RV7A horizontal intake cooling issues.

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Skyline
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RV7A horizontal intake cooling issues.

Unread post by Skyline » Thu Jun 28, 2018 4:04 pm

My CHT’s on a new Lycoming horizontal intake are too high. Some guys advize installing two vents on the bottom “cheeks” of the cowling to get the air out faster. Anyone done this small mod and did it work. Done the baffles over and over so that is not the problem.
A pic or two would be nice.
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Re: RV7A horizontal intake cooling issues.

Unread post by Alan stewart » Thu Jun 28, 2018 6:37 pm

Howzit
I added 2 louvers on my 9 , either side of the exhausts ,
my issue was high oil temp

Link to what I used.

http://mcnaughtans.co.za/louvres.html

Good luck
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Re: RV7A horizontal intake cooling issues.

Unread post by Chalkie » Fri Jun 29, 2018 8:12 pm

Skyline wrote:
Thu Jun 28, 2018 4:04 pm
My CHT’s on a new Lycoming horizontal intake are too high. Some guys advize installing two vents on the bottom “cheeks” of the cowling to get the air out faster. Anyone done this small mod and did it work. Done the baffles over and over so that is not the problem.
A pic or two would be nice.
1. Lycoming, horizontal intake? Does that refer to the cooling air or the air to the carb/injector body?
2. What is 'Too high.'
3. Which cylinder/s is/are 'too high?'
4. What airfield altitude do you normally operate from?
5. What CHT indication system do you use?
6. At what speed does this problem occur?

FYI, the air outlet in all the RV-6, -7, -8, -9 cowls are too big.
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Re: RV7A horizontal intake cooling issues.

Unread post by Chalkie » Fri Jun 29, 2018 8:19 pm

Alan stewart wrote:
Thu Jun 28, 2018 6:37 pm
I added 2 louvers on my 9 , either side of the exhausts , my issue was high oil temp
Alan, do you have the Van's standard 7 fin oil cooler?

If so a, 9 fin cooler would have fixed the problem. If you had the problem with Van's 'tropical' oil cooler (9 fin) then I would have questioned indication.

Maintenance wise: if a gauge displays 'out-of-limits-info' then suspect the gauge first. Believe me, it can save hours of agony. Been there, done that, have a few T-shirts...
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Re: RV7A horizontal intake cooling issues.

Unread post by Goose1 » Fri Jun 29, 2018 8:45 pm

Had oil temp problems on my RV8. Replaced the cooler with a deferent type and temp came down by 35*f
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!

Unread post by Leon B » Sat Jun 30, 2018 5:30 pm

Goose I give up!
is the left one better than the right? Brands?
I have the standard Vans 7 row and the internet?? will have me believe that the 6 row HE series from Classic Coolers do a better job?
If I can get away with a similar size cooler (but obviously more efficient) I will be happy because the location on the baffles lead to cracks that I can do without. Anybody have experience with the 6 row Classic aero HE series??
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Re: !

Unread post by Goose1 » Sat Jun 30, 2018 6:31 pm

Leon B wrote:
Sat Jun 30, 2018 5:30 pm
Goose I give up!
is the left one better than the right? Brands?
I have the standard Vans 7 row and the internet?? will have me believe that the 6 row HE series from Classic Coolers do a better job?
If I can get away with a similar size cooler (but obviously more efficient) I will be happy because the location on the baffles lead to cracks that I can do without. Anybody have experience with the 6 row Classic aero HE series??
When I got my RV it had 2 oil coolers and after the rebuild I wanted to remove the one on the baffles because the baffling kept on cracking and weighed reducing. So I started experimenting by taking the small one out off the oil system, oil temp was ok in winter but overheating in summer and the same happened with the big one. The last thing I could think off and try was to try a other type of cooler( Steward Warden) and It worked.
If you look at the gold colored cooler there is very small amount of air that can pass through to do the cooling and makes it a bad cooler. Now my RV only have the cooler on the firewall and the temps are perfect in winter and summer with the Gray Cooler
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Re: !

Unread post by Chalkie » Sat Jun 30, 2018 6:33 pm

Leon B wrote:
Sat Jun 30, 2018 5:30 pm
Goose I give up!
is the left one better than the right? Brands?
I have the standard Vans 7 row and the internet?? will have me believe that the 6 row HE series from Classic Coolers do a better job?
If I can get away with a similar size cooler (but obviously more efficient) I will be happy because the location on the baffles lead to cracks that I can do without. Anybody have experience with the 6 row Classic aero HE series??
Air is a good insulator, we put pink staff in our roofs, because air is a bad conductor of heat energy.

The 8 fin vs 14 fin cooler discussed surprised me, but if you look at the surface area of the fins between the oil passages, the 8 fin has more area. So, bigger (more fins) is not necessarily better.
Last edited by Chalkie on Sat Jun 30, 2018 6:44 pm, edited 1 time in total.
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Re: !

Unread post by Chalkie » Sat Jun 30, 2018 6:43 pm

Goose1 wrote:
Sat Jun 30, 2018 6:31 pm
When I got my RV it had 2 oil coolers and after the rebuild I wanted to remove the one on the baffles because the baffling kept on cracking and weighed reducing. So I started experimenting by taking the small one out off the oil system, oil temp was ok in winter but overheating in summer and the same happened with the big one. The last thing I could think off and try was to try a other type of cooler( Steward Warden) and It worked. [/quote]
Mounting an oil cooler on the baffle of No 4 cylinder is the best place, all you have to do is reinforce the baffle to carry the weight.

An oil cooler on the firewall behind No 3 cylinder would need a minimum 3" pipe.
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Re: RV7A horizontal intake cooling issues.

Unread post by Goose1 » Sat Jun 30, 2018 6:49 pm

Chalkie wrote:
Fri Jun 29, 2018 8:12 pm
1. Lycoming, horizontal intake? Does that refer to the cooling air or the air to the carb/injector body?
2. What is 'Too high.'
3. Which cylinder/s is/are 'too high?'
4. What airfield altitude do you normally operate from?
5. What CHT indication system do you use?
6. At what speed does this problem occur?

FYI, the air outlet in all the RV-6, -7, -8, -9 cowls are too big.
Oom Chalkie
I think this is the RV 7a I flew a week or two ago. Its a horizontal induction IO-360. 180hp with 5hr since new. All the cht is over 400 with the hottest one 426*F if I remember correct. Oil temp 190*F and oil press 80psi. Dynon engine monitor. We flew from Wonderboom. The only way I could get temps down was by reducing MP.

I have a question for the clever guys, how mutch air does a 360 Lycoming use per m at 2400 RPM at WOT. That amount of air is taken away from the cooling of a Horizontal induction RV. The one with the Vertical Induction have that amount of air more to use for cooling
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Re: !

Unread post by Goose1 » Sat Jun 30, 2018 6:54 pm

Chalkie wrote:
Sat Jun 30, 2018 6:43 pm
Mounting an oil cooler on the baffle of No 4 cylinder is the best place, all you have to do is reinforce the baffle to carry the weight.

An oil cooler on the firewall behind No 3 cylinder would need a minimum 3" pipe.
I forgot to mention that the 3” pipe was also done before the oil cooler replacement.
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Re: RV7A horizontal intake cooling issues.

Unread post by Chalkie » Sun Jul 01, 2018 10:41 am

Goose1 wrote:
Sat Jun 30, 2018 6:49 pm
Oom Chalkie
I think this is the RV 7a I flew a week or two ago. Its a horizontal induction IO-360. 180hp with 5hr since new. All the cht is over 400 with the hottest one 426*F if I remember correct. Oil temp 190*F and oil press 80psi. Dynon engine monitor. We flew from Wonderboom. The only way I could get temps down was by reducing MP.

I have a question for the clever guys, how mutch air does a 360 Lycoming use per m at 2400 RPM at WOT. That amount of air is taken away from the cooling of a Horizontal induction RV. The one with the Vertical Induction have that amount of air more to use for cooling
I would expect No 3 to be the hottest (426) this is not that bad for a new engine, 190 oil temp is spot on as the vernatherm closes at about 180, so my suggestion would be lean aggressively; all the way to peak EGT. On the highveld the chances of producing more than 75% power are rather slim, so you cannot damage the engine, no matter what you do with the red knob.

I am not going to post the EGT / CHT / Power graph again, open the engine manual and find the graph, you will see that the CHT peaks before the EGT, so AT PEAK EGT the cylinder heads run cooler. As cool as about 100F to 150F ROP.

As for the air the engine consumes, do not worry about that, this will not affect the flow of cooling air over the engine at all; as at cruise speed a lot of air 'spills' over the cowl inlets. The flow of air over and around the engine will be the same in vertical induction and the horizontal induction engines.
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Re: RV7A horizontal intake cooling issues.

Unread post by RudiGreyling » Thu Sep 20, 2018 10:23 am

It has been a while but the best advice i got and used and served me well in my 600 hours so far...So I hope it helps someone else too...

CHT is also a function of Oil Temperature. The standard supplied RV7 Oil Cooler is not good enough for highveld and hot african flying, throw away (or do not purchase) the standard Vans Fire Wall Forward packaged oil cooler and rather buy a genuine STEWART-WARNER or Airflow X Series from aircraft spruce of exact same dimensions for 'african conditions', it is drop in replacement, but much more effective.

You fit the RV7 oil cooler in the same locations as the plans suggest, on baffle behind #4, so all your hoses and routing still works out fine as per plans. To mitigate baffle/cooler cracks. Reinforce the baffle corner with an angle as per latest plans. Use ALL the bolt holes to attached the oil cooler, to spread the load, this means you will will have to buy extra bolts and nutplates. Fit a aluminium pipe spacer over the long bolt between the oil cooler ears, as a sandwich, to transfer load from rear ears to the baffle attachment. Use large washers under bolt heads to spread the load more into the oil cooler

Here is an old picture during my wiring that show the cooler in the corner that might help explain, good luck!
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Re: RV7A horizontal intake cooling issues.

Unread post by Jan » Thu Sep 27, 2018 6:52 am

Here is the graph Chalkie is referring to.
EGT_CHT Graph.jpg
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