Hey guys I wanted to bring this up because I was wondering if someone had any concrete information/research they could help me with.

I am looking for some information on what mufflers are restrictive and what mufflers are not. For example some flow charts, cfm numbers, etc. Anything to show to me what mufflers are restrictive and what are not.

I am personally looking for a muffler that is not loud, however I can't have it be restrictive with how much boost I will be running.

Let me know what you guys have experience with and how you feel/know it flows. Thanks.

Something else that might help would be pulley size, muffler size/brand/make/exhaust info, boost numbers. Boost changes a lot but if you drop 3lbs switching mufflers that is a pretty big sign that one is restrictive lol.

 

Unless your turbo you want back pressure.

 

Muffler is the least of your worries, You running the stock exhaust and DP still?

And the muffs on these cars are pretty big. I'm pretty sure just about any muff would drop some weight.

 

Enlighten me with this. Your saying I will make more power with stock exhaust than I would with say a 3" or even better a 2.5" exhaust? I may have taken this out of proportion but it sounded a little extreme itself.

 

Stock exhaust is restrictive. But as soon as you start opening up that restriction, you're going to lose boost. 2in pinch at 02 sensor at DP, and 2.25 pipe over the axel.

2.5in = below 300hp
3in = greater than 300hp

3in with below 300hp, you'll see loss. No more backpressure.

 

false

 

Ok this topic is NOT going the way I want. I am looking for information that shows what mufflers are restrictive and what mufflers are not, nothing else guys.

 

Dude your dumb. With a supercharged application you want backpressure.

 

Edit sorry zach let the discussion begin.

Pm me and let me know why I dont want less restriction on my supercharger set up.

 

will someone please step in and teach these kids something?

 

It's not backpressure you want. You want to maintain good exhaust gas velocity. Too large of an exhaust can also cause backpressure due to eddies (turbulence), because the exhaust cant flow fast enough through the piping. A 3" exhaust is too large for most of the SS/SC's on this site minus the TVS/Turbo cars. A good 2.5" exhaust has very little back pressure, flows great, and maintains great exhaust gas velocity.

 

I am currently running a 3" I/O magnaflow muffler that is essentially straight-through. Loud as heck.

This saturday I will be installing my new stainlessworks chambered muffler (see signature), which promises to be MUCH quieter, yet flow similar to a straight through setup.

I cannot offer flow numbers, but I can compare my boost before/after.

For example on the 100% stock exhaust I was pushing 21.5psi on the TVS.

When I switched to full header-back 3" exhaust it dove down to 18psi.

When I switch to the new muffler I will record the new peak boost and we will at least have a roundabout guess based on the percent difference between the two.

Say the new muffler bumps my boost up to 19psi due to added restriction, we will be able to say that it flows 5% less.

Without the proper equipment thats the best I can do for ya! Hope it helps.

Oh yeah, here are some stock flow numbers: https://www.cobaltss.net/forums/2-0l-lsj-performance-tech-47/flow-calculation-some-lsj-parts-67539/

 

Your right about the exhaust velocity, but you do want a good deal of backpressure with a supercharged car.

 

Why would that be? Flow = power.

I'm so tired of seeing people post that backpressure is good.

Velocity and flow are good.

 

Oh, i see that your smarter than guys that have built race cars for years, and the owner of a Performance shop. Cool dude good luck with that.

 

You don't want too much backpressure. But you want some. You lose backpressure = you lose boost.

Not sure what would happen with too much backpressure, but I couldn't imagine it'd be pretty.

/thread

 

I feel sorry for these "race cars" you've been bottlenecking for years.

Excessive backpressure is NEVER good. Its all about a good match of flow and velocity. Yes, there will be some backpressure, but thats not what its about.

 

Losing boost isnt a bad thing.

The less boost you can run on a smaller pulley the better. It means more air is actually flowing through the head and being utilized.

 

in for lulz

 

I think my head is going to explode from reading this....
If I see "back pressure" one more time in this thread, I'm going to lose it. Back pressure is bad... you never want back pressure... NEVER!

A properly matched exhaust will maximize flow and gas velocity... and losing boost is a good thing.
Remember, boost is simply a byproduct of restriction. If you can lower your boost, while flowing the same air... you will end up with a more efficient (and more powerful) engine.

 

hahn catback ... specs who knows ... sounds like complete **** on a blower ... sounds like complete sex on a turbo