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Thread: Weber Manifold for 8 port sierra motor

  1. #26
    1000+ Posts Frans's Avatar
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    Default Explanation.

    Hi All,

    My expierience from S Africa is that the 1400cc R5 motor (I think that will be the same as the Aus 1400cc R12 motor) came out with the head that had the ports directly next to one another. It is actually semi Siamese because the cutouts in the gasket is almost oval. That is basically the same head as we know in the 1300's and later 1100's. You cannot use the Datsun manifold on that head.

    The 1400cc R9 and R11 motors came out with a head that had the ports completely seperated by about 20mm. These heads are in principal a better design with improved flow characteristics. You can see that the distance between the first 2 ports are more inline with the sidedraught chokes and thus the air/fuel will flow in a straighter line as the other older head, where they go towards one another from the carb and then at the head they split out again to the valves. The ports looks like someone with knock knees.

    On Ross's head we welded 2 blocks on top (as seen in his pictures) because the top bolt is half in the head and half out. The one I did for Kiwia110 I screwed a block on to take the top bolt. Same thing different method.

    I had some pictures of his motor that you can see how far the ports were moved on the newer type heads. You will be able to see what I mean by having a straighter line to the valves. And you can see how little the ports needs machining to match the Datsun manifold.

    I hope this answers your questions.

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    Regards
    Frans.
    Attached Thumbnails Attached Thumbnails Weber Manifold for 8 port sierra motor-img_0002-1.jpg   Weber Manifold for 8 port sierra motor-img_0032.jpg   Weber Manifold for 8 port sierra motor-img_0039.jpg  
    Last edited by Frans; 9th March 2011 at 10:04 PM. Reason: Grammar!
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  2. #27
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    Just picking up on this thread. Anyone know where to get a manifold to fit two 45DCOE Webers onto a 688-02?
    Just Thinking out aloud but if I'm going to change the Carby I may as well go all out
    Last edited by LeMansTragic; 10th February 2018 at 10:41 AM.

  3. #28
    1000+ Posts renault8&10's Avatar
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    My advice having done it is don’t bother, stick to a single side draft dcoe.
    However, if you do want to go dual’s I have a contact in Spain that may be able to help but he is on Facebook. He’s on a few of the R8/10 Facebook pages, and I have added him as a friend. If you are on Facebook, send me a pm and I can give you the details and his name.

    He has just made a two piece manifold to suit one of the R12 engines. That should also fit an 1108 for your purposes.

    Otherwise, you are probably left with fabricating your own.
    Last edited by renault8&10; 10th February 2018 at 11:26 AM.
    KB


  4. #29
    1000+ Posts bowie's Avatar
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    I would love to hear more about the having done both, why you prefer the single.

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  5. #30
    1000+ Posts renault8&10's Avatar
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    Quote Originally Posted by bowie View Post
    I would love to hear more about the having done both, why you prefer the single.
    Convenience for the OP, with their engine's thermal efficiency and non-modified state in mind.
    Attached Thumbnails Attached Thumbnails Weber Manifold for 8 port sierra motor-kbr10engine.jpg   Weber Manifold for 8 port sierra motor-dscn1544.jpg   Weber Manifold for 8 port sierra motor-dscn1692.jpg   Weber Manifold for 8 port sierra motor-dscn1684.jpg   Weber Manifold for 8 port sierra motor-image.jpg   Weber Manifold for 8 port sierra motor-image.jpg  

    59 Floride, bowie and J-man like this.
    KB


  6. #31
    1000+ Posts bowie's Avatar
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    Fair enough.

    Cheers for posting those manifold pictures again to by the way.

    Works: 1999 Volvo S40 T4, (has Choo Choo's)
    Playing: R12, SuperPos, thinks It's a race car.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16
    Wanted Ye old K4J / K4M Click!

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  7. #32
    1000+ Posts Frans's Avatar
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    My .

    If you want to go all out you have to go twin SD. You have to then do an all out calculated extractor as well.

    Reasons: this is simple, you spend good money on a SD that has been designed to properly atomise the air and fuel in a fine combustible mist. Then you need to get that mist to flow in the straightest line of direction as possible. The mist that gets in touch with the walls of the manifold or port or valve stem or whatever is in it sway causes it to return back to a droplet that means nothing when you try to ignite it. With twin SD the route to the combustion chamber is almost a straight line. With a single it has to deviate from its natural line. I'm not saying that it won't be worth the while to do a single but HP is all about getting the max flow. The more flow the the more HP.

    Another old wife's tale is that the ports must be polished. That is a bad thing to do. It must be smooth and straight but not polished. If you take a can of spraypaint and you keep it close to a glass window and you activate the nozzle for 0.5s you will have a run of paint down the glass (polished port) Do that to a matt surface light cast aluminium and you might not have a run (non polished port).

    I had the privilege to automate the Flow Bench of TRD in ZA so that all flows could be selected and adjusted electrically and electronically. I was present with a lot of their testing and another thing that happens in flow is that the flow on the side of the port is just about standing dead still. If a smoke stick approaches the edge of a port while flowing air through the smoke is only sucked in with speed when it reaches 2-3 mm deep into the port. The same happens if you stand next to a flowing river, if you throw a twig in on the side it hardly moves, but when you throw it in the middle of the river it will be swept away with speed. So a polished port doesn't help in any case with flow because there isn't flow on the edge, but when the direction change comes in the port and the mist (which does have a bit of mass) touches the sides it will de-atomise if there is a word like that.

    Now that was a mouth full from my side. I hope it makes sense.

    Frans.
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  8. #33
    1000+ Posts Frans's Avatar
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    Sorry I was going to say that a downdraught causes 90 degree bends for the atomised fuel to follow and that is why a single SD is Better.
    Another thing is it will be good to get hold of the later R9 or R11 heads that have the ports further apart and and then more straight line.
    KB's head has the narrow positioned port as in his photos but it is sure good enough for decent HP.
    Frans
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  9. #34
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    You are 100% right Frans, but the OP is talking about sticking it on a std 1108. It may have a 10S head on it if he’s lucky, unlikely to have a decent cam or large valves though.

    I’ve driven both single and twin Weber setups on the same R10 with a 1.4 engine, and if I was in HIS position I would stick a single DCOE on it; use a modified R12 inlet manifold and have a custom pipe and muffler installed. That is the setup I had in the first few photos.

    Edit - Frans, we never got the R9 or 11 heads over here to my knowledge so we’d have to chase them from OS. Using your “farmer makes a plan” logic, we’d make the best of what we have!
    KB


  10. #35
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    Quote Originally Posted by bowie View Post
    Fair enough.

    Cheers for posting those manifold pictures again to by the way.
    Quite. I get a little twitch in the lower artery every time I see this..


  11. #36
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    I´m happy to have one of the R5 heads Frans is refering to.

    The intake/exhaust gasket looks like this with the pairs of inlet ports having 45mm centre distance. The openings is 28X32mm. I havent yet taken the manifolds of my C2J engine to see wether the ports are bigger or smaller than the holes in the gasket.



    Wery few if any SD carburettors have runners that close but if swithing to EFI is an alternative there is paired throttle bodies that should be a pretty good match.
    Last edited by Reidar; 10th February 2018 at 04:32 PM.

  12. #37
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    I feel like we have had a down draft / side draft debate here before. But I still feel like I want to talk about V engines where downdrafts are required due to packaging, and in some of these cases there would have been a 90~ degree change in direction no doubt?

    I imagine this is where a carefully sculptured inlet manifold (and the differences we see) would come into play to create the best path possible either way, so is it really that bad? The side/ down difference? (assuming you have a trick inlet manifold).

    What I mean is with a sidedraft on a upright engine, you are most likely changing the inlet manifold as well, which is probably where 50% of the fun is.

    Then again, what does a trick downdraft manifold look like on an upright engine
    Last edited by bowie; 10th February 2018 at 05:09 PM.

    Works: 1999 Volvo S40 T4, (has Choo Choo's)
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    I guess the carburettor or throttle body should aim in the direction where it is sufficient room for it.

    I've newer seen two double downdraughts on a Renault but its quite common on older fiats and fords.

  14. #39
    1000+ Posts bowie's Avatar
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    I am on the right track. it is about getting it as close to the valve as possible, with fewer bends as possible..

    Stolen from a Gemini forum..

    OzGemini.com ? View topic - Downdraft VS Sidedraft?

    Had to respond to this even though it is old now. There is absolutely no difference in the design philosophy of sidedraft or downdraft Webers; in fact in many cases the parts are the same. Typically the only difference is for physical design considerations, for example DCOE sidedrafts have the chokes set a fair way apart to match the distance between inlet ports on engines and can thus have their fuel bowl between the chokes, whereas DCNF downdrafts are designed to fit in the middle of V engines and thus have fuel bowls on the sides; meaning very different internal design. However there is no performance differential between side and downdraft Webers of the same size.

    However, the way you implement it on your car will cause a performance change. On a typical 4 pot engine, sidedrafts like DCOEs will generally give you the most top end power because of the ability to position them close to the intake valve and the straighter runners on the inlets. Downdrafts require a bend in the intake and thus have some reduced efficiency in comparison. However, thus can be turned in your favour, as you can often get longer inlet ports with a downdraft, which will give you far better mid range torque; the 'S' manifolds for sidedrafts on Geminis do the same. In addition, some engine bays have to have one or the other because of size restrictions: Alfa straight 4s used sidedrafts in their large engine bays, whereas Lancia with similar but FWD cars (HPE etc) have to use downdrafts. Every carby Ferrari, Lambo and Maserati that I am aware of, and the Porsche 911 etc uses downdrafts simply because of the engine shape.

    In my old Group C Escort, we had both setups. The homologated manifold was the twin 44 IDF downdraft manifold and this provided the best top end power, thus was used at Bathurst etc. However, putting sidedrafts onto this manifold with adaptors gave you an S bend like the Gem manifolds, with a much longer inlet tract which lost HP but gained torque in some areas, and this was used for places like Amaroo and Calder, and when it was wet. You will see downdraft 48IDF and sidedraft 48 DCOE Webers on A9X Torana Group C cars for the same reason.

    The Dellorto is, as Murray says, simpler - it was designed as a cheaper to produce copy of the Weber, but is as good in normal use. The only problem with them is that the ones you see in Australia have generally come off production cars (especially the 40 DHLA) such as Alfas and are often 'model specific' with less adjustment provided for.

    I don't know which is better in Geminis - Group C has to use the original inlet manifold so I have only ever used downdrafts. I suspect the S bend sidedraft manifolds won't give you the biggest top end you can get because of the length of the runners, but having the thermostat etc in the manifold stuffs up being able to get a short one in there. I suspect the dual downdraft manifolds would allow the shortest runner. BTW Murray, all the Weber manifolds have to have a decreasing cross section because you are going from a 40 or 44mm carby inlet to a 34mm inlet port on the head, doesn't matter whether they are side or down.

    John

    But thinking of our Sierra head designs.. with our valves being wait, only 15~ degrees lent over, a trick manifold trying to make that as straight as possible would involve a carby sticking out of the bonnet I suppose?

    Weber Manifold for 8 port sierra motor-img_20180210_161939381.jpgWeber Manifold for 8 port sierra motor-img_20180210_161647634.jpg

    Whats a modern honda head look like, I suppose the valves are waaaay lent over?

    I just realized too that a lot of you have been talking about a "better" head with the inlet ports spaced further, of which this 12 head I have is not.

    Works: 1999 Volvo S40 T4, (has Choo Choo's)
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    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16
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    Quote Originally Posted by bowie View Post
    I am on the right track. it is about getting it as close to the valve as possible, with fewer bends as possible..

    Stolen from a Gemini forum..

    OzGemini.com ? View topic - Downdraft VS Sidedraft?




    But thinking of our Sierra head designs.. with our valves being wait, only 15~ degrees lent over, a trick manifold trying to make that as straight as possible would involve a carby sticking out of the bonnet I suppose?

    Click image for larger version. 

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    Whats a modern honda head look like, I suppose the valves are waaaay lent over?

    I just realized too that a lot of you have been talking about a "better" head with the inlet ports spaced further, of which this 12 head I have is not.

    Hi Gents,

    For what it's worth, I have a cast ali Datsun/Nissan inlet manifold for twin SD Webers that I was going to use on my R9 engine but ended up manufacturing a complete inlet / exhaust set up for my race car. There is work to be done on it to fit, but I am sure that Frans can help.
    I am looking at ZA R1250.00 for it plus the freight cost to get over to wherever.

    Regards,

    Arthur.

  16. #41
    1000+ Posts renault8&10's Avatar
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    LeMans Tragic,

    You need to check out Potenz's current parts for sale ad STAT! and pick up that Lynx manifold and Sonic extractors for your R10.
    Not that readily available, and pretty good prices!
    LeMansTragic likes this.
    KB


  17. #42
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    stumbled across these pics of my extractors .r9 r11 head
    Attached Thumbnails Attached Thumbnails Weber Manifold for 8 port sierra motor-20150217_121246.jpg   Weber Manifold for 8 port sierra motor-20150217_121408.jpg   Weber Manifold for 8 port sierra motor-20150218_193521.jpg  

  18. #43
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    Quote Originally Posted by potentz View Post
    stumbled across these pics of my extractors .r9 r11 head
    Serous Eye candy there Potentz. Looks great

  19. #44
    1000+ Posts bowie's Avatar
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    Thinking of these close ports we have, I stumbled upon these the other day when looking at a turbo vw 1600 engine

    http://www.autoracingspeedshop.com.b...sca-kombi.html

    Those ports looks pretty close!

    Sure the orientation is a bit wierd but it might not be so terrible with a side draft carb of course. .. after they are shortened probably..

    Works: 1999 Volvo S40 T4, (has Choo Choo's)
    Playing: R12, SuperPos, thinks It's a race car.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16
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  20. #45
    1000+ Posts bowie's Avatar
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    Ah these are better.

    https://vwparts.aircooled.net/Bugpac...set-p/1039.htm

    So much VW after market

    Works: 1999 Volvo S40 T4, (has Choo Choo's)
    Playing: R12, SuperPos, thinks It's a race car.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16
    Wanted Ye old K4J / K4M Click!

    "More and more of less and less" - Marina Abramović

  21. #46
    1000+ Posts bowie's Avatar
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    Can't quite confirm what those port sizes are, some references day 35*32 others say 32*30.

    But geee-wilacas it looks suitable for our narrow port engines.

    #EDIT! Standard dual port heads are 35*32.
    Last edited by bowie; 4th March 2018 at 11:57 PM.

    Works: 1999 Volvo S40 T4, (has Choo Choo's)
    Playing: R12, SuperPos, thinks It's a race car.
    Previous: SuperGrumpy fuel spitting 504ti(ish), SuperComfortable 505 STI, SuperDoper carried my groceries Mi16
    Wanted Ye old K4J / K4M Click!

    "More and more of less and less" - Marina Abramović

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