Matronics Email Lists :: View topic - Timing adjustments in flight and affect on EGT/CHT

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Timing adjustments in flight and affect on EGT/CHT

Matronics Email Lists Forum Index -> RV-List

View previous topic :: View next topic

Author Message

n801bh(at)netzero.com
Guest

Posted: Sat Oct 23, 2010 2:06 pm Post subject: Timing adjustments in flight and affect on EGT/CHT

Your observations are correct.

Late ignition timing will lead to higher EGT's because  some of the firing event is already on the way out the exhaust pipe, so to speak. This is a simplified explaination but you sholud get the drift. Heat out the pipe is wasted energy.

Advanced timing lets the explosion happen sooner so there is a longer duration of downforce on the piston and that converts to greater power, that also is the reason the CHT's are higher with advanced timing. The head absorbs more heat because  the firing event happens earlier in the rotation of the motor and  it heats up the Cyl head and less is passed out the pipe. The more heat you can convert to rotation the higher HP you will make. Just get too greedy with the advance timing and detonation will set it and good bye pistons, then rings, then rod bearings. There is a fine line between optimum timing and disaster. Thats way FADAC is so good at what it does.  IMHO

Ben Haas

N801BH

www.haaspowerair.com



--------

- The Matronics RV-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV-List

retasker(at)optonline.net
Guest

Posted: Sat Oct 23, 2010 2:27 pm Post subject: Timing adjustments in flight and affect on EGT/CHT

It would be nice to see the results as listed in your spreadsheet.  

Unfortunately, not all of us have access to the latest and greatest 

Excel version.  How about saving a copy in an earlier format?



Dick



Wheeler North wrote:

 	  Quote: 	
		   



 Colleagues,

 Here is some interesting data from a flight I took yesterday. I've installed

 the Generation3 ignition system (http://www.g3ignition.com/) which allows me

 to vary timing from the cockpit.



 http://miravim.org/FlightData/index.php  links to a page where you can

 download the .xlsx file.



 The charts on the left of worksheet two show parameters of timing being

 changed from 20 to 35 deg BTDC then back to 20 at the very end. Note how EGT

 and CHT exchange. As timing is advanced EGT decreases and CHT increases. The

 one anomaly is the first section of CHT shows some cooling, I did not wait

 long enough for them to stabilize after a climb. I guess it takes five

 minutes, because I did wait three minutes.



 The charts on the left are about my very large cowl flap I have in the

 bottom of the cowl below/behind the carb. Note how it acts like a speed

 brake. I was also surprised at how much the EGTs also got cooler. This data

 shows that RVs get plenty of air in, they just need more air to exit,

 particularly during high load and high angle of attack.

 Thus the data shows that two things you can do for high CHTs is retard the

 timing (There is an SB that allows 20 Deg instead of 25), or make a bigger

 hole in the bottom, or both.

 The cowl flap is driven by one of the new Ray Allen hi thrust servos...

 which I don't see listed on their website, but the thing really puts out.

 http://www.rayallencompany.com/index.html

 W

    


	


-- 

Please Note:

No trees were destroyed in the sending of this message.  We do concede, however,

that a significant number of electrons may have been temporarily inconvenienced.

--

- The Matronics RV-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV-List

rv8tor(at)lazy8.net
Guest

Posted: Sat Oct 23, 2010 4:04 pm Post subject: Timing adjustments in flight and affect on EGT/CHT

Thanks very much for posting!



What was the density altitude? Fixed pitch prop?



John

--

- The Matronics RV-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV-List

Display posts from previous:

	Matronics Email Lists Forum Index -> RV-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum