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Duratec R400 exhaust noise


dickbowyer

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I have posted on here before about this topic. As an update, today at G'wood the 7" Race Exhaust with cat gave 98dB at 5000 rpm with the induction measuring 102dB so good for 105dB days but a bit doggy for 98dB days still.

 

Dick

Superlight SV Duratec R400

 

Edited by - dickbowyer on 27 May 2008 22:21:43

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Dick,

 

I've driven my R400 Duratec at Donington (98 driveby) without a problem but, having removed the cat, I think it is rather noisier. I was warned, to my surprise, that my car was now too noisy at Cadwell ( >105 driveby?), having passed the static test easily.

 

The noise meters are based on pseudo-science *thumbdown*; there is no standardisation of measurements and therefore no guarantee you will be welcomed at all tracks; I'm going to have to act- a Raceco can is being sorted.

 

Neil

 

Build pictures here

Guantanamo Bay Orange SUPERLIGHT R400......

 

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Please let me know how the Raceco can option goes. Were this a simple on/off replacement with, or without cat or CC C400 collector, I am sure there there would be a big market........... in the "Duratec era"

 

Dick

Superlight SV Duratec R400

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  • 2 weeks later...

Dick,

 

This weekend I had a trip over to Mike Riley's place in Derbyshire; he makes the Raceco systems in partnership with Ammo.

 

It was the first system he had made up for the new R400, so a few issues to work around.

 

The Raceco can is longer than the Caterham item you mention, so you will certainly need a non-cat collector. Mike cut this where the primaries join, to shorten the straight section but retain the existing bend in the pipe and allow it to enter the centre of the can rather than be offset. Some masterful TIG welding and a resited Lambda boss and the modified collector was sorted and mated to a newly built, repackable titanium sleeved silencer.

 

There was some work to be done on the rear mounting bracket; this differs from the K and there is no cutout on the offside rear wing.

 

Tested at Cadwell the next day; 93dB static at 5250rpm, no problem with driveby ( I don't think they had the meter out) but by no means boringly quiet!

 

I'm very pleased with the result- thanks to Mike for his time and effort- great to see him at work. Should have no problems with most tracks now- and easily repackable, unlike the CC item, plus much lighter and better looking! *thumbup*

 

 

 

 

Build pictures here

Guantanamo Bay Orange SUPERLIGHT R400......

 

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Hi Neil

 

Thanks for the feedback. Silencers go out the door and that is the last we hear of it. To have noise level information is very useful to us.

 

We are currently working in conjunction with an F1 and Indy Car exhaust supplier to make a new Duratec race exhaust system. There will be two versions aimed at the 250-280 bhp and the 290-310 bhp + power levels.

 

The first one will be finished this week with rolling road testing scheduled very soon. we were forced to make this because as usual there is nothing out there to fit the bill. The emphasis is, as always, on the best power, highest quality, highest flow, lightest weight and the lowest noise levels possible without going to a twin box system that will be complicated to make and sap power.

 

The Duratec is here to stay for a few years so it make sense to tool up to cater for it.

 

Thanks for choosing a Raceco silencer. Also thanks again for your feed back and I hope you enjoy your car on road and on track in the coming months. *thumbup*

 

Ammo

Raceco.com

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Just got this email from Tony Cummings who bought my previous 2 litre engine:

 

"Hi Ammo,

 

I saw the posting on BC about the Duratec exhaust noise level and thought you might like to know that my set-up with your 230bhp engine, Raceline exhaust and one of your 7" silencers on two occasions has given 89db @ 4500rpm static at two MSE Airfield track days.

 

Best wishes,

Tony Cummings"

 

If anyone else has noise information using our silencers I would appreciate an email to raceco@btinternet.com

 

Many thanks in advance for your help. *thumbup*

 

Ammo

Raceco.com

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the duratec is quite a lot quieter than my previous K exhaust noise.

 

will the new silencer be a double pass or twin silencing tube like the superbikes have. I was toying with making one of those to replace my current self extended length R300 silencer. But i dunno if its worth it as I'm currently on 94 db @ 4500 anyway. The noise on wide open throttle with the 2.5" bore tailpipe is the killer on drive by I find, making a lot of the static test only partialy valid. A twin pass or 1 perforated tube per 2 cylinders could work well I imagine like the big Apprillia motorbike.

 

 

 

here is C7 TOP

Taffia rear gunner

 

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Pat

 

With the 5" diameter "silencer" which was originally fitted, they measured me at 108 dB static (3/4 max revs) at G'wood. Once I had fitted the 7" competition box that CC subsequently supplied (for free) to replace the 5" item it went down to 102 dB but a recent visit had it at 98 dB but induction noise was in the region of 101 dB. Clearly a bit different on different days. Once Ammo has an "off the shelf" system, I will be back to him.

 

Dick

Superlight SV Duratec R400

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Dave

 

Entry level lowish power Duratecs are quite quiet. Once you start tuning for higher outputs noise levels go up.

 

My old 228 bhp 2 litre engine was very unobtrusive noise wise. My new 260 bhp 2 litre is noisy, not so much on the exhaust as on the induction side. I like the power and delivery but not the induction noise. It is a bit too much for me.

 

A Duratec airbox is planned. One that is quiet and doesn't sap power. Probably a fiberglass one with a carbon variant for the fetishists.

 

The new race exhaust system for the Duratec retains an absorbtion type silencer as these are best for flow and power.

 

I did a lot of testing with Superbikes on Ducatis, Suzukis and Aprilias. All with absorbtion type silencers. I wouldn’t consider anything else. I designed an Aprilia silencer that made more power and was quieter than the factory one as well as the ones from all the major suppliers. I know because we bought one of each to test. I still have all the dyno sheets and noise test results somewhere.

 

Also designed a two into one into two for an Aprilia that worked very well. One silencer per cylinder works well. Don’t know of any big twin that works better with a 2 into 1. With cylinder head and cam mods that we did we got around 132 bhp at the rear wheel whilst most other people were struggling to break 120 bhp. The dyno we used had seen engines making 116 to 118 bhp at the very most. This was around 2000. We actually approached Aprilia to race an RSV in BSBK even before the bike was launched but nothing ever came of it.

 

Sorry, went into a reminiscing mode there for a minute.

 

If the need is to make the engine quiet and you don’t mind losing power then you can do it with restrictive airboxes and silencers quite easily I would have thought.

 

I can’t see the point in this though. You build a powerful engine to then lose the power through the exhaust and induction.

 

We tried a double tube thingie designed by some French rocket scientists on a Yamaha 24 hour Endurance racer back in 1986. They swore blind that it was the best thing since sliced bread. The bike lost power. We put the absorbtion type silencer back on.

 

 

 

Ammo

Raceco.com

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What, like two cores in one housing with two exits? Or two separate silencers? Did consider and discussed something like this at length but decided to go for a single silencer on a Caterham.

 

I thought you meant a labyrinth type silencer with two tubes and a void, one entry and one exit so the gas has to go through a tortuous route to exit. This works as a silencer but is not good for power.

 

Ammo

Raceco.com

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aye

 

paired cylinders entering the silencer through 2 perf tubes sat side by side in a can say 8" x 7" oval design *thumbup* with a realy cool looking twin tailpipe exit 🥰

 

the end plates are availble from milner off road in this sort of shape me thinks - or 10minutes on the mig for Mike 😬 😶‍🌫️

 

here is C7 TOP

Taffia rear gunner

 

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I'm trying this here not finished yet so have no noise figures, seems to be working for the some of the VX cars, not sure either about clearance issues yet. there is also a weight penalty, it weighs 10lb's already and it's got no silencer wadding in yet.

 

Kevin R

 

black(but sometimes orange)-ali HPC

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Yes it could dave or even Ti 😬 but just got lots of stainless at work *wink*

i have tried to keep all the thicknesses down, the silencer is 1mm the end caps are 1mm the perf is 1.2mm and the pipe is 1.6mm

 

Kevin R

 

black(but sometimes orange)-ali HPC

 

Edited by - k.russell on 4 Jun 2008 21:51:45

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