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Gtr track car

Last post 11-25-2009 02:09 PM by R1hoon. 9 replies.
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  • 11-24-2009 06:57 PM

    • waxhead
    • Top 50 Contributor
    • Joined on 12-17-2007
    • gold coast
    • Posts 882

    Gtr track car

    I thought you guys may be interested in a gtr track car engine i am building for some one

    This is the nissan godzilla skyline

    Just been working on the head today and have the intakes close to finished

    Will just hit them with the sandblaster after this to get a uniform  finish on all the ports i dont want them in a polished state

  • 11-24-2009 08:24 PM In reply to

    Re: Gtr track car

    waxhead:
    Will just hit them with the sandblaster after this to get a uniform  finish on all the ports i dont want them in a polished state
    Why? I thought polishing ports was the go..?

    Tassie's number one scooter dealer.

    www.scootershoplaunceston.com.au

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  • 11-24-2009 08:57 PM In reply to

    • waxhead
    • Top 50 Contributor
    • Joined on 12-17-2007
    • gold coast
    • Posts 882

    Re: Gtr track car

    No it makes the fuel drop out of suspension and you lose power

    I polish them up as you can see then rough them up again but when I rough these ports up its uniform

    If you look into any of my two stroke engines you will see the same rough finish

     

    This is a picture of my old porting style on  mineralli scooter cases 

  • 11-25-2009 12:37 AM In reply to

    • 15UZU
    • Top 25 Contributor
    • Joined on 01-08-2009
    • Slacks Creek, QLD
    • Posts 1,140

    Re: Gtr track car

    waxhead:

    No it makes the fuel drop out of suspension and you lose power

    Correct, but this really more of an issue with carby applications (especially low RPM applications) than with EFI setups where the injector is positioned to spray towards the back of the open valve and the fuel spends much less time in the airstream.

    I've heard debates people have argued that the atomised droplets are more likely to stick & condense on a roughened surface compared to a polished one behind the valve (talking EFI application only). The theory is that the roughened surface will provide more of an opportunity (greater surface area & possible capillary grip) for the atomised droplets to hit & stick compared to a polished surface with finer texture which would permit the super fine droplets to bounce or slide quickly into the chamber & not stay on the wall long enough to puddle.

    I honestly don't think on a hipo street car it really makes that much of a difference that it's worth arguing about - would be different if you're talking F1 though I suppose.



    2010 PGO X-Hot 150cc - clocking up the kays
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  • 11-25-2009 07:20 AM In reply to

    • INMA
    • Top 50 Contributor
    • Joined on 03-19-2009
    • Posts 837

    Re: Gtr track car

    The port finish does make a huge difference.

    I had not been aware of sand blasting being suitable, we always used as cast on the atmospheric engines.  Superchargers might be a bit different.

    I can't see a lot of work around the inlet valve seats, I suppose just increasing the bost flows wharever you want, too easy.

    I am going back 30 years so things might have changed.

    2001 Yamaha Zuma, DR Evo 68 cylinder, Leo Vince TT derestricted, Delorto 17.5 (#98 jet), standard aircleaner, RMS fan, Race CDI, Standard oiler and premix @ 75:1 Shell SX2, Doppler SR3 variator, RMS clutch, RMS R rear shock absorber and Pirelli SL26 tyres.
  • 11-25-2009 07:42 AM In reply to

    • waxhead
    • Top 50 Contributor
    • Joined on 12-17-2007
    • gold coast
    • Posts 882

    Re: Gtr track car

    INMA:

    The port finish does make a huge difference.

    I had not been aware of sand blasting being suitable, we always used as cast on the atmospheric engines.  Superchargers might be a bit different.

    I can't see a lot of work around the inlet valve seats, I suppose just increasing the bost flows wharever you want, too easy.

    I am going back 30 years so things might have changed.

    Yeah I have always found that the rough port makes better hp everywhere

    I would be interested in reading an article that states otherwise

    I alwasy dedag head do my porting and then sand blast with garnett , leaves a beautiful mild corse finish

    I had the throats bored on the inlet side and have them blended them in to the port 

    Its hard to see in these pics are you are seeing the after pics and the step has gone

    In realty these are one of the best inlet ports i have seen in a long time and didnt need alot of work to get there flow right up there

  • 11-25-2009 09:21 AM In reply to

    Re: Gtr track car

    I guess the slightly coarse surface would create microscopic eddy currents that would help to keep the fuel suspended. In the same way the dimples on a golf ball create eddy currents that bring stability to it's flight. But then, if the surface is too coarse- like a really rough casting, then the turbulence would be much greater, and would have the opposite effect...

    just thinking out loud.

    Tassie's number one scooter dealer.

    www.scootershoplaunceston.com.au

    info@scootershoplaunceston.com.au
  • 11-25-2009 10:21 AM In reply to

    • INMA
    • Top 50 Contributor
    • Joined on 03-19-2009
    • Posts 837

    Re: Gtr track car

    Wax, do you use a flow bench?

    I did not see any signs of significant work in the combustion chamber.  On the Datsun L engines there was a need to relieve the area to the side of the inlets to improve flow when the valves were partially open. 

    2001 Yamaha Zuma, DR Evo 68 cylinder, Leo Vince TT derestricted, Delorto 17.5 (#98 jet), standard aircleaner, RMS fan, Race CDI, Standard oiler and premix @ 75:1 Shell SX2, Doppler SR3 variator, RMS clutch, RMS R rear shock absorber and Pirelli SL26 tyres.
  • 11-25-2009 12:17 PM In reply to

    • waxhead
    • Top 50 Contributor
    • Joined on 12-17-2007
    • gold coast
    • Posts 882

    Re: Gtr track car

     Yeah i have a flow bench i can use and i do some times but i more interested in the same flow between cylinders than trying to drag big numbers out of it

    Some times people spend so much time getting flow and loose power due to slow moving air

    The head is not finished yet

    Im just working the intakes and will go on to the exhaust soon actually as i write this i have the exhaust close to finished.

    In the combustion chamber i will be cutting back the quench area as its a known point for deto on these engines

  • 11-25-2009 02:09 PM In reply to

    • R1hoon
    • Top 75 Contributor
    • Joined on 10-02-2007
    • Brisbane
    • Posts 439

    Re: Gtr track car

    the scooter shop:
    guess the slightly coarse surface would create microscopic eddy currents that would help to keep the fuel suspended.
     

    CORRECT - and infact flows faster, that's laminar flow and boundary layer.

    I was going to write a witty and clever comment here, then thought "naa screw it" -- I'm just gunna be a smart a$$.
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