Jump to content
SAU Community

3.5 Inch To Big?

ClutchBurndout-:(
 Share

Recommended Posts

ClutchBurndout-:( Grand Master

ClutchBurndout-:(

Posted
Posted

hey all, this is more a "just curious" topic, but i purchased a car (havnt picked it up yet) and the car has a 3.5 inch zorst with a stock turbo, now in the past ive had a 3 inch zorst on the same system and found it enough, but will 3.5 inch be worse for the performance of the car? to me it seems like there wouldnt be enough back pressure.

Anyway, i guess the MAIN question is, how much of a drop in perfomance will there be with this exhaust? should i invest in a 3inch?

stock PSI to BTW

cheers

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/
Share on other sites
ClutchBurndout-:( Grand Master

ClutchBurndout-:(

Posted
  • Author
Posted
It will not hinder performance.

EPA issues however are most likely.

sound or pollution?

An exhaust CAN'T be 'to big' UNLESS you are going to give the exhaust 'to Big Al, your mate'.

Otherwise it is 'too big'.

But in this case, it isn't.

:P

i dont get it

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306028
Share on other sites
gwilkinson34 Collaborator

gwilkinson34

Posted
Posted
sound or pollution?

i dont get it

Lol. 'to' and 'too' - two (hehe) different words.

The problem will be with volume, but I wouldn't worry about it (unless you get defected).

The size shouldn't make any difference to emissions as long as there is still a cat.

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306048
Share on other sites
ClutchBurndout-:( Grand Master

ClutchBurndout-:(

Posted
  • Author
Posted
Lol. 'to' and 'too' - two (hehe) different words.

The problem will be with volume, but I wouldn't worry about it (unless you get defected).

The size shouldn't make any difference to emissions as long as there is still a cat.

no i don want to take the cat out, srsly, i dont want the extra 500rwkw from taking the cat out, its just to fast for me, so ill leave it in.

i was under the impression that you need some sort of back pressure, but iono

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306058
Share on other sites
gwilkinson34 Collaborator

gwilkinson34

Posted
Posted
no i don want to take the cat out, srsly, i dont want the extra 500rwkw from taking the cat out, its just to fast for me, so ill leave it in.

i was under the impression that you need some sort of back pressure, but iono

I believe the extra 500rwkw will make it too fast for you.

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306088
Share on other sites
ClutchBurndout-:( Grand Master

ClutchBurndout-:(

Posted
  • Author
Posted
turbo engines are rather different to natro engines when it comes to exhaust requirements. as has been said, you won't notice any difference between a 3" and 3.5" system. if it was on a NA car, then it would be a totally different story

ok, good thanks! :P

i dont realy care about the size, i just didnt want it to be any worse than a 3 inch, which i beleive is optimal for a stock turbo.

I believe the extra 500rwkw will make it too fast for you.

is that all you picked up? lol what about - don, srsly or iono, but its good to see u picked up a missing "o"

cheers mate :angry:

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306102
Share on other sites
gwilkinson34 Collaborator

gwilkinson34

Posted
Posted

As far as I'm concerned any of those 'made up' internet slang words mean you are speaking another language.

But mix up your 'to, too, two' or 'you're, your' etc while attempting English and it's just plain slack. :P

But srsly, your exhaust is fine.

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306173
Share on other sites
ClutchBurndout-:( Grand Master

ClutchBurndout-:(

Posted
  • Author
Posted
As far as I'm concerned any of those 'made up' internet slang words mean you are speaking another language.

But mix up your 'to, too, two' or 'you're, your' etc while attempting English and it's just plain slack. :P

But srsly, your exhaust is fine.

hehe ok cheers mate

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306181
Share on other sites
slo_sprint Apprentice

slo_sprint

Posted
Posted

It won't decrease performance, on engines with forced induction the less exhaust restriction the better.

My 33 had a 3.5" system with a stock turbo and very few mods and it was pretty damn loud (didn't have a cat or any mufflers bar the cannon though), did sound mint but.

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5306751
Share on other sites
discopotato03 Grand Master

discopotato03

Posted
Posted

Provided you have control of the fueling and timing it shouldn't be a problem , noise and cops aside .

The theory is that the best exhaust is no exhaust behind a turbocharger which obviously isn't going to cut it in a road car .

The turbo rally people like to start out big behind the turbo and step down in stages on the way to the back . What this is said to do is maintain gas speed in the exhaust system as the gas cools and contracts so to speak .

Its a way of having a large volume behind the systems chief restriction , all gasses are channelled and accelerated into the turbine housing , so the red hot gasses have room to expand into . The way to drive the turbine is to have hot gas at speed on one side and a large volume to spread out into on the other side .

As the gas cools it wants to slow down if the exhaust tract is the same all the way to the back , if it slows down too much you can have reversion issues if say the turbo/exhaust manifold/ports/valves/cams are sized to make high rev grunt .

So , the way to keep it moving is to step the tube size down in stages so that the gasses maintain some momentum and velocity .

My old dinosaur Subaru RX Turbo (1.8L 2 valve tiny port flat four GT2554R turbo) has a 3" tube from the turbo to the back of the gearbox and 2 1/2 from there . Its surprisingly quiet but both mufflers are in the 2 1/2 section behind the 3" cat .

It still has its AM radio tech computer and suffers no reversion crap/no pops spits OR drones anywhere .

I suggest that if you have to do something to reduce noise start at the back , its the cheapest easiest way that gives the least restriction in an exhaust system . Car manufacturers having been doing precisely this for some years now .

A .

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5307360
Share on other sites
ClutchBurndout-:( Grand Master

ClutchBurndout-:(

Posted
  • Author
Posted
Provided you have control of the fueling and timing it shouldn't be a problem , noise and cops aside .

The theory is that the best exhaust is no exhaust behind a turbocharger which obviously isn't going to cut it in a road car .

The turbo rally people like to start out big behind the turbo and step down in stages on the way to the back . What this is said to do is maintain gas speed in the exhaust system as the gas cools and contracts so to speak .

Its a way of having a large volume behind the systems chief restriction , all gasses are channelled and accelerated into the turbine housing , so the red hot gasses have room to expand into . The way to drive the turbine is to have hot gas at speed on one side and a large volume to spread out into on the other side .

As the gas cools it wants to slow down if the exhaust tract is the same all the way to the back , if it slows down too much you can have reversion issues if say the turbo/exhaust manifold/ports/valves/cams are sized to make high rev grunt .

So , the way to keep it moving is to step the tube size down in stages so that the gasses maintain some momentum and velocity .

My old dinosaur Subaru RX Turbo (1.8L 2 valve tiny port flat four GT2554R turbo) has a 3" tube from the turbo to the back of the gearbox and 2 1/2 from there . Its surprisingly quiet but both mufflers are in the 2 1/2 section behind the 3" cat .

It still has its AM radio tech computer and suffers no reversion crap/no pops spits OR drones anywhere .

I suggest that if you have to do something to reduce noise start at the back , its the cheapest easiest way that gives the least restriction in an exhaust system . Car manufacturers having been doing precisely this for some years now .

A .

thanks for the info, very helpful, so with the 3.5 system in there with stock dump and front pipe, its not helping it i assume haha, but i will invest in a 3 inch bellmouth for the dump/front.

i dont have an issue with sound at all, its quite quiet actualy...

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5307384
Share on other sites
mad082 Grand Master

mad082

Posted
Posted
so ive heard

What im wondering will a 3 inch dump/front pipe into 2 3/4 catback be aiight..is there any real point buying a whole system for 1/4 of an inch?

Or will i be captain sloooow.........

the only place you may lose some power is high up in the revs. general driving around and even just reving up to around 5000rpm probably won't make a scrap of difference. anything above that i think you would have to put it on a dyno to see the difference in power. don't think you'd notice the power when driving it. if you were aiming for 250kw+ then it might be worth going 3" though.

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5307439
Share on other sites
75coupe Grand Master

75coupe

Posted
Posted

so if you were after more responsive midrange power the 3.5" exhaust is too large, is that what people are saying?

I was told by a tuner that a 2.5" custom made exhaust would be better than my 3.5" hks, this is what I was told when I told him I wanted to get a tune done for a HKS2835 with supporting mods...

I did say I was after good midrange response, and that I was not interested in ultimate peak power.

I didnt know wheather to trust him or not?

this is on a 33gtst

Link to comment
https://www.sau.com.au/forums/topic/325866-35-inch-to-big/#findComment-5308677
Share on other sites

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • alburger87
      HY51 Fuga Hybrid

      By alburger87 · Posted

      Thanks! Will get it looked at before winter 🥶 other than that she's a mint ride love it aye 
    • joshuaho96
      How much roughly to convert stock r32gtr to single high mount turbo + ecu and tune

      By joshuaho96 · Posted

      FWIW a lot of the local owners that do a big build tend to have cars that are perpetually broken. 
    • Watermouse
      R34 GTT Battery Relocation To Trunk

      By Watermouse · Posted

      I just got this system but haven’t installed yet I got a Moroso sealed box (defect reasons) which will be set up same as their pic The quality is high grade, the correspondence I had with the owner (former head designer for Rockford Fosgate) was unbelievable, guiding me with what I needed. Even told me not to buy some things as it could be sorted in a different way at his loss. Just a bit of a bite with the exchange rate and don’t purchase gear in 1 hit that goes over $1,000 au, lol I forgot!  
    • elir32
      Rv37 400r questions

      By elir32 · Posted

      Thanks mate for that reply. Very helpful.    it’s a 2022 400R so would most likely lose those features as you say.     I did a quick compare of a rv37 nav and heading for sale in Japan to q50 model. I’ll pop pics below. Seems  Japan spec head into top, nav unit second below it   below pic Q50 aud delivered     differences seem to be Aus delivered has a different plug top left hand side of head unit- not sure what and where it goes.   and nav unit Japanese tv37 had an extra plug put    Again I’m really not sure what each of these differences mean!       the actual plugs on a v37 and q50 screens look identical on both screens… pics below for comparing. (One screen was is a us delivered one) but should be same gps signals etc as Australia.    If it were as simple as swapping a nav unit from q50 aud delivered im interested -just want to figure out what the missing plug is for before spending big $ on a second hand part for it to not work, and I guess with the head unit, if the band expander does the job (I got a 20mHz so should get the range I’m after) so should narrow my issue down to nav unit only.  I’d love to know what the extra cable on rv37 does and if I eliminate that part what it’ll do to the setup,    and also, if I can figure out what that head unit plug difference is, what does that cable do and where does it got can it be altered or re-plugged?! Excuse my ignorance what is ACP/AA, what does that stand for? (Apple car play? Android air play)? so If I swapped head units to save using a band expander, I’d likely lose those better features to have an oem Unit operational. Better to use a band expander and retain AirPlay options and newer version of head unit     provably best to band expand it, and focus on the nav unit. th isn’t  a big deal/ would be cool to have it working  from what I can tel we use a PAL Signal and Japan uses a NTSC signal  I don’t know if there’s a co better or if the screen only reads NTSC, or if it’s the tv module that needs replacing… no big deal don’t need it but more of a curiosity thing on that!   Thanks for the info re tyre sensors, helpful and great to know.  I was reading the online manual off Japan website and it seemed to make it sound more confusing than it is  I guess a rim replacement would require the sensors to be moved to a new rim to carry that option over?!     Thanks for the info regarding diagnostic mode. I appreciate your help mate. Trying to brainstorm here to find a solution to get as much gadgets as I can working! I plan to get my local Nissan tech to have a look too who used to be at an Infiniti dealer back in the day to see if any thing they have or idea can find a soliton. But hoping anyone here has gone down the same route to make life easier!!   i guess identifying the cable/plug differences and what they do would be a great way of finding out if the units are transferable    thanks again 
    • sonicii
      Rv37 400r questions

      By sonicii · Posted

      No idea about the remote start part. If the V37 nav is anything like other Nissan JDM vehicles, you can't get the factory Japanese nav working in australia, a card from a different car almost certainly won't work, those cards are usually matched to the serial number of the DCU.  You could be possibly swap out the components from a AuDM Q50 to get it working, but if this is a new model (2021+) 400R, then you will lose the newer features like ACP/AA.  That said, if you have ACP/AA, just use google maps.. I assume a band expander would be required to get the local radio stations, but don't forget the Japanese FM band is narrower than ours, so you still might not be able to receive all Australian stations. I can't see any reason the tyre pressure sensors won't work here, there is the sensor unit inside the rim and the receiver nearby in the wheel well.  I have never had to change the batteries on my 2015 Q50, so I assume they last quite a while.  A straight battery change shouldn't need them to be re-registered as they are the same unit, that should only be required if you replace a sensor with a new one.   Word of warning, if you ever go into the 'secret' diagnostics mode on the main screen, DO NOT EVER do a 'reset' in this menu, it will erase all of your model specific data in the DCU and you will need a trip to a dealer to re-program it all, which would be particularly painful being an import.  This applies to the AuDM Q50 too.
×
×
  • Create New...