DIY Exhaust

[HippoNZ]

Hi guys,

I just need some understanding here on what I can do about making my own 3" exhaust.
Does the pipe need to be made out of a special metal? - I'm assuming steel is the go?
When the term "straight through exhaust" is used does that mean the muffler - (the rectangle box thing)
is cut out of the situation?
The idea I had was to get work to cut/shape some 3" pipe steel then run a flexi pipe upto the manifold until I get my turbo.
Now what type of flexi pipe could I use that would resist the temperatures involved?

Just trying to get some ideas into my head....ones that will work anyway lol

cheers
Brett

[YNOT]

I've had a go at making my own exhaust, and failed dismally, so I'm no expert on the subject.
Straight through generally means no mufflers.
If you go to your local exhaust shop and ask for some 3" pipe and a few mandrel bends (have a look under your car and try to estimate what bends you will need) you can cut and weld the system together piece by piece.
I don't know about flexi exhaust pipe that will do what you want, you can get braided flex sections but they are only short and won't bend the way you want.

Actually I just remembered I have succeeded in making a new tail pipe for my last GQ, I made it from bits of BA Falcon exhaust that I got from my last job. I cut and tacked the bits together and a mate welded it for me. It came out better than I expected.

Tony

[david swb]

ok mild steel is ok to use will perish down the track so i recommend stainless steel & stainless steel muffler taking into consideration 3'' will sound throaty i imagine choose the flow of the muffler over all it will sound tough cheers dave swb

[the ferret]

Yeah, stainless is the go, a long as yer ok with welding it, you can just weld it with ordinary steel welding rods or wire as stainless rods are very expensive.
You will need a three inch dump pipe a well.
Cheers, the ferret
http://i608.photobucket.com/albums/tt164/ferret/dumppipe.jpg

[AB]

As ferret mentioned, must have a three inch dump pipe otherwise there is no point in having the 3" exhaust with the restriction from the start.

Below is a photo of the standard dump pipe versus the 3 inch.

[robbo0001]

ok, my question is this....if I put a 3 inch dump on a a 2.8 TD, the run a reducer to a 2 1/2 inch pipe set up with a straight through muffler (for legalities) would anyone see a drama?

This is what I am thinking....Mild steel...3 inch dump for turbo spool, then a reducer, remainder of the pipe mandrel bent and 2 1/2 inch for scavenging speed and a straight through (slimline and elevated) muffler for QLD regs----

[the ferret]

I'd go 3 inch dump, 3 inch all the way to the back bumper with a straight through muffler, block the EGR, clean inlet manifold and intercooler out, remove butterfly, a catch can, 200 to 1 two stroke in the fuel and.... vvvrrrrrrooooom, cackle zoom.
It'll pull the stick out of a rice pudd'n then.
Cheers, the ferret.

[robbo0001]

Yeah, Scotts Rods 3 inch are looking the goods.....can't justify a stainless system when the car may rust out, before the exhaust does!
EGR and manifold a done, butterfly is most likely next on the list (waiting on pyro and boost guages)...2 stroke is probable, very interested on possible benefits.

I can't knock the 2.8, fits the family well, does exactly whats reqired....and my dragging days are weel and truly over. Love it.

[BearGUST]

I wouldn't bother with stainless on a diesel - the oilyness of the fuel stops anything from rusting.

[HippoNZ]

Cheers for the info guys, probably will go standard steel as it is cheaper. It's not an immediate thing to get but as always I'm thinking of mods and that was on my mind and thought, hmmmmm now how would I go about that lol

[G-ForceCrew]

Hi Brett, Here's my ideas and others. 2.75in after the bellows. It fits over the diff better in the GQ.
Have a really good look into this. There are so many different turbo's. Some with internal waste gate's have the exhaust mixed together before the dump pipe and some have the exhaust mixed in the dump pipe. If you put the external exhaust mixing type with the internal dump pipe together you normally cant open the waste gate far enough. Most internal waste gate turbos will allow smaller exhaust system to be fitted. eg just one pipe comes off the dump pipe regardless of of the internal or external exhaust mixiing in the turbo housing design. Going to an external waste gate (remote) is more complicated with the exhaust system, $$$ more, but you can spool up the turbo at lower RPM with the correct A/R (turbo A/R) this gives less turbo lag and Manual or Electronic boost control is more controlable.
The dump pipe's above are two photo's that are different types of turbo designs these could both be internal waste gates and think from reading AB's turbo fit they both are.
Remote external waste gates runs two dump pipes then into a collector.

Heres my idea 2.75in after the bellows. sports dual port streight through
The bellows or fexilbe joint needs to site between where the exhaust

I was also going to make up my own exhaust then found the 3inch pipe is very hard to work with and the more welds the more heat effected zones and therefore weaker. Off roading and weak nah.

[hutchy84]

Hey mate

Just a little quick info for yourself if you were to go with a stainless exaust system you should only weld it with stainless rods - Yes I understand the cost of the stainless rods is a lot more than steel rods but for the trouble you will encounter later on really isnt worth the cost saving at the start of your exersize.

The reason being is that the normal steel reacts with stainless and it will therefore rust at your joints and proceed to crack as it makes the joint really weak so for the cost saving now and the repair dramas later on it really isnt worth saving that $ 50 dollars extra

And not to mention working on old exaust systems is a real pain in the A$%e