Wanted Smaller / Noisier Silencer for R300/400K System

[revilla]

As I don't track my car and I'm a bit of a child / hooligan at heart, I'm looking for something a bit louder than my current 6" silencer can.

Maybe something like a 4" can in decent condition that will either fit my existing catalyst or decat pipe, or could be modified to do so with a bit of welding.

Current silencer inlet pipe is slightly angled as shown in the picture below. Inlet pipe OD is 2.3/8" and ID is 2.1/4". Can is 6" diameter and length 70cm, and the total length from the rear mounting bolt to the front of the inlet pipe is approx. 85cm.

Let me know if you have anything interesting please!

Looking for a straight purchase, not looking for a swap as I want to keep the existing silencer as well.

Thanks,

Andrew

[SM25T]

Hooligan :-)

[7 wonders of the world]

CC have some (and other bits) on ebay....

https://www.ebay.co.uk/itm/Caterham-Exhaust-Silencer-3GX096BP-item-3/264663393476?hash=item3d9f2ae4c4:g:ZJIAAOSws4NeaKre

 

[revilla]

Thanks for the heads-up but unfortunately I don't think those systems are going to fit. The can looks too long. The front mount bracket is welded to the side of the can and the inlet pipe then protrudes quite a long way forward from that.

On my current system I've been unable to use the front mount as the can stops well short of it; as you can see from this picture, the mount hole in the chassis (which I've blanked off with a stainless bolt) pretty much aligns with the joint between the decat pipe the inlet pipe of the silencer.

(I know a fabricator could make up a mount that would reach, I'm just making the point that the layout looks quite different and my existing cat / decat pipe reach right back to the front mount position and are going to extend too far back to fit those cans behind).

[7 wonders of the world]

i tried goggling the part numbers first but this inconclusive, long shot but thought the one looked like an early K, though there have been many variants over the years...

you could make yours repackable and simply remove some of the material...  

[revilla]

I think maybe something like this might be OK but I'm only going from the picture and I haven't been able to check the measurements:

https://caterhamparts.co.uk/silencers/1083-exhaust-silencer-side-exit-non-catalyst-4-diameter.html?search_query=Silencer+rover&results=272

[elie boone]

Something like this maybe ? https://www.ebay.co.uk/itm/Universal-Exhaust-4-x-2-x-20-Silencer-Kit-Car-Resonator-Muffler-Back-Box-304/323472103515?hash=item4b5070985b:g:8WUAAOSwMVdYGwqN

 

[revilla]

Thanks Elie, I hadn't really thought about making one up from universal parts but it's an idea. I had a bit of a search on eBay and found some that are probably a bit closer - 2.25" inlet pipe and 26" (66cm) length.

e.g. https://www.ebay.co.uk/itm/Clamp-on-4-x-2-25-x26-Silencer-Back-Box-Resonator-Muffler-Stainless-Universal-/274057236661?_trksid=p2349624.m46890.l49292

They come with clamp-on ends; at that price I can get one, clamp it in place of the existing silencer and get a reasonable idea of how it might sound. It will sit all wrongly and need supporting at the back but if I like it then I can get a fabricator to make it up with an angled inlet pipe, an angled tailpipe and a rear mount.

If it needs a bit more space either end to fit the bends they are also easily available in slightly shorter lengths - 24", 22" and 20" (as in your link).

[blueyedbiker]

Sorry to piss on the bonfire chaps but there's enough people out there trying to keep our cars off the road as it is, is it wise to give them more ammunition in the form of increased decibels?  As a biker there's nothing that pisses me off more than the clowns who take the baffles out off the cans so that you can hear them half a mile away as they pull 18,000 rpm.

[revilla]

I know what you mean.

I'm not looking for "stupidly loud" and I know I need to drive considerately. As Ks go mine towards the quieter end at the moment (VVC on a plenum, no induction noise, much reduced overlap unless you really boot it). I'm only looking to liven it up a bit within the usual spectrum. I don't track the car, it's only for road use and I guess for me the noises and smells are all part of the thrill of the experience. I don't drive the car particularly hard (I'm usually shifting up by 6000rpm as the VVC is mapped and the cam timing has been tweaked to out all the torque lower down for road use), I'm no driving God, I'm not getting my thrills from hanging it off the limits on every corner, I'm running T1R tyres that slide at much lower G levels than sticky rubber. I just enjoy being out in the car and the "theatre" of it, for want of a better word.

I've spoken to Chris at Redline. He can get the proper Caterham part for me, but with a few weeks lead time (I think they're made to order). That's no problem as the car is off the road for the winter now. I'll probably order it later to be ready for the spring if I don't find anything used before then.

What I will do in the meantime is order a cheapish universal silencer of the same dimensions and just bolt that on to the car to see how it sounds, to get a rough idea of where it might end up. If it really is unsociable, I'll give it a miss.

[elie boone]

A Duratec R300 with a new Sigma peashooter can still passes a 98db noise limit. A K series 1.6 SS with a 20 year old std exhaust didn't.

[revilla]

I did some experiments today with a universal 4" silencer behind my current decat pipe. It certainly sounded louder. This was without any kind of tailpipe so probably "worst case". It also sounded more "interesting" with the pops and crackles more marked.

Things got interesting though when I tried to measure the sound level with a mobile app. I was measuring 50cm from the outlet at 45 degrees, 5600rpm (three quarters of maximum) static.

First I measured using my own phone. Old 6" exhaust, 86.5dB. New 4" silencer 88dB. Only 1.5dB difference.

The absolute numbers seemed low, so I used another phone, different brand, different app. Similar results, even a bit lower, 84.5dB and 86dB, but again a 1.5dB difference.

Suspecting that the microphones in these phones might be just overloaded and saturated I then measured a few metres away. As expected the numbers were a bit lower, but the difference was again 1.5dB.

I'm going to check it with a decent calibrated decibel meter so I know objectively how my noise levels compare to other people's.

[IanJ]

Hi Andrew,

I've got a couple of options for you, both from a 1997 1.6K Superlight with a long primary 4-1 race system.

1) Carbon Components Silencer

The carbon sleeve is damaged (both on the side and underneath) and needs replacing. The head of at least one of the caphead screws has been ground flat and there is a slight flat on the end of the exit pipe where it has grounded. I can send more photos if this would be of interest. This was a lot quieter than option 2) but if you get a new sleeve the I guess you could decide how much packing to use and/or get an internal sleeve to cover some of the the inner perforated tube.

2) Original 4" Caterham Silencer With Heat Shield

This is undamaged, but 23+ years / 40K+ miles old and non-repackable so it is loud i.e. has failed drive-by at Bedford and Donington trackdays and a 105dBA static test at Goodwood. It does sound great on a K Series, though. I'd only want to sell this as part of a complete system with the 4-1 race primaries which would make it the more expensive option, especially as I'm guessing you don't need the other bits!

I've PMd you as well - happy to discuss further.

[revilla]

Thanks Ian, I'll reply to your PM. Just out of interest can you tell me the length of the 4" can on the second system please?

[IanJ]

The can on the 4" silencer is 56cm long and it's 77.5cm from the end of the inlet pipe to the end of the can.

[revilla]

Perfect, thank you. That's an exact match for what I've been testing. I think a home-brew solution based on this should be OK. Thanks again.