[s-cars] 80tq: 20v Project Update, 415whp, 12.25, etc

[JShadzi at aol.com]

Scott, agreed on the turbo comment.  In fact, often a "controlled leak" can be used to push a turbo into a more efficient area of the compressor map, the extra flow just venting to atmosphere, but allowing the turbo to flow more air to avoid the surge or overspeed line.  Altitude can have the same effect.

Javad

>^v> (tm - hail mary), good post Javad.  I might add too, that some of these big turbos might actually produce better numbers at altitude because the PR vs CE places the motor on the map better.  A turbo working harder at altitude could quite possibly be a good thing.  A FPR working at altitude might also be a good thing (3.0 bar FPR means 3.0 * atmospheric = not necessarily 43.5psi).  I don't automatically buy the argument that there is an 'easy' correction, or even an 'increase' in power going to a lower altitude.  That would depend on a lot of factors.  In general, it might/should be true, but reality dictates that those living at altitude are special cases.  A whole bunch of chip tuners found this out on 1.8t and 2.7tt.  Several of them have made special trips stateside to get the feel of our low pressure ambient zones.
>
>Scott Justusson
>.987mb Chicago...
>In a message dated 11/11/2004 10:53:33 AM Eastern Standard Time, JShadzi at aol.com writes:
>
>>I'd also like to add the reality check that dyno's do not read the same (from one to the next), and its dangerous to assert (at any atmosphere) that dyno figures are universally discrete.  I want to go on the record with that.
>>
>>Dave, I believe that your uncorrected figure is realistic, if you went to a sea level dyno, I think you'd see a mild increase over those #'s, but no where near "Corrected figures".
>>
>>I like quoting uncorrected figures for turbo motors, but this still doesn't make up for the huge disparity in dyno calibrations, which make quoting HP figures almost useless anyway.
>>
>>Dyno figures are ultimately useful for comparing the same motor to its past performance.  I _always_ run on the same dyno for this reason, as dyno #'s are only very valid for baseline comparisons.
>>
>>Javad
>>
>>
>>>>
>>>
>>>Well, doing what Mike suggested, a complete removal of correction factors
>>>leaves mine at 340hp/362ft-lbs.  If you're suggesting that there isn't any
>>>difference between our altitude and sea level (in terms of power output), I would
>>>beg to differ.  The difference from a driving perspective is quite large.  Not
>>>sure where I'd go to dyno at sea level, but it would be interesting.  It would
>>>be helpful, as clearly you're indicating that you think our #'s are grossly
>>>exaggerated.  It would be nice to draw some scientific conclusion.
>>>Take care,
>>>Dave
>>>
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>