13-03-2014, 09:16 AM
Exactly that.
We've established that exhaust back pressure is one of the biggest restricting factors these engines face, both for power and reliability, so keeping the stock turbine housing and forcing it to drive ever higher boost pressures is a fast track ticket to a dead head/engine. When these engines are letting go on a stock turbo, it's due to the exhaust housing being so restrictive, which is why I don't understand the desire to keep the stock turbine housing AND make it work harder, thereby increasing back pressure further. We've exceeded the standard turbo's efficient flow capacity with a good stage 2, so the capacity for more exhaust flow is essential for further tuning. Reaming the housing as they do for a hybrid will give fractionally more flow, but nowhere near enough. And as Steve points out, it loses a lot of the turbo's efficiency in the process - would you try and tow a 18 tonne artic trailer with a landrover? Of course not, because while it might just do the job, any sort of efficiency goes out of the window and you'll be stressing the landrover to all hell - same principle.
We've established that exhaust back pressure is one of the biggest restricting factors these engines face, both for power and reliability, so keeping the stock turbine housing and forcing it to drive ever higher boost pressures is a fast track ticket to a dead head/engine. When these engines are letting go on a stock turbo, it's due to the exhaust housing being so restrictive, which is why I don't understand the desire to keep the stock turbine housing AND make it work harder, thereby increasing back pressure further. We've exceeded the standard turbo's efficient flow capacity with a good stage 2, so the capacity for more exhaust flow is essential for further tuning. Reaming the housing as they do for a hybrid will give fractionally more flow, but nowhere near enough. And as Steve points out, it loses a lot of the turbo's efficiency in the process - would you try and tow a 18 tonne artic trailer with a landrover? Of course not, because while it might just do the job, any sort of efficiency goes out of the window and you'll be stressing the landrover to all hell - same principle.