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R34 GTT - Before & After Exhaust

choyda

By choyda,
in Engines & Forced Induction

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choyda Veteran

choyda

Posted
Posted

Hi all,

Tomorrow I'm getting a 3" turbo back exhaust system from Exotic Exhaust. My current system is stock and the new system will be a 3" split dump system (mild steel) with a stainless steel cannon tip.

I thought I'd share the differences it makes (sound wise):

Stock - Startup

Stock - Light Revving

Stock - Close to exhaust

Tomorrow I will post the 'after' sounds.

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https://www.sau.com.au/forums/topic/75621-r34-gtt-before-after-exhaust/
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Abo Bob Grand Master

Abo Bob

Posted
Posted

You'll notice a definite difference in power and in cabin noise. You can sort of hear it chuffing away when you get some revs on and it is generally louder inside the car but you get used to it.

Having a split dump is good for top end power. You will notice how much freeer the engine feels above 6k rpm.

choyda Veteran

choyda

Posted
  • Author
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Now, for the after sounds:

Modded - Startup

Modded - Light Revving

Modded - Close to exhaust

I'll post pics a bit later but if u can imagine a split dump pipe that joins after about 20cm then 3" mandrel bent mild steel through a hi-flow cat and into a huge cannon muffler (I didnt think it would be this big but it is).

I may change the cannon to something less conspicuous.

zymotic Experienced

zymotic

Posted
Posted

Splits make it sound angry don't they... where is Exotic Exhaust located and how much did u pay (pm if you wish). I'm hunting for a zorst in Brisbane also for GTT. Tossing between $2k for a CES system or other options. How droney is it in cabin if u get up it (h8 droney!)?

choyda Veteran

choyda

Posted
  • Author
Posted
Splits make it sound angry don't they... where is Exotic Exhaust located and how much did u pay (pm if you wish). I'm hunting for a zorst in Brisbane also for GTT. Tossing between $2k for a CES system or other options. How droney is it in cabin if u get up it (h8 droney!)?

Exotic Exhaust is located in Sumner Park (Jijaws St). The service is pretty good and I spent $1250 all up. It took them about 5 hours but they were busy and I got squeezed in. If u want to meet up at some stage to have a listen, PM me or u can pretty much get me on MSN ([email protected]).

The car is quite loud/drowney in the cabin but apparently I'll get used to it (haven't driven it around much). There is a quiet spot between about 1800 and 2200rpm and then it gets loud and it goes quiet again after about 4500rpm. The performance difference is noticable though. At some stage tomorrow, I'll get pics of the dump and piping (u can see the top part in the engine bay).

zymotic Experienced

zymotic

Posted
Posted

Apparently the cannons are louder than say a SS twin tip, so that might help reduce the drone. Another option I'm thinking about is BATMBLS splits and hi flow cat with a Fujitsubo or similar cat back (bottom one in pic) can't see if thats got twin tips and not sure how droney vs restrictive that would be. Would work out about $1400 + labour, unless I can find a cheaper GQ Jap cat back.ex011.jpg

choyda Veteran

choyda

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Well I should now mention that I got defected at the BP Yatala Super Servo on the way to BWCP. 98dB - the limit is 90dB. The car has a cat and a cannon so I guess I will need a resonator/muffler to quieten it down. Good news was that I didn't get a fine because the officer knew it was a brand new exhaust.

I also have to secure my air filter.

choyda Veteran

choyda

Posted
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Yeah, thanks guys. The sound is awesome but I have been told by a few people that a silencer may not do the 8 or 9 decibels. In terms of the testing equipment, they use a microphone and a tripod and get u to rev. At idle, I was at 88dB and at 75% load (where they test it), it was 98dB. The testing method they show at this site is what they did: http://www.airpowersystems.com.au/us_spec/...swrx-hoe-r2.htm

Myth33 Enthusiast

Myth33

Posted
Posted

I noticed in that testing procedure that there needs to be at least 3 meters of open space between any side (front, rear and both sides) of the vehicle and other objects. This is probably so that the sound meter doesnt pick up reverbing noise.

If a car (including the cops) is parked next to your car in the spot where they test your vehicle, take a photo of the test being conducted with a date stamp on the camera and your license plate as well and dispute the defect.

Makes me wonder how many times they actually follow the procedure correctly.....?

For example the standard for testing exhaust noise states: "Engine RPM must be held steady at 75% of rated peak horsepower RPM"

Wonder how many cops know the actual 'rated peak power rpm' of all the different import RB engine versions? Or do they just look at your redline and tell you to take it to 75% of that. I'm sure thats how they would actually do it.

An R34 GTT for example makes Max Power of 206kw @ 6,400 rpm 75% of which would mean that they should of tested it at no more than 4,800 rpm

If they don't know exactly when peak power is made they are likely to base it off the redline which is closer to 6,600-6,700 rpm . So at 75% thay might be ask you to rev it too just over 5,000 rpm.

Its all a matter of inches when your talking after market exhausts and db, just something everyone might want to remind the cops of when they are db testing your vehicle!

choyda Veteran

choyda

Posted
  • Author
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Yeah they did have the cop car parked along the left side but in front of the car. The walls of the carpark though may have contributed to resonance. The test area was the caravan section of BP Yatala and the closest wall was about 4m away. The 75% load was 4800rpm. The officer had a chart of engines and RPM's but based it on the R33 RB25DET so I guess mine should have been different. Tomorrow the muffler and resonator etc get installed and tested. I hope it doesn't drain too much of the performance...

I will post after after sounds....

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