Exhaust Manifolds for Twin Cam

[BDA]

You might want to have Quicksilver dyno the motor with those headers.

[jbcollier]

Lock wiring is not a bad idea but do several retorquing after heat cycles until the torque is stable before actually wiring them.

[EuropaTC]

Lock wiring is not a bad idea but do several retorquing after heat cycles until the torque is stable before actually wiring them.

Do they come loose then ? When I took the manifold off my car to make a new one it had been in place for, well, I can't remember how long but it must be 10 years or more. Is this lock wiring a racing thing ?

Brian

[BDA]

A lot of it is a racing thing. A lot of it is a belts & suspenders thing and a lot of it is a coolness thing. I try to wire every bolt that doesn't have a lock nut on the other end but I admit that sometimes I just get lazy. I like doing it for all the reasons I listed but I find it especially useful as a way of KNOWING that a bolt is tight - and can't come loose. I'm so forgetful that that visual confirmation is a great comfort to me.


As for the brass exhaust nuts, they tend to lock themselves when they get hot since the coefficient of thermal expansion for brass is higher than steel (at least that's the explanation I heard many years ago but it seems I also remember in engineering class that the hole in a heated piece also grows). In any case, wiring tall exhaust nuts seems like a good (or at least a neat) thing to do though I've never seen it before. As for myself, I've been using jet nuts (metal lock nuts) for my exhaust. I have worried that the heat cycles might relax the steel but it doesn't seem to have.

[jbcollier]

You have to go through several heat/cool/torque cycles until the gasket settles.  After that vibration can cause them to loosen and the TC engine has been known to vibrate things loose and/or develop fatigue cracks.

[4173R]

I'm resurrecting this thread on exhaust manifolds for Twin Cams for continuity purposes, rather than begin a new thread on the same topic.

I've got a '74 twin cam (4173R) that needs a complete exhaust system. Within a month of buying 4173R I purchased another twin cam that runs and will be my driving car while I work on 4173R. The running vehicle has an exhaust system that came from "Lotus Prepared By Claudius" lotuspbc.com. It is a nice exhaust system although the header has been welded twice. I've been in contact with lotuspbc and they haven't made any headers in quite awhile. They will make a production run of 10 but at a cost that seems excessive, though I haven't determined if their price is negotiable. They will also coat the header with ceramic for an additional cost. I have not determined if there are 8 other Europa owners looking for headers to fill the production order.

I'm looking for a deep throaty muscular header, if that makes any sense, that is already in production. This thread began the header discussion. It is a bit dated since the last post. Nothing in the way of providing performance header vendors, other than 1st Performance and Exhausts Ltd.

Hopefully there is recent information on vendors with performance headers especially with many Europa's currently under restoration.

[Pfreen]

I am posting about headers here because I can use this website.  There is a long discussion of headers on groups.io.  I don't know how to attach files on that blog.

Anyway, I have used on my tcs both the RD Enterprises and what I think are the Dave Bean headers.  I don't know for sure because my car came with headers made by RS Engineering in California.  They look exactly like the headers in the photo Grumbebuns posted in this topic.  I called Ken about these headers and apparently Dave Bean worked with RS Engineering on the header design, so I think they are the same as the Dave Bean headers offered today.  Ken said they could make them but they were something like $2500 in S.S.  Mine are just steel.  Dave Bean also sells another header design for the Europa TC.  It looks like a 4-1 design.  I don't know the price, but I attached a photo of it which Ken sent me.

I attached a printout of the design and the analysis.  There is a header calculator at the website shown on the pdf file.  I am not sure the basis of this model but there are a number sites online which reference the same header design formulas.  It is probably based on transient gas flow dynamics and empirical data.

Anyway, the Dave Bean design matches the prediction very closely for putting the peak torque around 5500 RPM.  Also, the DB header primary length were matched within 1".  The only disadvantage I see is that the DB headers are much more expensive than the RD ones.  Another advantage of the DB header is that the 2-1 merge collector is horizontal to the ground so the ground clearance is about 1.5" more with these headers than the RD design.

The RD design has somewhat unequal length primary tubes, (approximately 3-6") and the merge collector is perpendicular to the ground, reducing ground clearance.  Also, the secondary tube length is very short.  The tube diameters are similar.  The DB secondary pipe ID is slightly larger at 1.375 vs 1.35 for the RD header.  The overall length "P" in the analysis is about 6" shorter than the DB design, so the peak torque will be at a higher RPM

I attached my chassis dyno run showing peak torque at 5000 RPM.  I think chassis dynos skew the torque curve to lower rpm because the transmission losses are not constant with speed.

For reference, my car has sprint cams and 10.3:1 compression ratio. 

From the dyno data comparing favorably with the header analysis program, it may be a good design tool.

[BDA]

Thanks for that, Pfreen! I believe the header discussion started with a guy who lives not far from me. I'll send him a link to this in case he misses it.

[rjbaren]

I bought headers from SJ Sportscars.  They are stainless steel and with the exchange rate now in our favor they were not too expensive.  Might be worth taking a look.

[EuropaTC]

I bought headers from SJ Sportscars.  They are stainless steel and with the exchange rate now in our favor they were not too expensive.  Might be worth taking a look.

Even without a favourable exchange rate I think they are good value, I paid more to make mine from tubing than it would have cost me to buy a ready made one from SJS. The only downside I can see is that from the photo on their website the primaries don't seem to match up well although that's a criticism that applies to the OEM cast iron manifold as well.  Even so I don't know how they manage to make them at that price.

Brian

[4173R]

Thanks for the info Pfreen.

I've been in contact with Ken at Bean. He provided some useful information about their headers and exhaust system.

I've got an email into Banks and will likely follow-up with a phone call to them and RD.  To Brian's point, the SS headers from SJS are intriguing. Ironically, they will likely last longer than the car. LOL

Ultimately, the question is, who can I buy headers from other than Bean, Banks, RD Ent, and SJS?

I'm getting the impression those are the only 4 who currently provide headers.

Thanks

Regards,
Jack

[Pfreen]

Paeco in Alabama sold them, but they appear to be out of business, or their website is at any rate.  Their reviews are not very positive as well.

[Certified Lotus]

I am very pleased with the headers and silencer (oxymoron as the exhaust system sounds very mean) I got from 1st Performance and Exhausts Ltd. in Norwich (Alex had them custom fabricated). It’s not cheap, but it’s also not expensive when you realize you get the whole system. I would do it all over again if I was building another car.

[BDA]

I went back and looked and they are beautiful and look very well made! I can believe they weren't cheap but if you have the money and motivation these look great! I reposted the picture Certified posted of them.

[Certified Lotus]

Thanks BDA. Here are 2 photos of it installed and a video of what it sounds like.

https://youtu.be/dlaZESDiYes