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    Thread: Increasing my rocker ratio

    1. Senior Member PowerDubs's Avatar
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      02-03-2010 10:51 PM #1
      This is about to get interesting.
      Rocker ratio changes are very popular way to increase performance in many makes of cars when guys hot rod them.. even with VW, but from what I've seen, only air cooled. I can't say that I've ever seen anyone change the rocker ratio on a water cooled car yet. Not that I've looked very hard..



      For several months now I have been talking with a couple engineers at Schaeffler about our rocker arms. The reason is that I want more than the 11mm lift that all the aftermarket cams have for the 24v VR6.
      Today I was happy to receive the following email-
      "found one that MIGHT be beneficial to you and it has a slightly higher ratio. There is
      no guarantee that it will fit or operate successfully without running a
      full analysis on it. These calculations take weeks, unfortunately my
      boss wont let me do side jobs like that. Buy a set (or one) and try it
      out on the bench to see how things line up.
      Good luck! Let me know how it works"


      Sounds like typical engineer disclaimers to me. They have the full specifications of both right in front of them, I'd imagine they would bother telling me about them if they didn't think they were going to work. I'm stoked!
      The 'slightly higher' ratio he is talking about is roughly a 14% increase over stock.
      They should jump the lift on the Schrick cams from 11mm to a hair over 12.5mm.
      I can't find my old email file from Willy @ Supertech with the specs on the stock valve springs, but if I remember correctly somewhere around 12.5 was the coil bind limit on them. I should have that info again tomorrow when he responds again. Looks like I might need to change them out if this rocker is indeed functional in this application.

      I also sent an email to the Schrick engineer I converse with to see what his thoughts are just for fun.
      While these rockers would be a cheap way to gain power on any of the 24v regardless of cams or head, I am especially looking forward to them as my ported head is capable of decent peak CFM over stock.
      aprox .430 VS .490 with the stock rockers and these new ones..about a 15cfm gain intake side at peak lift.
      For those of you wanting to know more about changing rocker arm ratios, here is a quick page with a nice graph showing area under the curve. By opening and closing the valves at a faster rate, the engine flows more air for the same number of degrees of valve duration. It is for old American iron, but the concept is the same.
      http://www.pontiacstreetperfor....html
      -Josh
      Current VAG collection- 08 TT coupe 3.2 MT | 06 Phaeton 4-seater 6.0 W12 | 04 VW R32 | 03 GTI VR6 - all of them 24v VR6 based.
      Current other- 00 M Roadster | 12 Kia Soul 1.6 stick |01 ZRX1200R | 03 KLX400R | 00 XR200R

    2. Member DasTeknoViking's Avatar
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      02-03-2010 11:23 PM #2
      Ran Comp Rockers on many V8s I've built...
      Interesting idea thats overseen by many in the import car game.
      Do they actually have a rocker arm that could be mounted in our heads ? What kind of price ??

    3. Member Slampig's Avatar
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      02-03-2010 11:23 PM #3
      wow, im liking this, excited to hear more info.
      im also curious on what this would cost also.

    4. Member r32dub88's Avatar
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      02-03-2010 11:32 PM #4
      subscribed!
      very interested in this, i knew my P&P would come in handy later on.
      Quote, originally posted by PowerDubs »
      I can't find my old email file from Willy @ Supertech with the specs on the stock valve springs, but if I remember correctly somewhere around 12.5 was the coil bind limit on them. I should have that info again tomorrow when he responds again. Looks like I might need to change them out if this rocker is indeed functional in this application.

      so even if springs are not required (which they may be) would they be recommended?
      also what about retainers?
      i would assume these rockers combined with this set would benefit significantly with a P&P head. correct?
      Specs:
      * 13.90mm max lift
      * Coil bind at 17mm
      * Rate 12.6lbs/mm


      Modified by r32dub88 at 11:33 PM 2-3-2010

    5. Member nkgneto's Avatar
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      02-03-2010 11:49 PM #5
      Good read, interested in price also.

    6. Member newcreation's Avatar
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      02-04-2010 06:15 AM #6
      Nice Josh i'll have to did up my old info i had on doing this.If i can find it this was before i moved on my old computer i back everything on my moms computer at the time to save it.Hopefully she has it.I though of the same thing but i was also doing the rest of the head to
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      02-04-2010 06:27 AM #7
      subscribed [IMG]http://**********************/smile/emthup.gif[/IMG]

    8. Member KoolTrix's Avatar
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      02-04-2010 07:35 AM #8
      subscribed [IMG]http://**********************/smile/emthup.gif[/IMG]
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      02-04-2010 07:43 AM #9
      Quote, originally posted by PowerDubs »
      While these rockers would be a cheap way to gain power...

      How cheap? Last I priced out doing similar it was getting pretty expensive.
      Quote, originally posted by PowerDubs »
      I also sent an email to the Schrick engineer...

      Schricks N/A cams for the 16v are 12mm/11mm and use stock valvetrain.
      The R32 and the 16v utilize the same rocker set up, springs, etc.
      I imagine you would at least be good up to 12mm lift.
      I was all about this after having my engine fora few months a seeing that cams might be a struggle. There is a gain to be had from this is there, but in stock form it is not as impressive as what you are going to see with you worked head. I plan on keeping the head stock for quite a while so I kept barking up the camshaft tree, found a solution and I am content to see what they do first. Here are HPR's AXW 16v numbers that I put into a chart, you can see that jumping from 11mm stock to 12mm aftermarket is minimal at this point. Headwork will most likely open the spread much more....

      Looking forward to what comes from all of this.

    10. Member newcreation's Avatar
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      02-04-2010 08:17 AM #10
      Josh was thinking if i am in there doing the rockers i never did valve train yet on a 24v.I was thinking of upgrading springs and retainers in the process not sure yet it it woud be worth it with the ration being low enough to still run the factory stuff.
      Now i am not sure on this particular cylinder head if we can upgrade valve train without removing the head.I know some motors you can pull the cams and then fill the cylinder with air and do the springs and reatiners.It would be nice to beable to do it that way and not have to pull the head.Hopefully someone can chime in here if they done so.
      Hopefully we can got that route if need be without pulling the head
      -JAMES-
      DRIVEN/Built /UM Turbo R - VR NATION

    11. 02-04-2010 08:32 AM #11
      wow, I'm a 1.8 guys and I'm excited about seeing how this pans out
      Quote, originally posted by r32dub88 »
      Specs:
      * 13.90mm max lift
      * Coil bind at 17mm
      * Rate 12.6lbs/mm

      ^ those are some "feel good" numbers, with assurance like that in your valvetrain you're not going to have to worry about a damn thing! If Powerdubs is right (considering he always is) that's a great improvement over stock.

    12. 02-04-2010 09:04 AM #12
      billy you said 16v rockers are the same?
      I had Jeff's spare rockers in my hand and my R32 rockers side by side and the rockers were clearly different in size with the 16v being shorter then the R32 rockers. I even went further as to find 3.6 rockers and those were the same as R32 rocker arms.
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      02-04-2010 09:35 AM #13
      Very interested in this as well. I always upgrade the rockers on small block chevys I build. Typically with crane rollers 1.6 or 1.7 but I never even thought about doing this with the VWs. I would think that this could be an easy upgrade. [IMG]http://**********************/smile/emthup.gif[/IMG]

    14. Geriatric Member need_a_VR6's Avatar
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      02-04-2010 10:22 AM #14
      Bills might be different, it's from a different (euro NA FSI) casting. We did a 'quickie' look at them didn't measure them vs the BDF or R32 ones.
      Some thoughts...
      The only way to change the rocker ratio is to change the location of the roller section that hits the cam. My concerns would be with the change in cam phasing if all else is left the same. I had to draw it out below. The numbers are just for reference, they mean nothing compared to actual parts. I just started drawing it out and some of the dimensions might be on the large side so the effect would be exaggerated.
      Stock type cam, stock rocker:

      Increase rocker ratio by moving center pivot toward lifter. This is a ~25% change in designed pivot and ratio. You can see that the lifter would have to pump up slightly to compensate:

      Now we take this bad boy to the old full lift cam angle, notice the offset from the new full lift cam angle.

      Also, notice that the true rocker ratio at full lift is higher. This is due to the rocker tip needing to 'slide' out to keep valve contact. Some of that can be mitigated with a radius on the end of the rocker arm where it hits the valve, but it was hard to draw
      I might redraw it with real numbers if someone could measure a rocker (length, pivot location, lifter ball dia, etc), and get me the approx base circle, tip circle, lift, of the cam, etc. That along with the difference in the new rocker pivot, I can calculate approx differences in how the new rockers will act. *Hint*


      Modified by need_a_VR6 at 10:23 AM 2-4-2010
      -Paul
      1995 GTI VR6 - Retired - 12.90@106 R32 power - 12.833@106 12v power
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    15. 02-04-2010 11:14 AM #15
      Quote, originally posted by need_a_VR6 »
      I might redraw it with real numbers if someone could measure a rocker

      I was wondering what the numbers were measured in, 12mm = 0.47 inches so I wasn't sure. assuming there is no fix yet, would you be able to advance/retard the cams enough to make the "New Lift" angle? Assuming your last numbers are correct, can the cam gears adjust up to 19 degrees? I know there is some adjustment there, maybe even enough to accommodate any angle between teeth?
      For example, the cam gear could adjust up to 20 degrees and each gear tooth is 20 degrees apart (not real numbers)


      Modified by Euro-tuner at 8:17 AM 2-4-2010

    16. Geriatric Member need_a_VR6's Avatar
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      02-04-2010 12:30 PM #16
      I just made up all the dimensions to illustrate the point, they have NO bearing on reality other then to show the difference in the relationships once you start moving things around.
      There might be ways to get the cams to be in the right spot. The thing I would worry about at first with having the centerline retarded is exhaust valve lift @ tdc would be higher. This could possibly be compensated with the vvt somewhat, or with different centerline cams.
      -Paul
      1995 GTI VR6 - Retired - 12.90@106 R32 power - 12.833@106 12v power
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    17. 02-04-2010 03:11 PM #17
      subscribed

    18. Senior Member PowerDubs's Avatar
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      02-04-2010 04:16 PM #18
      Ok.. lets start with the basics.
      #1. Stop asking me what engine the rockers are from. There is no way I am releasing that info yet as these could potentially destroy an engine if they do not fit correctly or smack pistons.
      I'll tell you 2 things about them though-
      They are NOT from a VAG product.
      They are NOT from any engine available in this country (unfortunately).

      #2. I have no idea what cost is yet. If there are similar to the stockers in cost then that would put them around $300ish for a set. I'm going to guess and say more since they have to be imported and don't appear to be as common as our stockers.
      -Josh
      Current VAG collection- 08 TT coupe 3.2 MT | 06 Phaeton 4-seater 6.0 W12 | 04 VW R32 | 03 GTI VR6 - all of them 24v VR6 based.
      Current other- 00 M Roadster | 12 Kia Soul 1.6 stick |01 ZRX1200R | 03 KLX400R | 00 XR200R

    19. Senior Member PowerDubs's Avatar
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      02-04-2010 04:36 PM #19
      Quote, originally posted by billyVR6 »
      There is a gain to be had from this is there, but in stock form it is not as impressive as what you are going to see with you worked head.

      True the ported head will gain more.. but remember this isn't about peak flow #'s.
      For those that didn't click the link above to read the article and see the chart..increasing the ratio "the opening and closing rates are much faster, and the area under the overall "curve" is much greater."
      For the rough guess $300ish these cost.. if they work I would call them a no brainer.
      CHART-

      -Josh
      Current VAG collection- 08 TT coupe 3.2 MT | 06 Phaeton 4-seater 6.0 W12 | 04 VW R32 | 03 GTI VR6 - all of them 24v VR6 based.
      Current other- 00 M Roadster | 12 Kia Soul 1.6 stick |01 ZRX1200R | 03 KLX400R | 00 XR200R

    20. Senior Member PowerDubs's Avatar
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      02-04-2010 04:39 PM #20
      Quote, originally posted by need_a_VR6 »
      I might redraw it with real numbers if someone could ....

      Sent you what I have so far. I think it is enough to be of some use.
      Happily awaiting pretty pictures.
      -Josh
      Current VAG collection- 08 TT coupe 3.2 MT | 06 Phaeton 4-seater 6.0 W12 | 04 VW R32 | 03 GTI VR6 - all of them 24v VR6 based.
      Current other- 00 M Roadster | 12 Kia Soul 1.6 stick |01 ZRX1200R | 03 KLX400R | 00 XR200R

    21. Geriatric Member need_a_VR6's Avatar
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      02-04-2010 04:44 PM #21
      I'll work on it tonight, sent you a PM for more details.
      -Paul
      1995 GTI VR6 - Retired - 12.90@106 R32 power - 12.833@106 12v power
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    22. Member killacoupe's Avatar
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      02-04-2010 07:59 PM #22
      benz 6cyl and v8 rockers are the same style as the r32's....ill take a measurement of them tomorrow [IMG]http://**********************/smile/emthup.gif[/IMG]

    23. Senior Member PowerDubs's Avatar
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      02-04-2010 09:26 PM #23
      There are a ton of cars that have rockers that are the same style. The INA engineer listed something like 15 different variables that make a difference.
      Seeing as these are the ones he recommends (and INA is the company that makes our stock ones) I don't think you need to look elsewhere at this point.

      At this point the only source I have found for them is a used parts place in the UK.
      I would like to find a source for them new, although I might buy 1 used to test.

      Heard back from Willy @ Supertech.. yes we will need to change the springs to run this much lift so that drives the cost up a lot, as well as much more involved install. This just went from cheap and somewhat easy to fairly pricey and more involved.
      Oh well.. no guts no glory!!
      -Josh
      Current VAG collection- 08 TT coupe 3.2 MT | 06 Phaeton 4-seater 6.0 W12 | 04 VW R32 | 03 GTI VR6 - all of them 24v VR6 based.
      Current other- 00 M Roadster | 12 Kia Soul 1.6 stick |01 ZRX1200R | 03 KLX400R | 00 XR200R

    24. Geriatric Member need_a_VR6's Avatar
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      02-04-2010 10:33 PM #24
      You'd probably only need to upgrade the springs if you use larger cams. It might be an inexpensive way to more lift/duration with stockers.
      -Paul
      1995 GTI VR6 - Retired - 12.90@106 R32 power - 12.833@106 12v power
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    25. Member
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      02-04-2010 10:46 PM #25
      Pdubs, this the article that I mentioned, it's a good read at the least...
      http://www.carcraft.com/techar....html

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