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  Take Off Fuel Flow Settings &CHTs

What's Your Takeoff Fuel Flow?

 

Are you frying your Continental Engine's cylinders with temps in the climb or in cruise of 400F or more?

 

The engine management gurus that I trust suggest that cylinder temps (CHTs) for our Continental Engines should be under about 380F for long cylinder life and engine health.

 

Takeoff fuel flow plays a part in the cylinder temperature equation. Here is a formula for what the gurus suggest for SEA LEVEL takeoff flow:

 

0.55 to 0.60 pounds/hour of fuel per each horsepower. So, take your standard IO-520 engine rated at 285hp, you would get 26 to 28.5 gallons per hour. You will find that this is indeed at the redline or above on your engine fuel flow gauge.

 

You will achieve much cooler CHTs in your climb AND greater engine longevity with this take off fuel flow. How should my mechanic adjust my fuel flow? Download this TCM SID97-3E for your mechanic and get to work!

 

Click HERE for some notes from Bonanza owner Dan M. on his experiences setting up his fuel flow per the SID97-3E

 

If you do nothing else on this topic, you and/or your mechanic should consider this CSOBeech Fuel Flow Resource page HERE. It is packed with the resources and videos on doing the fuel flow setup procedure.

 

So, now you're at a high density altitude or a higher altitude airport. What do you do with all that extra fuel flow you say? Not to worry, the folks at

 

 

show you how to lean to a target EGT for your takeoff and climb in this EGT Leaning Presentation.

 

Here is a BeechTalk quote from Walter Atkinson, co-founder of Advanced Pilot Seminars, regarding take off fuel flow:

 

"This FF thing is not about CHT. That's a secondary reading. It's about ICPs (internal combustion pressures). THAT relates to longevity along with CHT. We judge it by CHT since we cannot read ICPs directly in the cockpit--yet. If you have crummy Beech baffles, 380 is a decent max CHT Target. If you have BDS or Liquidair baffles, I'd be using 340 as a climb CHT Target.

So, this begs the question, why the SID97-3x FF numbers? As it turns out, there is an answer!  When TCM made the big bore engines to compete with the slightly higher HP Lycomings, the way they got the HP they needed was to skimp on the FF. Lycoming does not do this. Heck, I can make a 550 produce 330 HP at takeoff--for a little while--by reducing the FF to Best Power. If the 10 minute TBO is your thing, go for it!

The SID97-3x was to satisfy marketing concerns and was NOT the idea of the engineering department. If you are not concerned with longevity, use TCM's numbers. If longevity is your concern, we suggest using the FF numbers that we came up with based on the measured ICP data. Our recommendations are not pulled from a dark part of the anatomy, they are based on solid engineering data.

It's your engine. Do as you please."

 

See the BeechTalk thread HERE. Click the link below to learn more about Advanced Pilot Seminars.

 

 

Does your mechanic need the special gauge set up for this SID? Click HERE for details on how to put together a CSOB set of gauges and manifold "Ts" to perform the SID.

 

Are you leaning in the climb to altitude? If not, why not? That's my SOP for good power and CHT balance, to lean in the climb. Do you have a six-point engine monitor with CHT and EGT (exhaust gas temperature) readings? If not, why not? I am very pleased with my JPI EDM-760 with fuel flow and oil temp sensors. The engine management gurus I trust suggest an EGT for takeoff (at any altitude) and in the climb of about 1250-1300F. So, I lean to roughly these EGT readings on my JPI engine monitor. In cruise, running "Green of Peak" , GOP (the procedure formerly known as Lean of Peak but might be offensive to some Democrat owners, LOL) will reduce your fuel consumption AND get your cylinders cooler AND increase engine longevity!

 

DUH, who knew, removing some of the fuel for combustion would make the fire LESS HOT!!!! And no, you will not blow up your engine. Just do not try to lean aggressively below 8,000' and put your engine on the rich side of peak, this is where you can do some damage, it's the zone of highest internal combustion pressures, ICPs, and highest heat of combustion (we see this in our CHT readings).

 

See the "Red Box" diagram HERE.

 

I've been running my IO470L's for >750 hours "Green of Peak" and my engines and cylinders are just fine. To read more about "Green of Peak" operations Click Here.

Read Mike Busch's #59 Article on Leaning

 

By the way, the engine gurus recommend redline RPM and Wide Open Throttle for your climb to altitude. For noise abatement areas they suggest pulling back to 2600 rpm.

 

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