52 replies to this topic

[DaveyC]

My standard NA manifold and Milltek cat section and silencer are pretty much falling apart, leaking, rattling etc so I'm now looking at complete exhaust systems that will compliment the forged engine I've built. Before I spend over £2000 on some bits of stainless steel it would be good to experience what various options are available at the moment.

 

Would any of you fine gentlemen allow me to come and have a look at your exhaust setup, have a bit of a listen to the noise levels and have a general chin wag about your experiences with it? I'm based near Stratford On Avon but don't mind doing a bit of driving.

[FLD]

I have a full 3" tullet with decat silencer. You're welcome round but I'm a fair way from you!

[chris_uk]

I also have a 3" tullet with hjs cat.. But im also miles away..

[smiley]

At what power are you now, and where do you plan to end Davey?

(easier to discuss the options with that info)

 

[sford]

You must be the 5th car around here now! Good luck in the search. Tommobot has an SC though his is far from standard.

[DaveyC]

I'd estimate that with the right exhaust it'll be close to 300bhp. 

The old engine made about 250-260bhp with standard internals but that self-destructed on track back in October.

Currently around 230bhp because of the lower compression ratio of the new engine, broken exhaust etc.

2.8" pulley will be going on shortly after the exhaust. 

[Mr Apex]

I run a full 2.5" Tullett. You're welcome to pop down and have a tinker with my car if you like.... South Bristol, just off the M5.

[smiley]

After the Dutch broke a few tullett cat sections (default is magnaflow ceramic ones i think), we feel it's best is to spill a bit extra, and ask tullett to build in the HJS cat (which is steel and can handle the SC heat better), like Chris mentions. This is regardless if you choose a 2.5 or a 3" system.

 

 

Edited by smiley, 28 May 2015 - 09:12 AM.

[DaveyC]

I have read about the standard cats melting and finding the way down the pipe. My other concern is noise limits for 'quiet' track days.

 

I have asked Tullett to quote for a pipe with silenced decat and a pipe with one of their standard cats I can swap in for MOT time VS a pipe with an HJS cat (which they said was circa £300 more than the standard cat pipe).

 

Just wondering how much sound attenuation there is from a silenced decat compared to one of the HJS cats. I've only ever gone from dense OEM cats to silenced decats before (which gave an increase in noise) rather than a cat that is already less restrictive to a silenced decat. If there isn't anything in it noise-wise then I'd just go for an HJS to avoid the faffing once a year swapping pipes over.

 

Looks like it might be worth me taking a trip up north to have a listen to precisely both those systems!

[Mr Apex]

I have no problems with sound levels on track days - but I think that has a lot to do with my intake solution, which is pretty quiet.

[DaveyC]

I have no problems with sound levels on track days - but I think that has a lot to do with my intake solution, which is pretty quiet.

 

Have you got a build thread I can have a look at?

[ArticMonkey]

Welcome to come to essex in the next month or so. I'll have a twinned silenced 3" system from Matt Bentley racing with a tullet. 3" mani.

[techieboy]

3.0" Tullet de-cat silencer system on a Stage 3 car here.

 

De-cat silencer helps things over the standard Tullet cat but still too noisy for me/comfort. Kiss goodbye to Bedford/Goodwood/Donnington/Combe unless you're happy to not use full throttle.

 

Have a couple of mods to do to the main silencer when I can be arsed to extricate it which may knock another couple of db off, which may make a worthwhile difference.

[fezzasus]

The standard cat is well made, you shouldn't have an issue with it as long as you're not running very rich.

[ArticMonkey]

The standard cat is well made, you shouldn't have an issue with it as long as you're not running very rich.

You say that, but mine has now dislodged and wedged it self in my U-bend. That's from a Saab engine with harrop doing running in miles. Not pushing past 4k rpm. Though the map was running quite rich at the beginning. Only 300 miles in however .

[DaveyC]

3.0" Tullet de-cat silencer system on a Stage 3 car here.

 

De-cat silencer helps things over the standard Tullet cat but still too noisy for me/comfort. Kiss goodbye to Bedford/Goodwood/Donnington/Combe unless you're happy to not use full throttle.

 

Have a couple of mods to do to the main silencer when I can be arsed to extricate it which may knock another couple of db off, which may make a worthwhile difference.

 

Bedford is relatively easy for me to get to so that's the track I use most often. Might just have to forget about it then and go places with higher limits.

 

Any idea what levels you're reaching on drive-by tests?

[pete-r]

I have a standard manifold, decat and larini if you want to try it but I'm in swansea.

[techieboy]

Bedford is relatively easy for me to get to so that's the track I use most often. Might just have to forget about it then and go places with higher limits.   Any idea what levels you're reaching on drive-by tests?

Bedford Autodrome is 5 miles away from me. If I wasn't going to get kicked off the instant I went for a proper lap (too many mics at Bedford to), I'd probably be there every other week during the summer for one of their evening sessions. Anywhere from 98db to 105db depending on how far away it's measured and how on the throttle you are at the point it's measured, which way the wind is blowing and what the weather is doing at the time. With no "standard" for testing drive-by's it's impossible to really know and you're totally at the circuit's mercy as to how they monitor it. Too many variables to be able to give any kind of guarantee as to what to expect. Absolutely breezes through every static test I've ever been through though. Once I've changed the stuffing and modified the perforated tube, I'll probably take it up there and get them to run it around the circuit to test it, again.

[DaveyC]

I have a standard manifold, decat and larini if you want to try it but I'm in swansea.

 

I had a Larini on my last NA. Loved it. But I imagine it'll be effing loud when combined with twice as much exhaust volume and a howling supercharger on top!

 

Do you ever get it on track? Any idea of drive-by noise levels?

[DaveyC]

 

Anywhere from 98db to 105db depending on how far away it's measured and how on the throttle you are at the point it's measured, which way the wind is blowing and what the weather is doing at the time. With no "standard" for testing drive-by's it's impossible to really know and you're totally at the circuit's mercy as to how they monitor it. Too many variables to be able to give any kind of guarantee as to what to expect.

 

 

Hit the nail on the head there I guess!

 

I've built the car for hillclimb where Prescott have a 101dB drive by limit. No idea how it is measured, where it is measured etc but I imagine it'll be pretty close to the track.