Whats In My Back Boxes, Suggestions Please?

[GG]

Hi all!

Ok, this is the story, one of my back boxes has a rattle in it, I assume there is a couple of baffles in it?

I want to replace them and I was thinking of some ideas....

1. I want the retain the twin outlets.
2. I would like a improved exhaust tone.
3. I don't want the exhaust note to intrude in the cabin, unless accelerating hard.

So the questions are;

1. Does the engine need back pressure?
2. Can the original boxs be cut open opened and modified?
3. Will fitting 'non-standard' boxes cause a mal-function of the CPU/Engine Mananagment System?

I really would welcome your thoughts on this Guys....

 

[stradaman]

Be sure its not your cat breaking up. Bits will move down the pipes, and can get lodged in the rear boxes.
Engine if N/A, requires no back pressure. It needs high gas flow, through the exhaust.
No, it will not cause the ECU to log a fault, if aftermarket boxes are used.
Any box can be opened, and rewelded shut, if the metal is good. Take the perforated pipe out.
Me, i would replace with straight pipe. Cheapest, and will add power, and maybe slightly better on juice, due to better breathing.

Andy.

 

[GG]

Hi Andy,

Thanks so much for the concise and quick reply.

I assume N/A is Normally Aspraited?

"Take the perforated pipe out.
Me, i would replace with straight pipe".... So open the box, remove the pipe work inside and fit a straight pipe, so it will be a straight through pipe without any restriction?

 

[BennyD]

Correct. However, you might be better just getting a set of straight throughs (no boxes) as they would save a sh!tload of weight as well. The standard boxes are really quite heavy.

 

[GG]

Hi,

I would imagine that would be way too loud for everyday use?

 

[stradaman]

Hi Andy,

Thanks so much for the concise and quick reply.

I assume N/A is Normally Aspraited?

"Take the perforated pipe out.
Me, i would replace with straight pipe".... So open the box, remove the pipe work inside and fit a straight pipe, so it will be a straight through pipe without any restriction?

As Ian has said. Noise is a bit louder. lol

Andy

 

[GG]

Only a bit...........?

Well thats ok then!

 

[Parisien]

....eeeemmmmmm....GG ......BennyD is known on the forum as the decibel King.......if you're using the QP as a business tool...may not suit it to have simple straight through pipes.......not got an experience of the QP but on the 4200, de-silencing the back end does lead to resonance in the cabin....


P

 

[Parisien]

...having said that......the V8 noise is fab...esp when pushed hard.........................................


P

 

[BennyD]

If you are replacing the perforated pipe in the rear silencer with solid pipe, you are, effectively, turning them into straight throughs that weigh about ten times as much. The sound levels would be more or less the same.

 

[2b1ask1]

Don't the back boxes also perform a small duty of smoothing the airflow besides the crucial rear splitter? If these are removed and just a bendy pipe in their place, how does the i affect the handling at the crucial 95-120?

 

[BennyD]

Don't the back boxes also perform a small duty of smoothing the airflow besides the crucial rear splitter? If these are removed and just a bencdy pipe in their place, how does the i affect the handling at the crucial 95-120?

I didn't know there was an issue between 95 and 120. Perhaps the scuttle shake on the spyder masks it as I have never noticed a problem. It's planted up to 175.

 

[Parisien]

QP Newtons on about Ian.........not 4200


P

 

[BennyD]

I didn't know they have a problem either.

 

[2b1ask1]

No the 4200cc coupe goes very light at the back between 95 and 120 then it settles down and is planted; don't know if this is true of the QP and clearly flying is not a problem for you Ian!

My point is that the back boxes if removed leave a rather large hole to catch air imediately either side of the rear splitter and just behind the wheels; surely this has a negative effect, I was mearly asking if anyone had noticed?

 

[Parisien]

Not mentioned by Marios when fitting mine...sure they are lighter but space left aint that huge.....


P

 

[BennyD]

When I am out with other like minded individuals I spend a fair bit of time between 95 and 125 so perhaps I have got used to it skating about, either that or the spyder doesnt have the same issues as the coupe. It is less wing shaped in profile.

 

[jason23tong]

Hi, I opened up the rear boxes just to take a peek in side and I noticed that there is a flap which blocks one of the tailpipes during idle. I have removed them and had an Xpipe in place of the center resonator and its perfect for me. Not to loud inside and ferrari like rasp on the out side!

 

[conaero]

Great work, can you tell is what model these boxes where of, QP or Coupe?

 

[GG]

Great pics and thread!

Did you leave the fiberglass wadding out when you reassembled?

GG.