High TIT help for Rocket

[RocketAviator]

I have been painstakingly working with GAMI, even took the Rocket to GAMI and flew with John-Paul of GAMI (a great guy) to get my GAMI injectors balanced and my CHT temp down.  We were successful in getting the CHT's down and down by a large factor.... (dont tell anyone but we stole a Bonanza idea and wow did it ever work), however another remaining & continuing issue is high TIT.  Today we checked the timing and found that it was slightly retarded 17.4 & 17.6 BTDC We corrected both of the MAG timing to precisely 20.5 BTDC using both electronic inclinometer and a mechanical dial indicator for verification according to what GAMI recommended.  There was no appreciable TIT difference in the single test flight today.  

GAMI is sending me new injectors for tomorrow delivery the current GPH spread is low 19.1 #1, 19.2#2, 20.4 #3 Highest, 19.7# 4, 20.2 #5 & 20.0 #6 with highest CHT at 402 (rest below 390) and TIT 1623 @ 22.4 GPH @ 2430 RPM = 194 TAS @ 10,500.  This was an all out run for me as I don't like the high CHT nor the high TIT.  My goal is to see if I can run LOP and if so at what best cruise speeds.  My typical flight is 2.5 to 3 hrs @ mostly 12 - 15k.

 

Any suggestions or ideas would be appreciated

[KSMooniac]

This might be a silly question, but have you verified that you have no induction leaks and a properly functioning ignition system (ie try a lean cruise power mag check)?  Only after you've got those systems squared-away can you productively focus on the fuel injectors...

 

I suspect JP made sure you verified all that, but I thought I'd ask anyway...

 

A friend up here was able to get his Rocket to go LOP successfully, but I don't remember what his spread is after GAMI tuning.  He had a heckuva time chasing induction leaks and getting the fuel injection system setup correctly, though.

[aviatoreb]

I have been painstakingly working with GAMI, even took the Rocket to GAMI and flew with John-Paul of GAMI (a great guy) to get my GAMI injectors balanced and my CHT temp down.  We were successful in getting the CHT's down and down by a large factor.... (dont tell anyone but we stole a Bonanza idea and wow did it ever work), however another remaining & continuing issue is high TIT.  Today we checked the timing and found that it was slightly retarded 17.4 & 17.6 BTDC We corrected both of the MAG timing to precisely 20.5 BTDC using both electronic inclinometer and a mechanical dial indicator for verification according to what GAMI recommended.  There was no appreciable TIT difference in the single test flight today.  

GAMI is sending me new injectors for tomorrow delivery the current GPH spread is low 19.1 #1, 19.2#2, 20.4 #3 Highest, 19.7# 4, 20.2 #5 & 20.0 #6 with highest CHT at 402 (rest below 390) and TIT 1623 @ 22.4 GPH @ 2430 RPM = 194 TAS @ 10,500.  This was an all out run for me as I don't like the high CHT nor the high TIT.  My goal is to see if I can run LOP and if so at what best cruise speeds.  My typical flight is 2.5 to 3 hrs @ mostly 12 - 15k.

 

Any suggestions or ideas would be appreciated

 

Please tell us the Bonanza trick.

 

That TiT for that high fuel flow does sound bad.  Are you sure your Tit probe is reading properly?

 

After chasing down some induction leaks and swapping some injectors, with fuel flow balanced to no better than 0.4gph across, my engine runs fine and smooth at all fuel flows and well lean of peak.  And whether rich or lean my CHT is always cool, from 370 near peak to 350 maybe 360 ROP to 300-330 LOP.

[Parker_Woodruff]

I found a decrease in TIT on my 252 (when I owned it) by switching to Tempest Fine Wire spark plugs.

[RocketAviator]

This might be a silly question, but have you verified that you have no induction leaks and a properly functioning ignition system (ie try a lean cruise power mag check)?  Only after you've got those systems squared-away can you productively focus on the fuel injectors...

 

I suspect JP made sure you verified all that, but I thought I'd ask anyway...

 

A friend up here was able to get his Rocket to go LOP successfully, but I don't remember what his spread is after GAMI tuning.  He had a heckuva time chasing induction leaks and getting the fuel injection system setup correctly, though.

Scott, NO not a silly question as a matter of fact JP nor I have checked but I will!!!  Any specifics on how to check, since my engine was just reassembled in my mind this could be a likely candidate!  Thanks for the input!

[RocketAviator]

Please tell us the Bonanza trick.

 

That TiT for that high fuel flow does sound bad.  Are you sure your Tit probe is reading properly?

 

After chasing down some induction leaks and swapping some injectors, with fuel flow balanced to no better than 0.4gph across, my engine runs fine and smooth at all fuel flows and well lean of peak.  And whether rich or lean my CHT is always cool, from 370 near peak to 350 maybe 360 ROP to 300-330 LOP.

The Bonanza trick is i bored a whole the size of a quarter in the front baffle on #6, dropped the temperature 45+ deg on that Cyl!  Would not have believed it had I not seen it with my own eyes!  I will post a picture after I fly tomorrow.

[RocketAviator]

I found a decrease in TIT on my 252 (when I owned it) by switching to Tempest Fine Wire spark plugs.

I do have fine wire spark plugs but don't know if they are Tempest Fine Wire..I will check!

[rocketman]

Lacee - please be sure to post a picture of the quarter size hole on the baffle in front of cylinder #6! My #6 and #4 and to a lesser degree #2 all on the pilots side of the engine run higher than the odd cylinders. Go figure! 

[KSMooniac]

Lacee, JP told me an easy way to pressurize the induction system is to use the fitting for doing a compression check and just pressurize one cylinder while the intake valve is open.  I did that last weekend in fact and it worked great.  I taped over my air filter and could see the tape "inflate" a bit when I applied the pressure.  Then spray soapy water at every joint and look for bubbles...you'll know it when you see it.  If you just had work done, then there is a good chance you have a loose coupling or similar somewhere.  Getting everything sealed up is priority one before you spend time and money on the rest of the possibilities.

 

Hopefully you have Tempest Fine Wires and not Champions!  Do a search here and beechtalk.com if you have Champions...

[carusoam]

The Bonanza trick sounds like a hangar fairy or pixie hole on IO550s cyl#5. (front co-pilot side)...

-a-

[RocketAviator]

Almost but try Cylinder #6 on the pilot side.  I will upload image shortly.

The Bonanza trick sounds like a hangar fairy or pixie hole on IO550s cyl#5. (front co-pilot side)...


-a-

[RocketAviator]

Lacee, JP told me an easy way to pressurize the induction system is to use the fitting for doing a compression check and just pressurize one cylinder while the intake valve is open.  I did that last weekend in fact and it worked great.  I taped over my air filter and could see the tape "inflate" a bit when I applied the pressure.  Then spray soapy water at every joint and look for bubbles...you'll know it when you see it.  If you just had work done, then there is a good chance you have a loose coupling or similar somewhere.  Getting everything sealed up is priority one before you spend time and money on the rest of the possibilities.

 

Hopefully you have Tempest Fine Wires and not Champions!  Do a search here and beechtalk.com if you have Champions...

Will check and we are scheduled to test everything on Monday.  I think this is the method that my A&P said we would use but I will share your post with him to make sure.  Thanks for the good points.  I will check the Tempest VS Champion plugs Monday as well.

[RocketAviator]

Ok here is what I refer to as the Bonanza trick.... that worked well for me.

I also tried an idea from another post on this forum where I placed a small amount of silicone baffle seal material between the fins and the rear baffling of the #1 cylinder, I did not see any appreciable change.

[RocketAviator]

JP and I did do the mag check at altitude.

I am still trying to wrap my head  around how an intake leak would or could cause high TIT, can anyone help me understand this.  I realize it will lean or cause a lean situation at a given fuel flow but at some point the leaning is suppose to cause the all the temperatures to drop as you are starving the engine for fuel...

What EGT temperatures are any of the other Mooney Rocket seeing?

[KSMooniac]

When ROP, an intake/induction leak will make the mixture leaner for whichever cylinder(s) is (are) leaking, and drive the EGT higher.  Higher EGT on one cylinder will in turn influence the TIT measurement as well, but not as dramatically of course.  When LOP, the leaky cylinder(s) will be leaner and have a lower EGT (and CHT).  It doesn't sound like you've flown or tested LOP yet since your GAMI spread is relatively high currently.

[carusoam]

Scott,

Leaky intakes would probably cause an opposite effect... On TC'd intakes. Leak would possibly cause additional richness effect?

Lacee,

I'll try to find the picture of the pixie hole here somewhere... Looks similar to your picture above.

-a-

[carusoam]

Link to the IO550 pixie hole picture....

http://mooneyspace.com/topic/3680-high-cht-on-5/page-2?hl=+pixie%20+hole

For everyone else,

The cyl numbers for continental start from the back of the engine....

The alternator blocks cyl #5 on Ovations...

Best regards,

-a-

[KSMooniac]

Scott,

Leaky intakes would probably cause an opposite effect... On TC'd intakes. Leak would possibly cause additional richness effect?

Lacee,

I'll try to find the picture of the pixie hole here somewhere... Looks similar to your picture above.

-a-

 

Nice catch!  I totally forgot about the turbo part of the equation...I've been focusing on my NA engine and I believe you are correct.  The leaks still need to be found and resolved though to get the GAMI spread tightened up.

[Dave Marten]

Lacee, During your " TIT 1623 @ 22.4 GPH @ 2430 RPM = 194 TAS @ 10,500" run what was your MP and EGT per cylinder? Can't tell if your 1623 TIT number is high w/o reference to MP and clyinder EGT. What was the MP/RPM/FF and TIT during the climb? How is the factory TIT probe tracking with the engine monitor TIT probe?

[RocketAviator]

Dave, thanks I can email you or post a summary of the data here maybe better in case someone else sees something in the data, I'll post later tonight

[RocketAviator]

Lacee, During your " TIT 1623 @ 22.4 GPH @ 2430 RPM = 194 TAS @ 10,500" run what was your MP and EGT per cylinder? Can't tell if your 1623 TIT number is high w/o reference to MP and clyinder EGT. What was the MP/RPM/FF and TIT during the climb? How is the factory TIT probe tracking with the engine monitor TIT probe?

Dave,

The factory TIT is indicating about 28 degrees lower than the G3, the Rocket test indicates a 1732 TIT on the Factor and about 1760 on the G3.   Here is the last two flight data after correcting the timing per the GAMI electronic timing instructions method.  

Also GAMI has sent replacement injectors for cylinder #1, #2 & #5!

If you or anyone else has any thoughts after looking at the data I would appreciate any feedback.

Lacee

N1016U G3 Data 10180753.zip

[aviatoreb]

I tried out this lean test today.  I must say I have never leaned into the "redbox" at high power settings.  I still could not bring myself to try it at 35'' 2500rpm - 88% setting.

 

So I did it at 32'' 2400rpm.  Cloud cover today was such that I could not get to the 8000-12000ft recommendation without filing.  But I got to 7500 so it must be close.

 

I got 1694F as my max TIT.  So I presume it would be a tad higher at 8-12k.  Seems pretty close?  Or would I expect a higher reading at higher power at 12k?

 

Dave, what power settings did you do when you did the lean test?

[RocketAviator]

UPDATE:  Found 8 (7 small one large enough no bubble would form) inlet leaks.  Fixed all, test flew, however no appreciable improvement to the High TIT, however the MP reached slightly higher max point, only by one or two needle widths.

Then changed the 3 GAMI injectors with noticeable smoother engine while attempting LOP, but still not acceptable smooth and at anywhere close to what GAMI said I should expect regarding GPH and power settings.

 

Good news I flew 4.5 hrs yesterday at the first time ever 190+kts TAS @ FL13 @ 20.5 GPH with no CHT over 400 and TIT at 1560!  

#1 CHT seems to be the limiting factor as it ran around 298 to 403F!

So we are making progress, I plan to continue and find out why the TIT remains high. 

 

A person from the engine shop suggested I look at the exhaust as it was just changed out when the engine was torn down for the prop strike.  He suggested that it might be a factor. While investigating the exhaust there is one more bad thing (in my opinion) in that both the factory and the G3 temp prob appeared to have gotten overheated to the point that both were mechanically loose and both gave up their snap ring that holds them securely in place between the SS hose clamp and the exhaust pipe.  Has anyone else seen this before.  I have done the Rocket TIT test maybe 3 times but I never operated the engine above the 1650 TIT limit for any other reason. 

My normal TIT is 1600 or less!

[Parker_Woodruff]

Which brand spark plugs do you have?

[RocketAviator]

Which brand spark plugs do you have?

Champion Parker.