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  #21  
Old 01-24-2018, 12:38 PM
toc pilot toc pilot is offline
 
Join Date: Oct 2005
Posts: 47
Default cooling

https://www.facebook.com/18143611188...type=3&theater

I would not retard power on your climbout unless you are continuously hitting 400+ on climbout, reducing power to get the CHTs back to 350 before resuming the climb is simply not necessary in my opinion.
For better CHT cooling you can also instal "louvers" in the bottom of the cowling next to your door. Louvers can reduce CHTs a lot!
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Bill Hempel
RV-7: N17HB AEIO-390, Hartzell Composite C/S prop, Dual Skyview D1000. First Flight: Oct 2017
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  #22  
Old 01-24-2018, 01:31 PM
High_Flyer's Avatar
High_Flyer High_Flyer is offline
 
Join Date: Sep 2010
Location: Saint-Jorioz, France.
Posts: 185
Default Good baffles

Hi,
I have a RV-7 in East of France, similar weather as where you are...
My engine is a Aeropsport Power IO-375, with fuel injection and dual P-Mags (electronic ignition). My setup probably helps with lower CHT compared with carburator and "traditional" ignition...
During the first few hours after initial flight in summer I was seing hig CHT as well, but my engine was not broken in and the weather was quite hot (above 30°C). To mitigate the hight temps I was climbing at 120 Kts indicated for better airflow over the cylinders.
Now I have about 50Hrs on the plane and the engine break-in is done, and I'm able to keep CHT below 380 most of the time.
I believe the most important is to have PERFECT baffles.
That will help create a high pressure area in the top part of the engine compartment forcing air around the cylinders for cooling.
If you do not have good baffles this will make leaks over the baffles or on the side of the cowling likely and this will reduce the high pressure on top of the engine and reducing the flow of air around the cylinders.
When I built my baffles I took very good care of blocking every little hole, and making tight rubber seals. As others have said the inlet ramps are also important to allow a smooth airflow to enter the engine compartment.
Increasing the exit area will not help cooling the engine if the baffles are not good, it will only increase drag (your cowl flap will get in the airflow, so more drag).
In summary I believe the key is the pressure diferential between the top and bottom of the cylinders. The higher the differetial the higher the flow of air around the cylinders and thus better cooling.
Good luck...

EDIT: link to a good article on baffles: https://blog.aopa.org/aopa/2017/03/29/its-baffling/

Alain.
__________________
Location: France
RV7 (F-PRVZ), Tip Up, Aerosport IO-375, Dynon Skyview, VP-X, Day VFR.

Flying since June 2017.

Last edited by High_Flyer : 01-27-2018 at 10:03 AM. Reason: link added
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  #23  
Old 02-17-2018, 03:34 AM
givo givo is offline
 
Join Date: Oct 2017
Location: Padova , Italy
Posts: 15
Default

Quote:
Originally Posted by High_Flyer View Post
Hi,
I have a RV-7 in East of France, similar weather as where you are...
My engine is a Aeropsport Power IO-375, with fuel injection and dual P-Mags (electronic ignition). My setup probably helps with lower CHT compared with carburator and "traditional" ignition...
During the first few hours after initial flight in summer I was seing hig CHT as well, but my engine was not broken in and the weather was quite hot (above 30C). To mitigate the hight temps I was climbing at 120 Kts indicated for better airflow over the cylinders.
Now I have about 50Hrs on the plane and the engine break-in is done, and I'm able to keep CHT below 380 most of the time.
I believe the most important is to have PERFECT baffles.
That will help create a high pressure area in the top part of the engine compartment forcing air around the cylinders for cooling.
If you do not have good baffles this will make leaks over the baffles or on the side of the cowling likely and this will reduce the high pressure on top of the engine and reducing the flow of air around the cylinders.
When I built my baffles I took very good care of blocking every little hole, and making tight rubber seals. As others have said the inlet ramps are also important to allow a smooth airflow to enter the engine compartment.
Increasing the exit area will not help cooling the engine if the baffles are not good, it will only increase drag (your cowl flap will get in the airflow, so more drag).
In summary I believe the key is the pressure diferential between the top and bottom of the cylinders. The higher the differetial the higher the flow of air around the cylinders and thus better cooling.
Good luck...

EDIT: link to a good article on baffles: https://blog.aopa.org/aopa/2017/03/29/its-baffling/

Alain.
Hi Alain , very interesting, also the link very useful , thank you
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  #24  
Old 02-17-2018, 04:19 AM
givo givo is offline
 
Join Date: Oct 2017
Location: Padova , Italy
Posts: 15
Default

Quote:
Originally Posted by F1Boss View Post
I have a customer in Balzano who might be able to help you. Elmar Marinoni lives there, and flies a Rocket. You could ask him to have a look?

Strikler & Marinoni OHG - I do not have a telephone number. Sorry!

Good luck!
Hi Mark ,

thanks , I know Elmar quite well , in fact we flew together with my plane to check temps ... A question .... I', m still breaking in , does this contribute to higher temps ? Thanks Giulio
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  #25  
Old 02-17-2018, 04:21 AM
givo givo is offline
 
Join Date: Oct 2017
Location: Padova , Italy
Posts: 15
Default

Quote:
Originally Posted by caryr View Post
Quite a few of us have been there.

Rejet the carb to flow more fuel on take off.

You will be amazed how much this helps.
Hi Cary ,

can you please specify what exactly " Rejet the carb " means ? Thanks Giulio
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  #26  
Old 03-27-2018, 06:34 AM
givo givo is offline
 
Join Date: Oct 2017
Location: Padova , Italy
Posts: 15
Default

Dear all a short update on the temperature . After the 50 hours check of the engine and break-in done , we minutely checked the baffle in order to close also the minimum hole where you can waste air .

The result was surprising .

The CHT temperature during take off are hardly over 370 F and the difference between cylinder 1 and 4 is minimum ( before was substantial ) .

Thanks also to the good article on baffles: http://<br /> <br /> https://blog..../its-baffling/

we reached the determination of working on the minimum details of the baffling installation .

I also change the prop from wooden prop to a Hartzell two blade prop that has the blade shank more thin , I dont know if it counts anyway thanks to you all you really helped a lot
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