big tony

I Want To Go With Lg Headers In 2003 Coupe With Stingers At Both Ends Intake And Exaust.i Was Told That With The 3'' Exaust I Would Lose Low End Torque Especially Since I Was Going Without Cats.they Said Not Enough Back Pressure For A Basicaly Stock Motor.please Give Opinions.

02ElectronZ

Here is basically how I understand it. I assume you have the standard 346 CID LS1. Which means your engine cannot flow enough air to give you the right back pressure w/a 3" exhaust system, then your headers are not creating the most efficient scavaging of exhaust gases from the exhaust cycle. Therefore, reduced vacuum on the exhaust valve does not help it shut in time for the intake stroke to achieve maximum new air instead of exhaust. Kind of like backwash from your brother when you had to share a Mt. Dew. This is where you lose the torque. You also lose HP, but it is not as noticeable at low RPMs where you need torque, not HP.

Hope this helps. If not, PM me.

loudsam

What all are you planning as far as performance mods for your car? It's a KNOWN fact that Longtube headers are an absolute pre-req to other more serious "power-mods".

Plus, If your thinking of performance, than you must be pushing the revs high enough to realize good torque/horsepower gains from longtubes. IMHO, I wouldn't even think of doing anything else till I had LT headers on my car! Except for of course, air-intake!

IMHO, and from a little bit of performance driving, these ls1 engines were "BORN TO BE WILD"!!! Something like Dynatech Supermaxx have only 2.5" merge collectors, and they usually produce good low-end torque. Especially if your planning on doing more serious performance mods! But, the LG headers also have been shown to produce very good torque throughout the rpm range

big tony

Thats Why I Was Asking About 3" Exaust I Want To Go With Lg Headers But Was Afraid I Would Lose Low End Torque.thans You Guys For Answering.

vettenuts

You might also want to look into the Tri-Y design, which is different than the 4 to1 design. There are three companies that make them, Bassani, Bellanger and QTP. QTP are all stainless, the others are not. Here is a good article:

Header Article

Mr. Jones

LG long tubes are all stainless. call them and ask for examples/numbers on a stock setup. I don't remember anyone
loosing torque with any header install. 3" pipes or 2-1/2"

Michael Tucker

i went to LGM's site and did not see any graphs where tq or hp was lost????? can anybody show one that shows a loss?
Mike

2000BSME

I lost low end torque, noticeably, when I put on my Corsa Indy exhaust mufflers, I can imagine the 3" pipes having even more of a noticeable affect. I also noticed that engine braking decreased a slight amount with the Corsa Indy's, which made the car feel a little more comfortable at high rpms.

XPC5R

3" in the rear section may be overkill for an LS1 head/cam engine, but the gains from the headers alone will probably show you no loss over stock.

On an LS6 (stock heads and cam - 2001), the 3" rear section is they way to go. I tried many dyno runs with different configurationsand tuning with our LG LT equipped Z06, from dumps to tapered merge down to the factory 2.5" y-pipe into Z06 Ti mufflers. The more 3" tubing after the x-pipe, the more power and torque it made everywhere. The best combo was 3" dumps under the trans, which made 390 ft/lbs at the wheels ( with a halltech intake, shaner TB, LG LTs, tuning, and light flywheel).

If you go with H/C, then 3" is a must, otherwise you are leaving power on the table.

You can be sure LG did not use 3" unless it proved to be the best combo. The extra tubing size and weight cost more to mfg.

Michael Tucker

thats what i was thinking

Mike

FRC Rob

I put LG Long Tubes with their off-road 3" x-pipe on my stock (except for Vararam) '99 FRC. The top end is stronger, but the most noticable improvement is the low to mid range torque. Very noticable gain...definitely no loss!

Phil97SVT

I've got a full 3" system I fabricated about a year ago. The car went .1 to .2 faster than with the 2.5" rear system. Now its got a 90mm intake and TB and the gains are even greater.
Phil

CNB

I have these headers along with pre and post dyno graphs. Let me assure you there is no loss of torque anywhere. The mid range torque gains with these headers is huge.

Rag-Top Rick

Big Tony, you didn`t mention if your car will see track time or will be strictly a street car!
If strictly a street car, which mine is, a tri-y header with a 2.5in. system will give you a "broad torque" curve (bottom/mid range) while giving up a tad at the top end.
The tri-y will however give you tq & hp in the rev range used most on the street (merging in/out of traffic/canyon carving, etc) as opposed to an 4 into 1 which gives a little more top end and will benefit more at the track, IMO.

Either way you can`t go wrong, just do your homework before you buy.

Cheers, Rick

big tony

Thanks For All The Input Guys.my Car Probally Wont See The Track But Alot Of Street Romping.i Have Narrowed It Down To Lg Or Qtp Tri Y.keep Opinions Coming.

vettenuts

Other things to consider, ease of installation (if you are doing them) and track record for not coming up with errors. Other things to think about, when you put them on the tunnel plate will be fully exposed. I found the stiffening plate (I have the Backbone by VnM) to be a very worthwhile modification and it is simple once the exhause is off for the headers.

big tony

Well Guys I Just Pulled The Trigger And Ordered The Lg With Cats.they Seem To Have A Strong Following.i Hope I Did The Right Thing.

Rag-Top Rick

Big Tony, vettenuts brings up a good point, especially if you do the install yourself!
Install difficulty on the QTP`s vs LGM`s appear about even, however, the QTP`s "DO NOT" require dyno/ls1 edit tuning (they retain all 4 oxygen sensors) the LGM`s from what I have read (REQUIRE 02 simulators/TUNING,) which also adds to the cost.
If you have a reputable tuner in your area and don`t mind the extra effort/cost to have the car tuned, then it`s a non-issue, otherwise this is something to consider when making your choice.

As mentioned previously, do your homework, both are great choices so you can`t go wrong either way.

Cheers, Rick

vettenuts

Congratulations, and good luck. I think you will find this to be a very worthwhile mod, I know I did. I also kept all my original parts in case I sell the car some day.