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    Fellow Frogger! Balki's Avatar
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    Default ds engine build

    Im just about to start building a new engine for my safari, engine specs will be, full balance and lightened flywheel, balancing will include clutch plate and preasure plate, compression ratio checked for eveness and lifted just a little, camshaft timing ground for every cylinder to be spot on, now i have had one thought, would it be possible to put a CX 2400 cylinder head on it as the vales are 2mm bigger in intake and exhaust and together with higher compression would flow significantly more, any thoughts

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    Fellow Frogger! ds21bvh's Avatar
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    Hi Balki,

    Yes - I recall reading somewhere that a 2400 head will fit... not sure about the detail nor if there is a performance gain.

    Cheers,

    Mark...

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    UFO
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    Here's a pic (click on the link for more) of UK specialist, Aide Pease's DS25. Yes that is a CX2500 head on there.

    ICCCR 2012 Day 3 by UFO1966, on Flickr
    Craig K
    2009 C5 HDi Exclusive

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    1000+ Posts forumnoreason's Avatar
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    No water pump differences? I thought some mods were required.

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    Administrator GreenBlood's Avatar
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    Quote Originally Posted by forumnoreason View Post
    No water pump differences? I thought some mods were required.
    Isn't it just a matter of swapping the blanking plate and turning the head around?

    Cheers
    Chris
    74 D(very Special) >>Rejuvenation Thread<<
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    "Déesse" Roland Barthes, 'Mythologies', 1957

    The Déesse has all the characteristics of one of those objects fallen from another universe that fed the mania for novelty in the eighteenth century and a similar mania expressed by modern science fiction: the Déesse is first and foremost the new Nautilus.

    (Umberto Eco [Ed], The History of Beauty, Rizzoli, NY, 2004)

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    Real cars have hydraulics DoubleChevron's Avatar
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    Wouldn't your compression ratio fall through the floor using a head from a bigger engine ? The one pictured is probably running very high compression as I can see an LPG mixer on there. High compression and modified timing is the way to go for lpg.

    seeya,
    shane l.
    'Cit' homepage:
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    Fellow Frogger! Balki's Avatar
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    combustion chamber in the head between a cx and ds are the same only the valves are bigger, citroen didnt change a great deal between the engines only the capacity and valve sizes, even the camshafts have the same lift, ive been comparing engine specification for two nights in a row and all i can see is the valves are bigger and the rotation of the engine has changed

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    Administrator GreenBlood's Avatar
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    Quote Originally Posted by Balki View Post
    combustion chamber in the head between a cx and ds are the same only the valves are bigger, citroen didnt change a great deal between the engines only the capacity and valve sizes, even the camshafts have the same lift, ive been comparing engine specification for two nights in a row and all i can see is the valves are bigger and the rotation of the engine has changed
    No mention of valve size but Chris Dunham sees no problem fitting a CX head. The head only requiring the water pump studs and blanking plate swapping end for end. . . he had a prepared CX head advertised here back in 2013
    Citroen CX/DS ported & flowed head

    Cheers
    Chris
    74 D(very Special) >>Rejuvenation Thread<<
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    "Déesse" Roland Barthes, 'Mythologies', 1957

    The Déesse has all the characteristics of one of those objects fallen from another universe that fed the mania for novelty in the eighteenth century and a similar mania expressed by modern science fiction: the Déesse is first and foremost the new Nautilus.

    (Umberto Eco [Ed], The History of Beauty, Rizzoli, NY, 2004)

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    Fellow Frogger! Balki's Avatar
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    thast excellent thankyou, i better pull the head of a cx2400 wreck around here

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    Are you going to use the CX manifolds,they have a different stud pattern to the DS.
    Woody

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    Now go make me a sandwich Hotrodelectric's Avatar
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    Quote Originally Posted by UFO View Post
    Here's a pic (click on the link for more) of UK specialist, Aide Pease's DS25. Yes that is a CX2500 head on there.

    ICCCR 2012 Day 3 by UFO1966, on Flickr
    That's impressive. I would have thought the head would be different enough, you would need the 2500 intake and exhaust setup. At least with the 2400, you still have the choice of carb-vs-EFI. So now I'm wondering just how close the manifolds really are.

    That extra 2mm in/out should provide a pretty decent boost, seeing as th D is lighter than the CX. A lightened flywheel and increased valve duration, and you have yourself a factory hotrod. Drop in a set of Weber sidedrafts and you are going to be screaming down the track.

    Need a new electrical system to handle all that, yes?
    The measure of your character isn't what you do when people are watching- it's what you do when they aren't watching.

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    Quote Originally Posted by Hotrodelectric View Post
    That's impressive. I would have thought the head would be different enough, you would need the 2500 intake and exhaust setup. At least with the 2400, you still have the choice of carb-vs-EFI. So now I'm wondering just how close the manifolds really are.

    That extra 2mm in/out should provide a pretty decent boost, seeing as th D is lighter than the CX. A lightened flywheel and increased valve duration, and you have yourself a factory hotrod. Drop in a set of Weber sidedrafts and you are going to be screaming down the track.

    Need a new electrical system to handle all that, yes?
    That's OK HotRod, You can handle the electrics on your trip Downunder.

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    Now go make me a sandwich Hotrodelectric's Avatar
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    Quote Originally Posted by ScotFrog View Post
    That's OK HotRod, You can handle the electrics on your trip Downunder.
    The measure of your character isn't what you do when people are watching- it's what you do when they aren't watching.

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    Fellow Frogger! Balki's Avatar
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    i will check manifold differences but i can always make a set of custom extractors and possible remachine ds intake of modify cx intake manifolds, i also have an injection manifold lying around so maybe a wolf 3d aftermarket injection system might be in order

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    Quote Originally Posted by Balki View Post
    i will check manifold differences but i can always make a set of custom extractors and possible remachine ds intake of modify cx intake manifolds, i also have an injection manifold lying around so maybe a wolf 3d aftermarket injection system might be in order
    (Whisper it to me again.....)
    Gillian and Chris

    74 D Special, and now a 74 Pallas 23 5 speed with air(maybe). And now a Cactus!

    Oh, and a Holden.

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  16. #16
    Tadpole
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    Default I fitted a 2.1L Cx efi head to my 2.1L DS block

    Valve size were the same as the equivalent DS efi head, perhaps the valve difference you refer to, is for the 2.3L block?

    The oil drains from the top valve train to the sump are on the opposite side of the cylinder head from the DS, so they are not aligned to openings in the block. I had to block these off and drill a hole at each end of the opposite side of the Cx head, to enable the oil from where it collects to drain into two of the pushrod channels, so that the oil drains past the cam followers.

    The pick up holes for both the exhaust and the inlet require blanking and relocation.

    An additional hole needs blanking at the front in lieu of a Cx bracket beside the water pump and a water inlet to the left of the inlet manifolds has differently positioned holes for the water inlet piece which bolts on, which required a little alteration of the Cx part I had to fit that takes a temp sensor.

    ds engine build-cx-2.1-efi-exhaust-side.jpgds engine build-cx-2.1-efi-fully-skimmed-modified.jpgds engine build-cx-2.1-efi-head-inlet-side.jpgds engine build-cx-2.1-efi-head-modified-inlet-side.jpgds engine build-cx-2.1-efi-head-water-pump-end.jpgds engine build-ds-2.1-efi-head-exhaust-side.jpgds engine build-ds-2.1-efi-head-inlet-side.jpg

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    Fellow Frogger! Balki's Avatar
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    fantastic thanks for the pictures, so i gather that a ds21/ ds23 has the same valves size as the cx2400 head is that correct? only asking becasue if also have a ds21 injection engine laying in the shed

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    Fellow Frogger! deesse's Avatar
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    Hi,
    I thought this sounded like a good way to go for a modified DS engine when it appeared here about six months ago.
    Citroen DS 23 Safari RHD twin carb SOLD (1973) on Car And Classic UK [C534694]
    cheers Tony

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    Upgraded in 1996! I fitted a DS23 EFI engine, raised the compression ratio to 9.6:1 and converted it to run on twin Weber 44IDF carburettors rather than D Jetronic fuel injection. Fitted a Facet electric fuel pump, throttle cable, ITG air filter and high capacity alloy fuel tank (by Peacock Engineering). Also had the flywheel lightened and balanced, and fitted a new clutch. In 2001 Hayward and Scott made a bespoke stainless steel exhaust based closely on the standard mid-60s design but less restrictive. Lumenition electronic ignition was added and it was rolling road tuned by Aldon Automotive in Brierly Hill so the jetting is dead right. Then in 2007 I fitted an XM hydractive valve to the front suspension which cuts roll when cornering - a quite amazing improvement! Last year it had new front discs and engine mounts, and last month it had a new battery.

    Ummmm, Balki.. This is us.

    If not you then me.
    Gillian and Chris

    74 D Special, and now a 74 Pallas 23 5 speed with air(maybe). And now a Cactus!

    Oh, and a Holden.

    Lasya, Tibetan goddess of the moon and beauty who carries a mirror.

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    Fellow Frogger! marc61's Avatar
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    Quote Originally Posted by Lasya View Post
    Upgraded in 1996! I fitted a DS23 EFI engine, raised the compression ratio to 9.6:1 and converted it to run on twin Weber 44IDF carburettors rather than D Jetronic fuel injection. Fitted a Facet electric fuel pump, throttle cable, ITG air filter and high capacity alloy fuel tank (by Peacock Engineering). Also had the flywheel lightened and balanced, and fitted a new clutch. In 2001 Hayward and Scott made a bespoke stainless steel exhaust based closely on the standard mid-60s design but less restrictive. Lumenition electronic ignition was added and it was rolling road tuned by Aldon Automotive in Brierly Hill so the jetting is dead right. Then in 2007 I fitted an XM hydractive valve to the front suspension which cuts roll when cornering - a quite amazing improvement! Last year it had new front discs and engine mounts, and last month it had a new battery.

    Ummmm, Balki.. This is us.

    If not you then me.
    Hi guys, that was my car - its sorely missed! My favourite trick was to hit the throttle at 80mph and it would just blast to 90mph and go past the car in front before anyone noticed. Good breathing, twin carbs, nothing like it! Those were the days.

    I like your idea about the CX head, I didn't realise it had bigger valves. Assuming you go for twin carbs and get an exhaust that isn't restrictive which is kind of essential, the main thing I would look at if I did it again would be to get the compression ratio up. I skimmed the head just about to the max and checked valve/piston clearances with plasticine and got it up to 9.6:1. A noticeable lift in power and crispness of response. Further skimming won't get it much higher without mechanical damage, as the inlet valve will hit the piston crown (while on the exhaust valve side there is plenty of clearance). So it would be interesting to look into slight machining of the piston to create a valve pocket and push the CR up to 11:1 or a bit more. That will be fine on superunleaded or LPG and raise the power a lot over standard!

    Cheers

    Marc
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

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    Fellow Frogger! Lasya's Avatar
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    Cheers Marc! I'm really only after low rev gains in torque. (But would take the rest only if I had to.)
    Gillian and Chris

    74 D Special, and now a 74 Pallas 23 5 speed with air(maybe). And now a Cactus!

    Oh, and a Holden.

    Lasya, Tibetan goddess of the moon and beauty who carries a mirror.

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    Fellow Frogger! Balki's Avatar
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    thanks thats awesome, i wouldnt want more than 10:1 for street use with ordinary fuel but will look into putting a valve recess in the piston or maybe reducing valve lift and increasing the duration to compensate, i have thought it might be easier to fit cx big valves to the ds head rather then trying to put the cx head on the ds block

  23. #23
    Tadpole
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    Default DS 23 & Cx 2500 Valve sizes

    Quote Originally Posted by Balki View Post
    fantastic thanks for the pictures, so i gather that a ds21/ ds23 has the same valves size as the cx2400 head is that correct? only asking becasue if also have a ds21 injection engine laying in the shed
    The Cx 2165 head has smaller inlet valves than the Cx 2500, DS 21 & 23, with the Cx 2500, 21 & 23 valves being the same size. The CR of Cx 2500 is 9.1:1 Vs 8.75:1 for for DS engines.

    Interestly, the Cx inlet closes about 10 degrees before the DS inlet closes, so the dynamic CR should be greater on the Cx. I would deduct from this that DS CR could be increased to 9.5:1, clearance permitting, without any significant detonation.

    The attachments refer to the 814-1 and Cx Manual S2 manuals.

    ds engine build-cx-2165-px.jpgds engine build-cx-2165.jpgds engine build-cx-2500-px.jpgds engine build-cx-2500.jpgds engine build-ds-21-23-valve-sizes.jpg
    Last edited by Allplums; 12th May 2015 at 10:01 PM.

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    Fellow Frogger! marc61's Avatar
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    Yes I think working out the dynamic CR accurately is important. Then look to get it up and run always on superunleaded fuel (97 or 98 octane). I didnt look into it but presumably the piston crown on a D engine is reasonably thick, so say a 1-1.5mm well could be machined into it. Might be a good option compared with altering the cam - more duration will reduce the dynamic CR and lose low end torque, and more lift will cause the valve to hit the piston.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  25. #25
    Real cars have hydraulics DoubleChevron's Avatar
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    I'd invest the money on getting a CX petrol turbo engine spinning the wrong way .... Or seeing if we could find a Merak gearbox ( have a look at harrys website, it's a mirror image of the DS gearbox and spins the other way).

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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