Need Some Answers

Answered by reeding the in the post below LOL

On a Petrol a good size would be 2½- inch, 3 inch is most likely to big for the power you engine is putting out and you will loose the Low down grunt, a good set of tuned length Extractors will make the difference in the end.

On my 4.0 Ltr V6, I am running Twin 2¼-inch pipes out of the engine thro twin Cat’s into a single Lukey Turbo Muffler at the rear axel and into a Single 2¼-inch Tail pipe

I believe it did make a difference

It is a Petrol 4.5 litre

HI ya Turbo, did you find much improvement in H.P. and how about economy? Have both my Isuzu's booked in for mandrel bent systems later in the month. So for $900 a piece I hope I get a little more than a nice sound out the back.
Cheers Bruce

pressed the wrong button as i was saying before down low in the rev range the system is very noticeable it is quite loud up in the rev range say around 2000 to 3000 rpm it is a real deep drone obviously with the turbo whistling as well. If i was you i would be going for the 3 inch system as this will run the motor cooler than a 2.5 inch system and release the exhaust gases easier creating more power , some people remove the muffler as well all this doesis increases the noise down low and attracts the r.t.a. in queensland but it sounds very tough if your into that kind of stuff.It is important that you buy a mandrell bent exhaust this means that the exhaust is still 3 inches at the bends say to normal exhausts might be three inches on a straight run but 2 inches wide at the bend which will restrict the performance of the vehicle and make the engine run hotter .My exhaust system cost me 1100 dollars fitted but it has been the best investment of money i have made on both my turbo utes.

hi Bruce and Anne my systems have made a huge increase in power in both utes
1- 79series ute diesel cruiser standard non turbo 96 kw added turbo 121kw with standard exhaust added 3inch mandrell power increase to 141kw on turbo running a standard amount of boost.
2-78 series turbo ute standard 122kw, with 3 inch mandrell bent system power increase is now at 143kw and on both utes a better fuel consumption is noticeable but i have a lot of other mods as well hard to give exact figures money well spent.

Thanks for those answers Turbo, was told by a chap who specialises in 4.2 Nissans said the first thing you have to do to a turbo diesel to have a good exhaust system.
And being in the marine industry for some 20 odd years I can understand. A Yanmar 3.45 litrre turbo/ intercooled diesel 230hp, out of turbo 6 inches than into an 8 inch pipe to the back of the boat and that how they can get that H.P
Thanks Bruce

Haven't had my ute over the dyno guys but a quick test before and after the fitment of the mandrel bent system on the 4.2 gave a better 0-100 kph time by 16%.

It is more flexible right through the range and doesn't seem to run out of puff like the unmodded ones do in the lower gears, even being one this week. Just go wizzzzzouurr and time past to change gears. I agree with Bruce above, it is a cheap improvement. I have been getting better economy too but is it slower driving, the breathing or what. I think the breathing has a component in it. For those who have not looked in their dump pipe out of the turbo, they are about 1.7" in inside diameter = VERY restrictive. Change it. I actually have some pictures if anyone needs to see them I will have to find them again. Against 3" it is less than half the volume, just over 1/3rd actually.

Mine is from Beaudesert Exhaust Syetems and was under $800 landed at the door back before Christmas including the dump pipe.

It doesn't give any note though which was part of the question. Diesel turbos quieten down with just the turbo and no muffler but you can get sick of the drone some times I think. You can get a straight pipe if you want to absorb the rumble. Mine just hisses a bit more and the turbo release of gas is more noticible. I wus rapt in the improvement.

In helping Santa procure JohnR's 3 inch setup I asked about removing the muffler and was told yeah it sounded great. does it give more power? no

would like to get one on my GU some day
NickR

Gu, I can only presume you are refering to the Patrol engines? If you are, what a load of bollocks about the 4.2L......."if your doing a lot of heavy towing on the 4.2L then stay with the 2 and half inch you'll lose too much power if you got the 3" " It is a well known fact, FACT, that fitting a 3" mandrel bent exhaust AND the aftermarket bigger turbo dump pipe will increase horsepower and torque. Facts backed up by numerous people on here and dyno figures.

"Facts backed up by numerous people on here and dyno figures"
Can you show me dyno figures from a 4.2L towing a 2 ton trailer. SHOW ME THE FACTS
maybe the results are the same :-)
It's only what I was told by someone who has experienced both systems, and his conclusion.
I know the 3" gives more power and torque, but when towing heavy you'll need the bigger turbo to make it work.

Yeah Troll it is a 4.5 can i get a complete discription on what u did with your exhaust...

As in what brand and exactly what u did?

Well, extractors are pacemakers then the rest I don't know. The truck came with the extracktors but only had 2.5 to the first mufler and then 2 through to the back. I cut out the rear mufler and changed it to 2.5 and put a little dump pipe in the back that gives a nice little sounds. Sorry can't tell you much more than that, thats all I know