Interesting engine baffle observation...

[Shadrach]

Stefan, data from last flight: (from KIWI, elev 50') 29.4 & 2644; FF: 17.4

 

17.4 is typical of my max flow. Prop control was firewall, max RPM varies some from flight to flight, seems to be affected by Oil Temp. (IO360A1A)

What was the OAT? That actually seems a bit low.

[BigTex]

Boy, I've tried to get modern with WOT & 2650 RPM for climb several times (25 square was SOP when I owned my 1st M20E 30 years ago) but even at 110-120 KIAS CHTs are pretty hot. Pulling back to ~ 25" seems to result in cooler CHTs @ the same IAS.

Same here... I've attempted to fly the way our J friends do but my plane just isn't happy with those power settings.

[Shadrach]

Same here... I've attempted to fly the way our J friends do but my plane just isn't happy with those power settings.

Interesting, you actually have an enrichment nozzle (economizer) that you take off-line when you "pull back to 25X25". I wish that there was someone locally with an instrumented C model so I could see what happens to the numbers as the throttle is pulled and the extra gas goes away. What kind of climb performance are you getting at 25x25? I'm betting that you're giving up 200-400fpm depending on DA.

[jetdriven]

So leaner, hotter, less IAS, and less climb. These O-360 engines are installed in 172s and the like and they always climb at full throttle with no ill effects.

[Oscar Avalle]

Same here... I've attempted to fly the way our J friends do but my plane just isn't happy with those power settings.

Same thing here too. I take off full throttle but if I keep 2700 CHTs are way to high. But pulling back to 2550 helps a lot. Do I lose climb rate? Yes, trade off between high cht and climb rate, I prefer lower CHTs.

[Bob_Belville]

What was the OAT? That actually seems a bit low.

68F. 

 

Here's another flight: from home field 1270' OAT 85F; 28.1/2650; 17.4.

[Bob_Belville]

What was the OAT? That actually seems a bit low.

I did not find it so easy to find Lycoming data on T.O. FF. I think the IO360A best power FF @ 95-100% power is 90-93 #/hr =~ 15.0-15.5 gph. So my 17.4 gph seems to have an extra 2 gph for cooling. Not enough?

http://www.7ts0.com/manuals/lycoming/360/O-360-HO-360-IO-360-AIO-360-HIO-360-TIO-360_OM.pdf  (page 3-32)

[BigTex]

Cooling issues with older vintage planes isn't an issue with the way it's flown nor something mechanically wrong.  I'm convinced that much of the challenges we're having is cowling/baffling related.  Everyone knows about the WOT enrichment circuit but I don't think it cools enough to overcome bad baffling.  It's pretty obvious that the J cowling seems to cool our engines better than the old doghouse baffling with the old style cowls.  Because of these differences, we have to keep an eye on our temps and mange it according much more than the newer aircraft.  Can we tweak it and make it better... sure.  I did that by increasing the Cowl Flap opening more than the 1.5" spec.  BTW: this really helped.  But outside of re-cowling/baffling them, we'll still have to deal with this cooling issue.

 

 

[Bob_Belville]

Cooling issues with older vintage planes isn't an issue with the way it's flown nor something mechanically wrong.  I'm convinced that much of the challenges we're having is cowling/baffling related.  Everyone knows about the WOT enrichment circuit but I don't think it cools enough to overcome bad baffling.  It's pretty obvious that the J cowling seems to cool our engines better than the old doghouse baffling with the old style cowls.  Because of these differences, we have to keep an eye on our temps and mange it according much more than the newer aircraft.  Can we tweak it and make it better... sure.  I did that by increasing the Cowl Flap opening more than the 1.5" spec.  BTW: this really helped.  But outside of re-cowling/baffling them, we'll still have to deal with this cooling issue.

1. Are we certain that the WOT extra fuel feature is on the IO360 or only the O360s? What FF gph do Js see on T.O.?

2. My E has a 201 style cowl, not the doghouse. But I suppose that does not mean the baffles are the same. I am pretty sure the cowl flaps are not as sophisticated.

[jetdriven]

Bob, those look like M20J baffles or a functional equivalent. As far as enrichment circuits in the Bendix IO-360 fuel injection go, I am going to verify this when I get home. Set takeoff power the pull it back a little and watch the EGT

[Shadrach]

I did not find it so easy to find Lycoming data on T.O. FF. I think the IO360A best power FF @ 95-100% power is 90-93 #/hr =~ 15.0-15.5 gph. So my 17.4 gph seems to have an extra 2 gph for cooling. Not enough?

http://www.7ts0.com/manuals/lycoming/360/O-360-HO-360-IO-360-AIO-360-HIO-360-TIO-360_OM.pdf  (page 3-32)

Most angle valve IO360 owners I talk to report 18-19 GPH for takeoff ~sea level. The higher DA you report may be the reason you're in the mid 17s, but I don't think you have a 2 gal surplus by a long shot. When was the last time your fuel servo was serviced?

[Bob_Belville]

Most angle valve IO360 owners I talk to report 18-19 GPH for takeoff ~sea level. The higher DA you report may be the reason you're in the mid 17s, but I don't think you have a 2 gal surplus by a long shot. When was the last time your fuel servo was serviced?

Ross, the first flight I listed was from KIWI - sea level. OAT was 68F so DA was still near SL. The other flight was from 1270 MSL and 86F OAT but FF was the same. 

The engine is 700 SFRM, I find no log entry of a servo overhaul. Annuals note checking f.filter, checking/cleaning injectors. (FWIW, injectors are very well balanced, gami spread near zero per JPI EDM 930. Engine runs smooth LOP.)

[Bob_Belville]

Bob, those look like M20J baffles or a functional equivalent. As far as enrichment circuits in the Bendix IO-360 fuel injection go, I am going to verify this when I get home. Set takeoff power the pull it back a little and watch the EGT

Byron, I just looked at a recent flight. At about 800' AGL I pulled throttle back from FW. Indicated HP from 86% to 75%. (~24.5/2550 -- my prop does not permit 25sq.) EGTs and CHTs declined.

 

My baffle system may be J-like but as previously reported I seldom see CHTs anywhere near as low as those I read about here from you and other 201 operators. And I ain't in TX! My last trip was to ME & MA. 

[Bob_Belville]

Bob,

Just as a data point for you, my takeoff fuel flow at sea level is typically 18.5 to 19 GPH.

Jim

Thanks Jim. I've been looking through my Lycoming parts, technical manuals and find almost nothing on the fuel injection system. Seems curious that the FT boost circuit is not more clearly documented. That might be the difference in the FT flow difference between my -A1A and J version(s) of the IO360. Or my system may be out of spec. Can't tell which though I suspect someone here will know. 

[Shadrach]

On 10/14/2013 at 9:27 AM, Bob_Belville said:

Thanks Jim. I've been looking through my Lycoming parts, technical manuals and find almost nothing on the fuel injection system. Seems curious that the FT boost circuit is not more clearly documented. That might be the difference in the FT flow difference between my -A1A and J version(s) of the IO360. Or my system may be out of spec. Can't tell which though I suspect someone here will know.

Bob, the main difference between your (our) engine and the J's is the dual mag and the counter balanced crank. Same cylinders, same pistons and same C/R. Your FF is 1gph or more on the light side for take off, but I'm basing that opinion strictly on the limited data I have seen here... EGTs on the take off roll may tell you something. You really ought to see ~1100-1150 at full throttle SL on a standard day to have nice cooling margins.. If you're plane is showing 1300 or more on take off, I'd investigate by doing a quick but thorough lean to peak and back at low level. You want to be min 200 ROP [or more] with the balls to the wall.

My plane runs in the 1100s on take off, which is about 250 to 300 ROP.

[Bob_Belville]

Bob, the main difference between your (our) engine and the J's is the dual mag and the counter balanced crank. Same cylinders, same pistons and same C/R. Your FF is 1gph or more Lon the light side for take off, but I'm basing that opinion strictly on the limited data I have seen here... EGTs on the take off roll may tell you something. You really ought to see ~1100-1150 at full throttle SL on a standard day to have nice cooling margins.. If you're plane is showing 1300 or more on take off, I'd investigate by doing a quick but thorough lean to peak and back at low level. You want to be min 200 ROP [or more] with the balls to the wall.

My plane runs in the 1100s on take off, which is about 250 to 300 ROP.

Ross, that it very interesting. My JPI 930 is a wealth of info. A recent flight indicates EGTs went from 1225 (taxi, leaned) to 1325 when I took off then settled in closer to 1275 during a long climb. (I climbed to 11,000' and leaned LOP - peak was ~ 1500 so I was climbing @ 200 or so ROP.)

 

Perhaps importantly, my EGT probs are about 7" below exhaust manifold mount flange, probably a little hotter location than spec which would be closer to the flange.