Attention: TDR Forum Junkies 
My Garrett Stage 2 PowerMax turbo still runs well and is the most drivable turbo I have ever tried but it has been making noise for a couple years and a local shop suggests I replace it soon. It sounds like something is dragging, much like when a water pump is failing. We've checked the compressor side and all seems fine so it must be on the exhaust side.
Because this 12 valve is in a Ford Excursion that has front and rear HVAC there is very little room for options. From talking with turbo dealers compound turbos would be the best solution to achieve even faster spoolup while flowing more air for decreased EGTs. I just can't envision the installation, even with the primary mounted above, possibly through the hood. My hope is to somehow make a single turbo be a final, permanent solution.
Garrett dropped the PowerMax line years ago and I was informed through a Garrett dealer that it can't be rebuilt and there are no parts for it. They have no direct replacement model either so I would have to change sizes either smaller or larger. I think if they had a GTX wheel option for this turbo it would possibly be enough of an improvement, advertised as 10% faster spooling and upper flow.
The only option to make things work as a single that I've so far come across is to use a spool valve. I keep coming back to the BD Diverter Valve. What I've read on the forums varies greatly. I've seen reports of over 150 max hp increase while some say mid and upper range power is decreased.
My biggest hesitations are that it might not be worth the money and effort in gains, and that they may still have failure issues. I've read some folks have burned up turbos because the valves would fail closed. Some require constant maintenance and cleaning, and that soot and heat can destroy the valves. I've also read that they increase heat and high EGTs is a problem I am trying to solve.
The idea is that I could upgrade to a larger turbo and using the diverter valve still be able to enhance spoolup. Physical space is a huge concern. My Garrett has very little clearance to the heater box as it sits now on a PDI three piece manifold. The diverter valve would space it out at least 2" toward the box, which I'm pretty sure would actually put it over an inch through it.
I can imagine tilting the engine to make it fit but am hoping there are some members here with experience with various spool valves who can provide me with enough current, up to date information that will convince me either way whether or not I should try modifying to fit a diverter valve with a larger turbo. Most of the posts I've found are several years old.
As a point of interest I was advised that the way my engine is setup I would be making a very cool 800-850 hp to the ground with my current turbo over a large ball bearing primary. That sounds like fun but the turbo being recommended was $4,500, which I expect could budget fabricating an entire compound kit. A single would be so much simpler.
Because this 12 valve is in a Ford Excursion that has front and rear HVAC there is very little room for options. From talking with turbo dealers compound turbos would be the best solution to achieve even faster spoolup while flowing more air for decreased EGTs. I just can't envision the installation, even with the primary mounted above, possibly through the hood. My hope is to somehow make a single turbo be a final, permanent solution.
Garrett dropped the PowerMax line years ago and I was informed through a Garrett dealer that it can't be rebuilt and there are no parts for it. They have no direct replacement model either so I would have to change sizes either smaller or larger. I think if they had a GTX wheel option for this turbo it would possibly be enough of an improvement, advertised as 10% faster spooling and upper flow.
The only option to make things work as a single that I've so far come across is to use a spool valve. I keep coming back to the BD Diverter Valve. What I've read on the forums varies greatly. I've seen reports of over 150 max hp increase while some say mid and upper range power is decreased.
My biggest hesitations are that it might not be worth the money and effort in gains, and that they may still have failure issues. I've read some folks have burned up turbos because the valves would fail closed. Some require constant maintenance and cleaning, and that soot and heat can destroy the valves. I've also read that they increase heat and high EGTs is a problem I am trying to solve.
The idea is that I could upgrade to a larger turbo and using the diverter valve still be able to enhance spoolup. Physical space is a huge concern. My Garrett has very little clearance to the heater box as it sits now on a PDI three piece manifold. The diverter valve would space it out at least 2" toward the box, which I'm pretty sure would actually put it over an inch through it.
I can imagine tilting the engine to make it fit but am hoping there are some members here with experience with various spool valves who can provide me with enough current, up to date information that will convince me either way whether or not I should try modifying to fit a diverter valve with a larger turbo. Most of the posts I've found are several years old.
As a point of interest I was advised that the way my engine is setup I would be making a very cool 800-850 hp to the ground with my current turbo over a large ball bearing primary. That sounds like fun but the turbo being recommended was $4,500, which I expect could budget fabricating an entire compound kit. A single would be so much simpler.
