Polo GT Tuning

Discussion in '8-valve' started by matt1471, Nov 12, 2003.

  1. matt1471 Forum Member

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    i've got a Polo GT lump in my mk1 golf, fitted up with pipercross induction kit, 4 brach s/s manifold and ashley competion system. Looking to get a cam in the near future and uprate the injectors to G40 ones or 8v GTi.


    Are there any other, cheapish mods that i can, possible myself from home to increase performance? things like ported throttle body etc...


    how do i do that?!


    thanks guys, matt
     
  2. Polo Classic Forum Member

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    No need for bigger injectors. Even with the cam, you shouldn't need a remap. You can get yourself a Dremel and match the outlet of inlet manifold to the gasket.

    As for cam, go for something like the Schrick 268 or similar. I would also loose the Pipercross induction and go back to std airbox with K&N panel. The airflowmeter is very sensitive to viberations
     
  3. matt1471 Forum Member

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    err...so what? just make the end of the inlet manifold bigger?? by hom much and how deep into the manifold should i go?


    interesting comment about the pipercross...i've had i't fixed in place, so it's not going anywhere! i would put the original box back on, but it won't fit in the engine bay!! hence why the piper x!:p
     
  4. Polo Classic Forum Member

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    It is called port matching. You just remove some material to make the transition smoother, but do not polish it up.

    Some of the GT inlet manifolds is cast very thight around the injectors, and you can probably remove some material around there also. When you have the manifold in your hand you will understand what I mean. Took me max one hour to port match my GT inlet manfold to the gasket on the G40 head. First porting I ever did
     
  5. matt1471 Forum Member

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    cool...does it make a difference? so do the same around the injectors as well u say?


    i just make the ports on the inlet manifold the same size as the gasket, yeah?
     
  6. prof Forum Addict

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    re:Intake Port Matching

    I have seen way too many people hog out the intake ports and runners to match the gasket. This is a very bad idea, there is no reason to make the largest part of the port even larger. Only when heads are very modified does this area need to be worked. Instead of hogging the ports to the gasket size, use the gasket to take measurements from and match the ports only. Take as little metal away as possible. The ports should not be matched on the port floor, this is where velocity is lowest and any port matching will not help flow a measurable amount. Is is actually good to have a mismatch here. A step down into the head can create some turbulence that can reintroduce dropped out fuel back into the airflow (a ski jump effect). With large ports and runners, the fuel will drop out and run along the port floor at low rpm and this does help. A step here can be as big as .125" without effecting top-end power.
     
  7. Golden Forum Junkie

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    Another important point about port matching is too many people just sit the gasket over the studs and use that as a template. You need a far more accurate way of holding the manifold/gasket in a repeatable accurate way. My favourite is to use a pair of roll pins between the manifold runners.
    Heres a good trick, once youve found a good way to hold the assembly accurately together spray, paint (nothing that wont wash off easily with thinners or something) down the manifold and head port, then you can see on the mating faces the miss matches. It can help to do this first to try and estimate the best initial position before you get a fixed position for the manifold.
     
  8. Hardhitter New Member

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    I've never had any problems with my p/x induction kit. A bit of port matching wouldnt go amiss. Maybe a re-map too.
     
  9. Hardhitter New Member

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    Forgot to add, it's worth doing an oil breather catch tank. You can make one for less than a tenner [:^:]
     
  10. madmk4 Forum Member

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    Guys, you dont want to be enlarging the ports on the 1300 head.



    They're already enough of and 0 shape as it is.

    the main work in the the valve seat, theres a horrible step, that is best to be cut down, and then blend the seat and port together, more commonly known as throat blending.


    When youve done this, youd be surprised how much larger the ectual size of the valve is, at least a mm bigger, and you cna geta better seat to if you're good enough.


    Theres a few other bits and bobs that could do with tidying up on the head aswell,most of which are fairl obvious..
     
  11. madmk4 Forum Member

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    Adding onto that, the 1300's head is rather a rough finish to, could eb alot lot better. but when you do it, make sure whoever does it doesnt get rid of the lump on the port wall, its on the right hand side on most.. it's rather important.
     
  12. matt1471 Forum Member

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    how do i go about making an oil breather catch tank?


    what will it do?
     
  13. dj chris New Member

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    some guy on porka.net is selling polo gt chips
     
  14. Hardhitter New Member

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    It's pretty easy to make an oil brether catch tank. You needa 1m length of 25mm borerubber hose and a 1 litre bottle, I'm using an empty oilbottle.


    You remove the oil brether pipe that goes in to the inlet pipe, the breathervalve and run the 25mm hose straight from the cranckcase brether pod into the tank. Block the hole left in the inlet pipe and thats it.


    Basically it stops oil vapour being burnt in the engine, which lowers octane level. Plus you dont get oily depsits and water vapour in the inlet.

    Forgot to add that you need yo drill some holes in the top of the tank to vent fumes and pressure.
    Edited by: Hardhitter
     
  15. nuttinnew Forum Member

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    How easy is it to compare how well a head has been modified compared to a std one with the two on a bench? Would I have to pop a valve out?
     
  16. madmk4 Forum Member

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    Yup.





    You really need to take them all out to check that the work is of a good quality, and the ports have been evenly treated, same sixe tc etc throughout the head.
    Edited by: madmk4
     
  17. tallika_fan

    tallika_fan Forum Member

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    I bought one for my GT. I think i'll have a go at the catch tank at the weekend.

    As for the conversion mate, did you do it into a Driver? I was going to carry out this very conversion myself though didn't in the end. How long did it take you and what did you need extra?

    Cheers
     

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