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Exhaust upgrade... - Induction/Turbo/Manifold/Exhaust - The Lotus Forums Jump to content

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Hi folks, ive had an SJ's SS Exhaust manifold and downpipe assembly for a couple of years now. While it did ok as a temporary job its time to upgrade to something better. (I was one of the ones who had some difficulty with fitting (by my garage) which did involve a bit of cutting and welding).

Does anyone have a suggestions where to go next? Its a 1986 N/A S3. Quicksilver is a no and as far as im aware Alunox only make them for the Turbos?

Many thanks folks.
 

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Brett,

I think Lotusbits do a full stainless system for ours with a larger bore, but it's not cheap.

SWLC have remanufactured the manifolds, but that wouldnt be any sort of upgrade I guess.

Edited by DaveyT

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Hi Dave, 

Ive seen the Lotusbits one up close. Its very impressive but as you say v expensive. I did consider going back to the cast manifold, i still wonder if there wouldnt be much difference going back to standard....

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There are several points I consider important on choosing a manifold for the Esprit:

1) - On performance there seems to be modest room for improvement if engine is near stock tune. Lotus deliver 172-180 BHP from the 2.2 with the cast main manifold as a starting point. Two mates had equipped 907 Esprit with a large bore 4-2-1 fabricated system, finding that agreeable. That was with something like 1 7/8 inch primaries, only tolerable with the 4-2-1 configuration as that scale would just kill the power band in 4-1 layout. That said, a respected American builder supplying top-tier NASCAR and ProStock NHRA teams has held forth at length on the folly of large-bore mindset. I'll attach a link if found, meanwhile I suggest 1 1/2 inch is correct for primaries in a 4-1, not far off in the case of 4-2-1. The summation statement amounts to keeping energy, therefore velocity, high as possible through to the silencer so as to maximize scavenge therefore cylinder fill. This is altogether intuitive in my view and is consistent both with OEM practice in general and with successful tuners for decades. Contrarily, we seem inclined to regard exhaust pressure ( that which motivates flow, in fact ) like constipation, to be improved via an enlarged passageway as if that were logical in the slightest. I suspect the same pretzel logic in play when one loads "flushes" of one kind or another into the oil or fuel.

2 - Proximity to the exhaust side engine mount  on S1/2 cars means attention to heat management. Stainless does not conduct heat as readily as mild or cast, the lighter mass of tubular retains less energy so less cooking of the kit when stationary. Points to consider include insulation wraps and ducting for favourable airflow.

3 - Installation concerns are well documented in a number of threads including one active at the moment in this category. The difficulties described in terms of successfully hauling together an array of 4 separate primaries seem entirely predictable. 

 

Calvin Elston posts.pdf

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if anything is found i would be interested dont think sj,s has much perf improvement ???

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Mine rattles and shakes. I think it was fitted the best it could have been but im thinking now of seeing if someone can fabricate a new one..

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