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Stage 2 limit. (MRC)

Darren McDonnell Mar 11, 2020

  1. Darren McDonnell

    Darren McDonnell Registered User

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    So I have an MRC stage two setup and made 471ps but I am now trying to see what I can do to push that figure a little higher with out going to a stage 3 throttle Body.

    I asked MRC about removing the cats and they advised against this as the charger needs the back pressure to run properly.

    what could I do to improve the performance a little more if I went for a map tweak.

    Cheers
     
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  3. cadguy77

    cadguy77 Registered User

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    What pulley ratio are you running?

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  4. Dippy

    Dippy Registered User

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    It depends what you are focussing on. As noted above, the pulley ratio is the main driver - increase it and you increase torque across the range. However when it gets very high (above 3), as well as thermal issues the engine faces airflow restriction, so the peak power becomes limited. That's where the TB solution comes in. I believe that MRC's original tuning work on this platform nearly reached 500PS based on their 'standard' intake mods and the biggest pulley they tried (I don't know what size). So I'd suggest that you could increase your peak to 49xPS with a bigger pulley and improved cooling.
     
  5. cadguy77

    cadguy77 Registered User

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    What he said Great advice

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  6. jdp1962

    jdp1962 Grumpy Old Man

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    But also be prepared for the possibility that having found an extra 20 or so PS, you might not notice a meaningful difference in real-world driving. The law of diminishing returns is very much in play here.
     
    Cerbera9 likes this.
  7. Andy Butcher

    Andy Butcher Registered User

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    I would have thought MRC would be the best people to ask really, they seem to be one of the tuners at the top of the game at the moment.
     
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  8. Cerbera9

    Cerbera9 Registered User

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    I have a MRC tuned car that is now dual pulley with test pipes, Merc HX and WMI. I would definitely recommend going dual pulley and cooling mods are a must. Test pipes actually loose you power until the car is tuned for them, what they do give you is peace of mind that there are no cats to fail.
     
  9. Darren McDonnell

    Darren McDonnell Registered User

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    What pullys did you have on yours and is the Merc HX capable of handling the extra heat. I dont really want to have a tune done with WMI as i dont like things that can run out. I might still install it for the extra cooling if doing a track day but wouldn't want it tuned with it.

    I think I just had the standard MRC pulley which I think am right in saying that its a 189 pulley.
     
  10. Dippy

    Dippy Registered User

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    MRC have just published results for a B8.5 S4 with "stage 3" mods - about 540PS/640Nm peaks. But that's with 102 RON race fuel so those figures would be somewhat less with 99 RON. A few years ago I might have been buzzing with enthusiasm about it but now it just interesting and I doubt I'll take my S5 tune any further, especially since the law of diminishing returns seems to also affect my driving ability/confidence as the years accrue! :(
     
  11. Cerbera9

    Cerbera9 Registered User

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    I have the MRC stage 2 crank pulley which I've measured @ 179mm and a Forge SC 57mm. Yes the Merc HX helps with the extra heat, and recovers well. I don't have the car tuned for Meth only have the Meth installed for cooling and its on a switch so I can turn the system off when its not needed or runs out.
     
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  13. Cerbera9

    Cerbera9 Registered User

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    Whats considered stage 3 mods? Is that on a manual or DSG car?
     
  14. Darren McDonnell

    Darren McDonnell Registered User

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    What sort of power does yours make.
     
  15. Cerbera9

    Cerbera9 Registered User

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    Anywhere between 435bhp and 504bhp depending on what dyno you put it on. Don't get too hooked up on chasing power figures.
     
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  16. Darren McDonnell

    Darren McDonnell Registered User

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    Cheers. Yes I know that, Its not the first car i have modified.
     
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  17. cadguy77

    cadguy77 Registered User

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    Does anyone know if the owner of this car is on any forums? Would like to see a build thread for this

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  18. Dippy

    Dippy Registered User

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    It's a B8.5 so IIRC that means it has to be an s-tronic.
    I put the stage 3 in "" because of course there's no definition, but as far as I'm concerned I think the stages for a B8/B8.5 can be considered:
    stage 1 ECU remap only
    stage 2 ECU/TCU remap, intake mods and pulley(s) to a ratio which does not (necessarily) require a cooling upgrade
    stage 3 ECU/TCU remap, intake mods and pulley(s) to a ratio which does require a cooling upgrade

    Of course since there is a range of possible pulley ratios and intake mods (TB, with or without s/c porting) then stage 3 has to be a bit variable.
     

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