Exhaust Modifications _

1. Exhaust Manifold  

The new exhaust manifold has been fitted. I used the new version now sold by South West Lotus. They have reformulated the casting and claim they do not suffer from cracking. I would recommend resisting the temptation to ceramic coat new manifiolds to help reduce engine bay temperatures and increase exhaust gas velocity thus improving the turbocharger spool up times. Since the turbocharger is both oil and water cooled so it is hoped that the turbo will be able to cope with the additional heat stress.

Additional Note:

I know of no ceramic coating system that will survive more than about 2-3 weeks before flaking off. Exhaust wrapping is not something I would recommend you do without undertaking considerable research into the pros and cons.


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2. Custom Centre-Exit Exhaust

A complete centre-exit exhaust system was fabricated by Graham at Exhaust-by-Design which is located near Finmere in Oxfordshire. I gave Graham the brief to make up a 3in diameter straight through stainless steel system from the turbo back, exiting in the centre with twin 3in slant-cut chrome end tips. There is very little room to get the 3 in bends and some silicencing in a centre-exit system. We were also unsure how much silicencing we would need. Our first attempt resulted in a system that was 105 dB at 4000 rpm. I had to drive it home and could only bear to rev to 3000 rpm in central Oxford. It was like a Nascar.

I took it back the next week and Graham introduced a second straight through silencer box.

So far I am very pleased with this version and it is bedding in nicely, the tone is good and the noise level is very acceptable. produces a good burble on the overrun.





















Our research has shown that moving up from a 2.5in to a 3in exhaust system is a major jump. In terms of exhaust gas flow you have an increase of 44% in flow efficiency. That will improve turbo response but also gives you more sound to deal with. In addition, the larger pipe diameter does lower the overall exhaust note.





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