67 M20F Rajay Question

[TNIndy]

We've been working on getting rated boost from our Rajay turbo system. Sent the turbo to Maine Turbo for bench testing, had then waste gate adjusted then verified it's closing fully with an endoscope. Now we are looking at airflow and ducting again. We noticed two fittings that no longer have anything connected. Can anyone tell me what these are? The pic is of the pilot side of the aluminum box that the turbo boost air enters. It seems these would be constantly leaking boost pressure.

[N201MKTurbo]

Those fittings probably go to the injector air bleeds or the fuel pump. Where are your injector air bleeds connected? And where is the fuel pump pressure port connected?

[N201MKTurbo]

Do you have a pop off valve in your system?

All the turbo systems I’ve worked on that wouldn’t make full boost we’re because of the waste gate or the pop off valve. Never the turbo. It is either leaking exhaust or a compressor side leak.

[M20F]

One goes to the injector bleed and the other back to the pump.  Best picture I could get for you from my 67F set up.  The injector bleed runs up in second pic and then connects up top in the first pic to the spider. 
 
All of these installs though are a bit different and over 50yrs they get even more different.

At what altitude does it stop adding inches?   I usually run mine 26/26 and around FL190 is when it starts to drop out. 

[TNIndy]

Thanks for the help. My MP tops out just under 22 at 11,500 ft. Am I incorrect in the assumption that those two fittings being open allow MP to bleed off? 
My injector bleed runs to the rear of the engine under the mag but I can’t see where it ends. 

[M20F]

Here is a 3rd picture of the injectors.  So off those fittings.  Up to a pas through fitting in the cowl and then on to the injectors. 

[Shadrach]

Paging @M20F-1968

[LOCOLJ]

9 hours ago, TNIndy said:

Thanks for the help. My MP tops out just under 22 at 11,500 ft. Am I incorrect in the assumption that those two fittings being open allow MP to bleed off? 
My injector bleed runs to the rear of the engine under the mag but I can’t see where it ends. 

I am not sure about MP bleed off, but in my system the air inlet box will capture boosted air from the turbo by closing a flapper and thoes two fittings capture the higher pressure air in the box  and distribute it the the injectors and fuel pump.  In your picture, the lower fitting that is aft should have a line going to the fuel pump and the other fitting has a line going vertically to a bulkhead fitting through the baffling and then to the rest of the lines for the upper deck pressure to the injectors. If the waste gate is fully closing then you are likely loosing boost pressure between the turbo and the fuel servo.  If those fittings are open they might be your source.  Also look at the condition of the hose from the turbo to the air inlet box, the inlet box for holes I found a few there, and make sure the flapper is fully closing with its gasket is in good shape.   Not much left to investigate...

[TNIndy]

15 minutes ago, LOCOLJ said:

I am not sure about MP bleed off, but in my system the air inlet box will capture boosted air from the turbo by closing a flapper and thoes two fittings capture the higher pressure air in the box  and distribute it the the injectors and fuel pump.  In your picture, the lower fitting that is aft should have a line going to the fuel pump and the other fitting has a line going vertically to a bulkhead fitting through the baffling and then to the rest of the lines for the upper deck pressure to the injectors. If the waste gate is fully closing then you are likely loosing boost pressure between the turbo and the fuel servo.  If those fittings are open they might be your source.  Also look at the condition of the hose from the turbo to the air inlet box, the inlet box for holes I found a few there, and make sure the flapper is fully closing with its gasket is in good shape.   Not much left to investigate...

Thanks, this helps. Sounds like we should cap them off to see if MP increases and start reviewing all the STC’s to see if we can find a reason both lines were rerouted. 

[Ragsf15e]

47 minutes ago, TNIndy said:

Thanks, this helps. Sounds like we should cap them off to see if MP increases and start reviewing all the STC’s to see if we can find a reason both lines were rerouted. 

So do you already have other pressurized lines leading to the injectors and fuel pump?  That does seem pretty weird either way…

[Dick Denenny]

Don't know if you already have this but if you don't it might help

DickMooney Turbo 21 POH Rayjay.pdf

[M20F]

10 hours ago, Ragsf15e said:

So do you already have other pressurized lines leading to the injectors and fuel pump?  That does seem pretty weird either way…

I would ensure this first.  Is it rerouted or missing.  Should be easy to tell for the injectors.  

[TNIndy]

The line is rerouted and connected behind the engine under the mags. All I had was my cell phone light so I couldn't see much. I will look again tonight and see if I can trace it down. 

[philiplane]

On 9/9/2023 at 1:16 PM, TNIndy said:

Thanks for the help. My MP tops out just under 22 at 11,500 ft. Am I incorrect in the assumption that those two fittings being open allow MP to bleed off? 
My injector bleed runs to the rear of the engine under the mag but I can’t see where it ends. 

those fittings are two giant leaks. They should be connected to the magnetos for pressurization, or to the injector shrouds for the same purpose if the air isn't coming from elsewhere. If it is, then they need to be capped.

[TNIndy]

Looks like it is routed straight to the fuel pump. It was difficult to get good pics. I haven't had issues other than getting enough boost from the turbo

[M20F]

That pipe right in the front of the cowling what is that hooked to down below.  If you look at my pictures same set up but that line is hooked to the unhooked lines you showed.  

[TNIndy]

40 minutes ago, M20F said:

That pipe right in the front of the cowling what is that hooked to down below.  If you look at my pictures same set up but that line is hooked to the unhooked lines you showed.  

It's going to the fuel pump. The last picture shows it terminating at the fuel pump. 

[LOCOLJ]

As I previously explained, that box where the two fittings are is the airbox to capture pressurized air after the turbo and direct it to the servo infeed and the other pressurized components when the turbo is in use.  In the STC, the only components listed  that get pressurized are injectors and Fuel pump, no magnetos.  Connecting these two components to another port is not listed in my STC docs.  You have to account for the pressure loss in the airbox if you don't want to reroute the hoses to where they are suppose to be.  As you stated, capping them off may help, but something caused someone the reroute the entire system? From your pictures and description it would appear that currently the injector upper deck lines are connected to the fuel pump pressure port? As others have recommended, It would be advisable to get the manuals and try to get things sorted.

[TNIndy]

I've got the correct routing from Rajay. I need to dig through the logs and other STC's to see if I can find any mention of why they were rerouted. The sad thing is that three different shops worked on the MP issue. Turbo has been off twice for testing and inspecting. No one noticed two open fittings coming out of the air box. Thanks to everyone for the help. Once I get this all worked out, I will post what we find. 

[M20F]

3 hours ago, LOCOLJ said:

As I previously explained, that box where the two fittings are is the airbox to capture pressurized air after the turbo and direct it to the servo infeed and the other pressurized components when the turbo is in use.  In the STC, the only components listed  that get pressurized are injectors and Fuel pump, no magnetos.  Connecting these two components to another port is not listed in my STC docs.  You have to account for the pressure loss in the airbox if you don't want to reroute the hoses to where they are suppose to be.  As you stated, capping them off may help, but something caused someone the reroute the entire system? From your pictures and description it would appear that currently the injector upper deck lines are connected to the fuel pump pressure port? As others have recommended, It would be advisable to get the manuals and try to get things sorted.

This is correct.  The fuel pump and injectors.  Quick fix is a hose from the airbox connections I showed (the disconnected ones in your picture) to that injector framework.   Then follow the hose off the fuel pump and see what that connects to.  It should again be that airbox but would be interested where it goes. 
 
If you just sealed those 2 AN fittings you might get the MP but without pressurizing the injectors the plane will run poorly.  

[N201MKTurbo]

2 hours ago, M20F said:

This is correct.  The fuel pump and injectors.  Quick fix is a hose from the airbox connections I showed (the disconnected ones in your picture) to that injector framework.   Then follow the hose off the fuel pump and see what that connects to.  It should again be that airbox but would be interested where it goes. 
 
If you just sealed those 2 AN fittings you might get the MP but without pressurizing the injectors the plane will run poorly.  

The engine won't just run poorly, it will quit above ~4000 feet.

I was on a flight to Santa Barbara at 15000 feet and the engine started running very rough. I was over Apple Valley CA and spiraled down and landed. The engine started running OK when I got down to pattern altitude. I looked the engine over and didn't find anything, so I took off and continued on my trip. The runup was fine and the takeoff was fine, so I turned on course and started to climb. Climbing through about 4000 the engine started getting rough again, so I returned to the airport again. I looked the engine over a little closer and fount one of the hoses to the injector bleeds had come apart. It seems I forgot to tighten the hose clamp. This affected two cylinders. after tightening the clamp the engine worked fine. It was basically running on two cylinders with the air bleeds disconnected.

[TNIndy]

35 minutes ago, N201MKTurbo said:

The engine won't just run poorly, it will quit above ~4000 feet.

I was on a flight to Santa Barbara at 15000 feet and the engine started running very rough. I was over Apple Valley CA and spiraled down and landed. The engine started running OK when I got down to pattern altitude. I looked the engine over and didn't find anything, so I took off and continued on my trip. The runup was fine and the takeoff was fine, so I turned on course and started to climb. Climbing through about 4000 the engine started getting rough again, so I returned to the airport again. I looked the engine over a little closer and fount one of the hoses to the injector bleeds had come apart. It seems I forgot to tighten the hose clamp. This affected two cylinders. after tightening the clamp the engine worked fine. It was basically running on two cylinders with the air bleeds disconnected.

So why do you think it runs well now? Those fittings have been disconnected for years, I don't get much boost with the turbo engaged but I do get about 3 to 4 psi. 

[N201MKTurbo]

41 minutes ago, TNIndy said:

So why do you think it runs well now? Those fittings have been disconnected for years, I don't get much boost with the turbo engaged but I do get about 3 to 4 psi. 

Are you saying that the air bleed lines are not connected to anything? Are they vented to ambient pressure? I thought they were hooked to your fuel pressure hose somewhere. 

Its kinda hard to keep track of what's going on here.

[TNIndy]

Sorry for the confusion. The air bleed line is connected to the fuel pump. The two fittings at the air box don't have anything connected. 

[N201MKTurbo]

14 hours ago, TNIndy said:

Sorry for the confusion. The air bleed line is connected to the fuel pump. The two fittings at the air box don't have anything connected. 

Where is the line from the fuel pump connected? There has to be pressurized air coming from somewhere.