Jump to content
SAU Community

Recommended Posts

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 .

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".

  • Like 1

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?

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 .

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 :ph34r:

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

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.

post-43588-0-89317000-1394576690_thumb.jpg

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

Edited by GTScotT
  • Like 2

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.

attachicon.gif774839_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 :yes:

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

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

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

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 -_-

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!

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.

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 .

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

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.

  • Like 1

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

    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
    • But first....while I was there, I also swapped across the centre console box for the other style where the AV inputs don't intrude into the (very limited !) space.  Part# was 96926-4GA0A, 284H3-4GA0B, 284H3-4GA0A. (I've already swapped the top 12v socket for a USB bulkhead in this pic, it fit the hole without modification:) Comparison of the 2: Basically to do the console you need to remove the DS and PS side console trim (they slide up and back, held in by clips only) Then remove the back half of the console top trim with the cupholders, pops up, all clips again but be careful at the front as it is pretty flimsy. Then slide the shifter boot down, remove the spring clip, loose it forever somewhere in the car the pull the shift knob off. Remove the tiny plastic piece on DS near "P" and use something thin and long (most screwdrivers won't fit) to push down the interlock and put the shifter down in D for space. There is one screw at the front, then the shifter surround and ashtray lift up. There are 3 or 4 plugs underneath and it is off. Next is the rear cover of the centre console; you need to open the console lid, pop off the trim covering the lid hinge and undo the 2rd screw from the driver's side (the rest all need to come out later so you can do them all now and remove the lid) Then the rear cover unclips (6 clips), start at the top with a trim tool pulling backwards. Once it is off there are 2 screws facing rearwards to remove (need a short phillips for these) and you are done with the rear of the console. There are 4 plugs at the A/V box to unclip Then there are 2 screws at the front of the console, and 2 clips (pull up and back) and the console will come out.
×
×
  • Create New...