405 DKZ Head on 205 DFZ Block
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  1. #1
    Fellow Frogger! Aprilia's Avatar
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    Default 405 DKZ Head on 205 DFZ Block

    I have a series 1 205 GTI XU9J1 engine and I'm looking to put a DKZ stock head from a 90 405 XU9JAZ engine.
    I found a post by Peter T., saying this was a good combination and would have around 10.5:1 .
    I dropped the head into a local machine shop ( not a pug guy ) to skim and 3 angle cut. He seemed to think that sort of compression ratio was not good for head gasket life and recomended a decompression plate to drop it closer to 9.2:1.
    The car will be a daily driver and I'm looking for low to mid range torque, any info much appreciated.

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    Quote Originally Posted by Aprilia View Post
    I have a series 1 205 GTI XU9J1 engine and I'm looking to put a DKZ stock head from a 90 405 XU9JAZ engine.
    I found a post by Peter T., saying this was a good combination and would have around 10.5:1 .
    I dropped the head into a local machine shop ( not a pug guy ) to skim and 3 angle cut. He seemed to think that sort of compression ratio was not good for head gasket life and recomended a decompression plate to drop it closer to 9.2:1.
    The car will be a daily driver and I'm looking for low to mid range torque, any info much appreciated.
    Just fit the DKZ complete.
    10.5 to 1 is too high in my experience, especially with standard management and camshaft.
    Graham

  3. #3
    1000+ Posts PeterT's Avatar
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    Graham is right. You need more cam timing and better management to run 10.5:1. Keep it at 9.5:1 max with std components.

    '92 205 Mi16
    '90 Mi16x4

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    1000+ Posts cam85's Avatar
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    Live on the edge!!!
    94 205 Gti Classic #9
    91 205 Si
    87 205 GTi Race Car
    http://www.aussiefrogs.com/forum/res...-race-car.html

  5. #5
    Fellow Frogger! Aprilia's Avatar
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    If I install the complete DKZ engine, can I still use my inlet manifold and injectors, ecu , also is there any loom or wiring modifications I that I need to do ?

  6. #6
    1000+ Posts PeterT's Avatar
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    Yes, you can install the complete engine with 205 parts. However, as the head is being reco'd, I'd get the guy to enlarge the chambers slightly so that you can use a standard head gasket. It will be a much better result.

    '92 205 Mi16
    '90 Mi16x4

  7. #7
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    I'm running 10.5:1 (my machinist said it was 10:1 but the math says 10.5) with the SI head on the DFZ block with the standard Jetronic and Peters cam/timing with approx 11 degrees ignition advance.

    I'm loving it, seat of the pants it feels like it would give my Clio 172 a run for its money...but then maybe there's just an enhanced impression of speed in the gti. So far, 600k in, apart from some issues with the idle (which I think I've sorted now), I can't see a downside.

    Am I right in thinking you'd find out pretty quickly if your head gasket wasn't up to the task with the higher compression?

    Dave

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    Quote Originally Posted by DaveT View Post
    I'm running 10.5:1 (my machinist said it was 10:1 but the math says 10.5) with the SI head on the DFZ block with the standard Jetronic and Peters cam/timing with approx 11 degrees ignition advance.

    I'm loving it, seat of the pants it feels like it would give my Clio 172 a run for its money...but then maybe there's just an enhanced impression of speed in the gti. So far, 600k in, apart from some issues with the idle (which I think I've sorted now), I can't see a downside.

    Am I right in thinking you'd find out pretty quickly if your head gasket wasn't up to the task with the higher compression?

    Dave
    Head gasket won't be a problem, more about pinging.
    The modified cam will reduce this as it drops the effective compression a little.
    Graham

  9. #9
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    Quote Originally Posted by GRAHAM WALLIS View Post
    Head gasket won't be a problem, more about pinging.
    The modified cam will reduce this as it drops the effective compression a little.
    Graham
    I was expecting a lot of pinging, but with 11 degrees advance I can't detect any, if I push it beyond that I can just detect it under load when hot. Maybe when the weather heats up and I have the air con on it'll make itself known, wait and see.

  10. #10
    Fellow Frogger! Aprilia's Avatar
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    Thanks for the info guys.
    I have a complete DKZ engine from a 91 Series 3 GTI 165,000 km, that I will install. It only needs a timing belt, tensioner, water pump and I'll check the shims. So avoiding engine surgery.
    The 405 DKZ head was one I pulled from a wrecker.
    Hopefully another month and she will be up and running.
    Attached Thumbnails Attached Thumbnails 405 DKZ Head on 205 DFZ Block-img_0062.jpg   405 DKZ Head on 205 DFZ Block-img_0064.jpg  

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