3" exhaust

[batesy]

Hi all i have a 07crd & i want to put a 3" exhaust on it but i have been told they are too big for the 3l can anyone shed some light for me pls. thanks.

[threedogs]

Hi mate the Beaudesert 2.75" seems to suit the ZD30 Cr diesel better than a full 3" system
Throws less errors

[Hodge]

Yup as TD said they are a tad too large. Makes the car over boost and also something to do with losing back pressure. My 2 & 3/4 gave the car plenty of more balls especially when the nads were installed afterwards .

[Hodge]

Sorry forgot to mention that's not to say others haven't done it. Many have the 3,inch with good results.

[MEGOMONSTER]

Mine is a 2011 GU8 3lt CRD and I have a 3" Taipan XP exhaust and I haven't had a problem as yet and it been on for over two years. I have found the Taipan 3" exhaust isn't as droony as other 3" exhaust which is a good thing for me.

[batesy]

A little bit pricey for me i dont understand why you get errors i thought the quicker the gases got away the better.

[batesy]

Can get a 3" with cat & stainless muffler fitted for $800 can't quite afford a beaudesert $1300+ shipped to melb, then i have to fit it.

[Ronin]

this mob have a sale going on which bring the price to $995 http://genieperformance.com.au/product/nissan-gu-patrol-3l-turbo-diesel-wagon-2000-2011-exhaust/ without the cat, cat is 195 extra.

and its a stainless steel exhaust.

[Bulbous]

A little bit pricey for me i dont understand why you get errors i thought the quicker the gases got away the better.

I saw a link somewhere that gave a really good explanation of this. If I find it then I'll post it up.

To summarize, it's all to do with the diameter of the pipe and the speed which the gas can flow. Paradoxically the smaller the pipe, then the faster the gases flow, and at low revs this is important.
The Exhaust gases pulse out and with a fast flow (narrower pipe) then it can actually create a vacuum behind the pulse that actually helps to suck the gases out of the engine. (Scavenging I think it's called).
As the pipe gets larger then the pulse slows down and the vacuum decreases which can end up reducing the power.As the revs increase then the pulse rate also increases and the scavenging effect dies down as the flow increases. The larger pipe helps here.

Thus the diameter of the pipe is a compromise between low rev torque and high rev throughput (HP) Too Big and you lose the low end torque, too small and the engine will choke at high revs. This effect happens on both Petrol and Diesel engines, but I think that the lower revving characteristics of a diesel make the loss of torque a lot more noticeable.

[Bulbous]

I found the link - this guy explains it much better than me
http://www.dsmtuners.com/forums/frequently-answered-dsm-questions/168578-exhaust-straight-scoop-backpressure.html