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10 years old and Still going strong...

Discussion in 'A4/S4 forum(B5 Chassis)' started by Rallyman, Aug 16, 2010.

  1. Rallyman
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    Rallyman LPG Abuser & have VAGCOM

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    I took my lpg powered A4 TQS Avant to Dave Walkers (emerald) rolling road last week for a power run & comparison of the LPG system vs Petrol........ Solid line is petrol & dotted is LPG.
    It is strange that a year ago the LPG was making another 10bhp and the power from the petrol was 170bhp .......
    Anyway it has now done 158K miles and still on the original turbo....
    [​IMG]
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Looking at your graph, its running a LOT richer on LPG thru most of the rev range, which most likely explains the lack of power...
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  3. Rallyman
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    Rallyman LPG Abuser & have VAGCOM

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    LPG AFR is the green dotted line below the Petrol (AFR4), showing less then the petrol.

    What is strange though is there is less torque on LPG but more power, I'm thinking that I decrease the injector size (LPG) to weaken it....

    What should a standard TQS (AJL engine) torque figure be ?
    #3
  4. gaz71
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    gaz71 1.8T Quattro Sport AJL

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    Mine's 11 years old with a postal remap.

    [​IMG]

    Hope that helps
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    The LPG isnt less than petrol... The AFR is lower, which means the engines running richer. Only when the mixture leans out towards the upper RPM range does the power finally come up to match the petrol value.

    AFR of 10:1 is far too rich, so your obviously going to make less power. It makes more power right at the top end, because it ends up very slightly leaner than the petrol fuelling.

    Whats odd is the way it tapers down as the revs climb. Simply changing the injector size isnt going to fix that, you might just end up making it dangerously lean at the top end if you dont fix whatevers causing the taper.
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  6. Jonion
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    Jonion Member

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    Yep, LPG is weaker than ptrol.
    But I'd say that on petrol it's slightly too weak lower down, and slightly too rich on LPG in the same area.
    Around 11:1 is not far off what you want.
    Can it be mapped ?
    #6

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