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Discussion Starter #1
We were tuning our 16V on the dyno today and noticed a torque dip starting at about 3300 RPM and ending somewher around 3500-3600RPM. I did a search and noticed a lot of 16V naturally aspirated motors have a torque dip starting at 3000-3500RPM. Some are worse than others. We tuned the advance and fuel to minimize the drop but still have a little dip. Anyone tell me why? We are pulling really good numbers out of the motor (on an 90 degree day with crazy humidity) but are curious as to what this is. Do not have a long history with VW motors.
BTW - Wheel HP is north of 165 right now - stopped pulling power at 6750 RPM - Curve was still climbing. Did not get a chance to finish A/F curves or timing above 6500 - Ran out of time on the dyno.
 

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Discussion Starter #2
Re: Torque Drop on Dyno (rivethead)

Spoke to a couple different engine people including Berils - Everyone seems to think that it is a harmonic issue on the intake. I have seen this drop on ITB cars as well - Could be in the head design. I have worked out a lot of the drop with timing and fuel. HP numbers keep climbing. See what we get when we run it to 7500-8000. Have to know the limits.
 
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