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VE SS - High Ratio Rockers.... With AFM?

Discussion in 'VE Holden Commodore (2006 - 2013)' started by bigdaddycool, Aug 22, 2014.

  1. bigdaddycool

    bigdaddycool Member

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    I got a 2009 VE SS with the L76 which has AFM, RamJet OTR, HighFlow Hurricane Cats, Tuned etc....

    There is an issue which is the stock cam sucks..... doesn't make power until 3800rpm really and dies pretty quickly as it passes 5200rpm........

    I dont want to fork out thousands for a cam, just wouldnt do it.......

    But I noticed some stuff about changing the rockers over to a higher ratio........ Which I guess mostly improves top ends but also improves as the rev range increases and with my mods I think its probably the right solution........

    Has anyone had this done with a AFM based engine? If so..... how long ago, any issues, did it improve power and what ratio did you fit?

    The ratio rockers would be a damn simple fit....... over an expensive cam if it gives me the difference in power im looking for.
     
  2. 07GTS

    07GTS Well-Known Member

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    don't bother with high ratio rockers for the money and power gain its not worth it, think i made bout 10rwkw going from standard 1.7 to 1.8 is no big leap, just save up for a cam it's much better, i ended up getting a cam so my rockers are sitting in they shed doing nothing now so compete waste
     
  3. bigdaddycool

    bigdaddycool Member

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    5-10kw is all im after
     
  4. 07GTS

    07GTS Well-Known Member

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    if 10kw is worth 6-800 for the rockers then go for it, I'd sell u mine cheap but I don't think they suit the L76 only ls1-ls2, if u need push rods I have some different lengths new but only used at idle for a few mins..
     
  5. 07GTS

    07GTS Well-Known Member

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    might need to do valve springs after the higher ratio rockers, can cause valve float up top...
     
  6. bigdaddycool

    bigdaddycool Member

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    Every 10kw costs you $1k as they say...... rule of thumb.

    I have no plans to do cam unless the engine gives up and hopefully thats not for another 100,000kms

    Car ran 220kw atw mafless before hi-flow cats which was rather low for a SS....... done the cats, want to do this and then get a touch tune and hopefully it'll sit around 245kw.... AFM car for you with a little arse cam
     
  7. delcowizzid

    delcowizzid on holiday

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    rockers dont add much cam add 20-30% to your total hp
     
  8. PIR4TE

    PIR4TE Banned

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    I did mine eighteen months ago, no issues all positive, yes improved power but I have L77 on e85 (see below), I used Yella Terra Ultralite 1.85. I would probably do Mace 1.9 if I had the chance again.

    Following read is a wall of experience - at first the +30rwkw leap from stock with tune and OTR, plus sales testimonials attributing larger diameter bolt-ons to better performance, lead me to believe larger diameter pipes in and out of the engine will result in increased air flow = equals more power = faster car. That was way too simplistic:

    The engine’s stock peak HP RPM is 5300, with HP being a product of RPM, limited by valve events (specifically 0.480" lift). Opening the engine to replace the camshaft in the middle is effective but somewhat drastic.
    By comparison increasing lift and duration simply by removing the rocker cover reveals the the upper valve train, replace the stock items with high ratio rockers, high performance valve springs, and moly rods, is quick, less expensive, simple.

    Higher ratio rockers immediately gives you revised event duration same as LS3, and lift as per LS2. The result is stock manners, AFM, while slightly increasing volumetric flow and the engine’s redline through calculated control of components.

    Flex fuel responds better to more trapped Ve as you can tune for higher cylinder pressure without knock at lower RPM (higher torque per ci). So dialing in timing with an e85, more lift and colder plugs delivers more torque across the board, while revised events increase volumetric flow and redline, which results in more HP up top.

    However although the fuel, timing, valvetrain is capable of much more power using these events, the heads want better flow than is available through the stock manifold. This is across the board, not just up top.

    In fact the stock CSA of the runners are way too big to deliver air at the velocity required for the 6.0 to realise potential torque. The manifold is a compromise in the first place, adding more lift and slightly more duration spikes intake velocity without the corresponding increase in flow.

    So while 12-20rwkW better than before at high RPM with HSV extractors, mandrel bend and hi-flow cats, the main restriction becomes the intake manifold and to a lesser extent the throttle body. Also while the MAF can be scaled it is not as reliable as SD only at this state of tune due to frequency resolution. MAFless or bigger MAF.

    For the GenIV intake to deliver more flow with less velocity you need to derestrict and port the plenum and tumble the charge through the runners using a radius bar. This induced tumble slows velocity and increases CFM, and is race proven to promote better combustion in the chamber across the range. In my car it added 15rwkW and

    So yes, rockers are worth it on our engine (better with flex fuel), plus modded HSV headers, plus modded intake manifold and throttle body. With this combo it is possible to increase Trapped Volumetric Efficiency without spending or changing a lot.

    Personally I spent too much to discover all this, but am confident the car was one of the more powerful VEs using bolt-ons. The next worthwhile stage FWIW has been to further increase potential torque through really long Tri-Ys and x-pipe, and multiplying it earlier using a shot peened 3.27 TrueTrac diff. Bottom line is a change in handling and character 0-100 in 4.8, massive in-gear accel, and excellent highway kickdown.
     
  9. SSVSE

    SSVSE New Member

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    the real deal info yet again.

    cheers to u Pir4te!
     
  10. bigdaddycool

    bigdaddycool Member

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    PIR4TE. Some of which way over my head ......... and I tune and have spent years across diff commodores tuning. (Update: 10 mins later..... Re-Read .... yup go it, head ache for ya hard to follow :D)

    I figure rockers would take like an hour to fit....... Not sure of the effects on the timing, ve tables etc..... would be interesting to see it up on my vcm scanner against the wideband.

    But my in case, the cam is clearly holding back the car........ I've now seen how the hi-flow cats have removed the riges in my ve table as there is now more airflow there compared to when I had the stock cats.......

    I'm a little on the fence about headers myself.......... I switched mine out from the standard ss to hsv for a note change mostly....... as i run dj pipes..... so it fixed their small drone, i also have adjustable ends on them.

    But the standard ss headers you now also find on the vf gts lsa, basically they may not have 'better flow or a better note' but what they are better at is keeping the engine more in check towards the afr....

    Its more important to have spot on fueling then some wild beast that cant hold a steady afr (by steady I mean much closer or as close as it can be) across all driving conditions......

    The plain headers actually do help will controlling the engines flow characteristics. I'm not sure on your mods progressiveness but when I changed to HSV headers I lost power in certain spots only to pickup a little bit up top...... so overall wasn't worth it....... but the exhaust note is nice so there is that.

    So anyway back to rockers....... never done them, blown some off in my time on a vz v6 somehow.... and fixed that but never changed them.

    I noticed some up online for like $500 which aint bad...... Where did you buy yours, how much, did you fit them yourself, did you replace the springs or pushrods? Can you put a link up to them for me. Maces 1.9 is a bit too much I wouldnt risk that high.

    ------------

    PS.

    My advice to anyone who has a stock SS....... ONLY do hi-flow cats and maybe an OTR........ leave the rest alone unless your going to do a cam, no headers etc. You'll find the stock headers are best for the cam thats in the car...... and will provide you with the 'fun' power it has available as well as helping hold the fuel ratio's more steady then either hsv headers or long tubes which at the end of the day is way more important for the car and power then some myth and magic concepts of more airflow = more power. Unless you have changed the cam, dont do headers period. Just my opinion.
     
    Last edited: Aug 26, 2014
  11. Stock AFM SS Wagon

    Stock AFM SS Wagon New Member

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    Old thread dig but better than starting a new one, when you changed the stock headers for HSV tri v6's what other mods did you have? I have a stock 2011 SS AFM wagon and I have the opportunity to fit HSV headers for $300 to standard exhaust, and later maybe fit Mace cold air intake with pod and get a tune, I'm after more usable driveability don't care about top end power.
     

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