Exhaustive Selection

[Graham Sewell]

My 5 year old live axle sounds like she needs a new exhaust because the silencer is starting to rattle - noticeable on shutting down the engine (minor) and also for some odd clunking noises when the engine cold and misfires slightly going round a bend (right hander at slow to moderate town speeds).

 

I initially thought the clunking was suspension or rear axle, but have checked everything is tight twice (or consecutive weekends) and also nothing appears untoward when running fast on a country road (200 mile round trip).

 

The choice seems to be staying with another rear-exit or changing to a side exit. Noise levels are not a special issue as I will not be going on track days, but I do not want to go deaf either.

 

Any recommendations?

 

Cheers,

 

Graham

[Mike Bees]

Rear exit is probably more passenger-eardrum friendly, which could be relevant if you do a lot of miles with a passenger. Otherwise it makes no odds really.

 

Mike

[Geoff Johnson]

It must be worth getting a side one (less than a week since I spent £'s on one). I am told 20 BHP more & free's up the engine for further upgrades when it was being choked before. A bit nosier in the car, whereas before the overriding noise was the carbs (Vx 2.0 Carb) now about the same from exhaust & carbs. Nice bit is when it pops & burbles on the overrun it makes me laugh out loud

 

Geoff

[Roger King]

Depends on engine spec whether it is worth going for the side exit system.

 

Up to about Supersprint spec the side exit system really makes very little difference to the outright power figs on the rolling road, although it can make the engine a bit freer revving.

 

Beyond Supersprint power figs the side exit system becomes almost essential if the engine is to realise it's full potential.

 

Two points:-

 

The Caterham side exit system has unequal length primaries, which is not a good idea in theory. In practice, it is a good general purpose system that will suit a wide of engine specs; it is also very well made. For ultimate power you would need an equal length system made to suit your own individual engine spec.

 

The one problem with the Caterham system lies in the fact that the silencer cannot be repacked when it becomes noisy. Techcraft make an excellent range of silencers that can be dismantled to repack as necessary. Maybe the Caterham primaries and collector coupled with a Techcraft silencer would be the way to go.

 

 

 

[Mike Bees]

Geoff - I was assuming that the same manifold would be used in both cases, in which case side/rear exit is unlikely to make a jot of difference to the power.

 

A note about the Techcraft silencer - make sure you have a mount to attach it to the chassis at the front as well as the back, otherwise it will tear the front apart pretty quickly (witness the reinforcing that's on Darrens).

 

Mike

[Crudders]

Graham - my exhaust rattles like a b*st*rd but it's not the internals, just a poor fit between the collector and two of the primaries (the ones that don't have a bolt fixing). This wouldn't account for your clunking but it might be worth checking if your car has the two bolt fixing connection (I think later cars have a more satisfactory design). I've tried every known type of sealant and jointing compound to stop the racket on mine with not a great deal of luck - anyone got a solution short of welding!?

 

Crudders

[Graham Sewell]

I found the real source of the problem. The rubber strap that holds the tailpipe in place had sheared the steel bracket at the bottom. When the car was stationary you couldn't see the gap, but whenever I turned hard right, the tailpipe would swing out, the tyre would lean in - this cause contact and without the strap to hold it in place the exhaust got propelled into the chassis by the tyre. This caused the large knock that could be felt through the chassis (giving me the impression that this was initially a suspension problem).

 

All new mounting hardware is on order, including the rubber bobbin as this became a pivot point rather than a support point. Should be ready for Brands Hatch (only the parade lap - but better than nothing) smile.gif

 

Cheers,

 

Graham

[Pierre Gillet]

Roger,

what would be the benefit of replacing on a 1.6 K the Caterham exhaust system, which includes a catalyst, by a pipe replacing the catalyst portion coupled with the caterham side silencer or equivalent? This would prevent me from having to enlarge the hole in the ali side body to have the four primary pipes through the body , an operation that I am reluctant to do, but to get the benefit of the power taken by the catalyst, however without the benefit of having longer primaries. Also it would really be less expensive!

Cheers,

Pierre

[Roger King]

Pierre,

 

I'm sorry, but this is a mod that we haven't tried, so I can't give you any definite answer to your question.

 

I suspect, if your 1600K is standard that it would make only a small difference (if anyone else has tried this they will know if I am wrong or right)!

 

If your engine has been modified then it will posssibly make a reasonable difference. If, on the other hand, your engine is heavily modified, a proper 4into1 or 4into2into1 system would be essential.For example, we have recently done a 195bhp upgrade for a customer on a 1600K, but this figure would not have been possible without a competition type system.

 

Roger King

[Pierre Gillet]

Roger,

thank you very much for the advice. So I will wait until I can do some essential modifications on the engine itself!

Regards,

Pierre