Gt3076R Antics , Better Late Than Never .

[Dose Pipe Sutututu]

^ chop up a XR6 turbo cat to fit..

[discopotato03]

Yep they are 3" through on the later BF Turbos and people say their std exhaust is god for around 320 Kw . The twin pipes and mufflers looks like an interesting idea too .

Not conformed yet by my exhaust may be a HKS Drager with oval mufflers mid and rear , will confirm later . Anyone else have this kind of thing with the two internal pipes in the rear oval ?

A .

[Dale FZ1]

At the likely power ceiling of this turbo you won't have any appreciable gains by taking the system to 3.5 inch.

Identifiable downsides - and I have the experience here - include:

packaging difficulties. Physical room available means it is just harder (not impossible) to get the bends to flow nicely and maintain clearance to mechanical bits. Also depending on your ride height (affected by wheel/tyre packaging and any suspension mods) you may have ground clearance issues if running a second muffler between the cat and rear suspension cradle

silencing difficulties. because of the issues with making bigger bends fit, you are robbed of some length from the muffler. So you end up with a shorter muffler with less packing. Also the sheer internal volume of the pipe work IMO means pressure waves are belting down the pipe with less interference and able to make their way out the tailpipe with less noise suppressed than a 3".

cost. Price up the relative differences between bend sections in 3 vs 3.5 inch. It is significant when building a system.

weight.

I have no doubt it is possible to get a good streetable result with 3.5 inch, but it would take some work and yours might be a guinea pig. My 3.5 system has a very loud idle but in every other respect comparable to the previous 3" for the ability to suppress drone at motorway cruise, and high rpm noise. I just don't feel that the airflow required for 300ish kW necessitates the bigger pipework.

I'd suggest drop the existing system off, consider sticking in a quality aftermarket cat as others have successfully used, and physically inspect your mid and back muffler to ensure neither has been sneakily necked back to 2.5".

[34GeeTeeTee]

I have been using a 3" system the whole way through my build and it is dead quiet! With the GT and the HTA it still works fine!

[Joshbigt62r]

What brand 3" exhaust is it matt?

[Piggaz]

I have been using a 3" system the whole way through my build and it is dead quiet! With the GT and the HTA it still works fine!

But half of it is flying out of the vent to atmo gate?

[Dose Pipe Sutututu]

But half of it is flying out of the vent to atmo gate?

only on boost man, get it right lol

[Piggaz]

^^ I know that ya bonehead! lol

[Dose Pipe Sutututu]

^^ I know that ya bonehead! lol

So what's the problem? Haha.. Don't be jelly you don't have a screamer like us cool kids lol

[Piggaz]

So what's the problem? Haha.. Don't be jelly you don't have a screamer like us cool kids lol

*rolls eyes* lol

[discopotato03]

I caught up with the exhaust people late this afternoon and there opinions are .

Existing cat is RS and needs to be replaced by something better , they like 100 cel metal core ones .

They asked the power goal and say 300 tread wasps is around the 3-3.5" cusp . 3 quieter but 300+ grey area . They use 3.5 on XR6s which is logical on a 4L IMO .

Dale my exhaust already has two oval mufflers and clearance isn't an issue . I roll on 245 45 17s and no it's not low for a Skyline .

Anyway the plan is to get it on the hoist and have a good look at what's there . The cats going and I finally found someone who agrees that those spring loaded "cup joints" are a good idea and keeps them in stock . The rally people who used to do my exhaust work said big exhausts act as great engine steady bars meaning they transmit a lot of noise and vibration into the system and often they ring like a bloody bell . Naturally this is transmitted into the cabin space pissing the ocupants off no end .

If this cup joint can go behind the gearbox hanger it will unload the exhaust and very likely give the manifold studs an easier time . The plan is to have 3.5" to the cat and probably taper down to 3 behind it for for the mid and rear mufflers . The rear to have as much can area as possible .

Anyway joint and cat first and suss out the rest .

A .

[34GeeTeeTee]

What brand 3" exhaust is it matt?

Apexi... Super Megaphone II from memory...

But half of it is flying out of the vent to atmo gate?

Mebe

But even plumbed back it hauls ass! Hard to know if there is any difference due to traction issues i guess....

[GTScotT]

Apexi... Super Megaphone II from memory...

I had one of these...

It was f**king amazing... I'd never heard an SR like that...

I took it off the car to trial a straight pipe and see if there were any gains... Left the Supermegaphone at my dads... Came back a few weeks later and he had taken an angle grinder to it because it was 'taking too much space'.

And that was the day I lost my shit.

However, a few weeks later I wen't back to visit again and found it on the back of HIS car................................ NOTHING SUS. Photo attached.

TL:DR Apexi Super megaphone exhausts are amazeballs, even on a 70s Porsche.

Edited March 11, 2014 by GTScotT

[34GeeTeeTee]

I had one of these...

It was f**king amazing... I'd never heard an SR like that...

I took it off the car to trial a straight pipe and see if there were any gains... Left the Supermegaphone at my dads... Came back a few weeks later and he had taken an angle grinder to it because it was 'taking too much space'.

And that was the day I lost my shit.

However, a few weeks later I wen't back to visit again and found it on the back of HIS car................................ NOTHING SUS. Photo attached.

774839_10151233635634211_1320273578_o.jpg

TL:DR Apexi Super megaphone exhausts are amazeballs, even on a 70s Porsche.

Was yours super quiet? Even with all the mods it still remains silent and i love it

Can drive around town and nobody would know it was modified... Until i get in a carpark and the diff starts

[GTScotT]

Was yours super quiet? Even with all the mods it still remains silent and i love it

Can drive around town and nobody would know it was modified... Until i get in a carpark and the diff starts

Truth be told it made lots of noise... But it was a very different noise to what you would expect... Had zero drone and was very breathy. No real 'bass' to its tone, and certainly wasn't a tractor in any way.

It was fairly silent. f**king old wog father and his angle grinder -_-

[34GeeTeeTee]

Truth be told it made lots of noise... But it was a very different noise to what you would expect... Had zero drone and was very breathy. No real 'bass' to its tone, and certainly wasn't a tractor in any way.

It was fairly silent. f**king old wog father and his angle grinder -_-

Yeah the RB sounds very different compared to others i have heard!

Lolz @ old wog!

[skylinecouple]

I don't think there is a difference between 2.5ltr and 4.0ltr. it is about air. Remember the engine is an air pump, and a 4ltr making 270kws vs a 2.5ltr making 270kws flows similar air. It's called boost. Going back a while I was spending an hour a day looking at every exhaust shop from around the world and discovered at 270kws that was when you could or should step up to 3.5" but only if you were pretty sure you were going to make more power. So if 300kws is what your looking at then maybe 3.5 is where it's at.

Mostly the dump of course but having felt the heat coming out the back of my exhaust on the dyno I have always thought the theory of cooling gases from engine to tailpipe just a little flawed. Ok, so the tailpipe isn't glowing red, but it's still bloody hot. And hot gases are expanded gases. So for fu*# sake will somebody do a back to back 3" vs 3.5" ? Don't change anything else, just the exhaust.

[discopotato03]

Gary I think the cooling theory holds water but possibly more of an NA than forced principle . The exhaust people I speak to say that from dyno experience 3.5 is where it's at power wise approaching 300 RWKW . This is not to say that 300+ can't be done with 3" though no two built exhausts will be exactly the same .

I have to compromise because my 33 is a daily and loud exhausts isn't an option . I have considered and did ask about staying 3.5 through the cat and first muffler and stepping down for the rear one , half way and easy to change if that was quiet . Realistically 3" after the cat is probably acceptable 90% of the time for a car that isn't raced on or off public roads .

Interested in other opinions , cheers A .

[34GeeTeeTee]

Gary I think the cooling theory holds water but possibly more of an NA than forced principle . The exhaust people I speak to say that from dyno experience 3.5 is where it's at power wise approaching 300 RWKW . This is not to say that 300+ can't be done with 3" though no two built exhausts will be exactly the same .

I have to compromise because my 33 is a daily and loud exhausts isn't an option . I have considered and did ask about staying 3.5 through the cat and first muffler and stepping down for the rear one , half way and easy to change if that was quiet . Realistically 3" after the cat is probably acceptable 90% of the time for a car that isn't raced on or off public roads .

Interested in other opinions , cheers A .

Kurtis made the same sort of power as me on a 3" with his gate plumbed back... It can be done so just do it lol

[GTScotT]

I think this is the first thread ever where we have contested the size requirement of 300kw... It has ALWAYS been 3" so I am not sure why it has suddenly changed.