100bhp/litre from a na 1300 8v; feasible?

Discussion in '8-valve' started by nuttinnew, Apr 24, 2005.

  1. nuttinnew Forum Member

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    After reading various posts I see 100bhp/litre from a 1.8 16v is not beyond the realms of sensibility but would it be likewise with summat like a Polo GT engine? I'm guessing Digifant would have to be binned for tbs and standalone for a start.



    Just curious, sorry [:$]
     
  2. greg s Forum Member

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    Yep, there's a race series in Germany which uses GTs and they run
    somewhere around 100bhp/litre. Twin carb manifolds and Schrick cams
    were quite easily available last time I looked into it. Our resident Polo
    clever clogs, jbmg40, will know all the details.
     
  3. theboymike Forum Junkie

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    It's probably just about possible, but you'd be limited by the valve area of the 8v and you'd probably have to replace a lot of the internals to allow it to safely rev high enough.

    Throttle bodies and stand alone management would be essential, and it'd probably be a pig to drive below about 5k [:[]

    Edit: Beaten by Greg, who seems to have provided a much more conclusive answer :lol:


    Edited by: theboymike
     
  4. darrynK

    darrynK Forum Addict

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    1300cc is cross flow head so good for power and efficiency. bigger valves (max is 2mmbigger) along with non-hydraulic head and a helluva lotta work and it's possible :)

    TSR once got 111bhp/litre outta a 1300cc (145bhp)
    Edited by: darrynK
     
  5. fthaimike Forum Addict

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    Was that the weird one where the piston was something like wider than it's stroke length or somthing? if it was i was amazed at the power from the thing.
     
  6. DEX

    Dex Paid Member Paid Member

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    that's not an especially weird combination - a lot of engines are *over-square* - it has two main benefits, firstly the shorter stroke allows a higher max revs, but also the greater bore means more room for large valves


    as for 100bhp/litre out of 1.3 8v

    a lad in the RAFMSA runs a 1.3 nova tarmac rally car - it's got over 100bhp atw so has got to be pretty close.
     
  7. Dub Nutta Forum Member

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    1.8 16v should see 130-140bhp/litre in full race form.

    as for the polo,deffintly possible, would need to look at steel rods and pistons i would think but due to small stroke and low piston weight you might be ok up to 8kish.

    You would need a serious head with alot of work and a nice, schrick do a 268 cam but you might need to look in to a custom grind.

    Why not fit a 1.6 bottom end from the Mk4 polo, that would give a nice increace in torque.
     
  8. KeithMac Forum Junkie

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    What`s the torque like on the 1.3 100bhp/litre cars?
     
  9. prof Forum Addict

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    it'll be a bit poor for a daily driver tho, depends what you want to do with it
     
  10. DEX

    Dex Paid Member Paid Member

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    i'd expect about 100 lbft from a 1.3 8v making 100bhp/litre
     
  11. prof Forum Addict

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    at 6k?
     
  12. DEX

    Dex Paid Member Paid Member

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    at almost exactly 6k, with peak power at around 7k
     
  13. jbmg40 Forum Member

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    1300 8v is a very capable engine, the rods and crank are tough too, but
    high compression is required to get the most of it, meaning aftermarket
    pistons really.



    Sorg sell a kit based on a 37/32mm valve head, twin webers, fourbranch
    and high comp pistons that'll see you over 100bhp, or 110 on throttle
    bodies. This is fairly easily replicated 'at home' and would drive and
    idle like a real car.



    The real deal kicks in when you let them rev how they want to though,
    race spec motors will put out 170bhp if you're willing to shift
    everything up the rev band a long way.



    324 deg cam with 12.5 lift, moving 38.5/33mm valves, throttle bodies, steel rods, and 9000 rpm limit will get you there...



    Or the ultimate for the 1272 is to convert to 16v, which in race tune
    will see over 200bhp @ 11000 rpm, with useable power between 6 and just
    under 12krpm [8D]



    For those wondering why you'd do that, rather than just use a 1400,
    1600, 1800 etc etc, you got to bear in mind the light weight and
    simplicity of the old 1272 motor- they're like a textbook diagram of a
    4 stroke ohc engine - no complexity, no problem [:D]
     
  14. amstrange1 Forum Member

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    What size valves are stock GT ones?


    I have a GT lump lying around needing re-ringing and fancy a bit of a summer project. I'm thinking along the lines of 4-branch, headwork (maybe larger inlet valves?), cam (276 deg perhaps?) and some kind of pikey inlet manifold to fit some bike TBs I have along with Megasquirt.


    I am I being naiive to expect around 120bhp from that combination? Would possibly look at getting the crank and flywheel machined too, but not sure whether it'd be worth it?
     
  15. philip walker Forum Member

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    Chuck a motorcycle engine in.....GSXR 1000 is well over 100hp. Bikes broke the 100hp per ltr years ago
    Mid mounted in a spaceframe.
     
  16. jbmg40 Forum Member

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    Salzmann sell a rear mount frame kit using polo parts to take bike
    engines, so its doable even if your not a pipe bending genius :)
     
  17. greg s Forum Member

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    What did I say? Clever clogs! :lol:
     
  18. jbmg40 Forum Member

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    [:-B] [:$] :lol:
     
  19. nuttinnew Forum Member

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    Just fcking leave it :lol:Leave the Google alone.

    If only we got GKs over here [:^(] It certainly seems I'd be better off strting off with a solid lifter head than the GT engine I have. Big valves would be the next step (after a vernier, my blue GT was never right) but then that's going to be a good few 100s, am I right in thinking an early 1400 16v head goes onto an 1300 bottom end?
     
  20. Armour

    Armour Forum Junkie

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    I looked into this a while back, WL Motorsport is a cracking site for throtle bodied 1300 8v's :)

    It's a lot of money to go that route, nice to be different but same old story G40 will be quicker for less most probably!

    Alan
     

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