Lotus Elan

5 speed exhaust manifold.

PostPost by: RedBarnMan » Wed Oct 11, 2017 8:36 am

Can anyone provide a definitive answer to the question " does a 5 speed +2S130 need a special manifold" Sue Miller reckons a 4 speed manifold will fit OK whereas Kelvedon state theirs is not for 5 speed. The manifolds don't look that different at first sight so what is the issue.
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PostPost by: rgh0 » Wed Oct 11, 2017 9:52 am

The standard manifolds sold these days go very close to the 5 speed box. The original Lotus 5 speed ones were the same as the 4 speed and were also very close to the 5 speed box. Bigger manifold pipes make the clearance even less and these day most of the manifolds sold use bigger pipes than Lotus did originally.

Some careful heating and bending may be required and needs to be done via a trial fit before you get them ceramic coated.

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PostPost by: CBUEB1771 » Wed Oct 11, 2017 12:22 pm

This is an interesting question. The Service Parts List for the Elan +2 shows part numbers of 050 S 0150 and 050 S 0151 for the fabricated tubular exhaust manifolds for cylinders 1/4 and 2/3, respectively. The Parts Bulletin for the five speed conversion shows part numbers of A050 S 0150Z and A050 S 0151Z for the analogous parts, in this case common to the Elan and the Elan +2. The part numbers certainly suggest that the fabricated manifolds were revised to suit the Lotus five speed gearbox.
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PostPost by: rgh0 » Wed Oct 11, 2017 12:34 pm

CBUEB1771 wrote:This is an interesting question. The Service Parts List for the Elan +2 shows part numbers of 050 S 0150 and 050 S 0151 for the fabricated tubular exhaust manifolds for cylinders 1/4 and 2/3, respectively. The Parts Bulletin for the five speed conversion shows part numbers of A050 S 0150Z and A050 S 0151Z for the analogous parts, in this case common to the Elan and the Elan +2. The part numbers certainly suggest that the fabricated manifolds were revised to suit the Lotus five speed gearbox.


Sounds like Lotus heated and bent the manifold for the 5 speed also and added the Z code :lol:

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PostPost by: CBUEB1771 » Wed Oct 11, 2017 12:56 pm

rgh0 wrote:Sounds like Lotus heated and bent the manifold for the 5 speed also and added the Z code


Ha, ha, either that or a blow of the big mallet!
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PostPost by: mikealdren » Wed Oct 11, 2017 2:38 pm

Interesting, this probably explains why the manifold didn't fit my 5 speed very well when I replaced it many years ago. I didn't realise there were different versions. A bit of careful leverage solved the issue.

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PostPost by: NickD » Wed Oct 11, 2017 11:03 pm

Not quite a definitive answer as my experience relates to an Elan rather than to a +2, but I'm currently using Paul Matty's stainless manifold with the Lotus 5 speed gearbox and it fits fine. Their website says "will fit 4 or 5 speed" - see https://paulmattysportscars.co.uk/produ ... d-y-piece/
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PostPost by: RedBarnMan » Thu Oct 12, 2017 9:55 am

Thanks for the helpful inputs.

Just measured pipes on my mild steel manifold which is original. Top pipes are 35mm diameter, Kelvedon say theirs are 38.4. A 25 year old Double S made Y piece in stainless that I have on the shelf has a 35.5 ID so that is consistent with the original manifold piping. The chassis (which again is original) top flange has been 'adjusted' by hammering the edge down to create a larger clearance to the pipes - likely to have been done by the factory before the body / engine was fitted as there is not enough clearance to swing a hammer with the engine in. So it seems to me that so long as you don't go for large bore manifold pipes it may well be that a 5 speed can take a standard manifold. However, I've not crawled under the car yet to see where else clearance is marginal.
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PostPost by: rgh0 » Thu Oct 12, 2017 10:07 am

The tubular manifolds were close to the chassis and potentially Lotus did some "clearance enhancement" at the factory for both Elans and Plus 2 on the top left hand flange where the pipes go down behind the engine mount. Certainly this is required for the larger pipes people sell today. The lower front left hand corner of the 5 speed box comes very close as well due to its square bottom shape and potentially the Z version had the pipes bent to clear this also with suit bale clearance adjustment tools of an oxy and hammer and lever.

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PostPost by: mbell » Thu Oct 12, 2017 8:50 pm

My original chassis has also been "adjusted" for extra header clearance with what I think are original or oem style headers.

The exhaust fitment is extremely close to the gearbox, so I think it will be down to the individual exhaust you buy and might need come adjustment. Very likely for a bigger bore exhaust.

Personally I've wondered if it would be sensible to trim some of the cooling fins on the bottom of the gearbox casing to improve clearance and lower heat transfer, driving my car yesterday the gear selection was much more tricky when it had been sat idling and the gearbox oil had heated up.

i probably should make my 3rd attempt at fitting the exhaust to see if i can improve the clearance and move to Redline MT90 rather than MTL.
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