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  1. #1
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    Twin Turbo Update - - Dyno Results....

    A big thanks to John St. Pierre (RevHigh) for coordinating todays Dyno event. Thanks also to Brian and the guys at Ultimate Performance for being such gracious hosts. I think it was a great success for all involved.

    OK. Now for the numbers...

    361 RWHP
    524 RWTQ

    Here's the graph...
    .

    .
    Do notice that the RPM scale across the bottom is not accurate. This is due to the fact that the dyno software wouldn't allow for engine configurations that fire every 60 degrees of crank rotation (read: V12's). To calculate the actual RPM, you must multiply by 1.5 and subtract 1000. Sounds convoluted, I know, but it's the only way we could get the computer to register the car so we could make the runs. Rest assured, however, that this has no impact on the peak HP and TQ numbers - - although I do admit that the actual curves would look a bit different (ie crossing at 5252 RPM's).

    Unfortunately, I was so busy configuring my fuel and timing curves that I forgot to take any pics. Thus I'm hoping that Faisal or one of the other guys will post some pics and/or videos of the event.

    I'll share more of the technical details of the experience with you in the coming days. Stay tuned...
    - John
    '92 850i Twin Turbo

  2. #2
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    ***Corrected Graph Below***

    Since the dyno couldn't be configured for a V-12 engine,
    I was forced to re-calculate the horsepower points on the
    graph as shown below. In case you're wondering, the formula
    I used was...

    HP=(TQ x RPM)/5252

    The upper left hand corner of the graph shows the points
    and how they were calculated. So as you can see, the dyno
    results are as follows....

    444 RWHP at 5750 RPM's
    524 RWTQ at 3890 RPM's

    I think I like those numbers even better...!!! OH YEAH !!!

    Here's the corrected graph...
    .

    .
    Rgds...
    - John
    '92 850i Twin Turbo

  3. #3
    ScottJackson
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    That's more like it...

    I thought that the earlier results put the HP awfully low. 444hp at the wheels is sweet. Yes, pictures and videos please. Get some old tires and do some donuts, some drifting around corners... everything but wrecking :) I need some more motivation to get my twin turbo stang project done. Too bad it'll only be 8 cylinders. But I guess mine will be 8.4 liters. There I go talking again, "WILL be". Time to start doing. And I just started looking at a Datsun 280Z that I can probably get cheap for a V8 swap... darn darn. Keep the updates rollin

  4. #4
    badmonkey
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    A/F is not good!!!


  5. #5
    ScottJackson
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    what's so bad about it?

    maybe lean around 1250rpm when the test starts, but who knows just how accurate it is at that point anyway if it's going thru that rpm extremely fast on a dyno pull? Do you mean that it should be richer (more safe)? For relatively low boost, I personally think his A/F is pretty good. I'm no expert though, that's very certain. Also, I've read a lot more on blowthrough carb stuff and maybe that's completely different. With carbs, if you get as good of A/F as his car, that's just great.

  6. #6
    badmonkey
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    Looks very lean


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    Actually, the A/F is just fine. The sensor was...

    ...reading near 16:1 at idle - - this being due to the fact that they stuck the probe into the tailpipe (post cat). I have a wideband O2 controller in the car and it never eeked above 13:1.

    The only reason I had them record O2 was so I could get a sense of the curve and compare it to the readings from those recorded with my wideband. Rgds...
    - John
    '92 850i Twin Turbo

  8. #8
    badmonkey
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    How much boost? 13:1 is lean for a turbo....


  9. #9
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    If you look at the curve correlating that 13:1 was

    ...the leanest, then you'll see that most of the RPM range was in the 11.5 to 12.5 range. That was with 7 lbs of boost. Rgds...
    - John
    '92 850i Twin Turbo

  10. #10
    Paul E
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    Re: Actually, the A/F is just fine. The sensor was...

    >>reading near 16:1 at idle - - this being due to the fact that they stuck the probe into the tailpipe (post cat). I have a wideband O2 controller in the car and it never eeked above 13:1. <<

    Actually, above ~4000 rpms, the precat and postcat afr readings should be very similar.. By 4k rpms, the extra O2 in the cats that would normally make the post cat readings lean has been scoured out.. So, many of us who have measured the tailpipe sampling widebands at the dyno hvae found that the results mirror our precat widebands pretty well.. Of course at idle, it will be way off.

  11. #11
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    Hey John..Were you looking for a better Wastegate?


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