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    Thread: How much better is V9 supercharger G trim than F trim?

    1. Member
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      '09 Jetta 2.5
      04-02-2009 12:43 AM #1
      Im getting my v9 F supercharger rebuilded at vortech and im upgrading it to G trim. I keep on reading about the limits of the F trim and that they can't go to high rpm, what about G trim? Would I be able to reliably boosted at 12-13 psi? What are the major advantages?


      Modified by vr6-kamil at 11:01 AM 4-2-2009

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      '09 Jetta 2.5
      04-02-2009 02:02 PM #2
      oh man

    3. Member R32EEEK's Avatar
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      04 R32T
      04-02-2009 02:12 PM #3
      You might have better luck asking in the FI section:

      http://forums.vwvortex.com/zeroforum?id=113

      but beware the tubo nazis

      -rick


    4. Member carma's Avatar
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      04' R32 HPA EFR Turbo
      04-02-2009 02:17 PM #4
      I'll be doing this eventually also (upgraind from F trim to G trim). AFAIK it will give you 1.5 more PSI at the peak, and the boost will come on 500RPM sooner. Marcel wrote a big detailed explanation on it in the CVP+VF SC threads. Check the link in my sig, it might be that one. Are you swapping the gears, or trading up entirely? I called Vortech yesterday about this and they said I had to send them the charger, I couldn't do a gear swap, and that I would get between $500-$1000 (depending on the SC condition) credit towards the purchase of the V9 G-trim.

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      '09 Jetta 2.5
      04-02-2009 02:25 PM #5
      No Im not doing the gear swap and it's only costing me $250 to upgrade to G trim with the $650 new bearings and seals rebuild by vortech

    6. Member carma's Avatar
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      04' R32 HPA EFR Turbo
      04-02-2009 02:32 PM #6
      Wow, that's cheaper than doing a swap. Is it warranty work?

    7. Member carma's Avatar
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      04' R32 HPA EFR Turbo
      04-02-2009 02:35 PM #7
      Here's that info Marcel posted, hope this helps:

      Quote, originally posted by HPA motorsports 1 »
      The V9 has two trims, and F and a G. The F is a left cut of G map. The step ratios differ between these blowers, and this results in different boost ranges. Our V9 has a 1.72 step up ratio @ 48,000rpm. Working with what we had in our kit, the F trim, we set out to optimize the track. Frustrating for us was that this blower made little boost in the original stage 2 configuration.

      Next has been the debate about pulley diameter and RPM. All V9 blowers use a gen 3 gear set from Vortech which has a gear ratio of 3.61. This is a key fact when optimizing impeller speed for durability and efficiency.

      48,000 is the target RPM for efficiency and 50,000 is the RPM target for durability with our f trim V9. With the stage 2’s 2.62 diameter pulley, we see that at around 6800RP +/-.

      Crank P dia. X 3.61(step up ratio) x shift point / all divided by blower pulley diameter = impeller speed.

      Downsizing the pulley will be detrimental for two reasons.

      1) The R32 has a 5.41” crank pulley and if the blower pulley is reduced in size, the tension required to hold the belt will overload the main axle of the blower causing premature one sided wear on the oil seal.

      2) If the pulley is reduced, the RPM would have to be limited anywhere in the range of 6200-6500 RPM to avoid over spinning the impeller, any RPM past 6200 will be on the down side of the flow rate for the V9

      Theoretic boost from the Vortech V9 F trim is a simple calculation.

      (14.6est BP x1.72)-14.6BP = 10.5psi @ 48,000 impeller speed.

      For those at altitude, you would use the est Barometric Pressure for your location less 14.6. HPA is nearly right at Sea level so 14.6 is what we use for our calculations.

      Please note; this is the estimated output measured in the boost track just past the compressor and not in the intake manifold.

      Instead of focusing on the pulley, we have taken some additional steps to optimize the Blower’s intake track which has resulted in over a 1.2 PSI gain in our boost track at the compressor outlet.

      The G trim is worth 1.3-1.5 psi more with the same dimensions that we are setting the F trim up for. it has a step up ratio of 1.8 @ 48,000RPM


      IF, you opt for what Vortech labels as an HD unit, this uses the straight cut gears and has a lower ratio 3.45. The G trim with a 3.45 will behave similar to the F trim running the 3.61 as the impeller RPM's shift downward with the 3.45 ratio.

      The formulas are in my post above, so you can run the exact numbers and see what you should except for boost out of the blower at 6800rpm based on your altitude from sea level. 48,000 impeller speed efficiency point is the target.

      G trim in HD app, 3.45

      (5.41x3.45 x 6800)/2.62 = 48,400rpm
      @ 48,000 the G yields a 1.8 step up ratio

      (14.6x1.8)-14.6 =11.68psi @ 6800RPM – theoretical Boost at blower.

      The same G trim with the Gen 3 gears would look like this

      (5.41x3.61x6800)2.62=50,688

      The max boost with the G trim and Gen 3 gears would be reached earlier in the power band (6500RPM)and the durability threshold would be then just past redline allowing a slightly more usable powerband.

      We will have the G trim retro fit in our V9 blower but will retain the Gen 3 Helical gear set to retain the 3.61 ratio, but as you can see, we are speaking about a 500RPM swing, not to bad!

      Hope this makes sense.

      The Vin plate on your blower will define your trim and gear set and the service staff at Vortech seem very quick at getting that info.






      Modified by carma at 12:04 PM 4-2-2009

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      '09 Jetta 2.5
      04-02-2009 02:59 PM #8
      Yeah I was told that it will definitly be warrantied for 1 year and he said that he wasn't too sure about the 3 year but will know after getting the supercharger back from the rebuild

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      '09 Jetta 2.5
      04-02-2009 03:20 PM #9
      Ok that's kinda hard to understand. I do get most of it but get lost in couple point that he makes like so the maximum pulley on the V9 G trim shouldn't go smaller then vf stage 2 2.62" or something or it is where it's most efficient and the whole 1.3-1.5 psi more then F trim.

      So that would mean if I run original stage one 6psi pulley on G trim it will be 1.3-1.5 psi more output. Man so that would mean that I would have to lower the compression on my vf stage one because Im not even runing intercooler, right?


    10. Member carma's Avatar
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      04' R32 HPA EFR Turbo
      04-02-2009 03:29 PM #10
      You might be safe, it all depends what the PSI is at the intake. Not only that, I'm running 7.2PSI on stock compression. But of course I have the air->water charged setup, so that lowers the intake temps. You probably will be safe, I think after like 9PSI or something you go boom. Or is it 10PSI? If you're at 7PSI I'm sure you'll be fine. But take every word I say with a grain of salt since I'm fairly new to the FI scene .

    11. Member R32R1's Avatar
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      project roided wookie
      04-02-2009 04:04 PM #11
      I have and think im the only one who has a VF stage 2 with G-trim gears. One thing for sure is it's loud. You KNOW there is a supercharger underneath the hood. As far as power goes, I have never driven an F-trim .:R yet so I cant compare but I can say I haven't had any problems with it yet and still no complaints.

    12. 04-20-2009 08:37 AM #12
      That's good to hear R32R1, I stumbled across this thread as I'm currently weighing up the different supercharger kits for my UK R32 and was wondering if a V9 G-Trim on VF Stage2 piping was possible, obviously the piping, intercooler and connections can take the extra boost pressure without issue then..?

      Did you order the G-Trim with the VF Kit or is it something you've added yourself later? Also, are you running anything other than a standard VF Stage2 kit, like uprated injectors, fuel pressure regulator, compression reducing head plate, etc?

      Obviously your mapping is different to the provided GIAC programme, but I'm just wondering if there is anything else 'needed' to safely run the G-Trim with 'off the shelf' VF Stage2 Hardware?

      I plan to have the car mapped over here in the UK (mainly incase of any issues so I can get them sorted on my doorstep), so really I'm just trying to make sure I have all the best possible parts from the offset...

      Cheers for any help in advance,
      Leon.


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