Exhaust Pressure Testing

[Exploded_Muffin]

Never used with factory connect.. cut off and welded on 2.5” to 3” transitions and v banded.

Have you got any more sound clips of your car Greg? Tryna gauge the volume of the 3" S-type paired with catless headers

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[Gregory347]

No more sound clips… what specifically are you looking for? just an FYI the s type without the resonator is obnoxious in my opinion… I ran it for a few months with the Borla xpipe and gesi gsport cats on and it was too loud and raspy…cold starts were cringe… i put the resonator on and went ffe… it sounds great in my opinion…cold starts are just right now… the Borla resonator necks down to 2.5 even though they say it’s 3”… the minimal loss in flow at my power level is negligible…I am 53 years old for perspective..,

 

[Exploded_Muffin]

No more sound clips… what specifically are you looking for? just an FYI the s type without the resonator is obnoxious in my opinion… I ran it for a few months with the Borla xpipe and gesi gsport cats on and it was too loud and raspy…cold starts were cringe… i put the resonator on and went ffe… it sounds great in my opinion…cold starts are just right now… the Borla resonator necks down to 2.5 even though they say it’s 3”… the minimal loss in flow at my power level is negligible…I am 53 years old for perspective..,

Looking for FFE with manageable volume, don't like overly loud setups.
You mentioned you didn't see a power difference with the 2.5" borla resonator vs the 3" s-type's X-pipe.
About how much power is your setup making?

 

[Gregory347]

Looking for FFE with manageable volume, don't like overly loud setups.
You mentioned you didn't see a power difference with the 2.5" borla resonator vs the 3" s-type's X-pipe.
About how much power is your setup making?

To me it's manageable and the sound is pleasant, not raspy or trumpety. Some exhaust setups for these cars sound like total crap. Bottom line is I couldn't enjoy the car before the resonator was installed.

It made 838rwhp with the resonated setup. That is with a Procharger p1x running a 4.13" pulley. Motor is stock only has opg/cs. May eventually drop to 4" pulley. Want to see what it does at the track as is. Car wasn't dyno tested back to back with the x pipe vs resonator. The shop owner/dyno operator says maybe loosing a few hp with the resonator at my level, for me it's inconsequential. No records to be set just here to have some fun.

 

[K4fxd]

If you trust Westech they found a big reduction in HP using 2.5 inch exhaust VS 3 inch at the 450 HP level.

 

[Gregory347]

If you trust Westech they found a big reduction in HP using 2.5 inch exhaust VS 3 inch at the 450 HP level.

I do.. but guessing by the 450hp level mentioned they tested a normally aspirated engine… exhaust physics/dynamics not apples to apples comparing how a na vs forced induction is affected by the exhaust diameter…

 

[Joshinator99]

You can definitely make big power through a resonator style muffler. On my Camaro, the long tubes and AWE Touring catback were insanely loud! I added a dual 3’’ in/out x-pipe resonator muffler to it and it made a huge difference in sound. Still not quiet lol but tolerable for cruising. Everyone told me it would stop me from making big power, but I went from 837 WHP, to 927 WHP, to 955 WHP, to 1059 WHP with that resonator still in place. Only 18 psi boost at that level too. So as Greg alluded to, with forced induction the exhaust tuning just isn’t as critical.

 

[Angrey]

You can definitely make big power through a resonator style muffler. On my Camaro, the long tubes and AWE Touring catback were insanely loud! I added a dual 3’’ in/out x-pipe resonator muffler to it and it made a huge difference in sound. Still not quiet lol but tolerable for cruising. Everyone told me it would stop me from making big power, but I went from 837 WHP, to 927 WHP, to 955 WHP, to 1059 WHP with that resonator still in place. Only 18 psi boost at that level too. So as Greg alluded to, with forced induction the exhaust tuning just isn’t as critical.

I think part of the problem here is the mix up of terms and the broad consensus/understanding of what they mean. You're using the term "resonator" in a very specific sense and I think it has more of a broader application.

I just purchased a set of shorty "resonators" that are flow through style (meaning the 3" cross sectional area isn't disrupted. The sound suppression comes from perforations on the tubing perimeter where an enlarged section features some sort of sound abating material (steel mesh, fiberglass, etc).

There are numerous designs for suppressing sound and the dominant factor in whether or not they restrict or affect power is whether they disrupt or impede the primary flow cross section.

Flowmaster used to feature what they called a "delta" muffler which was simply an enlarged chamber with a series of internal chevrons that the exhaust flow would have to travel around and bounce pressure waves off them. Glass packs and other straight through designs are pretty common.

Just about any design that maintains the original piping cross sectional area and seeks to absorb energy on the periphery is going to have a less detrimental affect than those that disrupt the primary path.

You can watch several videos and engineering studies that try to determine the optimal volume/length of exhaust exit that maximizes scavenging from the engine. Once that's achieved/addressed the rest is simply fluid dynamics of getting the exhaust to leave the vehicle in some place that makes sense (i.e. after you've addressed the scavenging, the rest doesn't really help, it's simply a matter of trying not to hinder the flow).

The edge between aiding the exhaust stroke on each cylinder by providing a high velocity/low pressure stream and then having the engine "fight" to push the exhaust is very narrow.

Flow through designs do a better job of not impeding flow however they're also not as proficient at reducing sound levels (at many frequencies).

To avoid overthinking things, the bottom line is that more volume is generally better, both for flow and power but also for sound suppression (in chambers).

And to your point about the power increases, you have to be careful in making spurious relationships. It's like saying "Yeah, he's a douchebag, but he managed the company to a profit of $10M last year so he must be doing something right." You can't judge absolute results, you have to compare them to the alternative. What would the alternative have produced? So just because you increased power doesn't necessarily mean the exhaust setup was optimal, when compared to ANOTHER configuration it might have made less power increase than the alternative.

 

[engineermike]

This is a really good article on the subject. Short story is that packed core (magnaflow, borla) reduce higher frequency/rasp and reactive (corsa, anything helmholtz) reduce specific low frequencies/drone. That’s why I’m using both types. Also of note is that noise and flow are NOT mutually exclusive.

https://www.enoisecontrol.com/wp-co...engine_exhaust_sound_control_barrier_wall.pdf

 

[TEXAS HEAT]

Thanks for the link, purchased one and can confirm mine is a true dual 3" resonated x as well.
How much would you say the volume increase was going from the 60661 to this?

I'll be pulleying down to the 100mm pulley soon on the G3 and my 2.5 exhaust with the 2.5 magnaflow tru-x won't cut it anymore
I have catless headers and paired with the 3" borla S-type I plan to purchase I feel the MF2469 won't do enough to quiet it down.

As an experiment I also purchased two 50mm wastegates and if I can find someone to fit them on my current 2.5" exhaust I'll forgo purchasing the 3" S-type

Now that the exhaust is a full 3" all the way back with the Jones resonated X, the most noticeable difference for me was the absence of the nauseating low frequency drone of the Borla 60661 at cruising speeds (1800-2000rpm) I have the Jones 3" X mated to the Borla 3" S-Type and the exhaust is still very authoritative on cold starts and under heavy load (WOT) but now there's very minimal coyote rasp upon part throttle acceleration and cruising and low load driving is very subdued. I absolutely love how the exhaust sounds now and imo, it's has been the best exhaust combination I've had to date. The driving experience is so much better now and my wife will actually ride in the car with me on road trips.

 

[WildHorse]

With superchargers at least, You need the exhaust header primary to outflow the total CFM flowing into the cylinder. Whether it's a 1.5" or 2.5" primary. Obviously, anything over 2" in a s550 is moot. Exhaust port on these things are pretty stout.

 

[Cory S]

And I still make decent power and almost touching 8’s with this factory bottleneck mid pipe connection. ALIENS!!! 2.08” ID!!!!!

 

[K4fxd]

And I still make decent power and almost touching 8’s with this factory bottleneck mid pipe connection. ALIENS!!! 2.08” ID!!!!!

Probably will go faster without the bottle neck.

 

[Cory S]

Probably will go faster without the bottle neck.

I mean, I’m sure it wouldn’t go slower. I hope not anyway. . By comparing data on setups/DA/weight etc, I’m right on the money with others with giant full 2.5-3” exhaust systems. If it freed up 20-25 crank HP, I still wouldn’t bother changing any of it though.

 

[80FoxCoupe]

I mean, I’m sure it wouldn’t go slower. I hope not anyway. . By comparing data on setups/DA/weight etc, I’m right on the money with others with giant full 2.5-3” exhaust systems. If it freed up 20-25 crank HP, I still wouldn’t bother changing any of it though.

Look at it as you are running what you should be running. The others you are making the comparison with are not running what they should.

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