Rajay turbo

[Chris Strube]

I recently had a Rajay turbocharger added to my 1965 M20E.  It doesn't give the performance I expected.  According to the STC paperwork, it should develop 27 inches MP up to FL200,  then hold 25 inches MP up to FL250.  Mine has a vernier "2nd throttle", with about 5 inches of movement.  Only the last inch starts raising the MP, then it will hold 27 inches at full rich up to FL180, and then start decreasing with altitude.  Does anyone have experience with this STC?

thanks,

[Marauder]

I recently had a Rajay turbocharger added to my 1965 M20E.  It doesn't give the performance I expected.  According to the STC paperwork, it should develop 27 inches MP up to FL200,  then hold 25 inches MP up to FL250.  Mine has a vernier "2nd throttle", with about 5 inches of movement.  Only the last inch starts raising the MP, then it will hold 27 inches at full rich up to FL180, and then start decreasing with altitude.  Does anyone have experience with this STC?
thanks,

Find John Breda on this site. He has a lot of experience with these.


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[N201MKTurbo]

Is the pilot controlled waste gate fully closing?

[carusoam]

So...

it looks like we have a few things...

1) Our guy with the most PP knowledge on these things is John Breda... but I can't remember his exact screen name.... @1968M20F....?

2) two throttles are...

• an actual throttle...
• a manual waste gate control...

3) of the two throttles, one should be going fully open while the other should be fully directing exhaust pressure through the turbine...

4) To keep from melting things, it is best to have somebody actually explane how this is best operated...

5) realistically, flying at 25000' with only needing to read an STC manual, sounds slightly inadequate...

6) under the cowl, See if the controls are working to their full extent...

7) has the system been rebuilt, OH'd or is it new?  

8) have you seen the turbine blades yourself? Are they nubs where the blades used to be?

9) expecting linear control doesn't fit how the system actually operates... like opening and closing a butterfly valve... the first and last 10° make the most differences....

10) what pressure differential can you achieve at 10k’ on your MP?  20” is normal for an NA engine.  Are you expecting a few more inches like 25” or STC should be clear about this number...

11) How much pressure is leaking out of the system?  Soap and water bubble study around every hose connection...

12) if the pressure is all good... what kind of fuel flow are you seeing?

Trying to be helpful, from a PP kind of way... not a mechanic...

Best regards,

-a-

 

 

[MIm20c]

What was the OAT during the climb?

[M20F]

I would have to dig the manual out but mine (recently overhauled) does 27 till around 18-19 then loses a inch per thousand from there.  It will true out 160-165 at FL190.  

My controller works same as yours and the cabling was replaced/adjusted by Maxwell.  

So for what it is worth have the same experience as you.  

[Brian Scranton]

Hi Chris, I have one and just ran into the same. Your cable needs adjustment. You're not getting fully closed is my bet. It's a pain in the ass to do--maybe 2-3 hours of yelling at your turbo. 

[FoxMike]

I could write a book on RAYJAY as I owned one for 15 years.  First you do not get much boost until the waste gate is almost closed.  This is due to two things the turbo must be spinning at high RPM to put out any boost (low turbo RPM only causes back pressure) and the induction system is inefficient.  Because the IO360 is so efficient an engine a lot of heat is absorbed in the power stroke (a good thing) and less gets into the exhaust system to turn the turbo.  For this reason you do not an outrageous amount of power increase at high altitudes.  I found 20-21K to be the optimal altitude range.  Their are two ways to get a little more power one is to increase engine RPM (higher exhaust flow) and a richer mixture (more unburned fuel in the cylinder gets out to the exhaust system.  Either shortens your range significantly.  I seldom fly my TLS above FL210 as the advantages of higher are very few and the risks are significantly higher ( read about the the Acclaim pilot whose  O2 system leaked and caused his demise).  I do have some induction tubing in good shape that are left over from my RAJAY days if you need them.

[MIm20c]

@Brian Scranton or others. Should I be concerned with TIT temps when the waste gate is closed?  Econo cruise setting is 7 gph peak exhaust temp which puts my TIT at 560-575.  Normal go fast mode puts the temps in the 515-530. 

[Brian Scranton]

You have to mean 1560-1575 (not 560, right?)...as long as you are below 1650, you're fine...but I lean on the conservative side and try to keep my TIT below 1600 at all times. I can't believe you are getting 7gph...you must be 50-75 LOP. That's pretty remarkable. 

[MIm20c]

Yes, 15__. I have not been able to go LOP yet. Still learning the system and trying to use the throttle butterfly or turbo to even out the egt’s. Cylinder number 2 is 80-90 degrees cooler than the other three. This evens out at different throttle positions or if I add some TN.  

For me just building time and having fun I like to run at 7-7.5 gph at peak egt. At that power setting I know it will not harm the engine but I’m not sure if it’s too hot for the turbo with the waste gate closed. Sounds like it’s still a good idea to keep it well below 1600. 

[carusoam]

MIM,

What engine monitor do you have?

The chances of running an O360 LOP very well, are pretty small.  There is no control over the fuel distribution. Doing it at higher %bhp is going to be interesting.

How Good is the condition of your dog house?  Cylinder cooling depends heavily on how well the dog house is working.  M20Cs with old dog houses often need some sheet metal help.

Extending the idea of running LOP, while under pressure, with crummy fuel distribution, sounds like a handful.

You might want to share a flights worth of engine monitor data... EGTs and CHTs can be pretty interesting in an ordinary flight...  MP and %bhp data are a bonus...!

Are you familiar with the 'red box' theory?   A Method to avoid engine hazards...

Best regards,

-a-

[MIm20c]

10 hours ago, carusoam said:

MIM,

What engine monitor do you have?

The chances of running an O360 LOP very well, are pretty small.  There is no control over the fuel distribution. Doing it at higher %bhp is going to be interesting.

How Good is the condition of your dog house?  Cylinder cooling depends heavily on how well the dog house is working.  M20Cs with old dog houses often need some sheet metal help.

Extending the idea of running LOP, while under pressure, with crummy fuel distribution, sounds like a handful.

You might want to share a flights worth of engine monitor data... EGTs and CHTs can be pretty interesting in an ordinary flight...  MP and %bhp data are a bonus...!

Are you familiar with the 'red box' theory?   A Method to avoid engine hazards...

Best regards,

-a-

I’m using the jpi 830 which helps to monitor temps. I’m only running peak when showing 50-58 percent power (roughly 2400/19.5 - 2400/22).  The doghouse is in good condition except for around the alternator and starter which were replaced ~150 hrs ago. 

I was thinking using a slight bit of turbo would even out of air distribution but you’re correct that the fuel will still be a problem. When I’m on the turbo the fuel flows increase to 10-12 gph to keep things in check (~100 ROP). 

[FoxMike]

Chris,

I reread your original post again and should add that using full rich is not a good idea at altitude.  I had a friend with a RAYJAY powered Beech who flamed out in the FLs due to to rich a mixture.  You should have EGT or TIT in the 1400 to 1500 range for climb.  I always flew mine at peak EGT in cruise and if I needed more power I would lower the EGT 100 degrees.  Depends on how your servo is setup but full rich may maybe holding you back.

[MIm20c]

@FoxMike I cruise around 1450 egt but my climb is closer to 1250. My thought is I set the mixture when climbing at 25/25 and just add TN to keep the same MP to my cruising altitude. 

@Chris Strube What speeds were you getting at fl200 with a short body?

[carusoam]

The uniqueness of this set-up, If I’m paying attention properly...

It is a TN'd M20C... it’s got a carb with two fuel jets. No servo.

The Second Jet is adjusted to turn off when the throttle is reduced slightly.

It is a challenge to find other Cs with so much instrumentation and a turbo normalizer too...

Normal cruise power 20" of MP can use 10gph (roughly speaking)

full power getting off the ground 28" and 18gph (M20C POH) 3gph is probably lots of cooling...

Cutting back the mixture will show up in high CHTs.

25/25 should be interesting. 26/26 would be too... the limitations will need to be watched closely. Overheating cylinders or turbo parts will get expensive quickly...

The extra heat load on the exhaust parts between the exhaust valve and the turbo can be a point of concern.  High temps can increase the wear resulting in an exhaust failure...  Look often for any signs of leaks.

Always use a CO meter.

PP thoughts only, not a mechanic...

Best regards,

-a-

 

[MIm20c]

@carusoam Thanks for the detailed reply. The only time I use the 25/25 is during the climb full rich.  Without the turbo I start leaning the engine  at 4-5k ~ 1200-1250 hottest egt. With the turbo I just stay full rich until I level off. I have not cruised above 2400/22 on (or off) the turbo and the highest I’ve been is just over 14k for a few mins. At that altitude my TAS was 158 which is 3 gph and 10 kts higher vs off the turbo at 7.5-8.5k.  Not worth it IMO with my small fuel tanks.

Thanks for the info on the exhaust system.  PO replaced it a year ago for over 6k so I want to take care of it.

I still have a lot of testing to do, should be fun!

[carusoam]

The EGT locations on your bird, are mostly not identical with any other Mooney.  Later Mooneys got standardized factory installed probe locations....  

Because of this detail, the absolute EGT doesn't give much information...  very useful when discussing °F LOP Or ROP...

The TIT is an important measurement for the health of your turbine blades. Does the RayJay have a specific TIT location?

Or is it using the standard EGTs for the info?

Best regards,

-a-

[MIm20c]

The system does have a TIT probe in between the waste gate and turbo IIRC. The other egt probes look to be in the same position (offset etc) as a io550 but I have zero knowledge of other TC(N) setups. 

[carusoam]

Having the TIT in the standard location is best for the turbine blade health.

The individual EGTs upstream are an average Temp over time.   One flame goes by every two rotations of the prop...

The TIT will appear to read a higher temp, even when it is further downstream... this is an affect of four flames heading towards the turbo in the same amount of time.  Averaging them together as one piece of data, the TIT will probably read higher than any single EGT...

In the O with the IO550 The ship's EGT thermocouple is in the exhaust flow combined from three cylinders on one side of the engine.  Same thing happens here... the average temperature is higher than any single EGT...

MP, oilP, fuelP and EGT / TIT all have difficult to measure timespans involved... averaging them to get a smooth reading isn't always easy...

Best regards,

-a-

[Brian Scranton]

Hey Chris. I lean via TIT. 100 ROP when I am 24.5/2500 (~65% per the RayJay manual). 

Just following up on your original ask--you can go in and adjust the cable that actuates your wastegate. It's too loose right now. To do this, push your vernier knob in 2 or so inches, pull your lower right cowl panel, find the cable, trace it to the waste gate arm...loosen the nut that attaches the cable to the arm, let the arm swing shut, and pull the cable through until tight. Then retighten the nut. That should do it for you. 

[LOCOLJ]

Where exactly is the TIT probe suppose to be located on the exhaust/turbo? Perhaps folks could share pics? We do not have a TIT and was wondering how much the measured difference between  EGT vs the TIT actually is?

[N201MKTurbo]

1 hour ago, LOCOLJ said:

Where exactly is the TIT probe suppose to be located on the exhaust/turbo? Perhaps folks could share pics? We do not have a TIT and was wondering how much the measured difference between  EGT vs the TIT actually is?

My TIT is about 1" from the turbine inlet. I insert it so the tip is in the middle of the pipe.

My TIT runs about 100 dF above the highest EGT.

Edited October 25, 2017 by N201MKTurbo

[kortopates]

42 minutes ago, N201MKTurbo said:

My TIT is about 1" from the turbine inlet. I insert it so the tip is in the middle of the pipe.

My TIT runs about 100 dF above the highest EGT.

That is the standard and norm for all of the TSIO engines. Most of the time TIT is right at 100F higher than the EGTs but not always. I've seen it everywhere else too (bottom and middle) but its not common.

I've see a few installations with out EGTs, just TIT, which is crazy IMO.

I've seen a couple missing TIT too, but that I would consider a real safety of flight issue on turbocharged engine. You don't want to take off with an elevated TIT.

[Chris Strube]

OK, I've had the wastegate control adjusted, and am now getting "almost" book MP.  I climb at 2700RPM, full rich, engaging the turbo at 3500ft ASL to maintain 27 inches MP.  My fuel flow is 17 GPH.  This is according to the STC manual.  Once at altitude, usually 15000 to 19000, I reduce RPM to 2600, pull the mixture back to 10 GPH, close the cowl flaps, and increase the MP back to 27 inches.  The numbers on the EGT gauge mean nothing, it's just a relative pointer to show peak EGT, and mine is about 75 deg. LOP at 10 GPH.  The engine temps drop from 380 CHT to 300 CHT, and the oil temp drops from 210 to 190.  TAS is about 170KTS.  These numbers are from my recent cross-Canada trip - 10 provinces in 30 days.  I'm happy with my installation now, just wish I had more room!