Question aimed at rubjohnny

Discussion in '8-valve' started by Umptibalongo, Oct 3, 2019.

  1. Umptibalongo New Member

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    Rubjohnny this ones aimed at you but all advice is extremely welcome

    I’ve recently (like a year ago) done a head swap on my mk2 1.8 8v GT , I mistakenly got a digi head but followed your advice , blocked the injectors and stuck a Weber dfev 32/36 on it ,also I did head work and got a TA technics 4-2-1 manifold whacked on

    And it’s great

    My question is ...

    My next move is rebuilding the block with 11:1 CR pistons and new rods

    New oil and water pumps

    New black diamond clutch

    Also , later ..

    I’m planning to port the original head

    40mm intake 35mm exhaust valves

    3angle valve job

    Neumann 268 fast road cam

    So question is

    Have I missed anything ?

    Will it blow up ?


    (I don’t want a Valver btw)
     
  2. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    That is a question for a tuner.
     
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  3. Tristan Forum Junkie

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    It won't blow up unless you do something wrong whilst building it, like leave something loose or get the timing wrong for example. Compression is fairly high for a road car, so try use quality fuel and not too ignition advance. I'm assuming you're using good quality forged pistons?
    Have you an oil cooler, and a good radiator ?

    It's quite a bit of money to throw at an 8v, Lord knows I've been there and done it myself, so you have to be sure it's what you want, and won't get tired of it soon.
    Mine is 2.0, TSR Digi head I tweaked a little, slightly higher compression, TSR fast Road cam and stainless 4 branch, with careful adjustment to the fuelling by adjusting the AFM , and tbh, it's not that much faster up to 70mph than my mates standard but blueprinted 1.8 8v digi. It didn't really bother me much as I had the bits almost free, but for the price of forged rods and pistons you'd probably have 160bhp of ABF fury...
     
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  4. Umptibalongo New Member

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    It’s not necessarily just about speed for me
    I’ve owned this motor since 2001 and most of that time it’s been in a crap state of repair
    The idea of building a bulletproof brutal 8v is more interesting to me than owning a faster 16v or turbo .. or whatever
    You think oil temp could be an issue ?
    I’ll look into that
    (Was gonna go with wossner 83mm forged pistons , now I’m thinking wiseco 82mm)
    Thanks for the reply dude
     
  5. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    One thing Tristan did not mention was how you plan the control the engine.

    With all you have done to it, it will be far from the stock VW ECU control window, so the standard ECU needs to be either remapped or binned for an SEM.
    Having actually played with stock Digifant 2 ECUs, they are still rubbish after a lot of calibration and mapping effort.

    That is why I said this question is for a tuner or folks who have actually modified their cars and had them mapped, with hardware changes similar to what you have gone and done.
     
  6. Umptibalongo New Member

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    It’s got a carb .. unless you mean that little black plastic thing under the top right hand side of the bonnet ? Not sure what that is
    Forgive my massive ignorance
    It’s a digi head with the injectors blocked off and a Weber .. won’t that work ?
    Cheers for the reply ;)
     
  7. Tristan Forum Junkie

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    You're wasting your time, frankly, trying to build a high spec 8v that's still breathing through a stock carb. You'll need a pair of Webers or similar, or throttle bodies unless you go down the route of using a digi manifold and throttle body with oe style injection. And then you'll need a proper ignition system capable of a fat spark and an advance curve you can optimise. Which a stock carb'd car won't have.

    For my own, I'm fitting a standalone engine management system, by Omex, purely as a learning thing and because I have it sitting on the shelf for years from another project.
    That's what my good friend Toyotec was alluding to in relation to controlling the engine


    "black plastic thing", if that's the box up near your rhs bonnet hinge, that's your ignition amp, or on an injection car the (outdated, almost useless) ECU.
     
  8. Umptibalongo New Member

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    Ah , makes good sense that it would have breathing issues

    Although I was under the impression that the twin choke downdraft 32/36 dfev Weber could feed anything up to a 3.0 Ford Granada ?

    I guess it’s a different type of performance

    I don’t want to go down the injection route

    I want the engine to look like a stock carb model and all the mods (excluding the manifold) to be internal

    This is really helpful guys thanks
     
  9. Tristan Forum Junkie

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    You would be well advised to chat to Jason Moyle, JMR, aka Mr Hillclimber. He knows his onions when it comes to making the 8v really work.
    Have you had your current setup optimised on a rolling road? That's the only way to ensure it's working well.
    How much more performance are you looking for?

    Oh and one thing you didn't mention in your original post was a vernier pulley.
    If you really insist on keeping the carb, I'd still advise on something like a DTA s40i, for the ignition, Alex who owns the company is a VAG enthusiast.
     
  10. Umptibalongo New Member

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    Well , I haven’t used a rolling road but there’s a massive improvement from the first round of mods .. it definitely flows much better , revs like a dream so I’m happy

    I forgot to mention a vernier but I wouldn’t get a fast cam without one (isn’t that a way to rectify your advance curve?)

    Yeh MR hillclimber knows his stuff ive read loads of his posts !

    Also I forgot about needing a stronger spark for higher compression , denser fuel air mix and all that
     
  11. Tristan Forum Junkie

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    Vernier is more for fixing cam timing, not ignition.
     
  12. Umptibalongo New Member

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    so , the “black plastic thing” is useless...
    would it be simply a case of removing it and replacing it with one that’s up to the job ? (DTA s40i)
    As in
    Does it just plug in and go ?
    I seriously doubt it’s that simple haha
    Would be great if it was tho

    Also is replacing the coil for a heavy duty one the solution for a fatter spark , logical no?
    Cheers
     
  13. Tristan Forum Junkie

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    Certainly not plug and play.
     
  14. Umptibalongo New Member

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    I’ve found a local dealer for the DTA s40i which is nothing short of a miracle because I’m in south Tenerife
    So I’m guessing without this level of spark management the motor would run extremely poorly ? Or is it just that it wouldn’t run at 100% efficiency ...
    Also .. I’ve been thinking maybe just whack a Neumann 268 fast road cam in it for the time being ... then later on do the head work ... then the ECU ... then finally the pistons and rods (and at some stage an oil cooler)
    Gets expensive all this doesn’t it x(
     
  15. Tristan Forum Junkie

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    I think the idea of just throwing in the cam and optimisation of what you have on a rolling road could surprise you, maybe if you want to pull the head and do some porting and polishing.
     
  16. Umptibalongo New Member

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    Yeh I could run that setup for say a year while I seriously tart the other head up (the original one) bigger valves , 3angle job , port match the intake , polish the chambers then see how that goes
    The whole idea of a rebuilt block was to theoretically return to zero miles and throw a new clutch in there and be bulletproof
    But I can’t do everything at once
    As they say in Spain
    Poco a poco
     
  17. Tristan Forum Junkie

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    One step at a time.
     

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