Tubular manifold for TCS

[Bread Van 74092397P]

Can I ask, if anyone has fitted the stainless exhaust system, that Europa Supplies market, to their Twincam, or Special?  I am asking the question, because a tubular manifold forms part of this system, which for me, would be an improvement over my original cast manifold. I am aware that Lotus, originally supplied a tubular manifold, but this was only suitable for early Twincams, with the 336 gearbox, it didn't work for the later 352/365 units, due to conflict with the revised gearchange mechanism. So is the Europa Supplies manifold a different pattern, from the original, will it fit later cars? 

https://www.lotus-supplies.com/parts/exhaust/twincam/stainless-steel-exhaust-system-cast-manifold

Dave

[BDA]

Those look pretty and Richard does excellent work but I'm not familiar with any of them so I can't say if there is an issue with any particular tranny linkage. SJ Sportscars (https://www.sjsportscars.com/parts-and-accessories/SJ074S0004.htm) has a complete set for £395 and like Lotus Supplies, they don't list any exclusions. I think I would probably call r.d. and DBE and ask them about what they have. Their shipping is likely to be much cheaper than anyone across the pond. If it's close, you can check with Lotus Supplies and SJ Sportscars.

[EuropaTC]

I'm not familiar with that particular manifold as I made my own a few years back but it's a similar layout. My TC has the 352 box with the cast iron manifold and to be honest I thought both 336 & 352 boxes pre-dated the tubular manifolds.  I'd have guessed the move to a tubular one only came towards the end of the run with the BV engine when they fitted them to the Elans as well.

However, the geometry on the manifold side doesn't depend on the gearbox, it doesn't go anywhere near until you get to the 90deg bend into the silencer box. The parts manual I have shows the Y piece & 90 deg bend fabricated as one unit whereas mine is like the one shown in your link, a separate Y piece & 90deg bend which you can alter to get the correct angle for the silencer box entry.

I suspect that's where the difference lies ? Either the single assembly of the Y piece & bend wouldn't give the correct angle for all the gearbox/silencer combinations or maybe in the bolt pattern or mounting bracket on the silencer box itself ?

Brian

[Bread Van 74092397P]

Hi BDA & Europa TC,

Thanks for your feedback, trying to return my Europa to the road, after many years sat in a garage, lots of issues to address. Would prefer to get rid of the cast manifold, as the flat joint to the exhaust, always seemed to be detaching itself. My Lotus parts manual, has a note on their tubular system, saying 336 box only, prior Nov.71. I concluded this was down to the differences in gear linkages. The earlier linkage goes through a 90 degree angle, as it leaves the chassis, moving it away from the engine, and presumably the exhaust manifold. The later linkage is much closer to the engine, and probably in the path of the tubular manifold.

I am hoping that the stainless version is a different pattern from original, and would fit. Europa supplies were not answering phone calls, but eventually replied to an email, saying it would fit, but didn't qualify it. I'm not sure the technical knowledge is there, since Richard passed things on. I'll contact SJ Sportscars, as suggested, it looks like the same system as Europa Supplies.

Can't afford the exchange rate for the US suppliers, with the pound almost on parity with the dollar, but it might benefit you guys over there!

Dave

[BDA]

Sorry I didn’t notice you are in England. SJ Sportscars would be my next stop.

[Bryan Boyle]

One thing to be aware of in fitting is interference between the outer 2 pipes and the shift linkage for the 352/365 boxes; not to denigrate RD's design (because it DOES work, but could stand a little tweaking), but, at the position of the shift tube and the header, there is no clearance as delivered.  Whether the lotus-supplies or SJ system has the same issues, I don't know, since I've not seen them in the flesh nor tried to install their systems.  Everything on these cars needs slight 'fettling' to get it to work.  Just the nature of the beast, so it didn't bother me.

Now, whether the question was my car just being a fluke, or a basic design issue...I had to *ahem* adjust the outer two pipes to create clearance, as well as slightly adjust the length of the rotation centers on the center Heim joint and the pivot on the transaxle so I was not banging up against the header by trying to go into first gear or reverse.  It's still tight, but nothing is hitting now; the #2 pipe is touching the engine mount, though...all around it's about a 1/4' off side to side and front to back as delivered.  This may be due to the manifold pipes being proud of the flange on the head side by 3/16" or so (which is the side they're welded on...maybe if they were welded on the outside of the flange also, the flange could be surfaced flat and maintain gas tightness pulling the bits further in when mounting up to the head?) and perhaps adjusting the jig to move the rear 2 pipes back 1/4"?). 

I've made suggestions as to improvements (and offered my car as a pattern), otherwise, the system (even with the *ahem* adjusted downpipes) and slightly wider pivot length (and we're only talking about 3/16") does what it says, works just fine, and sounds pretty sporty with a new muffler when you play with the loud pedal.  Realize, also, that you will have to trim the lengths of whatever system you choose, mostly the cross-pipe up to the muffler, to make it all slip together nicely.  No doubt, though, that the improvement in breathing is most welcome.

[EuropaTC]

Hmm, good point on the shift linkage, I didn't think about that.

The CI manifold wasn't as bad as you might think, I'm sure I read somewhere that it was good for up to 150bhp. I'll admit that surprised me because the casting is nowhere near matched primary lengths, maybe that's not as critical as the books would have you think ?

I also had problems with that joint though, probably made worse by the fact my secondary tubes were stainless so there's an expansion difference to contend with as well. I ended up making it into a spigot & socket design with a small sleeve in the secondary flange going through the gasket area, that worked very well and stopped the leaking problem.  I just made a tubular one because I wanted something that looked racy....   

Brian

[Blitzen]

Its been a while so my memory is a bit foggy but I think I have the Banks exhaust, which I assume has not changed.  It fit with the 352, no problems.

[Bread Van 74092397P]

Hi everyone, thanks for all the responses, loads of information, and first hand experiences. My existing system is stainless, joined to the cast iron manifold, so the different expansion rates, may have something to do with the unreliable joint. It looks as if the tubular versions, may not be a straight fit, probably why Lotus switched to the cast iron edition. I'll do some more checking with the suppliers, as may not have the engineering skills to make adjustments, other than a big hammer!

Dave

[BDA]

I'm not sure Lotus switched from a tubular header to a cast iron manifold. I think the headers were an option. I don't know that I ever saw a set of Lotus headers but they would have been in mild steel.

[jbcollier]

The cast manifold was used on the Federal engines.  I thought all the others used tubular manifolds?

[rjbaren]

I bought stainless headers, Y pipe, and intermediate pipe from SJ Sportscars for my U.S. Twin Cam Special with the 5-speed transmission.  They fit no problem.  I think RD Enterprises has mild steel headers.  But ... RD does have a beautiful polished stainless performance muffler that fit nicely with SJ Sportscar's stainless exhaust system.  They have a mild steel performance muffler too.

[Bryan Boyle]

Hi everyone, thanks for all the responses, loads of information, and first hand experiences. My existing system is stainless, joined to the cast iron manifold, so the different expansion rates, may have something to do with the unreliable joint. It looks as if the tubular versions, may not be a straight fit, probably why Lotus switched to the cast iron edition. I'll do some more checking with the suppliers, as may not have the engineering skills to make adjustments, other than a big hammer!

Dave

Don't discount the BFH adjustment tool.  Sometimes, it is necessary (even if not elegant...)

[BDA]

Bryan, you may have to translate “BFH” for those unfamiliar with the term. 

[EuropaTC]

Bryan, you may have to translate “BFH” for those unfamiliar with the term. 

Bryan Favours Hammers ?