Jump to content
SAU Community

Recommended Posts

wanting some advice on mufflers here...

currently i have 3 inch from the downpipe all the way back to a cobi resonator and then out an RPS muffler at the back. I've been thinking about changing the cobi to another muffler instead of a resonator so i've been looking at those.

a couple of questions

has anyone used a borla, vortex or a flowmaster muffler on an RB before?

is there any reason why you wouldn't use these? n/a vs turbo muffler etc?

Link to comment
https://www.sau.com.au/forums/topic/439901-muffler-selection/
Share on other sites

There is no such thing as a turbo muffler.

There are mufflers of various sizes with various levels of flow and sound attenuation. The bigger and less restrictive the flow path through the muffler the less the attenuation. You can get away with a bit less attenuation in a turbo car because the turbo itself does some silencing.

All it really means is that a muffler that is low restriction is better suited to a turbo than an NA if noise is a concern. Both engines benefit from having as little restriction as possible, turbos possibly benefiting more than NA.

Both engines benefit from having as little restriction as possible, turbos possibly benefiting more than NA.

yes... technically they dont call it a turbo muffler just a muffler suited for turbo applications...

also less restriction the better in general BUT I believe for NA cars, the exhaust system is more critical as in, they plan for the bends, lengths etc to encourage a better scavenging effect since the pressure of the gases leaving the cylinders is not as pressurized as a turbocharged car. this is probably why when u put ur hand at the exhaust opening (when its not so hot), u can feel the gases coming out in pulses..

at least thats wat i have read so far... :)

i guess you're hitting the nail on the head...what makes a turbo muffler a turbo muffler? is it a straight through design? if thats the case many mufflers can be used.

for turbocharged exhaust systems, scavenging effect is less critical i believe... thus designers usually just want straight pipes with minimal bends... thus they usually point sideways near the rear of the car...

as for the internals of the muffler... most aftermarket ones are straight thru with steel wool etc... totally unlike ur OEM designs... which are misaligned /disjointed pipes with tons of sound deadening stuff in the middle...

also less restriction the better in general BUT I believe for NA cars, the exhaust system is more critical as in, they plan for the bends, lengths etc to encourage a better scavenging effect since the pressure of the gases leaving the cylinders is not as pressurized as a turbocharged car. this is probably why when u put ur hand at the exhaust opening (when its not so hot), u can feel the gases coming out in pulses..

Correct design for NA exhaust is that you have to get the primary lengths and the secondary lengths right (and the diameters right to get the velocities into the right range) in order to get your pulse tuning. After the collector at the end of the secondaries, you don't want to go too big a diameter pipe (in the aim of minimising restriction) because you still want to retain a decent gas flow velocity in the downstream pipe.

Turbo exhausts just want to get as big as practical as soon after the turbine as practical in order to get the back pressure as low as possible. A really excessively big diameter exhaust on a turbo that didn't need it to be that big might hurt power......maybe...... from the gas speed being too low and causing some problems that some people talk about but I have a hard time imagining. But in general that size is probably bigger than what you can actually fit into most cars anyway.

Back pressure is a bit of a crock, it hurts power production on any setup.

On a turbo the rear housing is already a restriction causing back pressure, go too small and you lose top end flow and engine torque.

On an NA a restriction should be built into the merge collector imo, not in a reduced exhaust size for the entire exhaust length. The worst idea I have seen is those X pipes some of the V8 guys use, which apparently help with creating vacuum before the X for a reduced flow. Siamese merge pipes are much better design imo as they don't harm exhaust flow.

Hey Scotty, how much benifit do you think there is in have a merge in a V8 exhaust system?

My old mans designing his set up atm and is deciding on whether to put a merge in or not.

Engine a 500ci+ producing around 700-800HP. Primaries are 2.25 into a 3.5" collector down to twin 3" pipes.

Any tips or recommendations on mufflers?

Yep, look up what a Siamese merge is, it's just a small slit between the two pipes, barely affects flow, but causes each pulse to create vac in the other pipe. Take some inspiration from the merge collectors on Burns Stainless site, they are some of the best I have seen.

Don't use Hooker mufflers, they have restrictors in them to quieten the exhaust volume. I gained 30kw changing to a Varex, both running 3.5 inch. Any straight through absorption muffler should be fine, the quality decides how long it lasts.

Is anybody still running a standard system?

my s1 Stagea still has the Nissan exhuast on it, with whatever cat they fit during compliance.

it's all 2.5" stainless and very well made, nice bends, well mounted etc.

As you'd expect from Nissan!

Only mod I've done is remove the "p&o cruise ship" rear muffler and fitted a 2.5"id- 4.5"od stainless eBay cannon and everyone asks if it's full after market as its reasonably loud.

You have a stock stainless system? Must be rare, I have never seen one on a Stagea before. If it is a Jap system it won't be 2.5 inch, they only use metric tube. ;)

V8 Soarers have stock stainless, as did the Golf I worked on the other week. Not many manufacturers use it due to their bean counters.

Sorry, 63mm then?

it has the Nissan emblem on the mid muffler box and on various bits I can see the Hitachi/unisia symbol.

And it definitely is stainless.

I also had (previously owned) a Holden hsv VS manta, and it had a pretty nicely made twin 2 1/4" stainless system.

But probably only due to being a HSV model. As it had HSV embossed in big letters on the muffler boxes.

Edited by nicksamaniac

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
×
×
  • Create New...