GTI cam for increased power

Discussion in 'Mk2' started by davidut5, Oct 14, 2018.

  1. davidut5 Forum Member

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    It sure likes to drink, over 11L/100km. 370km with 43l, done on two full tanks since engine repair.
     
  2. davidut5 Forum Member

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    I completed the exhaust with stainless steel 304 and 409 51mm dia. tig welded by me.
    First i had 2 straight through mufflers but was way too loud, then added another one. I can say now that is almost perfect.
    With only 1 muffler it spits some flames too, with the two mufflers faint flames at exhaust tip.
    Drove in the rain the other day and it distorted touching somewhere when water splashed under the car.

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    Last edited: Mar 17, 2020
    erreesse likes this.
  3. davidut5 Forum Member

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    Some things still bother me, like on cold starts i hear a faint deep knock, goes away when warm that could be piston slap. When i got the block i measured 0.08mm with the new pistons, the manual says 0.03mm. Few days ago i removed the sump and plastigauged the rods(0.038-0.045mm, picture down, side play 0.15mm) and four main(0.030-0.045mm) all were in spec. Could be wrist pin to rod, but my old motor from witch i got the rods was fine, so i suspect piston slap.

    Another thing is it has low compression, about 8 bar on all four, i could put my finger on the spark plug whole and block the air and even feels like its pulling my finger in, although cam timing is correct. The pistons are still wet with oil after 1000km, does not seem to use oil.
    Ring gap was 0.45-0.50mm.

    And i fixed my saggy seats backrests, that grass is rotten, maybe i will fit some of them recaros.[:D]

    I can reach top speed in 4th gear:lol: so very long ratios, i have the mk3 gti box if its better.
     

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    Last edited: Apr 18, 2020
  4. Jon Olds Forum Junkie

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    Tappets can be slow to fill with oil, even new ones, I have stripped the top and bottom end of my citi twice and found nothing wrong. New set of tappets
    has cured 95% of it, but the noise goes in 2 secs only, so who cares?

    Jon
     
  5. rubjonny

    rubjonny Administrator Staff Member Admin

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    for tappets it helps to use proper mann/genuine vw oil filter as they have a non-return valve in to stop oil draining back into the block. the mk3 oil filter housing has one of these built in I believe
     
  6. Jon Olds Forum Junkie

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    thanks, think there the ones I use, bought a 'slab' of filters a long time ago and still using them.
    Unlikely a non return valve only could maintain oil pressure in a shutdown engine, IMHO. Too many leakage paths.
    And if the engine shut down with a valve open, as it will, that hyd follower will be 'working' until the next start.
    Good banter though
    Jon
     
  7. rubjonny

    rubjonny Administrator Staff Member Admin

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    No so much pressure, just keeps some oil up in the head ready for the next start. Same as how the non return in the rear washer jet pipe keeps a bit of water in the pipe so you don't have to hold the stalk back for ages every time you want to use it
     
  8. davidut5 Forum Member

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    I have installed a AEM wideband afr gauge, and i get about 14.5 wot. I have read it should be about 13, is this correct?
    Air meter unplugged 11.8-12.8 high rpm
    Lambda unplugged 13.5-14.5 high rpm
     
    Last edited: May 9, 2020
  9. davidut5 Forum Member

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  10. davidut5 Forum Member

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    What i hear from intake is similar to this video, pops are more random and lower intensity, quite few more than the video. No doubt it has something to do with my crank timing and/or 2.0 ecu on 1.8.
     
  11. davidut5 Forum Member

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    I ordered a Autotech 270 cam and will modify dual spring seat from GU or AAM head to fit my obd2 AGG head with single spring.
    I have to buy new lifters, are they the same dual spring vs single? I think they are different from what etka says. But again this could have something to do with the valve 7mm vs 8mm.
    Will i be fine with AGG obd2 lifters?

    How about this https://www.skdeziner.com/autotech-...hydraulic-lifter-cylinder-heads-p-132826.html
    I paid 205quid at heritage.
     
    Last edited: Jun 21, 2020
  12. davidut5 Forum Member

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    The cam arrived, i may have gone a little mild on it. Hopefully over the weekend ill put it in with new ina lifters, may fix that piston rattle on cold! [:D]
     
  13. rubjonny

    rubjonny Administrator Staff Member Admin

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    yeah looking at etka the tappets change based on age to match the valves & stem seals
     
  14. davidut5 Forum Member

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    Yes, agg only came with 7mm valve stem so only one part number.
     
  15. davidut5 Forum Member

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    I have installed the cam, but i am dissapointed. Butt dyno feels a decrease in power. Hehe, i guess it needs a tune and/or adjustable cam pulley.
    Top rpm afr climbs to 15, so looks like fuel sistem is not doing its job.
    Also a good point the mk3 lifters are 20gr lighter than mk2 1.6 ez i had, 72gr vs 52gr.
    I gave up on my ideea with dual springs after i meajured both dual spring 12.1mm until coils bind on the mk3 aam, and 13.1mm on single spring agg head until coil bind.
    Idle got a little worse, not too bad.
    AGG cam has 10.6mm lift and Autotech 270 has 11.4mm.
     

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    Last edited: Jun 27, 2020
  16. Jon Olds Forum Junkie

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    Cam timing first, more fuel top end, keep it coming
    Jon
     
  17. davidut5 Forum Member

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    If i had a vernier, how would i check/adjust cam timing? Cam degree wheel maybe?
     
  18. Jon Olds Forum Junkie

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    Easiest way is to time it 'straight up' quite easy with the engine installed. (ish, with some tooling..)
    You need to establish 'real' TDC. Adapting a spark plug to be a piston 'dead stop' so the engine cant rotate past it.
    2mm down the bore ideal.
    Be gentle
    Mark the flywheel at this point through the gearbox hole.
    Rotate other direction so you have before/after TDC engine 'lock'. Be gentle
    Half the two marks, this is true TDC
    At this point your cam should have equal lift on inlet/exhaust follower (need a dial gauge on the follower parallel
    to the valve). Obviously not on the compression stroke, but on the other stroke.
    Adjust your Vernier for equal lifts. (this should match the cam specs)
    Easier on mech followers, remember to subtract the latch from the specs
    Easy enough on 8V, a pig on 16V (two adjustments, always seem to go the wrong way when you adjust 16v, or its just me, LOL)
    Cam advance is more inlet than exhaust lift on TDC non compression.
    I start timing straight up, as that's what the cam designer intended. (symmetrical grinds only)
    Hope this makes some sense, it sounds more difficult than it is.
    Jon
     
  19. davidut5 Forum Member

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    I have found true tdc using modified spark plug, and flywheel mark is spot on. I have to measure cam lift 180"
    after tdc cyl 1 for cam intake/exhaust valves to be equally open, if i got it right.
    Autotech says cam has 0 overlap but a degree wheel calculator comes up with 4" overlap.
     

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  20. Jon Olds Forum Junkie

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    ok, 4 crank degrees when both are closed, quite a mild cam then, so you have to look for full lift inlet at 110 degrees and exhaust at 111 degrees, I think.
    Get a degree reading at 5 thou before full lift and 5 thou after, average
    Jon
     

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