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Reply to "Looking to buy a Speedster with a 1640cc engine"

First off, that was an awesome dyno pull. They clearly know what they are doing. Clean area and a clear process.  Process is everything.  In earlier days, I got certified on a SuperFlow CycleDyn.  The real usefulness of a dyno is in crafting the shape of the curves and it's interesting to see how people's  "butt dynos" reacts to documented changes.  By smoothing the curves and increasing the area under the curves you usually get a much faster car, and if you've calibrated the transitions well you get great throttle response.  That's something Stan alluded to elsewhere in our records and it's huge when it comes to the "butt dyno" readings.  

There are several places that the operator can make the actual numbers higher or lower on purpose, and some are out if their control.  First is the machine calibration. If the tuner recalibrated the dyno after the baseline run and before the finished tune run...he's playing with you.  There are the expected driveline losses, and for a 4 wheel drive these can be considerable.  Then there are the losses from tire to drum and these can be huge, too. You can change a dyno number by 5% or more going from under inflated to overinflated or simply from cold to hot tires. Then there's air temp and humidity.  They have corrected hp/tq calculations to supposedly make up for that, but they really can't because denser air behaves differently. That won't be a big difference, but it's there nonetheless.  

You can tune an engine with 150 wheel hp, really get it running right and it now makes maybe 155 hp.  You give it the customer without any info and ask them what they think and they will swear it's gotta be making 175 now!  Then you show them the before and after graphs and explain why it's faster.  If they're smart, they are thrilled.  If they only wanter to "hit a number" they won't be happy.  Most tuners aren't good teachers and too many people fit the "hit a number" category. Most tuners just don't want to deal with people because they are less predictable than engines.

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