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ive seen matty's ute when he picked up my bonnet was very nice tidy sleeper another good example of a well converted ca18det ute looked very trick!
i went with single 3'' pipe and i have just got 103mm clearance and mine ute is 4'' lower than standard with 15'' 50 series tyres only scrapes on the cat but is empty anyway and its tuked up hard 2 the floor, the twin system is a good idea though! defently worth lookn into

Alright ,I assume you have a turbo engine . I usually run high comp. engines but there is a difference in exaust. I use a try-Y 180 degree header ( extractor ) design . 4-2-1 . You can use bigger & longer tubes which will give you more torque, which means wicked ecceleration. better off the corners!!

lol!

Thanks Chris. I can live with an extra kilo. I'll take it to a couple of exhaust shops when my thumb heals and see what they think.

Thanks again Matty

Lets do the maths.

CSA = cross sectional area.

3inches = 76.2mm

CSA = pi x R^2 = 4560 mm^2

For 2 equivalent pipes = CSA / 2

2280 = pi x R ^2
R^2 = 2280 / pi
R = sqrt (2280 / pi)
D = 2 x R
D = 53.87mm = 2.12 inch (2 and 1/8inch)

So you'd want to use 2 x 2.25 inch.

Steel density = 7850 kg/m3
= 7.85 g/cm3

Standard exhaust wall thickness = 1.5mm

So for 3 foot of 3inch vs. 3 foot of 2 x 2.25inch weight..


3inch
-------------------------------------------
Circumference = pi x D
3inch x 3 foot x 1.5mm thickness
Standardised to cm to make formula easier.

7.62 x pi x 91.44 x 0.15 = cubic volume of the steel in that length of pipe
Mass in grams = 328.24 cm^3 X 7.85
= 2577.5grams = 2.577kgs
-------------------------------------------

2.25 inch x 2
-------------------------------------------
Circumference = pi x D
2x (2.25 inch) x 3 foot x 1.5mm thickness
Standardised to cm to make formula easier.

2 x 5.387 x pi x 91.44 x 0.15 = cubic volume of the steel in that length of pipe
Mass in grams = 464.25^3 X 7.85
= 3644.4grams = 3.644kgs
-------------------------------------------

An extra Kilo.. Talk about doing it the hard way...but I didn't have to leave my computer or bourbon and coke

I have considered having the flange relocated but this will still only give me a very small amount of extra clearance. I would really like 15 - 20mm more ground clearance.

Chris - would 3 feet of 3" pipe really be alot lighter than the same length in the smaller diameter?
Thanks again for the replies
Matty

if it's the flange that does it, can you move the flange a foot or so either direction? If you don't have a split dump, could the flange be moved to the bottom of the engine bay for instance? That way the exhaust can still be pulled apart & you don't need to screw around making a twin system.

There is a certain area under the car where you shouldn't have a low point in the exhaust. My exhaust is 3 inch, and never bottoms out.

The cat converter must be as tight up to the body as possible.

Have someone stand perpendicular to a speed hump that frequently gives you trouble. Drive over it at a speed you normally would, and have them mentally (or digital photograph) the point where the car bottoms out on the speed hump. Once idenfied, make sure that part of the car has it's exhaust bits as snug to the body as possible.

Using more exhaust hangers stabilises the exhaust, and stops it from drooping when going over speed humps also. Hanging 3 inch on the standard hangers is a bad idea.

Getting stiffer front springs is also a good way to reduce the spring compression at slow speed.

Cheers,
Chris

twins is too heavy..unless it's titanium.

i have seen a twin in twin out muffler box.

I think I recall ca18det_man having twin pipes for this reason. I think there is even pics. He dont seem to have any drawbacks.

"Note- I only recall - might be wrong"

Thanks for the replies.

I would rather keep the single 3" from the diff onwards as I don't want to buy new mufflers etc.

There are currently only a couple of photos of my ute on the Queensland Raceway site but that's it. I now have a digi camera so I will post some up when I can.

The exhaust has already been modified for more clearance but I would like more if possible. It's not a hanger issue just a big pipe under a low car issue hence the split pipe idea. I simply can't get anymore room with a 3" diameter pipe.