Ken in AZ
ill-tempered
- Joined
- Oct 2, 2006
- Messages
- 358
Just curious if one could set the wastegate to open at a set drive pressure to acheive their desired drive pressure ratio in accourdance with boost.
The way I'm thinking is that this would tell the efficiency of ones wastegate since drive pressure should theoretically stay the same throughout all rpm ranges if the wastegate is properly sized to the application.
Here's my logic and let me know if i'm way off. If there were no wastegate on the turbocharger then you may hit your desired boost level of 45psi at 2000rpm and have a drive pressure of 55psi, however at 3800rpm you have the same boost level but the drive pressure is over 70psi. Obviously this would be inefficient. Now take that same turbo and add a 100% efficient wastegate and set it to open @ 55psi drive pressure and theoretically it would maintain your desired max pressure of 45psi throughout the rpm band. all while maintaining your drive pressure.
The only thing I'm not taking into account is the volumetric efficiency and airflow increase of the engine and as RPM increases which could cause the boost to fall off as RPM increases.
Does this make sense to anyone? I may have answered my own question but I'm thinking about trying this and the only reason why is because when testing the cracking pressure of my wastegate it would crack at 40psi but it wouldn't completely open until 55-60psi. If I connected the signal line to the drive pressure port then I would have a better source to open the gate since my turbo produces high drive pressure ratios and the wastegate has trouble managing the boost down the 1/4 mi (ie: boost creep)
Thanks
Ken
The way I'm thinking is that this would tell the efficiency of ones wastegate since drive pressure should theoretically stay the same throughout all rpm ranges if the wastegate is properly sized to the application.
Here's my logic and let me know if i'm way off. If there were no wastegate on the turbocharger then you may hit your desired boost level of 45psi at 2000rpm and have a drive pressure of 55psi, however at 3800rpm you have the same boost level but the drive pressure is over 70psi. Obviously this would be inefficient. Now take that same turbo and add a 100% efficient wastegate and set it to open @ 55psi drive pressure and theoretically it would maintain your desired max pressure of 45psi throughout the rpm band. all while maintaining your drive pressure.
The only thing I'm not taking into account is the volumetric efficiency and airflow increase of the engine and as RPM increases which could cause the boost to fall off as RPM increases.
Does this make sense to anyone? I may have answered my own question but I'm thinking about trying this and the only reason why is because when testing the cracking pressure of my wastegate it would crack at 40psi but it wouldn't completely open until 55-60psi. If I connected the signal line to the drive pressure port then I would have a better source to open the gate since my turbo produces high drive pressure ratios and the wastegate has trouble managing the boost down the 1/4 mi (ie: boost creep)
Thanks
Ken