Jump to content
SAU Community

Recommended Posts

I am currently using a 3.5 inch exhaust from the cat back on my r33 s2, it hangs down to low with clearance of only 75mm, Is this exhaust to big for the rb25det. What size would be better suited to the car and what type of performance and sound levels are being acheived.

Mod so far are

FMIC, Microtech lt12, Turbosmart Eboost 2, Split fire coils.

Any help with this would be very helpfull.

Link to comment
https://www.sau.com.au/forums/topic/224564-best-size-exhaust/
Share on other sites

is it just a custom job exhaust?

or is it actually a brand design exhaust?

maybe check the rubber linkage that hold the exhaust in-place..

happen'd to my old car..one fell-out and i was movin all-around..lol

but didnt drop low at all from wat i can remba....

also mayb take a photo???

Hey Newboost,

The 3.5inch cat back exhaust your using isnt to big for the stock Rb25 turbo. Although if its riding to low and your looking for a change, a 3inch system from the turbo back would be the best option. Would give you a good performance gain and would also sound nice. If you dont mind it riding low and just looking for performance than the 3.5inch cat back will be fine. You will just need to get a 3inch Dump/Front pipe and a 3inch Hi-Flow cat.

:ninja:

I do have a 3 " dump pipe and hi flow cat, It is a brand system not a custom job. (Xforce exhaust system) Has anyone got 3 " system from Liverpool Exhuast in sydney. The sales guy told me that if i was to use his setup i shold get an extra 15 to 25 rwkw or he just trying for the extra sale.

If only you were in WA i would swap my 3 inch x force for the 3.5, its fairly new too.

That liverpool dude is full of it

Out of interest off topic how do you like your eboost 2 i too have one. I have read great things about them but when i took it to xspeed they were "oh you got one of those and chuckled"

Edited by Pattygtst

on the subject of the eboost2 i have also got mixed answers when it comes to getting it tuned correctly. I have not yet found any one that seems to know how to set it up correctly. everyone who has has had a go has managed to set up only half and i am still looking for a good tuner in the Melbourne area. I have gone to Pro Maz for tuning and found to have some problems in the way they setup the overboost settings and it is not holding peak boost levels.

well just ring around and ask if they are familar with the eboost 2, maybe even talk to turbosmart apparently they are very helpful

Xspeed apparently got a guy from turbosmart flown over to there workshop to show them how to do it. They also said that they tested it compared to the blitz profec spec2 and that apparently held boost better. I dont know but mine holds very well,

They say it all comes down to how good the solenoid is. HKS apparently have the best one.

But if you check out alot of car mags there wild about the eboost 2

I guess it just comes down to the tuner

  • 3 years later...

3.5 inch is only good when your running a lot of power like 300 kw isnt it?

Is this true? Is there a direct relationship between power output and exhaust size, in turbo applications?

Car's getting a high-flow cat and back including piping tomorrow, excluding the rear muffler which is already 3", should I go to 3" for the piping, or keep it 2.5", keeping in mind it's still using a stock dump and front pipes.

Car is a 25DE+T with R34 turbo, doubt i'll be running 9psi any time soon, and given that a standard GTST exhaust can flow that, should a custom 2.5" one do it also?

What is the standard piping size of a GTST front-pipe? As I can't measure right now...

get a 3 inch for sure bud..

standard nissan cats are pretty good youd be better to invest 200$ in one of these

http://justjap.com/store/product.php?productid=17317

they make a shitload of difference to the feel of the car, you wont regret :thumbsup:

Cheers for the reply.

I was keen on 2.5" to keep noise down, but with a *very* long term power goal of around ~220rwkw, didn't know which way to go. Given i'm still running the N/A cat, centre pipe and centre muffler I think even 2.5" would be an improvement.

What size is the standard dumo/front pipes on a 33 GTST? (what's currently on the car) As I don't see much point going bigger?

To the OP - if you have 3.5in on now keep it - yes 3in would do for now but no point in changing it just secure it a bit better if its hanging down. You may be glad of it later if your power ambitions grow like most people's do!

You can get a 3" exhaust legal with two large as possible mufflers and a CAT.

So there is no issue there if it is built right.

Some off-shelf jap exhausts that are quiet - are not a "true" 3" either. They have restrictors inside them to get them quiet. Some brands have made under 90dB either way, but you can certainly do it without the restriction.

You can get a 3" exhaust legal with two large as possible mufflers and a CAT.

So there is no issue there if it is built right.

Some off-shelf jap exhausts that are quiet - are not a "true" 3" either. They have restrictors inside them to get them quiet. Some brands have made under 90dB either way, but you can certainly do it without the restriction.

dont even need two large mufflers to make 3" legal. mines got a hot dog muffler and a large oval muffler and its legal (as tested by the RTA).

What dB @ what RPM?

I always talk in Vic laws - 90dB @ 4700rpm for a RB25 (from around 40cm away)

tad over 3500rpm 89dB @ a little over 3500rpm and 50cm (45 degrees from exhaust tip). if i was to take it to 4700 im not sure if it would pass but its only a 16x11x6 muffler and you can fit an 18x12x8 in the back comfortably.

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

    • H2 (for cars) will never happen. It's not reasonable for any number of reasons. It's also not reasonable for almost all of the industrial uses that the fanbois say that it will be used for, again for a large number of reasons. There are some cases where it will be good. But, even those will be massively hampered by the economics. The only way that H2 can be economic is if we somehow manage to get from where we are to the other side of the economic-valley-of-death in which no-one can operate. You need there to be sufficient renewable generated electricity to be available so that it is effectively free. Once you are there, you can do whatever the hell you want and hang the efficiency. But until you get there, the ever diminishing value of electricity makes it harder and harder to encourage businesses to build the new generation capacity, and they will simply stop investing in generation projects. (I kinda think there needs to be just government money spent on building the required capacity in a non-commercial way, similar to how the first fossil fueled grids were built, as national-government owned utilities. And probably some nuclear in there to start. But this all should have started 10-15 years ago to avoid the chasm of death that we face right now). Synth fuels will be much more likely, but will only occur is there is at least some renewable H2 production, because you need H2 to do it. And you need stacks of free (or at least extraordinarily cheap) energy because assembling molecules back into fuels is exactly the opposite process to burning the fuel, and the reason we burn fuels is because there is so much energy squeezed into each molecule. So you're somewhat subject to the same economic valley of death problem as above anyway. That is unless people are willing to pay the current equivalent of $5 or $6 per litre of petrol-ish liquid fuels. Can you imagine it? The squealing at $2 now is bad enough.
    • This is so cool. Get a dashcam that records audio and hopefully you'll catch it.  Maybe there's a brand or some kind of markings on the back ? Are the pics hand drawn? I love it so much.
    • Hahaha yep, point(s) taken. I just like seeing different things and an EV in an R32 is pretty different. I'm not on the EV band wagon, I'm waiting for synthetic fuels or hydrogen personally. 
    • I mean it's probably likely that people overestimate their skills in dialling in a setup and noticing the changes. I had SK shocks and springs, and added heavier springs and got them revalved by Sydney Shocks to suit based upon what I told them I wanted the car to handle like. I got back a completely different feeling set of shocks, which probably (?) feel great on track but holy hell are they rough on tram tracks and the like. The shock dyno actually looks pretty similar to Shockworks (from what I can surmise from a screenshot of a youtube video - and my dyno printout...) Truth be told I doubt I'd be any faster or slower with either setup, or camber/castor combination. I also had whiteline eccentric castor bushes up front of my R34. I removed them and put in poly non-adjustable ones to soothe my OCD (nobody ever set the castor the same side to side, and it'd be near impossible to do) and be happy the wheel is centered in the well now for clearance reasons. Yes I wanted it to move 1mm 'back' :p I've effectively set my castor back to stock, negating all the benefits of that which is supposedly massive. I've probably also altered toe and camber in a negative (detrimental) way. I can't tell any difference steering the car.
×
×
  • Create New...