tire pressure -- ever looked closely @ the tire of a car while on the dyno? quite a bit of deformation.... next time try running about 45 psi, you'll be suprised

Straps -- the straps used to tie the car down will also usually pull the car downward, loading/deforming the tires thus increasing drag. if your dyno operator is comfortable with it, try running the straps slightly loose

Heat -- while heat in the engine is not good for ignition timing/detonation resistance, heat in the exhaust manifold has a noticable positive affect. next time your doing a power pull try to get some heat in the manifold by doing 2 slow, low power pulls after cooling the car, this will keep the cyl head & engine temps down, but put some heat in the manifold

Oil -- on a AWD car, there are signifigant parasatic loses through the drivetrain, while i havent seen this on an awd car/evo, i have seen improvments RWD V8's by simply switching out the gear oil to a less protective, but lighter oil

Correction factor -- the big one
typically dynos will have a "correction factor" which is an external mulitplier entered either by the dyno operator, or when the unit is installed. next time your on a dyno dynamics, ask the dyno operator to hit "Ctrl X" to see if your dyno is using a correction factor

Exhaust venting -- some indoor dynos use a slip fit tube over your exhaust tip to route exhaust gasses outside. i have seen cases where this has introduced backpressure & lowered readings. hooking up an evacuation fan to this line resulted in lower backpressure than the car would normally make on the street, while power did increase, the tune was off when the car hit the street as the suction on the exhaust was no longer present

Clean air -- if your dyno does not have a good breeze or flow of air from the front of the car to the back & out a door your car may be taking in less than clean air, while this is less noticable i have seen changes when doing cars back to back in a poorly ventilated area simply by opening up the doors & venting out the built up fumes


ill add more later, i hate typing & my fingers are starting to hurt

 

I agree on some and disagree on some of this.
Is the point to have a faster car or to slightly inflate your ego by tricking the dyno? As long as you do uniform testing, who cares about extracting a tiny bit more by being sneaky.

I'd rather know the truth than a slightly manipulated version of it.

 

in my opinion, dynos are a tool to be used for tuning & getting an idea of your power output. while they all give out "HP" numbers, there are too many variables when dynoing a car to be comparing dyno numbers to one another, yet people still do it. i just figured id throw out a few things i had seen that had more of an affect than most people would think

 

I dont think any experienced dyno operator with any record of sobriety will set the straps slightly loose with a 350 awhp evo

By far the easiest way to fudge some dyno numbers would be calculate your data log lab results with a log done down a 6% grade

 

You could have 50 more peak hp than another evo and still get your A$$ handed to you on a road course.. so dyno #s mean absolutely nothing to me.

 

There is no point to this thread. Unless there are evo dyno competitions or money involved in getting the highest number printed out on a piece of paper, this will help nobody unless people try to keep these variables constant each time they visit the dyno.

Scorke