Dealing with the drone

[trev4]

Thought I would share my efforts with the group.
A little background. After adding a chunk of hp and having the pre cats removed I have found the exhaust note rather unpleasant the car had a low hollow drone when cruising on the motorway which I found headache inducing, I re packed the silencer with little improvement.
Mat Smith suggested the possibility of adding some silencers in the rear tail pipes, with this in mind I paid a visit to Demand Engineering a local exhaust specialist with a good reputation and plan was hatched to cut the tail pipes just after the silencer, increase the rear tailpipes to 3'' and insert two small 2'' silencers inside causing no more restriction than the original system also the modification is totally reversible as the old tailpipes can be put back on.
I have to say that the gamble has payed off and the car now has a much better tone, it still sounds unmistakably TVR when you put your foot down but cruising is now a joy and I want to drive the car again which I haven't wanted to do lately.


I realize this won't be of interest to the like it loud boys but it maybe to others.

[2 sMoKiN bArReLs]

I thought this was going to be a thread about keeping the missus quiet

[N7GTX]

Any chance of a video clip to hear it?

[trev4]

I will try to post a video clip but I am not very technically advanced, if anyone wants to hear it in the flesh I will be at Cadwell park on Monday.

[Franksy]

I use a similar system. I like it loud, so on the road I have a straight through 2 x 3" centre exit tail pipe rear section. For track days I swap over with an identical rear section, but containing internal baffles. See you at Cadwell on Monday.

[carsy]

I often read about this droning noise at cruising speeds when people have altered the exhaust in one way or another but i have to say with my pre cat Griff with standard manifolds and axhaust i have never experienced it just a glorious noise at all rpms.

I wonder if it has anything to do with the later style manifolds.

[Brithunter]

What is the difference in th manifolds? I know there is the bolted flange then the later clamp type flange. Is this the difference?

[trev4]

The exhaust specialist thought it was a combination of removing the precats and the poor original exhaust design, apparently it's not good practice to increase the size of pipe at the rear of the car it should either stay the same size or even reduce a little at the rear.

[trev4]

It will be interesting to see what the dB level is now, when I came back from a little run out last night my better half commented that it didn't sound quieter to her.

[BoostedChim]

I'd definitely be interested in this, I wonder if they have a jig. Unfortunately I'm quite a way from them. Do you mind me asking how much they charged?

[CHIMV8 500]

At certain revs i also have the drone,interested to hear any progress on this.

[trev4]

The conversion cost £500 including vat which seemed a lot of money but when I checked how much a decat y piece was from act it didn't seem so bad.
Just to clarify things I still have a small amount of drone at 60 mph but it's a much lower level that I can live with, the best bit is at all other speeds in top gear the car is remarkably quiet until you put your foot down then it's a TVR again.
I am in north Essex is anyone wants a gander.

[trev4]

Forgot to say I did ask about the possibility of them making up a bolt on set if others were interested but they said it would have to be bespoke fitted to each car otherwise if one wasn't quite right they would just get slagged off on the internet, which I thought was fair comment.

[ChilliWhizz]

Droning on a TVR has naff all to do with exhaust system design, it's age related. No not the car, the driver. It's at its worst during your 40's and 50's, but as you enter the twilight years it starts to fade. I SAID IT STARTS TO FADE.

[N7GTX]

ChilliWhizz said:

Droning on a TVR has naff all to do with exhaust system design, it's age related. No not the car, the driver. It's at its worst during your 40's and 50's, but as you enter the twilight years it starts to fade. I SAID IT STARTS TO FADE.

Say that again?

[trev4]

So yesterday I went to the Cadwell park track day, great day by the way anyhow went to get noise tested and expecting to be told I was around 90 dB or less and was really surprised to be told I was 100 dB which is slightly more than before.
It was a damp start so that may have had an effect on the readings but I'm still slightly confused but pleasantly surprised.

[QBee]

Damp morning always makes the decibel readings higher in my experience, and Cadwell isalways higher because they test you right next to a building

[trev4]

QBee said:

Damp morning always makes the decibel readings higher in my experience, and Cadwell isalways higher because they test you right next to a building

I did wonder if that Building might have something to do with it, I don't know why they bother really they let some seriously loud cars out my favourite was a yellow Serb which when he lifted just by the Marshall at the track entrance would explode and spit flames