Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: shootingsight on Tuesday,September 24, 2019, 12:09:39 PM
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I just ordered a set of exhaust headers for my non-crossflow R16 from RD-Enterprises. Seems the 'recommended' approach is to split the cast headers I have. I am a little loathe to do this, both because it is irreversible, and because I was thinking about upgraqding the inlets as well. Are there success stories people can share?
I noticed the inlet ports for 1-2 are right next to each other, and the ports for 3-4 are adjacent as well. The cast manifold has four seperate passages. I'm thinking to make a flange with a single large tube that covers both ports, so the manifold becomes two large tubes with just a 90 degree bend, versus four smaller tubes. I'd use a vertical pipe as a collector and sit my Weber down-draft on top of it.
This then got me thinking about going to dual carbs. Especially if I get side-drafts (God forbid, a pair of old Strombergs) but likely something more modern. Now the inlet manifold would literally be just a straight pipe with a flange at each end. Or can I even adapt a fuel injection system?
What have people done?
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Looking at Webers, it appears the DCOE 40 is a dual throat side draft of about the correct size for a 1600cc engine.
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People have separated the stock cast inlet section from the exhaust side to use headers with downdraft 32/36 DGV type Webers. Like you stated the process is kind of irreversible. The second option is to use a manifold for the single side draft 45 DCOE which is probably the better option. The three makes in the day were Hermes, Warneford and Else and the various clones of each. I have an Else clone on my S2. Since you already have a header this link may not help you but Aardvark International sells an integrated header and intake made from steel tubing.
http://www.talbotco.com/lotus_cat.htm
I don't know if Aardvark is still in business. There is also a fellow member selling a Warneford manifold and 45 DCOE Weber in the Classified section.
http://www.lotuseuropa.org/LotusForum/index.php?topic=3292.0
If you do plan on making your own inlet manifold, good luck with your effort. If it were that easy, there would be more products out there.
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Wow, the Aardvark integrated system would have been nice if I had asked the question before ordering the header I did. That said, I own a mill and a TIG welder (which I'm still learning to use), or maybe I use a torch and braze. I've been looking for an excuse to learn to weld better, so I think I'll make a down-draft manifold and start with my 32/36 DGV, and if that works, a future project can be a side-draft option based on a 40 or 45 DCOE. If nothing else, you convinced me I was not crazy in my thinking. On this subject. Pretty sure I'm crazy on others :-)
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PM sent.
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Phooey. I CADed up the head flange and got drawings for the carb flange, and was all ready to start practicing welding when I made the mistake of having lunch with two engineer friends. The first explained thAt he knew someone with a 3D printer that can do wax and there are aluminum foundries that could cast it. The second gave me the name of someone who does direct laser sintering of Alu or stainless or titanium. So now I likely have to make several manifolds just so I can try the techniques.
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If you do decide to go ahead and have one or more manifolds cast or printed (sintered) then I might be interested in buying a manifold from you, but more than that I would be interested in hearing more about how you get on, what it comes to when you price out those options, etc.
FYI, Serge explored a lot of options for making an intake manifold for his car, and wound up 3D printing it from high temp resilient filament. My guess is that you'll find it costs too much to have cast in small quantities, or to have it printed in aluminum or steel (let alone titanium).
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So now two people are interested in getting one. I'll definitely see this to fruition.
I have the great fortune in life that I am retired, so I get to spend time on things that interest me, rather than necessarily what I need to do to earn a salary. Learning is a passion, and I'm a nerd, so I will definitely look into these and report back. The beauty is that once I figure out the technology, making a downdraft versus a side draft is purely CAD time, and I drink beer while I do that, so it's not even really work.
I actually have 5 technologies of interest:
1. Direct Laser Sintering. Pile of metal powder, laser melts it layer by layer, so it makes your part.
2. Binder printing. You 3D print a mixture of plastic and metal powder by extruding the molten plastic with high density powder in it. It prints nicely because the powder is carried in the liquid plastic binder. After printing, you put it in an oven, and the plastic burns off and the metal powder particles eventually fuse. Does not need a high power laser like #1, because you are just melting the plastic, not fusing metal on the printer, but you do get about a 20% shrink as the binder burns off, so on odd shaped parts warpage can be an issue. Might work, since I was planning on putting these on a mill and facing off the flange surfaces anyhow. For the rest of it, slight warp is no issue.
3. 3D print in wax, then make a lost wax casting.
4. 3D print in sand, and make a direct casting.
5. Laser cut the flanges, then TIG weld stainless tubing. I think this is a simple design for a side draft, slightly more complex for down draft.
Several of these can be done in various metals. For #1 I know someone with ability to do Titanium, Stainless, and Aluminum. For the others I do not know, but aluminum casting is not difficult. Luckily I live in Cincinnati, an old machine tool city, so I know there are several casting places in town.
If I trade-mark these, I'm going to mess with people's minds. I think the company name will be 'Lucas Electric'.
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I've already gone down this road of looking at commercial casting of intake manifolds. Unless you have a special relationship with a casting company, be prepared for sticker shock on the cost of low production casting. For a hobby, the upfront costs forced me to put my project on the shelf for now.
http://www.lotuseuropa.org/LotusForum/index.php?topic=3177.0
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If you are going to build your own manifold, do some research on manifold design. You’ll also want to be careful about selling them. What fits on your car may not on another. Some exhaust headers curl upwards and reduce available clearance quite a bit.
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OK, I made progress. I got the downdraft manifold drawn in CAD. I learned a lot about working with lofted elements in SolidWorks too. Attached are a few renderings, and sectional views. I can print the flanges on a regular printer in 100% size and physically lay them on the block to assure fit. So this should be enough to get the quotation process started. I did find an on-line 3D printing company that allows you to upload STL files and gives an instant quote .... in aluminum it was $2,200. So that's a non-starter, though I have a buddy who has a 3D printing company that does metal. I might be able to get a better price.
Plastic 2D options were in the $250 range, and this company was in Belgium, so I'm hoping there is a wax printing company in the US that will be cheaper ... or I can figure out how I can get my own printer to print wax so I can look at investment casting.
The other option is to get a bunch of tubing and cut bits and get some flat stock, then learn to weld....
(https://dl.dropboxusercontent.com/s/hqlnf9gaem6u5nw/Intake%20manifold%20Downdraft03.JPG?dl=0)
(https://dl.dropboxusercontent.com/s/tl59tuqmgekjwts/Intake%20manifold%20Downdraft03a.JPG?dl=0)
(https://dl.dropboxusercontent.com/s/y9lrrtjnstqc560/Intake%20manifold%20Downdraft03b.JPG?dl=0)
(https://dl.dropboxusercontent.com/s/g4vmweywh6i4ljd/Intake%20manifold%20Downdraft03c.JPG?dl=0)
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Shooting, great 3D cad. Lots of promise. The carb on my car is a Weber 32DIR37 replacement. I will do more research to see if the manifold on the 1.5 is the same as a 1.6.
Sandy
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Found an on-line quote for binder printing: they print it in plastic that has high density 420 stainless parts in it. Then they fire it in an oven to burn off the polymer and get the powder to sinter, then they dunk it in liquid bronze which flows into the voids. That is $870, so still high.
I also found that I can buy wax filament for my 3D printer, but have not yet understood how they manage internal supports. Someone suggested there are low temperature wax, so you can heat it and melt out the supports, but I have not found a source yet.
Next investigation is into printable sand, to see if the mold can be 3D printed.
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It would be better to have separate runners to each cylinder. This helps to isolate individual intake pulses and allow some ram effect. Ideally the runners would start larger and gently taper down to the port’s size. I’m not an expert in these matters. But there are books and websites on this.
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I did some reading on it. There are advocates of a Helmholz design, where you want the resonant frequency of the air inside to match the frequency of the valves opening. However, it only optimizes at one RPM, and indeed and half that RPM would actually hurt.
I'll try to take my existing manifold and block all openings but one, and see if I can measure it. I have an oscilloscope and a microphone, so by slapping the last opening with my hand, it will ring the inside volume and I can measure the frequency.
The other theory out there is to make everything as big as possible and reducing drag, which would suggest combining runners so when one cylinder opens, it can suck from a bigger pipe, and flow restriction goes with the 4th power of diameter, so doubling the cross sectional area will give 1/4 the drag in the pipe. I'll read more and see where it goes.
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Shootingsight - I was puzzled to see CAD drawings of a downdraft manifold when I thought you were planning a sidedraft manifold. On re-reading your post I saw that you did say downdraft, so I was hasty and sloppy when I posted. I'm sorry about that.
But then, part of the reason I made that mistake is it doesn't make sense to me to go to all the trouble of designing and manufacturing a new downdraft manifold that is similar to the original. Surely it is easier to split the original manifold. Ok, it's not reversible but so what? It doesn't sound like you intend to ever put it back to stock, and if you are concerned about resale value then it seems to me that the classic car market likes Weber sidedrafts. The Hermes style manifold is period correct and I believe it would add value.
Having said that, if you want to do it anyway despite what anyone says then good on ya! I'd still love to hear what you come up with.
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I plan on doing both, assuming costs work out.
I do not want to cut the original, in case I screw it up, and now I'm out a manifold. Since I own a downdraft, I thought I would first make a downdraft, and then later go to a side-draft. Indeed, I bought the side draft carb and manifold that was in the 'for sale' section, however I also want to make one. I spent my career in prototyping, albeit for packaging. So this subject is of interest to me beyond just getting myself a manifold or two.
I added internal runners. I'll send this to my buddy with the aluminum 3D printer to get a cost estimate. As stated, for a full-up commercial place in Europe, the price was $2,200 (though it drops to $2,000 if I do three :-). I found a US based aluminum for $2,200, but if I do 3 it is only $1,100.
Also found another printer in the US who can do it in steel for $1,400. So progress.
(https://dl.dropboxusercontent.com/s/spsvtjm36a7ytib/Intake%20manifold%20Downdraft04.JPG?dl=0)
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Better. Paired intakes on a four cylinder work against each other so at least some separation makes a huge difference. That said, you can buy a used manifold to cut up moderately easily. Apply what you are learning to a proper side draft manifold. As far as I understand, currently available single side draft manifolds do not have separate runners as it’s easier to cast them that way. If you could design a single side draft with separate runners that would be well worth the expense — yes, obviously, the separated runners would have to join but the extended separation would make a big difference.
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(https://dl.dropboxusercontent.com/s/ni36qbchipc11i0/Intake%20manifold%20Side%20Draft%2001.JPG?dl=0)
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Now make it clear the header pipes without too much “swan-necking”. I also would not extend the partition quite so close to the carb flange.
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I'll 3D print this in plastic to assure fit.
(https://dl.dropboxusercontent.com/s/keaqxqk2v2afh50/Intake%20manifold%20Side%20Draft%2001a.JPG?dl=0)
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Didn't Serge Sleurs 3-D print an intake? As I recall he used heat resistant plastic and tested for compatibility with gasoline.
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I'm calling BS on Helmholtz resonance in the intake. I found a cool app for my iPhone that does a frequency sweep with the speaker, and plots the intensity of the response via the microphone. When a system goes into resonance, the response will peak - referred to as a bode plot. Think about a trampoline. If you bend your legs very slowly, you body just moves up/down by the distance you bend your legs, so there is a 1:1 response below the resonant frequency. Also, if you jiggle your feet up/down very quickly, your body stays stationary. So there is a 0 response if you move at a frequency higher than resonance. But in between is a sweet spot, where you kick your feet a little, and the response is magnified.
So, I hooked an amplified computer speaker up to my iPhone, and placed the speaker at the inlet port of my new headers and ran a sweep from 50 Hz to 500Hz. The strongest resonant peak was at 200 Hz, which is 12,000 cycles/min, which corresponds to 6,000 RPM for a 4 cylinder exhaust.
I have not run the test yet on my intake manifold, but since the runs are MUCH shorter than the exhaust headers, the resonant frequency is going to be a lot higher. So Formula 1 or a motor cycle might put the intake in resonance, but not likely my little Renault engine.
Here is the plot.
(https://dl.dropboxusercontent.com/s/pxxph82lul2s0ld/2019-10-02%2017.35.27.png?dl=0)
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Of course you could have figured out the resonant exhaust frequency by blowing down the pipe like a trumpet player and listening for the note. If your app is correct is should be about a G3. Test for equal tuning by doing each of the four pipes. ;D
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No need for the partition to go as far as you have it:
https://www.mgexp.com/phile/42/457774/DSC_9718.JPG
One last wrinkle. Pairing 1&2 and 3&4 is not ideal in a four cylinder, inline engine. Best is 1&4 and 2&3. This can make for awkward lengths and shapes though:
https://www.lynxauto.com.au/ford-1600-kent-crossflow-1-x-weber-dcoe-manifold.html
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LOL, I used to be a trumpet player, so actually, blowing on the header was what I first tried. However without a mouthpiece, it didn't work. But now that you have thrown down the gauntlet, I will figure out how to mount a mouthpiece.
I did put the speaker on different ports. To my pleasure, they all came out close to 200 Hz, so it is a tuned system.
As to what ports get paired, I'll look at that. Yes, it is messy, but the benefit of 3D printing is being able to do things that are not ordinarily possible. Are there any twin barrel side-draft carbs with vertically aligned ports? Alternately, are there itty-bitty carbs that would allow a dual .... or even 4 carb arrangement? Perhaps motorcycle carbs? Read the bottom of this page - four motorcycle carbs is a Spitfire setup .... I may have to follow this further. http://www.triumphspitfire.com/carbchoices.html (http://www.triumphspitfire.com/carbchoices.html)
Alternately, alternately, people have spoken of Mega-Squirt as a computer/controller that allows you to mix up fuel injectors, temp sensors, mass flow sensors, O2 sensors, and tie it all together to get a fuel injection system. A quick look at throttle bodies suggests they are only about $50 each.
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Ha! I was right. Helmholtz is nonsense on intakes.
The goal on intakes is to develop ram flow. Once your piston reaches Bottom Dead Center, the suction stops. So your goal is to make sure the flow in the intake manifold has enough momentum that the air keeps flowing, packing in extra fuel/air before the valve closes. This is what justifies long/thin runners over a larger pipe.
So as air flows, the momentum of the incoming air is m x V, mass x velocity. So if the intake manifold runner were the same diameter as the piston (and pretending for a second that there were no flow resistance in the valve - ignore that for the sake of the example), the flow in the intake manifold would have the same velocity as the piston going down. However if the pipe had half the cross sectional area, the air in the pipe would have to move twice as fast ... and if it had 1/4 the area, 4x, and so on. However there comes a point where (as I said above), drag through the pipe is a 4th order factor of diameter. So as you go smaller, the drag goes up. So there comes a point where the extra drag from a smaller pipe is less than the benefit of the extra velocity ... and therefore extra momentum in packing the piston with extra air. I'm going to have to ponder, and I'm not sure it is easy, to figure out where that crossover is, but it is the momentum that counts, and based on comments, it seems 1 round 2" pipe is not as good as a 2" pipe with a center divider.
That brings me to the second half of the revelation. Momentum does not work as well if there are flow restrictions. Going around a corner is a flow restriction. This is why down-draft carbs are not as good as side-draft. In side draft, you get a straight shot, so you can develop better straight line momentum of the gas. So when JBCollier told me the manifolds should not have too much 'swan necking', that was why. Bends in swan necks slow you down.
SO now I'm thinking four straight pipes with four single barrel motorcycle carbs. No bends. Gotta figure out how to size carbs, but a cycle of 800cc going at 12,000 RPM is the same as a 1,600cc at 6,000 RPM in flow rate. I have to think aabout pipe diameter though.
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Well that ran full circle .... the Mikuni website describes the PHH series carbs they used to make for automotive use, but with fuel injection growth, the market has died off and they are discontinued .... they recommend going to DCOE carbs from Weber as a close substitute ....
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Straight runners won't work as there will be clearance issues. The ports curve in side the head as well. Definitely keep curves to a minimum and make sure the curves you do have are open and have smooth transitions.
Yes, you can use four motorcycle carbs. Mikuni has flat slides meant for 4 stroke engines. They flow very, very well indeed. Much better than a Weber or Dell sidedraft.
This is fun BUT it is pointless to have massive flow capability when the engine itself can't take advantage of it. Porting the head, fitting larger valves, higher compression, more cam overlap and lift, etc.
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I hear you. Without engine tuning, you get to a point of diminishing returns. I'm not looking to do a total rework on a Renault engine, but if I can get the 80 for the 20, I'm good. I am also curious if new manufacturing techniques, like 3D printing can make something that was never before possible, so this is not really changing science, but just optimizing it based on possibilities.
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SO now I'm thinking four straight pipes with four single barrel motorcycle carbs. No bends. Gotta figure out how to size carbs, but a cycle of 800cc going at 12,000 RPM is the same as a 1,600cc at 6,000 RPM in flow rate. I have to think aabout pipe diameter though.
Do a search on "Jay Mitchell" at the Yahoo list.
I'm pretty sure he did a motorcycle carb conversion - Mikuni, I think.
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I'm running Keihins off a Honda CBR900 (or Fireblade depending on where you ), though they are hung off the side of a Zetec. They were selected as they were cheaper than DCOE's, and supposedly they were more tractable than DCOE's. I can't say for certain they are more tractable, but they are very smooth once I sorted out the idle jet size.
The manifold was made from steel plate for the flange, and cut & shut steel mandrel bends. I did smooth the welds on the insides of the runners, but I'm sure I could have made them even smoother if I spent more time.
(https://image.ibb.co/dawAsR/Chassis-Complete.jpg)
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Are they 38mm? What did you end up with for jet sizes? I have a set off a CBR1000R
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They're 38 mm. The mains are at 1.6 with the needle in the center position and the idle jets are I think 55's.
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Roddymac, awesome drivetrain and chassis!
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I put together an excel sheet that lets me enter plenum volume, runner length, runner cross-section, and it uses the Helmholz formula to calculate the resonant frequency. I've come up with two solutions:
1. Resonance at 3,000 RPM, which will have a secondary resonance at 6,000.
2. Resonance at 6,000 RPM.
I then went to the hardware store and for about $50 I bought PVC drainpipe. If I build this as one big diameter pipe, running parallel with the crank, and have four runners, kind of like what is pictured, I can actually measure the resonances, plus it will be easy to build. At issue is that the 3,000 RPM has to be a lot bigger to get the lower frequency. I could then look at space and mount the DCOE either fore/aft or sideways.
(https://www.autoaccessoriesgarage.com/img/group/main/38/3889_1_lg.jpg)
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This is probably too late but I noticed that when I made a post on this thread I uploaded the wrong photo sorry. This is the else version
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This is probably too late but I noticed that when I made a post on this thread I uploaded the wrong photo sorry. This is the else version
Not wishing to hi-jack this thread, but I have an Else manifold and a tubular 4 branch exhaust, does anyone have experience on what sort of gains can be made with just the Weber 40 and exhaust (ie without any engine work)?
My guess would be 10-15 bhp max..........
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Needs a cam at a minimum. Port matching would be nice as well. 40 is a bit small. 45 would be better.
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JB, if he only did the intake and exhaust what HP gain could be expected?
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I found a pretty good page on sizing the carbs.
https://archive.cnx.org/contents/a0a6da11-6437-404f-8cd3-10853a08b685@2/selection-and-tuning-of-weber-dcoe-carburetors (https://archive.cnx.org/contents/a0a6da11-6437-404f-8cd3-10853a08b685@2/selection-and-tuning-of-weber-dcoe-carburetors)
They happen to use a 1600cc ford engine with peak 6500 RPM as one of their illustrations, so a lot of it applies directly to my case of the wedge Renault R16.
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How much more is hard to say. When most people say they want more power, what they really want is more torque. Actually give them more top end power and they may be unhappy as their engine is now putting out less power in the mid-range. Oh well, sorry for the off topic.
If you put a single weber and a header on an otherwise completely stock wedge, I would expect 10 or so more hp in the top end and a bit of loss in the low to mid-range. Fit bigger valves, port, re-curve the distributor and grind the cam? 100 to 140 hp with the drive ability falling as the hp rises.
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So what do you recommend for more mid-range torque? I agree with you, I'm not on the track with my engine living at 6,000 RPM, it spends a lot more time in the 3-4,000 range (well, it really spends a lot more time in the 0 RPM range, until I get the rebuild done).
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Fit a tubular header and a Weber 28/36 DGV.
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There is an Europa S2 for sale on Ebay that has a twin Weber manifold for the wedge head engine. That's quite a rare manifold.
https://www.ebay.com/itm/1971-Lotus-Europa-1973-LOTUS-EUROPA-TWIN-CAM-SPECIAL-JPS-32/143432325646 (https://www.ebay.com/itm/1971-Lotus-Europa-1973-LOTUS-EUROPA-TWIN-CAM-SPECIAL-JPS-32/143432325646)
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Very rare manifold with 2 downdrafts. Hermes made a dual Weber sidedraft manifold for wedge heads, but have never seen this before. What's with the TC JPS Special in the ad?
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I actually have two of those twin Weber dang downdraft manifolds with carbs on my shelf. I would be willing to sell 1 set if anyone is interested.
Serge
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Serge,
I have messaged you....
Cheers,
Mark
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Old topic
Just making the Hermes style Twin 45 side draught inlet manifold along with the exhaust manifold, this is for the later Trafic round inlet port wedge head not the rubbish Lotus head although changing the head flange is easy now I have found a good laser company
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The 1470 head was just a production Renault head. Agreed, it's not the best. Performed pretty well, that said.
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here are some photos of the head flanges of the round port head I intend to use
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The 1470 head was just a production Renault head. Agreed, it's not the best. Performed pretty well, that said.
Not bad, and Hermes made it go well but I wonder if the 138bhp was a slide rule figure as I have spent a huge amount of money & time making a twin cam Aston work & its generally stuck at 92 bhp per ltr except for 1 engine & Hermes claimed nearly 94 bhp with a poor head shape which is hard to get high compression on, I wonder if one ever went on an engine dyno & whose or was it a rolling road which can be would up or down depending on what you wan't to see.