New carbon fibre can exhaust..

[ChrisGB]

Do you need high gas speeeds in the silencer? -  A lower speed may reduce the noise level without increasing back pressure.
It could be that the section/area changes will bounce stronger pulses than the end of the exhaust so the total length may not make much difference.

Of course I could be completely wrong!

The problem with slow moving gas is that it forms a plug in the system reducing flow. The other problem is that there is no way to realistically route piping to run the two silencers in parallel. I think the easy way for now is to just get the second box in there in series.

I had a mate drive the car today while I was standing by the roadside and it is louder outside than I thought it was  s:oops: :oops: s:oops:   Sounds like a race car running a straight pipe once under full power. Does sound nice mind.

Chris

[ChrisGB]

Little update:

Had the second can fitted today. A second straight through box, this one 4.5" diameter with 2" bore 19" long. The sound at town speeds is now pretty much as quiet as the stock setup, but much deeper (sets off car alarms  s:lol: :lol: s:lol:  ) Once under power it is also much more civilised and should comfortably slip past the trackside noise meter (or the blue flashing light meter). Still sounds good, but not bonkers loud, just perfect for the road IMO.

We weighed the system at 4.5Kg, so less than half the weight of most alternatives and providing better level of silencing. Getting weight out of the back makes a big difference to the balance as you would expect. With the carbon fibre exhaust system and the manifold and cat replaced with light weight PPE gear, I must be quite a lot of Kgs lighter at the back.

Hard to tell if it has made any difference to the running, but on the dyno tomorrow, so we shall see. Feels OK though.

Cans and fitting provided by PJ Engineering who did a nice job of cramming it all in there. Website here:

http://www.pjengineering.co.uk/

Chris

[custardavenger]

Pics?

[ChrisGB]

Pics?

Cannot see much really. It is all tucked in where the stock system lived. These are lame attempts, but the camera is too bulky to slip into the engine bay:



Also forgot to mention, big reduction in underbonnet heat as these cans don't conduct much heat through the walls.

Chris

[markiii]

looking at their website they are nowhere near you Chris, I'm guessing you had to leave teh car with them?

[ChrisGB]

looking at their website they are nowhere near you Chris, I'm guessing you had to leave the car with them?

They did it while I waited. First day up there for the first silencer was a bit of a long day. They had not done one of these before and initially we agreed a particular design that would make dropping the second can in an easy and quick job. Unfortunately, they kind of forgot that we were looking at mandrel bends to fit it in the space. They gave me the impression that they did mandrel bending, but it turns out they had to buy the most difficult bend in as they only do crush bends on site.

When I went back for the second one to be fitted, it was a half day to get it done.

I reckon that if they worked with tight radius mandrel bends throughout, it would be a fast build. I am tempted to re plumb my system in all mandrel bent tube. The dyno today showed gas flow to be OK, so not essential work, but I reckon I may do it to tidy things up in there a bit more, possibly when I strip it down to re pack the silencers.

Jason, they guy who fitted the system, did say it would help if anyone else wanted one set up, to leave the car with them to make a proper jig.

On these systems, I would say that if you have the main cat in place, or a turbo, one silencer is probably enough, will be loud but not mental. For non turbo, cat less applications, two is a must IMO.

They also just sell the silencers as complete units to your measurements or as kits. Mate it up with some off the shelf bends and it could make a lovely DIY project.

The quality of the noise is really nice, sort of gutsy and sophisticated.

Chris

[markiii]

hmm based on the weight I'm wondering about asking them to take a look at teh vxr