Good evening all.
I have a 3 litre idi that was previously running 39psi boost pressure for 65psi drive pressure with a 48mm inducer on the comp and a 48mm exducer on the turbine. The turbo couldnt make any more boost. I have replaced the turbo for a slightly larger turbo with 52.5mm inducer on the comp and 52.5mm exducer on the turbine. Exhaust housings arent directly comparible but are of a very similar size. The results are not what I was hoping for...The turbo can indeed make more boost but at the cost of very high drive pressure and no performance gain. 45psi boost results in 80psi drive pressure and slower acceleration times than the original smaller turbo at 39psi. To make 45psi on the new turbo the wastegate must be held closed completely, hence the high drive pressures.
My dilema is as follows, as the rear housing at the moment is essentially ungated as held closed it is taking 80psi drive to create 45psi boost. How do I rectify this? I cant overcome the thinking that I should downsize the turbine housing to allow the turbine housing to make better use of the exhaust gas and open the wastegate to bleed off any excess exhaust, lowering drive pressure whilst maintaining shaft speed to maintain boost pressure. Surely a larger turbine housing would require even more exhaust energy to maintain the shaft speed required for 45psi boost?
Any input much appreciated
Thanks in advance
I have a 3 litre idi that was previously running 39psi boost pressure for 65psi drive pressure with a 48mm inducer on the comp and a 48mm exducer on the turbine. The turbo couldnt make any more boost. I have replaced the turbo for a slightly larger turbo with 52.5mm inducer on the comp and 52.5mm exducer on the turbine. Exhaust housings arent directly comparible but are of a very similar size. The results are not what I was hoping for...The turbo can indeed make more boost but at the cost of very high drive pressure and no performance gain. 45psi boost results in 80psi drive pressure and slower acceleration times than the original smaller turbo at 39psi. To make 45psi on the new turbo the wastegate must be held closed completely, hence the high drive pressures.
My dilema is as follows, as the rear housing at the moment is essentially ungated as held closed it is taking 80psi drive to create 45psi boost. How do I rectify this? I cant overcome the thinking that I should downsize the turbine housing to allow the turbine housing to make better use of the exhaust gas and open the wastegate to bleed off any excess exhaust, lowering drive pressure whilst maintaining shaft speed to maintain boost pressure. Surely a larger turbine housing would require even more exhaust energy to maintain the shaft speed required for 45psi boost?
Any input much appreciated
Thanks in advance