252 LOP - Use factory TIT or GEM?

[cwright27]

Hello again all, thanks for the past help.  I'm very much in the process of learning my new machine.  How do you turbo guys lean in cruise?  I was taught to lean to 1450 TIT once past 3500ft and once level after a few minutes I can either go 50 ROP or 50 LOP.  Do you use the factory TIT gauge or your engine monitor?  I have a GEM insight and it has lean finding mode.  Should I use lean finding and once my first cylinder peaks, should I keep on leaning 50 degrees LOP on that cylinder?  Or should I use the factory TIT gauge?  Thanks for the help! (I don't have GAMI's and the spread in temps and egt's is pretty close for LOP)

[danb35]

Quote: cwright27

(I don't have GAMI's and the spread in temps and egt's is pretty close for LOP)

[Frosty]

I have a 231 with an intercooler and merlyn, not a 252 but close.  I pull LOP climbing out, one big pull maybe 1000 AGL when I am assured of making it back  to the runway worst case, then climb LOP adjusting to maintain 350-370 max CHT.  I am using a  JPI for CHTand EGT and the factory TIT but the TIT has never been a factor flying LOP.  It seldom gets to 1400.  I have 15 years and 1500 hours since factory reman.  The engine is running strong and sailing thru annuals.   I can't imagine ever wanting to go back to flying ROP.

[Frosty]

Chris, is your GEM certified as a replacement fot the TIT?  My JPI could be but isn't.  Your GEM may be more responsive but may not be accurate and isn't 'legal' if not certified.

Frosty

[David Mazer]

I have a 252 Rocket and, per Rocket's POH, lean to a TIT of 1500 to 1510 on the JPI.  I have tried to experiment with LOP but the TIT rose so fast and so high I didn't make it to the other side.  Maybe I just didn't pull fast enough.  I think I need to fly with someone that has done it before to see if I can get there.  I tried the lean finder on my JPI but it wasn't that helpful.

[Parker_Woodruff]

Quote: Frosty

I have a 231 with an intercooler and merlyn, not a 252 but close.  I pull LOP climbing out, one big pull maybe 1000 AGL when I am assured of making it back  to the runway worst case, then climb LOP adjusting to maintain 350-370 max CHT.  I am using a  JPI for CHTand EGT and the factory TIT but the TIT has never been a factor flying LOP.  It seldom gets to 1400.  I have 15 years and 1500 hours since factory reman.  The engine is running strong and sailing thru annuals.   I can't imagine ever wanting to go back to flying ROP.

[Shadrach]

Quote: cwright27

Hello again all, thanks for the past help.  I'm very much in the process of learning my new machine.  How do you turbo guys lean in cruise?  I was taught to lean to 1450 TIT once past 3500ft and once level after a few minutes I can either go 50 ROP or 50 LOP.  Do you use the factory TIT gauge or your engine monitor?  I have a GEM insight and it has lean finding mode.  Should I use lean finding and once my first cylinder peaks, should I keep on leaning 50 degrees LOP on that cylinder?  Or should I use the factory TIT gauge?  Thanks for the help! (I don't have GAMI's and the spread in temps and egt's is pretty close for LOP)

[Frosty]

Quote: Parker_Woodruff

Hey Frosty,

Congrats on being able to do a LOP in a 231.  What fuel flow are you getting and from what MP & RPM combination?

[Parker_Woodruff]

What altitude were you getting 166 knots?  Was that KTAS or KIAS?

[Frosty]

Quote: Parker_Woodruff

What altitude were you getting 166 knots?  Was that KTAS or KIAS?

[cwright27]

Thanks for the help guys!  Good info.  Am I right in assuming that what the factory TIT gauge is reading is a sum of all the egt's going to the turbo and when one cylinder peaks and comes down that temp is reflected in the overall temp that the gauge is reading?  I guess the problem going LOP with the factory TIT gauge is that there's no way to tell when the last cylinder has peaked and setting 50 degrees lean based on that last cylinder.....

[Frosty]

Quote: cwright27

Thanks for the help guys!  Good info.  Am I right in assuming that what the factory TIT gauge is reading is a sum of all the egt's going to the turbo and when one cylinder peaks and comes down that temp is reflected in the overall temp that the gauge is reading?  I guess the problem going LOP with the factory TIT gauge is that there's no way to tell when the last cylinder has peaked and setting 50 degrees lean based on that last cylinder.....

[Shadrach]

Quote: Frosty

 True, you need individual cylindar EGT to determine when all cylindars are LOP.  However there is nothing magic about 50 degrees LOP, or ROP for that matter.  It is an arbitary number of degrees to get off of the peak (BAD) EGT.  I have seen data that indicates 50 ROP can worse than peak. As indicated in previous messages, I run Wide Open Throttle, WOT, set my RPM, and then adjust speed with mixture.  I don't even look for peak, just one big pull to get on the lean side and then manage CHT.  As long as all 6 CHTs are below 380 I'm fine.  When one gets close I respond.  Either trail cowl flaps or start leaning.  When running LOP, leaning is slower and cooler.  Going richer is faster and hotter.

[RJBrown]

Quote: Shadrach

[Shadrach]

Quote: RJBrown

[donshapansky]

My Rocket and had never been able to run LOP smoothly or without getting very close to 1700 TIT during the leaning process.

After overhauling the cylinders in March, I went back to GAMI after doing a spreadsheet in .2 gph spacing and they changed 2 injectors to tighten up the spread to within .4 gph.

I have since flown 15 hrs LOP with excellent results as follows:

Granbury, TX to St. Cloud, MN 4:36 non-stop with 30 gallons remaining at 6,500' due to low level tailwinds vs higher headwinds. I have 100 gals useable.

Power settings were 32.5 inches @ 2450 rpm (72%) with 193 KTAS No 2 cylinder was hottest, 370F the rest in 350 +/-

2 days later I returned from Fond du Lac, WI at 12,500' with the same power settings, less tailwinds, I had 18 gals left after 4:36 ET. Hottest cylinder was No. 2 at 360F with cowl flaps closed. 197 KTAS and smooth running engine!

In conclusion I'm saving 6 gph or at least $35.00/hr with cooler CHTs and a ton more range than I thought possible with this engine combo. Incidentally my oil level is 12 qts (with a new air/oil sep) and after 15 hrs on this oil almost no change in level and the color is still golden!

[HeyChuck]

Quote: cwright27

How do you turbo guys lean in cruise? 

I have a TSIO360-SB in my Encore, which is similar to the -MB in your 252. My cylinders all peak within 0.5 gal/hr without gami-jectors. I climb full power (2600 rpm, 39", ~25 gal/hr) to my cruise altitude. That keeps my hottest cylinder (#6) below 380F. The others are typically closer to 350F in the climb. In cruise, I typically first set 2500 rpm and about 24" (varies with altitude) for about 60% power, and close the cowl flap. I then pull the mixture to the lean side (about 9.8 gal/hr). This brings the CHTs on all cylinders down to about 320F at lower altitudes (12K), or a little warmer (~340F) higher up (18k). For precise leaning at higher power settings, I use the JPI EDM-700 in lean-find mode by enrichening the mixture from the lean side to find the first cylinder to peak (the others remain leaner), and subsequently leaning to set that cylinder the desired number of degrees lean of the peak EGT. My TIT stays well below the redline (1650F) throughout this process (typically ~1600), and remains near or slightly less than its peak value when the power is set LOP. This SB engine runs warmer (15-20F) rich of peak, but still cooler than other turbo (and most normally aspirated) engines I have flown.

[donshapansky]

I don't have the 360 engine anymore, it's a TSIO520NB from a Cessna 414, 340, P210, Baron 58P 58TC etc. with feathering prop. rated at 305 hp in my application.

[aviatoreb]

Quote: donshapansky

My Rocket and had never been able to run LOP smoothly or without getting very close to 1700 TIT during the leaning process.

After overhauling the cylinders in March, I went back to GAMI after doing a spreadsheet in .2 gph spacing and they changed 2 injectors to tighten up the spread to within .4 gph.

I have since flown 15 hrs LOP with excellent results as follows:

Granbury, TX to St. Cloud, MN 4:36 non-stop with 30 gallons remaining at 6,500' due to low level tailwinds vs higher headwinds. I have 100 gals useable.

Power settings were 32.5 inches @ 2450 rpm (72%) with 193 KTAS No 2 cylinder was hottest, 370F the rest in 350 +/-

2 days later I returned from Fond du Lac, WI at 12,500' with the same power settings, less tailwinds, I had 18 gals left after 4:36 ET. Hottest cylinder was No. 2 at 360F with cowl flaps closed. 197 KTAS and smooth running engine!

In conclusion I'm saving 6 gph or at least $35.00/hr with cooler CHTs and a ton more range than I thought possible with this engine combo. Incidentally my oil level is 12 qts (with a new air/oil sep) and after 15 hrs on this oil almost no change in level and the color is still golden!

[danb35]

Quote: aviatoreb

BUT - right out of the box, in a brief try-it-out and see test with my CFI LOP - it seemed to run nicely cool, nicely smooth, and without even going to Gami's yet - which nonetheless I will before I make it a practice.

[FBCK]

How do you tell what the spread is on your injectors?  I too have a 231 with intercooler and auto wastgate.

[KSMooniac]

http://www.gami.com/gamijectors/leantest.php

[donshapansky]

GAMI says many rockets will run LOP without much change due the good airflow designed into the intercoolers, compared to the Cessna twins that use this engine the intercooler causes serious airflow disruptions from one side of the engine to the other.

What I have found now that I flown over 30 hrs LOP is that the density altitude directly relates to where the TIT and EGT's will peak. The flight to MN was the closest to STD I have seen and the fuel flow ended up at 16.5 gph to get all cylinders 50 LOP head temps were all in the 350 - 360 F range excpet NO 2 which the hottest always at 370 F.

Today at 9000 the OAT was 18C RPM 2450 MAP 32.5", fuel flow was 15.5 gph with No 2 50 LOP and CHT 365 hottest. My EDM 930 said we were getting 13.5 NMPG @ 215 KT GRD Speed.

[aviatoreb]

Quote: donshapansky

I don't have the 360 engine anymore, it's a TSIO520NB from a Cessna 414, 340, P210, Baron 58P 58TC etc. with feathering prop. rated at 305 hp in my application.

[aviatoreb]

Quote: danb35

Don't spend money on GAMIs if you don't need them--if you've got a nice tight GAMI spread without them (say, less than 0.5 gph), save your money.  If it's more than that, they may help.  But if your engine runs smoothly LOP (and far enough LOP), it's perfectly safe to do that without GAMIs or any other special equipment.