another 3" exhaust Q

[DieselTuner]

You will definitely notice a gain just doing a 2.5" cat back system, it will lower egt's and give you a bit more torque down low and through the midrange.

Removing the baffled muffler and using a straight through turbo muffler will do 95% of the work.

But, its literally no more expensive to just replace the full cat back with a bolt on system rather than pay someone to modify the stock system. And it means if anything is ever damaged or broken in the future it can be replaced with an off the shelf part, no modifications required. If someone that buys the car doesnt like it or wants it stock give them the system you took off.

 

[boostin_7]

Excellent, thanks again

 

[boostin_7]

So does fitting a larger dump & removing the cat give much more extra over jst a cat back?

 

[DieselTuner]

No.

Traditionally the dump pipe is the most critical part of an exhaust system on a turbo car.

Getting the wastegate and turbine gasses mixed and heading in the right direction is what it needed to do. Making the pipe size significantly larger than required really helped with this mixing.
On the flip side a poorly designed (like the twin or divorced dump pipe) or undersized dump pipe would cause turbulence and restriction in this part of the system

Fast forward to current VNT turbo's.
They run tiny exhaust wheels, most no bigger than a 50c piece. And massive exhaust housings! Which of course can be varied or shrunk when we are trying to spool the turbo up.

There is no more mixing of different velocity gases required. The job of the dump pipe has just been reduced to nothing more than directing gases in the right direction.

The hotter the gas is the faster it flows. So you can run a relatively small dump pipe where the gas is still up near 600deg or more, and expand it as the gas cools.

So Provide the system isnt grossly undersized in the dump pipe area, it will work just as well as a very large pipe.

 

[boostin_7]

Brilliant info mate.

 

[Kochie]

Will a larger system, say 3", increase the turbo whistle sound? One of my mates has a patrol that has exhaust and chip and the turbo whistle is really loud. Would that be from exhaust or more so the chip? Im happy with the stock power so just looking at doin the exhaust for now with no chip (probably end up chipping it later) was just wondering if I will get the same sound out of my turbo from just the exhaust?
Cheers

 

[miner-matt]

Will a larger system, say 3", increase the turbo whistle sound? One of my mates has a patrol that has exhaust and chip and the turbo whistle is really loud. Would that be from exhaust or more so the chip? Im happy with the stock power so just looking at doin the exhaust for now with no chip (probably end up chipping it later) was just wondering if I will get the same sound out of my turbo from just the exhaust?
Cheers

I had a GU wagon 2.8, threw a 3in system at it and the turbo whistle was loud and I had no chip.... Loved that whistle shame i cant get similar out of my nav

 

[gunning1987]

I had a GU wagon 2.8, threw a 3in system at it and the turbo whistle was loud and I had no chip.... Loved that whistle shame i cant get similar out of my nav

You can i have a good whistle on mine and i love it!!

 

[miner-matt]

You can i have a good whistle on mine and i love it!!

How did you get it may i ask? I have fitted a beaudesert exhaust which gave me a few benefits but hearing the whistle wasnt one of them...

 

[gunning1987]

How did you get it may i ask? I have fitted a beaudesert exhaust which gave me a few benefits but hearing the whistle wasnt one of them...

Remove the muffler and fit straight through pipe.

 

[Kingy89]

You basically want the very least amount of backpressure after the turbo.
However, if you go to a very large pipe the gas starts to expand to fill it and looses velocity, but its all honestly very marginal gains and losses we are talking about.


I have tested so many systems on the D40's. And at normal power levels there is no difference between 2.5" Cat back or a full 3" Turbo back with high flow cat. Not even 2hp anywhere in the rev range.
No difference in egt, backpressure or anything else.

However if you were running up near 30psi of boost, a rail pressure + injector extension chip, larger intercooler etc... Basically, if you were pushing it up to 140-150kw atw Then 2.75" or 3" would START to become beneficial.

Although, I dont see the point of going up only .25" if you were stepping up to anything you may as well go 3" so you again have a bit of headroom for flow.

How far can you safely push the boost up on a stock turbo d40. also have they got a turbo upgrade aval. i was under the impression this was not aval due to the vvarible vane throwing codes etc???

 

[miner-matt]

Remove the muffler and fit straight through pipe.

cheers

 

[Kochie]

Thanks for your help lads. Think ill be doing a 3" straight thru turbo back system to try and get some sick whistles out of it aswel as leave the window open for furthur upgrades later on
Cheers

 

[Orrsom]

I have a 3' stainless Taipan vortex system with a Steinbauer chip and snorkel. all together it gave me around 21% increase in power. pretty happy with that.

 

[d40ryan]

How far can you safely push the boost up on a stock turbo d40. also have they got a turbo upgrade aval. i was under the impression this was not aval due to the vvarible vane throwing codes etc???

mine runs 30 psi but i am now on the second and its not cheap. also you can do whatever you want you just have to have the money

 

[Kingy89]

mine runs 30 psi but i am now on the second and its not cheap. also you can do whatever you want you just have to have the money

Wait a min i was told that you can not run anymore the what it is running stock becasue they jump into limp mod.

What do you need to do to push that sort of boost. Just a boost controller or have you go to go through the whole dyno tuning etc and where is the best place for that i just want to run about 25 psi

not much more then factory.

 

[camo.b]

Boost controller and a boost guage.tweak it ip to 25 and roll!

 

[camo.b]

I'm near 30psi with a chip...goes very well.

 

[boostin_7]

whats standard boost? Ive got a GFB atmospheric boost tee left over from an old car I might chuck in...

 

[camo.b]

Think its 18 psi...dieseltuner said he likes the gfb one.go for it I say