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Thread: Z20 Top Hat an mods

  
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    dannysport18's Avatar
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    Z20 Top Hat an mods

    Well first up you have the std vauxhall top hat used on the Z20 cars
    inlet on std one is Internal Diameter 45mm outlet Diameter is 60mm



    note i have started to make the inside of this std one bigger with a Flap wheel

    next i also have one of the Norm29 ones he had made up very nice work andy
    inlet Internal Diameter 62.5mm outlet Diameter 60mm so a lot better then std


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    MikeWarner's Avatar
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    Looks good, but I doubt it will make any difference. Are you upsizing everything down flow of the turbo? If so, what boost are you running? You could increase lag, and also increase inlet temps and reduce air velocity (thus increasing back pressure).
    8 Astras in a row! Can Anyone Beat That?
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    Quote Originally Posted by MikeWarner View Post
    Looks good, but I doubt it will make any difference. Are you upsizing everything down flow of the turbo? If so, what boost are you running? You could increase lag, and also increase inlet temps and reduce air velocity (thus increasing back pressure).
    How would you get around this?

    Would it be a case of upsizing most things ie:
    tophat, powerpipe, intercooler pipes? or is all that still going to increase lag etc?
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    I am just going to play with the std top hat for now make it a few mm bigger inside an polish the insides
    I have changed all my pipe work from intercooler to TB to 51mm now

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    I see.

    Jonesy - upsizing increases the volume betweent he turbo and head, so is more compressible. Plus - as the same amount of air goes into the head, the air is effectively travelling slower, thus most susseptable to heat soak. The slower velocity also reducing ram effect (i.e. increases back pressure).

    An enlarged setup does reduce resistance if the air flow is greater - i.e. on seriously modified engines.
    8 Astras in a row! Can Anyone Beat That?
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    Mike - if all the pipework to tophat is say 58mm id, will the smaller id of the tophat accelerate the air or just cause a restriction - i.e. slow it down?

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    the casting of the top hat is crap inside you can clean it up a lot with a flap wheel an some polish
    also the top hat mods do work on high power cars
    also on the pipe work you have on the 888 the mk5 pipes dont look that neat with the bends in not good for air flow


    could you not just run 58mm pipe from the intercooler to top hat ? in a line say a custom power pipe ?
    like this but bigger with the sensor mounted on the pipe ?

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    Quote Originally Posted by dannysport18 View Post
    the casting of the top hat is crap inside you can clean it up a lot with a flap wheel an some polish
    also the top hat mods do work on high power cars
    also on the pipe work you have on the 888 the mk5 pipes dont look that neat with the bends in not good for air flow
    Hence why the pipework is being changed Danny

    The reason why we had to revert to the mk5 pipework is because of the Pace supplied pipe with MAP sensor mount - it is a bit too long. This meant that with a std type power pipe fitted the Pace pipe by the battery rubbed against the top coolant hose from the rad and split it!. The idea I have now is to use a mk5 std pipe with MAP sensor mount on the vertical up by the battery, and revert to a std type power pipe again to smooth out the air flow.

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    Quote Originally Posted by dannysport18 View Post

    could you not just run 58mm pipe from the intercooler to top hat ? in a line say a custom power pipe ?
    like this but bigger with the sensor mounted on the pipe ?

    that was one of my next mod ideas too,but a bit unsure now, i assumed it was a good idea
    Regal Phase 3.5,VXR Turbo,VXR AFM,VXR Injectors,Courtenay FMIC,Dbilias Flowmaster,Regal Precat,Miltek exhaust,Lightened Flywheel,Uprated Clutch,Denso Plugs,Veccy Pipe,Eibachs,308mm Discs

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    on the top hat thing you looked at at trax thats the one up top
    on the top hat i could think of one way to get around your front strut
    60mm 90° alloy cut an welded inpace
    also a alloy bend with 15 cm of legs is only £16 from the pipe shop

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