- Joined
- Nov 27, 2015
- Threads
- 99
- Messages
- 911
- Reaction score
- 2,498
- Location
- Torrance California
- Website
- www.hondata.com
- Vehicle(s)
- 23' Type R,22' Civic Si,18' Accord 2.0T,17' FK8
- Vehicle Showcase
- 1
- Thread starter
- #1
It is critical when on the dyno to have a lot of airflow over the intercooler. What we have seen with a number of dyno sessions is that without adequate air flow the intake air temperature will reach the point where more requested torque will result in a minimal power increase.
Look at the IATs and boost pressure over a run and the shape of the torque curve from the dyno. Symptoms are:
- torque peaks high and then tapers at high rpm
- IAT is more than 40F over ambient temperature
- boost is high (over 26 psi)
What is happening is that since the ECU is torque based as temperatures rise the ECU will target more boost. Since the turbo is at a point where efficiency is falling, more boost will give higher compressor discharge temperatures, and higher IATs. Higher boost will also give less ignition timing. Higher boost and higher temperatures will increase the change of getting knock, which will retard the ignition and decrease power for several seconds. None of this is good for power.
The good news is that you will not observe this behavior while driving as the air flow over the intercooler is much higher than with a fan on the dyno.
When tuning consider:
- more air flow
- limit peak torque using the maximum air flow table
- limit boost using the turbo maximum pressure ratio table (IAT)
As always on the dyno you would monitor lambda, fuel pump duty and knock.
Look at the IATs and boost pressure over a run and the shape of the torque curve from the dyno. Symptoms are:
- torque peaks high and then tapers at high rpm
- IAT is more than 40F over ambient temperature
- boost is high (over 26 psi)
What is happening is that since the ECU is torque based as temperatures rise the ECU will target more boost. Since the turbo is at a point where efficiency is falling, more boost will give higher compressor discharge temperatures, and higher IATs. Higher boost will also give less ignition timing. Higher boost and higher temperatures will increase the change of getting knock, which will retard the ignition and decrease power for several seconds. None of this is good for power.
The good news is that you will not observe this behavior while driving as the air flow over the intercooler is much higher than with a fan on the dyno.
When tuning consider:
- more air flow
- limit peak torque using the maximum air flow table
- limit boost using the turbo maximum pressure ratio table (IAT)
As always on the dyno you would monitor lambda, fuel pump duty and knock.
Sponsored