Rajay (BAE) turbo rebuild stupid question

[RamblinDMC]

If there's no obvious damage I wouldn't be too concerned about balance.




Right on! My own T3 was "professionally rebuilt". I had to re-rebuild it because the professional screwed up the carbon seal installation in a manner that isn't obvious unless you have specific experience in draw-through turbo setups (like the BAE). The "professional" also installed a compressor wheel that was interference fit to the turbine shaft which was a pleasant discovery.

The important question is: Why are you rebuilding it?

An even importanter question: Would you be interested in a set of BAE intake adapters that are set up for improved PCV and water injection?

What should I look out for when installing the carbon seal as it pertains to the BAE turbo/draw through setups? Is it not just as simple as installing it in the correct orientation? Any help is gladly appreciated.
I'm rebuilding it because it is leaking oil around the compressor housing and it smells of burnt oil. Also, from my understanding it was burning oil. There is no shaft play or damage to the impellers and housings. I'm also rebuilding it for the learning experience. It seems I always have to be occupied with a little project after work/school.
Last year I purchased the setup from SS Spoiler (Thank you again!) and I'm just now getting around to refurbishing the components for installation on my car.

I'm currently taking Thermodynamics and all the practice problems on turbines got me thinking of this project. Additionally, I've always wanted to enter into the foray of turbocharging and why not go all out?

For now my goal is to just get the turbo installed on the car, later I'll be doing some mods to modernize the setup.

[FABombjoy]

What should I look out for when installing the carbon seal as it pertains to the BAE turbo/draw through setups?

I've never taken a Rajay apart, but Garrett used either an "encapsulated" seal which is a sealed unit that is pressed in/out of the backplate, or a multi-piece seal that is integrated into the backplate. The press in/out type need to be pressed in with Loctite 515 or they will continue to draw oil around the seal. The type with a seal, spring, etc won't have this extra air channel and shouldn't require any special precautions or sealant.

I'm rebuilding it because it is leaking oil around the compressor housing and it smells of burnt oil. Also, from my understanding it was burning oil. There is no shaft play or damage to the impellers and housings.

My opinions, based on my own experience with building a T3 draw-through setup:

Aftermarket turbo cars with oil in the intake are almost always due to problems with the drain setup. Oil needs to leave the turbo ASAP and with no restriction. I can't believe DMC/BAE kits didn't leak oil into the compressor housing from day one. Every BAE setup I've seen has the center section clocked at 4:30 instead of 6. I've also seen BAE drains hoses with J traps. The drain hose is 5/8" (-10AN) which is the bare minimum for this size of turbo. The turbo is fairly low mount which doesn't give you much room for error. If you have any positive crankcase pressure the drain could slow down or back up.

The BAE drain location on lower crankcase dumps right into the oil deflector tray, another negative for a clear drain path.

If you have no shaft play and something isn't obviously wrong on the inside, you should consider tweaking the drain setup to be more optimal ( to further your studies )

Full disclosure: I've never examined a Rajay turbo up close. Maybe they have some kind of angled / funneled drain or are unusually tolerant of oil pooling. I'd certainly be curious to see some real high res pics of one disassembled.

[David T]

What should I look out for when installing the carbon seal as it pertains to the BAE turbo/draw through setups? Is it not just as simple as installing it in the correct orientation? Any help is gladly appreciated.
I'm rebuilding it because it is leaking oil around the compressor housing and it smells of burnt oil. Also, from my understanding it was burning oil. There is no shaft play or damage to the impellers and housings. I'm also rebuilding it for the learning experience. It seems I always have to be occupied with a little project after work/school.
Last year I purchased the setup from SS Spoiler (Thank you again!) and I'm just now getting around to refurbishing the components for installation on my car.

I'm currently taking Thermodynamics and all the practice problems on turbines got me thinking of this project. Additionally, I've always wanted to enter into the foray of turbocharging and why not go all out?

For now my goal is to just get the turbo installed on the car, later I'll be doing some mods to modernize the setup.

If there are no signs of oil leaking internally and there is no end play or run-out, it probably doesn't need to be rebuilt. If all of your leaks are external it is either a gasket or a fitting or a hose leaking. The reasons to rebuild are the bearings are worn (indicated by run-out and end play) causing the seals to leak. When it gets bad enough the impellers touch the housing causing damage to the housings and the impellers. Clean it up and reseal the external oil connections and you are probably OK. Use Never Seize on all of your exhaust hardware and new gaskets. When running a turbo you should replace the oil and filter more often and use a synthetic oil that can take the higher temperatures. You must use the highest octane fuel you can find and be very alert to any detonation. Don't let the boost go over 5 lbs. Never let the motor run too lean or with too much timing advance. Do you have the BAE docs? Make sure your install is as correct as you can make it at least initially. This set-up has no intercooler. It is not meant for it to be "on boost" continuously. Consider a boost gauge and an A/F gauge. There is no knock sensor to retard the timing to protect the motor so be careful. For optimal operation you should wrap the exhaust plumbing to the turbo and the turbo with heat wrap. Make sure nothing is close to the exhaust plumbing or the turbo like wiring of fuel or anything else, that stuff gets HOT! Make sure the distributor is set up correctly per the BAE docs.

[RamblinDMC]

If there are no signs of oil leaking internally and there is no end play or run-out, it probably doesn't need to be rebuilt. If all of your leaks are external it is either a gasket or a fitting or a hose leaking. The reasons to rebuild are the bearings are worn (indicated by run-out and end play) causing the seals to leak. When it gets bad enough the impellers touch the housing causing damage to the housings and the impellers. Clean it up and reseal the external oil connections and you are probably OK. Use Never Seize on all of your exhaust hardware and new gaskets. When running a turbo you should replace the oil and filter more often and use a synthetic oil that can take the higher temperatures. You must use the highest octane fuel you can find and be very alert to any detonation. Don't let the boost go over 5 lbs. Never let the motor run too lean or with too much timing advance. Do you have the BAE docs? Make sure your install is as correct as you can make it at least initially. This set-up has no intercooler. It is not meant for it to be "on boost" continuously. Consider a boost gauge and an A/F gauge. There is no knock sensor to retard the timing to protect the motor so be careful. For optimal operation you should wrap the exhaust plumbing to the turbo and the turbo with heat wrap. Make sure nothing is close to the exhaust plumbing or the turbo like wiring of fuel or anything else, that stuff gets HOT! Make sure the distributor is set up correctly per the BAE docs.

Thanks for the info. I'm fully aware of the dangers of turbocharging. I'm going to play it safe and keep the boost low. I do have the BAE docs and a used distributor configured for the turbo. I am planning to install a boost gauge along with an AFR gauge. In the near future, after I graduate college and start working, I also plan on converting the engine to EFI+electronic ignition so that I have more control. It may also be a good idea to mount a drip tank with a small pump under the turbo. But I'm getting ahead of myself. Right now the task at hand is rebuilding the turbo itself. I appreciate everyone's input and help so far. Tonight I'm going to try to remove the compressor nut.

[FABombjoy]

It may also be a good idea to mount a drip tank with a small pump under the turbo.

I upsized to 3/4" hose and ran straight into the side of the pan, and clear tubing showed this was enough, although I may graft on a 300 to 500mL vented drip tank for really really cold mornings. I'm also redoing PCV to ensure crankcase pressure is never an issue again.

I desperately did not want to run a scavenge pump as it seemed like another thing to go wrong

[David T]

I upsized to 3/4" hose and ran straight into the side of the pan, and clear tubing showed this was enough, although I may graft on a 300 to 500mL vented drip tank for really really cold mornings. I'm also redoing PCV to ensure crankcase pressure is never an issue again.

I desperately did not want to run a scavenge pump as it seemed like another thing to go wrong

If the turbo is being flooded by oil, one possible solution is to put a restrictor into the feed hose to reduce the amount of oil going to the turbo. If crankcase pressure is a problem you may have too much blow-by because you blew a piston from too much boost. Using multi-grade synthetic oil you should not have cold starting problems. If it is that cold stay off the boost till the motor gets up to operating temp.

[FABombjoy]

If the turbo is being flooded by oil, one possible solution is to put a restrictor into the feed hose to reduce the amount of oil going to the turbo.

Normally a journal bearing turbo should not need a restrictor. A ball bearing turbo perhaps. However on a PRV engine might be a good idea.

With a -AN4 feedline I tested cold/hot pressures at orifice sizes of .030, .045, .060. Even at .030 I measured 10psi/RPM. You won't really find any published specifications, though, other than a rule of thumb of at least 10psi/1000RPM.

If crankcase pressure is a problem you may have too much blow-by because you blew a piston from too much boost.

You say this a lot, like in practically every turbo thread on this forum. Do you have pics of a blown piston? Have you ever pulled down and analyzed a turbo motor for the failure mode? I've only found a single photo of a damaged piston in some Legend docs. In that case it was a broken #2 ringland, but they were testing as high as 14psi (sometimes on otherwise stock engines) and the failure conditions were not explicitly stated. Suffice it to say they were learning and probably not being gentile about it.

Crankcase ventilation system is barely adequate on a stock PRV, completely lacking any sort of cross ventilation. Blowby needs to be dealt with correctly, especially when turbocharged. Both Island and BAE don't even have check valves on the PCV orifice valve. I would really love to see some bona-fide failure data.

[David T]

Normally a journal bearing turbo should not need a restrictor. A ball bearing turbo perhaps. However on a PRV engine might be a good idea.

With a -AN4 feedline I tested cold/hot pressures at orifice sizes of .030, .045, .060. Even at .030 I measured 10psi/RPM. You won't really find any published specifications, though, other than a rule of thumb of at least 10psi/1000RPM.


You say this a lot, like in practically every turbo thread on this forum. Do you have pics of a blown piston? Have you ever pulled down and analyzed a turbo motor for the failure mode? I've only found a single photo of a damaged piston in some Legend docs. In that case it was a broken #2 ringland, but they were testing as high as 14psi (sometimes on otherwise stock engines) and the failure conditions were not explicitly stated. Suffice it to say they were learning and probably not being gentile about it.

Crankcase ventilation system is barely adequate on a stock PRV, completely lacking any sort of cross ventilation. Blowby needs to be dealt with correctly, especially when turbocharged. Both Island and BAE don't even have check valves on the PCV orifice valve. I would really love to see some bona-fide failure data.

I have seen it. One of our club members had one that blew the ring lands. I have discussed it in detail with one of the original builders of the Island Turbo kit too. I have heard from the founder and owner of Legend Industries, Fred Dellis on that exact subject. It happened a lot which is one reason the turbos have a bad rap. Part of the problem was trying to get just a little bit more power and cranking up the pressure. Part of the problem was the way the pressure is controlled. Part of the problem is that there is no blow-off or safety system to keep the pressure from getting to high. The stock pistons are cast, not forged and can't take much abuse. If you need any confirmation about the dangers of over-boost talk to Mark Levy or Rob Grady. While the ventilation system on the PRV could use some improvement, it works till you blow a piston.

[FABombjoy]

I'm not sure how to have a real discussion on this subject when presented with platitudes, 3rd party anecdotes, etc. Hastily engineered homebrew turbo kits (with no fuel tuning and no timing control) are not representative of what is possible today. If you're going to pop into every single turbo thread and respond with regressive statements I'm not sure how we can further discourse on the subject.

[David T]

I'm not sure how to have a real discussion on this subject when presented with platitudes, 3rd party anecdotes, etc. Hastily engineered homebrew turbo kits (with no fuel tuning and no timing control) are not representative of what is possible today. If you're going to pop into every single turbo thread and respond with regressive statements I'm not sure how we can further discourse on the subject.

I have been referring to the way the original turbo systems were set up. If you want to talk about what can be done to improve them then you are correct, quite a lot. Today we have systems that can control all of the operating parameters very precisely. That wasn't available back when these turbo systems were designed and installed. Now we can control timing, boost, fuel, and auxiliary systems any way we want. Big improvement. It would mean eliminating the K-Jet fuel system but that's just the price of progress. A big undertaking for any individual though. One of the most important things you can improve is the way boost is controlled. Next would be controlling timing and then fuel. Is that the direction you are going in? You would need to use something like a Mega Squirt and program it for turbos. That means a full-blown EFI and engine management system. A BIG project.