Ls1 Exhaust Systems

[Ben C34]

I reckon you'd be fine. As to the sound, exhausts ar hit and miss, and sort of personal.

The only way to know for sure is to do it.

[AngryRB]

interesting then cause ive got a 3inch jap muffler sitting in shed, sounded pretty angry on the rb but quiet on idle and cruise, be interesting to fit it up, pitty I cant weld myself cause exhaust shops are a rip off,

the cannon could be hidden from view so wouldn't be seen, just a 3inch pipe

[AngryRB]

so to clarify is the exhaust size universal, eg 2.5inch gets your 250kw, 3inch for 300kw etc as a rough rule?

[V28VX37]

so to clarify is the exhaust size universal, eg 2.5inch gets your 250kw, 3inch for 300kw etc as a rough rule?

Well, no. First up the LSx exhausts are typically twin systems and so 2 x 2.5" (~39 in2 area) is a fair bit more flow than 1 x 3" (~28 in2 area) Skyline system. Also the (catback) piping itself is often not the restriction, it's the other bits like cats and mufflers. Stock headers can also restrict flow if you're running big numbers.

[Ben C34]

Whilst thats completely true (its maths!)

Is the flow really required? A 3inch straight through muffler probably flows more than the stock rear dual resonator.

I'm sure I've seen flow calculators online for exhausts. It would be very interesting to see what an ls engine can flow through the stock exhaust.

Having to pay a shop to do it does suck. That's where I'm lucky having the equipment to mess around with an exhaust to get it where i want it.

[Ben C34]

Pipe Diameter (inches) Pipe Area (in2) Total CFM (est.) Max HP Per Pipe Max HP For A Dual Pipe System

1 1/2 1.48 171 78 155

1 5/8 1.77 203 92 185

1 3/4 2.07 239 108 217

2 2.76 318 144 289

2 1/4 3.55 408 185 371

2 1/2 4.43 509 232 463

2 3/4 5.41 622 283 566

3 6.49 747 339 679

3 1/4 7.67 882 401 802

3 1/2 8.95 1029 468 935

[Ben C34]

http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/#easy

[AngryRB]

interesting, thanks for the info ben exactly what Im after...

[V28VX37]

Thanks Ben C34, let's try this table again:

I see where they're coming from but I would still take the HP readings as indicative only.

For instance, I'm running 285 rwkw without air filter or lid. This is about 380 hp in the old money. Assuming 20% driveline loss would make this 475 hp at the engine. This is all through a 3" turbo back exhaust system - yet the table above suggests Max HP of 339 for this pipe diameter.

Now it's all getting awfully academic

[gtr jet]

Fuel and boost also make a difference to the pipe diameter required.

At the moment I make close to 500HP at the engine on E85 through a 3" pipe but that doesn't mean I can't make more by going bigger.

For 250-300rwkw on an LS1, a single 3" pipe would be fine.

[AngryRB]

Do the rules apply to the whole system or would having say a 2.5inch tip or silencer in a 3inch system/ muffler affect power in a big way?

[scotty nm35]

I had a similar conversation with a c63 owner, he was fitting an Xforce twin 3 inch system (don't know why, don't ask) and was told the 100 cell race cats I fitted had to go, his tuner said they would make the car detonate.

The exhaust would have been good for 600+kw ffs.

Bloody mail order tuners.

[R31Nismoid]

I love my twin 3" DPE on my LS3

Sounds excellent... And of course drone @ 80km/h in 6th, that's just a given.

Note definitely changed after the first 200km too, much deeper... That said I got it REAL hot fast, most would probably take 1,000km to do that.

[AngryRB]

so do they drone less after a 1000km's? Might be worth leaving it on for a few thousand km's if its going to get better, the sound I thought it was going to make was the sound that it made with the resonator taken off the back , so just the 2 center mufflers and open at the diff, nice and deep, meaty.

and yeah drone is at that 1300-1600rpm, right where the auto likes to be on a cruise.

Edited March 4, 2015 by AngryRB

[Trex]

I love my twin 3" DPE on my LS3

Sounds excellent... And of course drone @ 80km/h in 6th, that's just a given.

Note definitely changed after the first 200km too, much deeper... That said I got it REAL hot fast, most would probably take 1,000km to do that.

You're comparing thrashing and getting the exhaust really hot and bedding in, to driving around the street like a normal person. The exhaust will take longer than 1k to bed in.

[bozodos]

I love my twin 3" DPE on my LS3

Sounds excellent... And of course drone @ 80km/h in 6th, that's just a given.

Note definitely changed after the first 200km too, much deeper... That said I got it REAL hot fast, most would probably take 1,000km to do that.

Nice system, it's the one I would have got had I a spare 3k at the time.

You can't really lose with a bigger exhaust for an LS - for me its just ground clearance that is the issue! Single 3" will sound like shit and will be a restriction btw.

[AngryRB]

On the Di Fillippo website it actually talks about how they typically reduce the pipe size after the diff to keep gas speed up and that's what creates the best sound, but my catback system is 2 1/2inch to the tip,

I had a worked VS ute before this one, had stroker, cams, diff gears, 3inch exhaust but only a 2.5inch tip pointed to the ground, every time it started it was like the world was about to end, could hear it from blocks away,

I'm gonna just run it for a few thousand km's, drive it like I stole it lol

[AngryRB]

Anyone know much about extractors?

Im stuggling to decide wether to get TRY Y 1 5/8 with 2.5inch outlet OR 4 into 1, 1 3/4 with 3inch outlet...

A few things ive read are that the 4 into 1's will give it a great V8 beat to it but may loose torque on bottom end, other people say that when the car is tuned you wont loose bottom end but gain everywhere and just to choose for sound?

If the difference isn't that noticeable then im thinking the big 4 into 1's look the business.

[zebra]

If Standard cam, unported heads etc go Try-Y

If its ported, cammed, with short gearing or high-stall, and want to go drag racing go 4-1

There is a big difference in bottom end grunt, between the two

[AngryRB]

have you tried the two on the same car? Ive asked quite a few exhaust shops and they cant give a definite answer, I spoke to Hi Torque Performance, and he said the 4 into 1 will be fine and they don't lose any bottom when tuned??

but need more opinions before spending this amount of money...