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  #21  
Old 09-20-2018, 03:09 PM
meyer228 meyer228 is offline
 
Join Date: Jan 2016
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Quote:
Originally Posted by RV8JD View Post
With Van's redefining Vne in terms of TAS, my RV-8 with a YIO-360-M1B will exceed its Vne of 230 MPH TAS if I don't bring back the power in a descent. Van's (possibly conservative) redefinition of Vne in terms of a constant TAS value at all altitudes, limits the RV-8's downhill performance.


Sorry for the thread drift!
Yeah, that's kind of what I experienced. TAS VNE really easy to bust... No complaints. Just need to manage it...and descend earlier...
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  #22  
Old 09-20-2018, 11:21 PM
gasman gasman is online now
 
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Quote:
Originally Posted by meyer228 View Post
Cool..

Okay follow up questions - Do you find yourself doing anything a little more cautiously? Making sure you don't shock cool? Make sure you've get the CHT's in the "green" before take off??

Also, from what I understand the failure mechanism (if there is one) isn't necessarily catastrophic engine failure but, separation of the head from the cylinder and subsequent partial loss of power. Right?

As you could likely guess, I have purchase a 9a with the ECI Group B cylinders/heads. < Correction - I have Group A >

Thanks for sharing your info...
Wrong..... it will still produce enough power to keep the aircraft in the air. BUT the aircraft will shake violently enough that you will want to get on the ground ASAP. You will need to reduce power to avoid tearing then motor from it's mounts.
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  #23  
Old 09-20-2018, 11:26 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by RV8JD View Post
With Van's redefining Vne in terms of TAS, my RV-8 with a YIO-360-M1B will exceed its Vne of 230 MPH TAS if I don't bring back the power in a descent. Van's (possibly conservative) redefinition of Vne in terms of a constant TAS value at all altitudes, limits the RV-8's downhill performance.

Note where Redline is (in terms of MPH IAS) in the screenshots below, at much less than 75% power.

400 FPM descent at 9800':



600 FPM descent at 16,120':



Sorry for the thread drift!
Of course you have to observe all operating limits -but you descend at speed, throttling back just enough to observe Those limits, and get a nice fast ride downhill - you donít have to pull all the power off to where youíre worried about cooling in order to lose 10,000í in 60 miles....
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  #24  
Old 09-21-2018, 01:33 PM
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grubbat grubbat is offline
 
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Default Prop driving engine

Lycoming rep advised me to keep manifold pressure at 18" or above to prevent prop from driving engine. I used to think it was around 15" min but not so. Prop driving engine is not good. Constant speed prop really helps with the need to loose altitude while maintaining proper manifold pressure.
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  #25  
Old 09-21-2018, 06:04 PM
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erich weaver erich weaver is offline
 
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Originally Posted by grubbat View Post
Lycoming rep advised me to keep manifold pressure at 18" or above to prevent prop from driving engine. I used to think it was around 15" min but not so. Prop driving engine is not good.
Why not? Isn’t this essentially what happens every time we descend with a constant speed prop?

Erich
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  #26  
Old 03-03-2019, 06:26 AM
blastinbill blastinbill is offline
 
Join Date: Mar 2016
Location: Vienna, Virginia
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Default ECI Titans Group A

I have ECI Titans, Group A on the front and Lycomings (nitrided) on the rear of my O-360 A1A in my Comanche. 850 hours on the ECI's and 1230 hours on the Lycomings. No cylinder has been off the airplane since original installation and compressions in the 70's, although the ECI's are in the low 70's and the Lycomings in the mid 70's.
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  #27  
Old 03-03-2019, 10:01 AM
theduff theduff is offline
 
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Default ECI group A cylinders

You should read the AD carefully. IMSC, group A cylinders have to be pulled if their compression is 70/80 or below. If they’ve separated at the head to barrel interface ( via the soap bubble test ) they go in the dumpster but if it’s a valve or rings they can be repaired and put back in service until their service life of 2000 hrs This is different than Lycoming’s SI 1191 : “ If the pressure reading for all cylinders is equal and above 70 psi; the engine is satisfactory; less then 65 psi indicates wear has occurred and subsequent compression checks should be made at 100 hour intervals to determine rate and amount of wear. If the pressure reading is below 60 psi or if the wear rate increases rapidly, as indicated by appreciable decrease in cylinder pressure, removal and overhaul of the cylinders should be considered.” I’ve run group A cylinders and considered their potential for cracking no different than late ECI cylinders ( 60,000 serial numbers and above) . I had a recent experience with a Repair Station who didn’t want to hone and re-ring a set of group A cylinders with 1200 hrs snew. They felt once they came off the engine the next stop should be the dumpster. I guess I understand but that’s not what the AD says. As a data point these 1200 hr cylinders had exhaust guides worn beyond service limits and 3 of the exhaust valves were as well.
Just my thoughts and as they say “ Your mileage may vary.”

Last edited by theduff : 03-03-2019 at 12:13 PM. Reason: Additional info
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  #28  
Old 03-03-2019, 01:56 PM
rwarre rwarre is offline
 
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Default cylinders

Flying since 2009 with the group A. Almost 1300 hours, never a hick up, burns about 1 quart in 50 hours.
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