Jump to content
SAU Community

Recommended Posts

Hey guys. So my R34 GTT has a custom 3.5” exhaust (done by previous owner) with a high flowing cat, and then just a Varex cannon muffler on the back. The car does drone alot and is really loud even on highway driving just cruising, as you can imagine due to the Varex muffler basically being a straight through with the valve open. As much as i love a loud RB, it can be a bit much with no other muffling in line and just driving casually. I wanted to lower the volume output on the exhaust a bit, as well as remove the drone (probably a way to do both at once), and was going to do it all myself as I am a fabricator and have done exhaust work in the past, so the fab work isnt my issue, im just not sure on the right product or type of product to use to get the job done, and i doubt an exhaust shop would be wanting to help me as they wont be making any money from helping me, unless they supplied the product? Anyway any help or guidance in best way to approach this would be awesome

 

Thanks in advance

Go to SP mufflers and get the muffler of size you want and make a nice mid muffler.

It's about that simple! I have 2x 3.5 Magnaflow straight through Mufflers and while it's pretty loud with the Varex open, it's quiet enough with the Varex closed. You can also buy off the shelf Magnaflow straight through mufflers as well.

You also have a turbo to quiet the car down too. Don't overthink it. Buy my extra Magnaflow muffler sitting on a shelf doing nothing (buy it new, ignore this part)

7 hours ago, Kinkstaah said:

Go to SP mufflers and get the muffler of size you want and make a nice mid muffler.

It's about that simple! I have 2x 3.5 Magnaflow straight through Mufflers and while it's pretty loud with the Varex open, it's quiet enough with the Varex closed. You can also buy off the shelf Magnaflow straight through mufflers as well.

You also have a turbo to quiet the car down too. Don't overthink it. Buy my extra Magnaflow muffler sitting on a shelf doing nothing (buy it new, ignore this part)

Cheers. I more want it quieter with the varex open. I only have the varex closed when i start up and roll out the driveway to keep everyone happy on days i take the car to work at 5 AM or come home late. So just a mod muffler will do tge trick? Something like that would require a retune hey?

I did say "2x Magnaflows" then referred to a Varex. So to un-confuse that, my rear muffler is hot-swappable with a Varex.

When I had a RB Turbo, I had the 2x Magnaflows, then went LS and though "Oh that's way too loud" and ordered a Varex.

A mid muffler will definitely help a lot, even if straight through. SP Mufflers can make anything as big or as small as possible, which will help even more. Looking at my own exhaust I could make the muffler twice as long if I wanted to. Or you could go crazy and get 2x mufflers from SP and full every remaining space with muffling.

In my experience closing the Varex makes the car run VERY rich (obviously). I'd say adding a muffler *will* affect things, on a technical, physics level, but I don't think you'd need a retune as the actual effect would be the car running a *tiny* bit richer due to more restriction, on a strictly physics level, but you kind of don't have any option if you want the car to make less sound.

  • Like 1
48 minutes ago, Kinkstaah said:

I did say "2x Magnaflows" then referred to a Varex. So to un-confuse that, my rear muffler is hot-swappable with a Varex.

When I had a RB Turbo, I had the 2x Magnaflows, then went LS and though "Oh that's way too loud" and ordered a Varex.

A mid muffler will definitely help a lot, even if straight through. SP Mufflers can make anything as big or as small as possible, which will help even more. Looking at my own exhaust I could make the muffler twice as long if I wanted to. Or you could go crazy and get 2x mufflers from SP and full every remaining space with muffling.

In my experience closing the Varex makes the car run VERY rich (obviously). I'd say adding a muffler *will* affect things, on a technical, physics level, but I don't think you'd need a retune as the actual effect would be the car running a *tiny* bit richer due to more restriction, on a strictly physics level, but you kind of don't have any option if you want the car to make less sound.

Yeah great. Just got off the phone with SP, and will see about getting one of their mufflers to weld in in the next month or two. For me the varex is to get me out of the driveway, down the road and thats it. It stays open 99% of the time driving as it does definitely run rich with it closed as you said, and restricts the boost build up. Thanks for your help

  • Like 1
33 minutes ago, GTSBoy said:

Straight thru's have so little restriction that it's almost certainly not worth worrying about effects on tuning. Even a centre offset shouldn't upset things, but would be noticeably more effective (quiet).

Thanks mate!

I'm struggling with a similar issue on an RB26. Make sure you know whether it's volume or resonance. Mine seemed louder when cruising compared to at idle. I downloaded a decibel meter for my phone. Take my less than scientific results with a couple grains of salt, but the decibels were the same at idle and at cruise. Mine seems to be a resonance problem. At 2500-3500 rpm, the sound is different and "louder" to my ear. I think it's vibration from the pipe, the car body, the floor or something creating tone.

Anyway, consider that it may not be strictly a volume problem.

  • Like 2
1 hour ago, Kip said:

I'm struggling with a similar issue on an RB26. Make sure you know whether it's volume or resonance. Mine seemed louder when cruising compared to at idle. I downloaded a decibel meter for my phone. Take my less than scientific results with a couple grains of salt, but the decibels were the same at idle and at cruise. Mine seems to be a resonance problem. At 2500-3500 rpm, the sound is different and "louder" to my ear. I think it's vibration from the pipe, the car body, the floor or something creating tone.

Anyway, consider that it may not be strictly a volume problem.

Yeah i get what you mean. Mine thought i wouldnt mind being a bit quieter overall as well as have the drone taken out is more what i was trying to say. Im going to start with a mid muffler, and go from there 

It can be worth experimenting with adding a Helmholtz resonator to some systems, particularly if it is one tone that drones excessively. This is a short(ish) length of pipe teed off the side of the main pipe, ending in a dead end. The length tunes the frequency at which it works. You have to experiment to find the right length. There's a recent youtube vid where someone did it, might be worth a look.

5 minutes ago, GTSBoy said:

It can be worth experimenting with adding a Helmholtz resonator to some systems, particularly if it is one tone that drones excessively. This is a short(ish) length of pipe teed off the side of the main pipe, ending in a dead end. The length tunes the frequency at which it works. You have to experiment to find the right length. There's a recent youtube vid where someone did it, might be worth a look.

Yeah ive looked into those. I saw one guy who made his adjustable so he could fine tune it, but theyre a decent amount of work to get right and they only do one particular range of frequencies. I feel like if youre not worried about losing some overall volume in your exhaust (like me) and want an easy solution, slap a decent muffler in and that should do it, as a muffler should take out more of a frequency range but also you lose some of the volume, which is fine for me

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

    • My thinking is that if the O2 sensor is shot then your entire above described experience is pure placebo.
    • Here is the mess that I made. That filler there was successful in filling dents in that area. But in the middle area. I can feel dents. And I've gone ocer it multiple times with filler. And the filler is no longer there because i accidently sanded it away. I've chased my tail on this job but this is something else lol. So I'm gonna attempt filler one more time and if it doesn't work I'll just high fill primer the door and see where the issues are because guidecoat is of no use atm.
    • Ok, so I think I sort of figured out where I went wrong. So I definitely overthinked it, and I over sanded, which is probably a large part of the problem. to fix it, I ended up tapping some spots that were likely to be high, made them low, filled them in, and I tackled small sections at a time, and it feels a lot better.    I think what confused me as well is you have the bare metal, and some spots darker and some are lighter, and when I run my finger across it, it' would feel like it's a low spot, but I think it's just a transition in different texture from metal to body filler.    When your finger's sliding on the body filler, and crosses over to the bare metal, going back and forth, it feels like it's a low spot. So I kept putting filler there and sanding, but I think it was just a transition in texture, nothing to do with the low or high spot. But the panel's feels a lot better, and I'm just going to end up priming it, and then I'll block it after with guide coat.   Ended up wasting just about all of my filler on this damn door lol  
    • -10 is plenty for running to an oil cooler. When you look at oil feeds, like power steering feeds, they're much smaller, and then just a larger hose size to move volume in less pressure. No need for -12. Even on the race cars, like Duncans, and endurance cars, most of them are all running -10 and everything works perfectly fine, temps are under control, and there's no restrictions.
    • Update: O2 sensor in my downpipe turned out to be faulty when I plugged in to the Haltech software. Was getting a "open circuit" warning. Tons of carbon buildup on it, probably from when I was running rich for a while before getting it corrected. Replaced with new unit and test drove again. The shuffle still happens, albeit far less now. I am not able to replicate it as reliably and it no longer happens at the same RPM levels as before. The only time I was able to hear it was in 5th going uphill and another time in 5th where there was no noticeable incline but applying more throttle first sped it up and then cleared it. Then once in 4th when I slightly lifted the throttle going over a bump but cleared right after. My understanding is that with the O2 sensor out, the ECU relies entirely on the MAP tune and isn't able to make its small adjustments based on the sensors reading. All in all, a big improvement, though not the silver bullet. Will try validating the actuators are set up correctly, and potentially setting up shop time to tune the boost controller on closed loop rather than the open loop it is set to now. Think if it's set up on closed loop to take the O2 reading, that should deal with these last bits. Will try to update again as I go. 
×
×
  • Create New...