anthonyg956

Greetings all,

Just a quick fill in:

My plan is to run an x-pipe and true duals w/ no cats & series 40 flowmasters, I just ordered a set of TSP 1 7/8 Long tube headers for my LS1, and am getting ready to do the poly motor mounts also while im at it.... however, i have reached a dead end when deciding what size of tube is best for more horsepower and performance.... the 2 1/2 inch or 3 inch???????

I was looking around the TSP website and came across this:
http://www.texas-speed.com/p-373-tex...true-dual.aspx

However, being that they are out of stock, I decided to call my muffler shop to see how much they would charge to run 3" pipe all the way back after I install the headers...

My local muffler shop, told me that 3" pipe is an overkill, and that I would not have as much exhaust pressure as a 2 1/2 inch pipe (which they proposed), and told me that the 3" was going to: 1) be more expensive, and 2) not going to perform as well as the 2" 1/2.....

Bottom line... Are they just trying to go about it the easy route or do they actually know what they are talking about?...

Anyone with a little more knowledge than I in this area have any suggestions? Thanks in advance!

mikh338

iTrader: (16)

https://ls1tech.com/forums/generatio...-pics-too.html

mikh338

iTrader: (16)

how much power are you planning to make, what are your mods...if just bolt ons id just do 2.5 it will be cheaper and thats plenty. if you are making around 500hp the thread says 3" will be better. if you plan to make big power later on just do the 3" now so you dont have to do it again...

anthonyg956

Mikh
Thanks alot... This is not my first T.A..... But this particular car, I bought my car a couple of months ago and it was bone stock...I plan on having this as a keeper.... with that being said, I'm not looking to pinch pennies... just want a good and strong exhaust so I can focus on my next upgrade


So aside from the lid and the smooth bellow , this is going to be my second upgrade on the car...

But knowing how addictive it is to want to make your car better/faster... In the near future, being a 2000 I do plan on swapping out the oil pump, installing a pully, a cam and either an ls6 intake or just go with a fast (still undecided if i want to go with the 102 or the 90) ..... and getting a tune.... After that probably start working on my suspension(shocks etc.)

After that sky is the limit(new heads, Ford 9" and maybe even procharger)....

For now... I think I'm just taking it one upgrade at a time

Sladester2

iTrader: (1)

Smooth bellow... pointless really

mikh338

iTrader: (16)

well since in the future you want to do pretty much full bolt ons plus heads and intake and possibly procharger. deff do the 3" duals.

Zombiesoldier

iTrader: (1)

I'm thinking of buying a 3" "cat back" ( not running cats on mine) spin tech exhaust I found.. But tht just me, but I'm doing that because it's getting ready to get a cam and want as much flow as possible and my r has flowmasters right now which are pretty restrictive.

tuske427

iTrader: (1)

yes, your muffler shop knows what they are talking about. It's simple science about volume, velocity, "bernoulie", etc. Basically- if the pipe is too big the exhaust pressure is reduced and the gas won't flow as fast, which is why it hinders the performance. You also should realize that as exhaust gas travels back, it cools down. when it cools down, it condenses. This is why you'll see exhaust systems are designed with progressively smaller pipes towards the back. the smaller pipes help maintain velocity of the exhaust gas. (ideally, they would taper like a long gradual cone, but this is not practical, so they are stepped).

companies sell gargantuan exhaust systems because it makes them money. People tend to think that bigger is always better, but a proper exhaust system will take into consideration the power output of an engine and the size will be adjusted accordingly. With a stock or mildly modified engine, you should be fine with a 2.5" diameter exhaust.

(think about it. if size didn't matter all cars would come with one size exhaust because they could save money ordering one size tube...)

Also, a good exhaust will utilize mandrel bends. a Mandrel bender bends the tubing without reducing the diameter. Its a more expensive piece of equipment and not every exhaust shop has one. a good exhaust system (regardless of diameter) will have these. you can tell a non mandrel bent exhaust tube when the inner side of the curve is crimped or reduced in size. OEM exhausts have this. it works, it's economical, but power is ultimately sacrificed.

I hope this helps.

thunderstruck507

iTrader: (18)

This thread was linked to another in the conversion section. While 2.5" might be ok for mild applications, more aggressive builds will definitely benefit from 3".

A majority of people will eventually modify to that point and IMO it is better to do it right the first time.

I have never seen even a stock internal ls1 suffer performance loss from too large of an exhaust diameter. It is a myth that needs to die.

MaryAnne Mercadante

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