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What do you make of these power graphs?

Discussion in 'Motors' started by MeEsH BaKkA, 3 Oct 2009.

  1. MeEsH BaKkA

    Mobster

    Joined: 12 Dec 2002

    Posts: 2,948

    My car RR'd today what do you think of these graphs, something not right??

    [​IMG]

    [​IMG]
     
  2. Lumeycom

    Wise Guy

    Joined: 31 Jan 2008

    Posts: 1,238

    Location: S Wales

    somethings not right...

    Torque and power should cross at 5252rpm (mathmatical constant) - Yours doesn't, looks to do so about 4100rpm. Suggests to me that the RR is not set up properly.

    Also runs out of puff fairly early - is the car stock?
     
  3. Leeum

    Wise Guy

    Joined: 19 Sep 2005

    Posts: 1,242

    Was the result what you hoped? I'm assuming it's modified - what has been done to the car?
     
  4. Matt82

    Capodecina

    Joined: 13 Mar 2004

    Posts: 16,587

    the torque plot looks annoying
     
  5. Matmulder

    Wise Guy

    Joined: 21 May 2004

    Posts: 2,467

    Location: South Staffs

    I thought it depended on the car?

    And whats going on with the torque curve? Surely it should "peak" and hold, not drop off suddenly like that?
     
  6. Lumeycom

    Wise Guy

    Joined: 31 Jan 2008

    Posts: 1,238

    Location: S Wales

    (Torque X RPM) / 5252 = Horsepower

    Its one of those things that just is - remember that rolling roads measure torque and calculate horsepower. 1 horsepower = 550ft/lbs PER SECOND and that basic formula is extrapolated from it after some jiggery pokery thats far too boring to go into.

    As for the torque drop off its either a smallish turbo, weak actuator or poor boost control. Or actually, poor boost control is there as the torque line is a bit all over the shop.
     
    Last edited: 3 Oct 2009
  7. MeEsH BaKkA

    Mobster

    Joined: 12 Dec 2002

    Posts: 2,948

    The car has a remap and precat removal pipe (down pipe) stock power is 240bhp, I know this isnt a vaux forum im just after a second opinion on the graphs without tuners fighting over what could be the reasons.
     
  8. MeEsH BaKkA

    Mobster

    Joined: 12 Dec 2002

    Posts: 2,948

    The turbo isnt big im thinking as it is a tweaked Bluefin map mabey the car is boosting too much hence the 300lbft and low bhp
     
  9. kaiowas

    Capodecina

    Joined: 18 Oct 2002

    Posts: 10,245

    Location: Castle Anthrax

    They're plotted on completely different axes, you can make them cross wherever you want under those circumstances,
     
  10. Lumeycom

    Wise Guy

    Joined: 31 Jan 2008

    Posts: 1,238

    Location: S Wales

    I think that maybe your problem then, your simply running outside (and increasingly so as the RPM's increase) the turbo's efficiency zone in the turbo map.

    You also have boost control issues for sure, whether its a weak actuator or a poorly setup boost controller. Even if the turbo is running out of puff and being a hairdryer the torque curve should be alot smoother than it is. Its possible also that there are holes in the map that cause fuelling issues leading to less boost in the load zones.

    Assuming they are back to back runs would point to boost control issues as the initial torque spike as the turbo comes on song differ quite alot.

    Did you get an AFR graph with it? if so you can rule out fuelling issues

    Was it checked for det whilst running too? it could be pulling back the timing and readvancing it with signals from the knock sensor.


    edit - if its a variable vane turbo then i know naff all about them aside from voodoo magic happening inside :p
     
  11. Lumeycom

    Wise Guy

    Joined: 31 Jan 2008

    Posts: 1,238

    Location: S Wales

    Fair point, missed that :E
     
  12. Jonnycoupe

    Capodecina

    Joined: 19 Oct 2002

    Posts: 12,804

    Location: N.Warks

    That is a car having an asthma attack.
     
  13. MeEsH BaKkA

    Mobster

    Joined: 12 Dec 2002

    Posts: 2,948

    No AFR or boost tests it was just a power run, the boost peaks 100rpm later/earlier in one and the big peak is overboost I know that much just the rest of it looks like the side of a mountain.
     
  14. Lumeycom

    Wise Guy

    Joined: 31 Jan 2008

    Posts: 1,238

    Location: S Wales

    Difficult to diagnose without afr/boost graphs and someone checking det did not occur but I'm gonna go with small turbo running out of its efficiency.

    Or as Jonny says, car asthma :)


    edit - just a thought.... you have a decent airfilter on it yes? as in not some crappy ebay jobbie. Just thinking that a restriction intake side could cause it too.
     
  15. MeEsH BaKkA

    Mobster

    Joined: 12 Dec 2002

    Posts: 2,948

    hmm I think I will remove the map to be safe, could the actuator be set too weak? the general advise on the vxr forum is slacken it off once the precat is removed and allow the ecu to dealwith theboost although this sounds crazy.
     
  16. BigglesPiP

    Capodecina

    Joined: 8 Mar 2006

    Posts: 13,293

    Location: Near Winchester

    Are the dots the samples?

    I think the line plotting function is in a bit of a funky mood if this is the case.
     
  17. Lumeycom

    Wise Guy

    Joined: 31 Jan 2008

    Posts: 1,238

    Location: S Wales

    Sounds odd, but I'm not familiar with your car - more of an old school engine type with vems/megasquirt affairs ;) Learnt the hard way mostly lol :)

    Dastek dynos constant sample iirc
     
  18. Lumeycom

    Wise Guy

    Joined: 31 Jan 2008

    Posts: 1,238

    Location: S Wales

    [​IMG]


    ^^ My last torque graph before i sold it, top end drop was it wanting a little more lift on the inlet cam
     
  19. MeEsH BaKkA

    Mobster

    Joined: 12 Dec 2002

    Posts: 2,948

    I wish mine looked like that ^^

    I have spoke to thuner whos map I have and they are blaming Plugs (prob never changed didnt think of this) or the AMM but say there map is fine but then of course they would. Looks like it could be time to spend some money on a decent live map.
     
  20. Dr Who

    Sgarrista

    Joined: 11 Nov 2004

    Posts: 8,126

    Location: Wiltshire

    They cross exactly at 5250, try looking at the scales maybe?

    The power comes in nice an early, like a sledgehammer, then drops off fast (overboost valve opening? or maybe some wheelspin on the rollers?) After that, its a steady drop off, almost like the turbo just isnt big enough?
     
    Last edited: 4 Oct 2009