?

SO my buddies 451" nitrous car should have 1 3/4 on it...


I've never seen a car not gain going to 1 7/8... Regardless of the cam specs.

lemons12

iTrader: (71)

I guess we should start worrying about back pressure too.

I should probably go from a 5" to 3" and up my back pressure some.

dckmn52

ACTUALLY you seem to be confusing exhaust velocity and backpressure, and most of the power to be gained in exhaust theory is done by the end of the header.
But of course you knew that right...

redbird555

iTrader: (14)

I sincerely hope this was dripping with sarcasm because if you actually thought lemons was serious about back pressure and not understand velocity then this post is just as bad as all the others you made.

But in essence you're saying 1-7/8 headers arent good on ls1 style engines and that cam specs are wrong 99% of the time? Pretty sure thats what you said, in which case i hope no one listens to your advice here. Most of all I like how you just cited a page made by a "guru" and treat it as gospel. Show me some dyno results where 1-7/8 tanked power on any gen III motor, I'll wait. There are plenty of websites that say a single 3" exhaust is good to 500hp but people throw a 4" on the car and pick up power at much lower levels. Theory doesnt mean crap until its been validated and fact is this hasnt been, its been disproven.

There are 34234235 threads on here about how 1.875 headers gain power. I do a lot of engineering work and theory is all well and good. Theory will only get you so far when you ACTUALLY test things and stop reading internet articles you see what works outside of theory. 1.875 headers give up little to nothing on an ls1 down low and make more up top its been proven many times, I'll take results over theory any day of the week if I didnt I wouldnt have a job.