VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #11  
Old 11-13-2016, 09:06 AM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,502
Default Keep looking

Paul,
I very much doubt that your CHT issue is baffle related.
I know you said the timing was "good" where is is set?
What is your take off fuel flow?
It needs to be 26GPH no less!
Certainly good advice on all the baffle and clearing the fins from casting flash
but your temps are ridiculously high for a stock installation.

As a comparison, I added a set of louvers on the bottom of the cowl, (2x
6 inch sections) and rarely, even on 100F days see temperature above 380 in climb and around 300 to 320 in cruise. In winter I have to tape those louvers off to keep CHTs from dropping below 300F.
I am north of you in the SF Bay area.
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 400 plus hours
Over 2500 Gallons of E10 mogas burned
Don't believe everything you know.
Reply With Quote
  #12  
Old 11-13-2016, 03:52 PM
Bill.Peyton's Avatar
Bill.Peyton Bill.Peyton is offline
 
Join Date: Sep 2009
Location: St. Louis, MO
Posts: 1,542
Default

, +1 on what Ernst says. I see about the same temps in cruise as Ernst, in climb, as long as I keep the airspeed above 120kts, my temps stay below 400.
How many hours do you have on the engine? My temps did not come down until I had 20 or so hours. What is your timing? What is your FF rate? 24 to 26 is about normal.
__________________
Bill Peyton
RV-10 - 700 Hrs
First Flight Oct 2012
WA0SYV
Aviation Partners, LLC
Reply With Quote
  #13  
Old 11-13-2016, 09:34 PM
paul330 paul330 is offline
 
Join Date: Feb 2007
Location: Mpumalanga, South Africa
Posts: 952
Default

Engine has 45 hours on it.

Timing is whatever it said in the manual - 23 or 25 BTDC with Slick mags. Can't remember off the top of my head but it was checked spot on 15 hours ago.

Mixture could be too lean from what you have said. My field has a density altitude of around 4-5000' so whilst it may be good for this, it could be too lean compared to sea level. I'll check the FF on my next TO but I believe it is around 23gph. I can see why this would affect the climb CHTs but if you lean to a fuel flow in the cruise, how does the max FF affect anything?

Thanks for the advice.
__________________
Paul
Mercy Air, White River FAWV
RV-10
ZU-IIZ - "Zeus"
2017 Donation Made

Last edited by paul330 : 11-13-2016 at 09:37 PM.
Reply With Quote
  #14  
Old 11-17-2016, 04:14 AM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,036
Default

Paul,

Please note that quite a number of fuel control units in recent years are coming out of the factory at min fuel flow or worse. I suspect the old timers who built them knew they had to achieve MAX flow and set them up right. They will be retired and replaced by who knows what cheap labour. Just a hunch. But we have seen many in the last few years.

With a DA of 5000' approximately I would expect the flow to be in the 21.5GPH range. But that is a guess off the top of my head, but a pretty good one.

The cross check is simple, at full rich your EGT values assuming probes are about 2" from the flange, should be around 1280-1320dF. This is also dependent on the timing being right.

You should climb using the target EGT method, have a poke around the APS website, we have a download you can do which explains it.

I can climb in Australian summers at 120KIAS and not go past 380-385. Appropriately LOP and that is a variable, but at 10,000' that is 10-20dF LOP, and if you can get down to 9.3GPH it sounds like your GAMI spread is quite OK. Normal flow at that would be 10-10.3 GPH. Typical CHT in the cruise LOP would be 330-345 at this time of year (Summer) and 310-330 in winter.
__________________
______________________________

David Brown


The two best investments you can make, by any financial test, an EMS and APS!
Reply With Quote
  #15  
Old 11-17-2016, 09:26 AM
aerhed aerhed is offline
 
Join Date: Dec 2008
Location: Big Sandy, WY
Posts: 2,566
Default

My current rv10 will climb full throttle, 90kts all day and never hit 400. Bone stock cowl, baffles, louvers. Gear slot extended maybe 2 1/2 inches. They should all do this. If one can't, then something is being missed.
__________________
Actual repeat offender.
Reply With Quote
  #16  
Old 11-17-2016, 12:08 PM
sglynn's Avatar
sglynn sglynn is offline
 
Join Date: Mar 2008
Location: Anacortes, WA
Posts: 520
Default Lowering CHTs

Have you considered going lean of peak? Have you listened to or read this leaning article about the RED BOX? I fly my O-540 lean of peak which is way richer than any engine stumble. I use 6 temp probs so I can see what's happening. My plugs are always clean. Excess air can cool the temperatures.

http://www.eaavideo.org/video.aspx?v=2534345030001
__________________
Steve Lynn
RV-7A
90% Finished
Working on Wiring
Only panel left to go.
Anacortes, WA
www.mykitlog.com/sglynn
Reply With Quote
  #17  
Old 11-17-2016, 07:29 PM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,036
Default

Quote:
Originally Posted by sglynn View Post
Have you considered going lean of peak? Have you listened to or read this leaning article about the RED BOX? I fly my O-540 lean of peak which is way richer than any engine stumble. I use 6 temp probs so I can see what's happening. My plugs are always clean. Excess air can cool the temperatures.

http://www.eaavideo.org/video.aspx?v=2534345030001
Just a point of order. It is not excess air, for every intake at the same conditions there is the same amount of air, and there is no way physically possible for any "excess air" to do the cooling you get with LOP ops.

It is simple. Lower peak pressure in the cylinder caused by a greater ThetaPP angle. Nothing else.

As for the problems the thread starter is having, going LOP will lower his temperatures for sure, but he still is off the ball by a bit.
__________________
______________________________

David Brown


The two best investments you can make, by any financial test, an EMS and APS!
Reply With Quote
  #18  
Old 11-17-2016, 11:53 PM
paul330 paul330 is offline
 
Join Date: Feb 2007
Location: Mpumalanga, South Africa
Posts: 952
Default

Thanks again for all the input.

TO fuel flow @ 5000DA is 22.5 so that sounds about right. Climb CHTs at 120kts are fine - just occasionally creeping over 400F on the rear cylinders but well below 435F.

Now I have finally got all my EGT probes working, I have found that LOP gives me considerably lower CHTs - around 370F on the rear cylinders @ 6000' and around 350C @ 10k. Bearing in mind it is summer here and the temperatures at 6000' are still around 25C, I can live with that.

So, I'm pretty happy now but will try the old "washer between cylinder and baffle" trick next time I have the lower cowl off.
__________________
Paul
Mercy Air, White River FAWV
RV-10
ZU-IIZ - "Zeus"
2017 Donation Made
Reply With Quote
  #19  
Old 11-20-2016, 05:12 PM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,036
Default

Paul, on the weekend climbing through 4000-5000 I saw flow higher than that, I should have taken a photo.

I would try to get to a sea level port and do a takeoff there and see what flow you get passing 300'-600' when the numbers have settled down.

Should be around 25.5 GPH.
__________________
______________________________

David Brown


The two best investments you can make, by any financial test, an EMS and APS!
Reply With Quote
  #20  
Old 11-21-2016, 12:24 AM
paul330 paul330 is offline
 
Join Date: Feb 2007
Location: Mpumalanga, South Africa
Posts: 952
Default

Might be a bit tricky around here - at least until I do a trip to Cape Town

In any case, surely that only affects the climb CHTs? If you lean to a fuel flow in the cruise then surely it makes no difference what the TO fuel flow is......
__________________
Paul
Mercy Air, White River FAWV
RV-10
ZU-IIZ - "Zeus"
2017 Donation Made
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 02:37 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.