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Exhaust upgrade on x-flow


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To be honest, if you have a standard 1600 engine on twin 40s, you won't gain much by changing the system. Caterham's own 4 into 1 side exit system isn't perfect, but it's a good general purpose competition system and is well made. Unless you are aiming at ultimate power figs (over 175bhp), this is what I would recommend, although you might be better if the actual silencer was a Techcraft, simply because it would then be repackable when it gets noisy.


You will probably find that your engine is a little bit more enthusiastic at higher revs, but the difference will not be great. If you are aiming for 140bhp+, the side exit system then becomes essential.



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The 4-2-1 primaries are unequal length and the collectors have some horrible features inside. The standard Caterham 4-1 system seems to be quite a lot better, and is probably good value for money on a medium hot engine. As the carbs would then need retuning, you should think about incorporating other upgrades at the same time. Do I diagnose "upgradeitis" 🤔


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Me 😳 😳


Definitely not dear 😬


Currently working out what I need to dry sump the engine, where I can get it, and how much it will cost.

Also on look out for another engine though this is unlikely (winces at the thought of trying to explain that one)


So all in all - no plans to spend ANY money WHATSOEVER on the car except for fuel . . . . . . . Honest *tongue*

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I will be selling my engine soon. It will be absolutely complete from carbs to clutch, to make way for a swap. Spec includes:

1700cc with forged pistons

Big valves

40DCOE carbs with K & N filters

Dry sump with thermostat and oil cooler

Roller rockers

Lightened flywheel

Piper 285 cam (I think, either that or Kent 234)


I built it for durability, not power, but all it really needs is a better head and the 4-1 exhaust. I am looking for a good price, but if you are serious email me.



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