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

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

  1. jbmg40 Forum Member

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    Solid lifter heads are a good starting point if you want to rev higher
    - whatever you do though, if you want more than 90-95bhp you're going
    to want high comp pistons. There is an early 16v head that'll fit, and
    I'm sure that fitting the dizzy is just a case of removing the
    electronic sensor and bolting it in place. The problem is that the
    valver has a significant amount of chamber in the head, once again
    pushing you down the custom piston route.



    The junkyard option I'd go for if it were me would be: gt rods and
    pistons, solid lifter head, and a serious decking of the block to raise
    the comp to around 11 / 11.5:1 . A longish (276) duration high lift cam
    and a junkyard throttle bodies job, with most of the money spent on the
    rolling road setting up megasquirt or similar.
     
  2. nuttinnew Forum Member

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    AL; I keep being an anorak though and not wanting to cut the front panel to fit the G in. I've got a balnced GT bottom end, Schrick 285 and head to suit (plus all the injection and a G40 exhaust) and am pondering what to do next as it's about time this engine was used, if not in the Polo then in the 79 Golf I've recently acquired [:$]
    My daily driver atm is an early Golf2 1300 and it goes surprisingly well, so well it's probably best left alone tbh!

    I wish I had a cam for a solid head. Ah, just checked the part numbers and a cam in a knackered head I heave is the same as a GK :)

    Would the GT injection or a single Weber be hugely limiting?
     
  3. amstrange1 Forum Member

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    That's pretty similar to what I was planning actually. Though not sure whether to get a hydraulic head converted to solid lifters (at the same time as porting/flowing work), or get a solid lifter head worked on - or just to stick with a ported hydraulic head?


    What do you reckon about valve sizes John - keep them stock?
     
  4. jbmg40 Forum Member

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    I'd say if you can get larger valves then its pretty important,
    hydraulic heads are ok to 8krpm as long as the lift isn't too crazy,
    and they're less trouble. Larger valves means you don't have to go as
    crazy on the lift to get a larger curtain area.
     
  5. nuttinnew Forum Member

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    Hmm, Racepower have a done a couple of big valve G heads, I guess they'd be just as applicable to a GT.

    amstrange, Keith's twin carbed GT with flowed head put out a smidgen under 110bhp iirc, 120bhp with the spec you suggest I think is entirely reasonable to expect.
     
  6. amstrange1 Forum Member

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    Yeah, that's what I'd reasoned - I think a lot of Keith's power was thanks to good headwork, and hopefully with TBs (if I can get them mapped properly - that's a big if!) it should make as much power as Keith's twin 40s without the hassle.


    Keith's car was still running the stock cam too IIRC, so it makes me think that 120bhp is quite conservative. I've decided today that my priority needs to be getting my G40 fixed anyway! Then I'm going to convert my Mk2 Coupe S to run Megasquirt and the TBs - if that goes okay, only then will I spend on building up the 3F lump.
     
  7. Polo Classic Forum Member

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    GK's aren't all that, they are only good if you want to acheive 95-100 PS, that will be a cam, DCOE's and a 4-branch Thank you [:D] Anything over that and the HH is the better choice. HH is the 60 bhp solid lifter 1,3L engine found in the Mk I Golf. The difference between the two is that the HH has got the combustion chamber in the head, while the GK has got the chamber is the pistons. Better squish in the HH heads.

    Larger valves is a must in solid lifter heads. The ports are a bit smaller on the Schlepphebels than in the Hydro's.

    Here's a nice spec engine found on 86c.de

    Block HH (Schlepphebel) crank, rods and flywheel optimal lightened, Mahle-pistons, Head from ABU (Golf III 75 bhp)with mech. Renntassenlifters und 320 cam (12,5mm lift)
    Fully mappable fuel injection ( home made ), Injectors from Kadett GSI 2.0/16V (Vauxhaul Astra), ca. 155 PS

    Video: http://www.86c.de/clubautos/thorstenjohn/beschleunigung.mpg
     
  8. nuttinnew Forum Member

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    Anybody know the casting number for an HH head?
     
  9. jbmg40 Forum Member

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    Not off the top of my head... [:o)]

    Try PMing Marshall via the PSD forum, or catch him on MSN, I think he's
    got an HH around.
     
  10. greg s Forum Member

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    Is it the same as a GG (1.1) head?
     
  11. Dogwood Forum Member

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    Do you absolutely have to stick with an 8V? Using 40mm T/B's and a proper exhaust gives 100bhp/litre from an otherwise standard 1.4 16v. Still leaves loads of further tuning potential too.
     
  12. JD8v Forum Member

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    This thread is music to my ears, as i have a coupe s that needs more power. have u got any links to these guys, cant find em on the net. And would i just be able to change the pistons in and crank in my engine to get a similar gains to the GT.
     
  13. amstrange1 Forum Member

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    I have a few 1272 8v lumps lying around though, and buying an AFH or similar 1.4 16v costs money! :pI only really want to do it for fun, and on a strict budget - as I have a G40 I should be spending money on. BTW - Did you need a custom exhaust manifold to fit the 16v lump into the Mk3 Polo?
     
  14. Polo Classic Forum Member

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    My mate who runs an ABU block (Mk III Golf 75BHP) with AFH head just used his Supersprint for Mk II Polo. It is sligtly modified, as the AFH has square ports. can't remember if the ABU block is taller, might have added 10 mm because of that. Oilpan needs to come from a Mk II/III Polo, as the 6N ones are too deep and will hit the ground
     
  15. Dogwood Forum Member

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    Your tightness is duly noted! Manifold and system were a custom job.
     
  16. Armour

    Armour Forum Junkie

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    Hi Nick, spoke to you last time you had the Polo up at Kames, I used to have the Capri Green G40 that won the Kames show and shine for the last few years, could you maybe post or pm me some photos of your engine bay, if you have some of the engine/gearbox mounts that would be a great help! :)

    Cheers Al
     
  17. nuttinnew Forum Member

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    I can't remember (and I only looked about an hour ago [:$] ) but an HA is the same as an HH [:D] HH uses the same cam as a GK as well. I'll have another look at GG and GF tomorrow and write it down this time :)
     
  18. greg s Forum Member

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    I was just going to say that I've got a GG I can look at if you want.
     
  19. nuttinnew Forum Member

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    If you can get the casting number off of it I'll post up the HH one for reference :)
     
  20. amstrange1 Forum Member

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    :pWell, I am a scummy student...
     

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