Raceco silencer

The track noise regulations in Sweden has become much harder lately. The current limit is 95 dBA drive by measured from a 10 m distance. This limit is set by the SBF (Swedish motorsport federation) for all swedish circuits.

I know my car sounds a lot more than that, around 105 dBA. So far I've never been blacked flagged but I know it is a question of time. Also I wouldn't mind if the car was quieter as I'm not a big fan of loud noises.

The first step is to quieten the exhaust and that is now done with a Raceco 2.5" titan silencer built by Mike Riley. The high price made it a painful decision but it is very nice built and also a lot more quiet than the previous silencer. It take the edge of the bad part of the noise and what is left is a nice round sound. In fact the exhaust noise is now masked entirely by the (very nice!) induction noise.

It was a straight fit and no brackets needed to be fabricated.

It is also a bit lighter than my previous silencer - about 1.5 kg.

The car is much more quiet now but I think it still have a bit to go before I reach 95 dBA. So trying to reduce induction noise is next step.

Exhaust manifold leak

Last summer I bought new exhaust manifold because the old EU4 manifold was warped and had a crack in the collector. The new ones has been leaking as well. I don't know why, if it is a quality issue from the factory or if I have managed to warp them myself.

I've been asking around my local workshops if they could help me, but they all have been shaking their heads saying it would be too troublesome to fix the primaries at their milling machine and that it would be too expensive and not worth it. The last one gave me the suggestion to try to simply use some sand paper on a flat surface and grind them myself.

So I did.

I was sceptical at first but I think this will work!

I also went to a welder - Zanders - and had my silencer mounting brackets reinforced. They used to have a bit of flex and maybe that could be a part of the problem with the warped manifold. I still have a bit of flex. If this doesn't work I'll try to mount the silencer to the forward roll cage mount.

I made the brackets myself last summer. I think it is the third attempt, the others has cracked after track driving.

Read here to get an idea how it looks like on the car.

Exhaust gasket leak

It seems I can't get the exhaust manifold to seal against the head no matter what I do. I have even bought new primaries. It still leaked.

Now I have removed the gasket completely and tried to seal it with this stuff. No leaks, but lets see how long it lasts.

New exhaust primaries and collector

I could no longer ignore the fact that my exhaust flanged was warped and leaked, and I also found something that looked like a small crack on the 4-1 collector.

The exhaust system on the EU4-version of the car is welded and can't be removed without lifting the engine out - something I've had enough of for a while - and as one of the primaries has cracked before I felt like I just wanted to buy a new manifold that was more easy to remove instead of repairing the old one more time.

The EU4 collector also looked like it was limiting exhaust flow, but that was just an hunch.

So I removed the old system with an angle grinder and steel saw, and bought new CSR260 primaries and cat/collector from Caterham. The new system holds together with springs and can be mounted with the engine still in place.

Warped flange

Cracked collector - worse than it looked from the outside.

Old vs new cat/collector

The new cat/collector moved the silencer a bit outward, so I have to make new silencer mounting brackets. I'm also thinking about buying a new silencer but that can wait for a while.

Cracked exhaust manifold

Last time on Mantorp one of the exhaust primaries cracked completely. I left the car to a Ferrari race team who tried to weld it together in situ, but it was too tight so the result was not very good. No blame on them, they did the best possible under the circumstances.

Unfortunately the only way to get the exhaust system out is by lifting out the engine. So I did, and then dropped the system off to Tyresö Svets, and today the engine is back in. So much easier to take the engine out the second time!

To avoid this happening again, I now have fitted an additional exhaust mounting point in front of the silencer.

There is a threaded bush in the frame 802 mm in front of the rear mounting point. Drill with a small drill through the side skin and you'll find it.

The engine is out

Engine out due to a cracked exhaust primary. Easier the second time - I followed my step-by-step list from last time, and took it out only with help from my 5-year old son.

Silencer mounting bracket

When I bought my Caterham it was equiped with a big heavy rear silencer. Last winter I decided to remove it and modify the side silencer. After a couple of bad attempts with cracked welds and brackets I once again went to my local garage and extended the exhaust and welded a new mounting bracket. Hope it works this season!

Yes, the red spot is blood from my fingers

In order to decrease the bending force on the welds I have put rubber bushes between the brackets.

Thanks to Stefan Andersson Bil & Plåt