Jump to content
SAU Community

Recommended Posts

Hey all.

So I've got a completely stock r33 s2, and want to build it up as a bit of a sleeper. Really stock looking on the outside, but with a bit of a punch under the bonnet. Nothing too crazy, maybe would like to push up to 200kw over time.

The aim of the game is to have the car 100% legal, or as legal as is humanly possible. I got a Just Jap return pipe intercooler put on which uses the standard intercooler pipes and did not require the cutting of the body etc. First mod= legal. A dyno run after the installation revealed that the car has 145kw at the wheels.

The other day I chuck a high flow k&n panel filter in the standard air box. Noticibly smoother accelleration etc. Second mod= Legal.

Now it comes time for the exhaust. The car needs to be under the legal db limit.

I bought a second hand 3 inch dump pipe from the forums, ready to bolt on.

I also bought a second hand 3 inch cat back exhaust, minus the end muffler. The system is designed to bolt up to the cat and can accomodate an aftermarket muffler, and has a flange, so that the standard muffler can be bolted on as well (for when the EPA bites you in teh ass presumably. The idea is to not get to this point however). Both of these parts appear to be mild steel, not stainless.

So now, to recap, I need a 3 inch high flow cat and an end muffler to complete the system. (If anyone is selling any of these items btw, let me know)

My question is. What sort of muffler should I have put on that will flow well, yet ensure that the system falls within the legal db limit? Please also keep in mind that I would like the muffler to look as stock as possible- I guess that rules out cannons etc.

Does anyone have any suggestions? Also, does anyone have any idea how much of an increase in power this should net me? Any tips etc, let me hear them as I am relatively new to the scene and am keen to learn.

Cheers.

Link to comment
https://www.sau.com.au/forums/topic/250355-building-my-exhaust/
Share on other sites

Going 3" straight through you will be pushing it for legal db's!

Your best shot would be to talk to a good exhaust shop (some have a db meter handy), but i would recomend fitting a resinator of some sort

^^ you couldn't be more wrong. Easy to get a 3" legal. I have a 3.5" - 92dB, ended up with under 90.

And resonators do not work, so another piece of bad advice in afraid.

You need two decent sized mufflers. Simple as that.

A panel filter isn't illegal. You're using the stock airbox, that's all that matters.

So you cant use a pod filter in Australia? thats gotta suck

Australia's laws are so tight ass compared to New Zealand, I have to hand it to our 3rd world approach to things, lets me gets away with a straight through exhaust and ground clearance that turns me into a grader on any gravel road.

So you cant use a pod filter in Australia? thats gotta suck

Australia's laws are so tight ass compared to New Zealand, I have to hand it to our 3rd world approach to things, lets me gets away with a straight through exhaust and ground clearance that turns me into a grader on any gravel road.

Our exhaust law still states that it has to be under 95db :blush:

oh i see

damn aye

in regards to the exhaust but i have a 3 inch turbo back with high flow cat and rear resonator + cannon and atm mines losing boost pressure up higher in the revs so im only pulling 170 on the dyno instead of about 200 which my tuner reakons i should be seeing

so yeh I'll have to see if its the exhaust doing this but i suspect its the problem

boost is on the intake side, you cannot loose boost from an exhaust, as boost does not exist on the exhaust side

I think the poster about losing boost wasn't referring to losing it out the exhaust, more so eluding to the fact the exhaust might be a large restriction causing a drop in flow, causing a loss of boost.

As to a legal exhaust:

You will want a 3" exhaust, with a 3" high flow cat, a 5" bodied mid muffler, with some decent length, and then you will want as large of a rear muffler as you can fit.

I would also say to put the twin tips on the exhaust, and have them painted black.

I run a 5" mid, and a 7" end muffler (Cannon style) except they're not stainless, and not all shiney, and the whole exhaust, when looking at it from the back any more then 2 metres away, and it looks invisible, matched with a nice and quiet exhaust note, no issues there with the plod.

My mufflers are also 650 and 550mm long respectively. You want LENGTH AND DIAMETER for a good muffler. And yes, mine are both straight through and are custom built.

i had a 3inch exhuast on my 33 s2 with a hot dog as the centre muffler (needed the ground clearance)

and a full size muffler out the back and the db meter hit 89.5 on back off (wich is ur loudest figure)

and was given a certificate to state that the exhuast was legal in every way

just one thing to know....your front mount is not 'legal' in the true sense of the term...its only legal if you pass a free emisions test at the RTA in botany or penrith...

SORRY but my comments are for NSW...

Orig poster = Vic

Vic = the laws being discussed/applied here.

Can people from other states please refrain from posting about legalities if they do not know Victorian law?

All it does is confuse the issue for people reading at present, and then later on if they search and find this thread.

R31, It'd be handy if we actually knew the person was from vic.

Nothing in the post states location, and the only way we can assume he's in Vic, is being a Vic club member, and hey, they could have moved or anything since becoming a member.

Maybe get the board admin to show everyones state at least...

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

    • Very decent bit of kit. Definitely black it out I reckon.  
    • Because people who want that are buying euros. The people with the money to buy the aftermarket heads and blocks aren’t interested in efficiency or making -7 power, they’re making well over 1,000hp and pretty much only drive them at full throttle  best way to way make money is know your customer base and what they want and don’t spend money making things they don’t want. 
    • It's not, but it does feel like a bit of a missed opportunity regardless. For example, what if the cylinder head was redesigned to fit a GDI fuel system? It's worth like two full points of compression ratio when looking at modern GDI turbo vs PFI turbo. I'm pretty reliably surprised at how much less turbo it takes to make similar power out of a modern engine vs something like an RB26. Something with roughly the same dimensions as a -7 on an S55 is making absolutely silly power numbers compared to an RB26. I know there's a ton of power loss from things like high tension rings, high viscosity oil, clutch fan, AWD standby loss, etc but it's something like 700 whp in an F80 M3 vs 400 whp in an R33 GTR. The stock TF035HL4W turbos in an F80 M3 are really rather dinky little things and that's enough to get 400 whp at 18 psi. This just seems unwise no? I thought the general approach is if you aren't knock limited the MFB50 should be held constant through the RPM range. So more timing with RPM, but less timing with more cylinder filling. A VE-based table should accordingly inverse the VE curve of the engine.
    • I've seen tunes from big name workshops with cars making in excess of 700kW and one thing that stood out to me, is that noone is bothering with torque management. Everyone is throwing in as much timing as the motor can take for a pull. Sure that yields pretty numbers on a dyno, but it's not keeping these motors together for more than a few squirts down the straight without blowing coolant or head gaskets. If tuners, paid a bit more attention and took timing out in the mid range, managed boost a bit better, you'll probably see less motors grenading. Not to name names, or anything like that, but I've seen a tune, from a pretty wild GT-R from a big name tuner and I was but perplexed on the amount of timing jammed into it. You would have expected a quite a bit less timing at peak torque versus near the limiter, but there was literally 3 degrees of difference. Sure you want to make as much as possible throughout the RPM range, but why? At the expense of blowing motors? Anyhow I think we've gone off topic enough once again lol.
    • Because that’s not what any of them are building these heads or blocks for. It’s to hold over over 1000hp at the wheels without breaking and none of that stuff is required to make power 
×
×
  • Create New...