I have a YS 160 installed in a Genesis, prop is APC 17 x 12, fuel is 20% Cool Power Heil. With the cowl off the engine runs great 8000 RPM max and idle at 2100 no problem. The engine is new and only has 4 tanks through it. The problem is when the cowl is installed I only get 77-78000RPM, the engine is gets too hot and shuts down.
Before I start cutting more cooling holes in the cowl I was wondering if of you had any experience with this installation. Any help would be appreciated.

Mark

Mark,

You need around 2 1/2 times the air outlet area as you do intake to allow the air to pull through. What you've got now is the air stagnating in the cowl because it can't get out fast enough. You've got plenty of intake area, so make your air outlet larger and see if that helps. I've never needed to duct a YS because I've had enough air flowing over it, but if that still doesn't help, maybe take some foam and cover up your cheek inlets and that will direct more air to the head of the motor.

I hope this helps!

I had the same problem with my Genesis/ 160DZ combination. I had to open up several holes down the belly pan under the pipe to let air out. Solved the problem.

What Ryan said. Must have sufficient exit holes for it to work.

Greg Grigsby

I made some foam inserts in the cowl to guide the air around the cylinder. No extra holes in the front.

Thanks Guys,

I did add 4 more holes in the bottom rear of the cowl near the pipe exit(see picture) and there was some improvment but it still gets too hot and shuts down during ground run. I was thinking of making some more small holes below the ones on the cowl that would expose the pump adjustment screw and two more like half moons on either side that would expose more of the cylinder cooling fins(see picture).
Reco,how is the foam attached? Any pictures?
Burtone, any pictures of the Genesis with those extra holes/

Best,

Mark

On my Angel Shadow I added a hole (2" diameter) in the middle of the bellypan to let air out near the front of the pipe. Also, guys around here were opening the fuselage part in front of the motor on their Genesis.

You also have to consider that your motor isn't getting the same amount of cooling when it's not at cruise speed. Fly the airplane before you put more holes. If you put more holes in the front, then you'll have to put more holes in the bottom to let that air out. You have to have more outlet area than inlet area to act as a vacuum.

Something to consider.

I had the same problem with a VF3. I had too much inlet!!! Not in the right place. I know that sounds counterintuitive but let me try to explain. It looks to me like you have 2 inlets on the side of your spinner. Block them off and give it a fly.
You may be exhausting warm air and not getting rid of the heat.
When I covered the side holes in the cowl, all overheating problems were solved. You need to have as much of your inlet air going over the head as possible
Try putting tape over any inlet that isn't going over the head and fly it!
I love a simple fix!!!
This worked for me and I hope it will work for you...
Let us know.
RC

On the Valiant I found that I got better cooling by taping off the left (looking at nose) cheek and half of the bottom most opening. Motor ran much cooler. I still think a hole should be made in front of the cylinder.

You need more exit holes.

I'm not sure if multiple slots work as well as a single BIG hole.

Try a 16.5X12 for break in and 30% instead.

Make sure you arent running it on the ground at WOT for more than a few seconds at a time. If the engine does not respond to HS needle changes (richer) while at WOT something may be wrong with the pump...maybe just the setting.

Colin.

Colin is right, bumping up the Nitro will help. The other key is forcing the air over the head. All the air in the world doesnt help if it doesnt go to the right spot,

Arch

I think the engine is too lean, does it smoke alot?

It isn't to lean, there is a lot of smoke actually it's a bit on the rich side and the HS needle responds normal at WOT.
I put an opening in front of the pump with the hope of getting some more air on to the cylinder, ran the engine this evening without any change, RPM down(77-78) and the the engine shuts down as its gets to hot. With the cowl off it just runs fine 8000 RPM max and idles great.
Next I will try some 30% and if that doesn't work then I will cut some exit holes. I have looked at many pictures of the Genesis online and a lot of people have less exit holes and some have more or less inlet holes. What I don't know is the fuel and prop they use. I will update after next run.

Mark

Just noticed that you were running 20%. The guys here ran 30% with the 17x12. Maybe a lighter loaded prop in addition to a more directed airflow with 20% would work.

What's the temperature in your field?

He's in Trinidad...very similar conditions to Caracas.

Colin.

In Caracas we are at 28 to 29C year round, a travel a lot to Curacao which is about 30min flight and there it's about 32C, and Trinidad is on the other end, so I'm not sure at their field temp.
My point is , if there field temp is hinger that 32C, he needs to richen the engine more and change fuel to 30%, we run YS on the rich side, and not just a bit.


Regards

31C is the field temp here in Trinidad. I tried another run this evening (29C) with the cowl side inlet air holes blocked as someone suggested. nil fix
I normally run these YS engines about 1/8 turn open from max RPM. Is that too lean?
Saturday I will try the 30% with a 16 1/2 X 12 prop and see what happens.

Mark

I measure the peak RPM and open until it drops 200-300RPM, always fly like that and never got an engine overheat. You can try using some foam to around the engine to force the air through the cylinder. Have you run it with the chin cowl removed?

Mark,

Curious how long on the ground you are running the engine and at what rpm (max or idle or other) is the engine shutting down? Cooling holes work when the plane is flyng not on the ground. More details about the ground running scenario would be helpful in diagnosing your issue.

I live and fly in Houston TX which in the spring, summer and early fall has comparable conditions to Trinidad in air temp and humidity. Ask Mark Mendonca, do you know him? My typical cooling cutouts are similar to yours, no foam in chin cowl. Just wondering if you are asking the engine to run on the ground with the chin cowl on for a unreasonable period of time. Have you flown the plane to see how the engine performs while it's properly cooled?

It runs just fine with the chin cowl off.

This evening I did another run, this time I used a 17X10N prop and the same 20% fuel. Max RPM 8500 then I open the HS needle to get 8250. Put the cowl back on and got 8250-8220 the engne did not get as hot as before and ran pretty good. idle was a bit rough at frist but setteled in at 2450 ok, I know that's bit high.
So it looks like it was just too much prop for a new engine on 20% fuel. I think I should still open up the plug access hole at he bottom of the cowl to get some more air out and as Glen said I will get a lot more cooling in the air.
Glen, Max RPM on the ground isn't for more than 12-15 seconds intavals. The airplane hasn't flown as yet. What was happening before was with the cowl on the max RPM would just keep dropping off then everything would get rough and shut down. Yep, I know Mark pretty well. So tomorrow I will try some 30% and see how that works and may be I will try a 16 1/2 X 12 prop. Keep you guys updated.

Mark

Mark,

In my opinion running a DZ for 12 to 15 seconds at full throttle static on the ground with or without the chin is hard on the motor and is more and likely running hotter in that situation than what the Manufacture intended.

The following is the recommended initial running procedure for the DZ series by the YS US importer.

1) Set high speed needle at 2.5->3 turns open, start motor at idle position
2) Run motor at a fast idle only for 10 minute intervals for 20->30 ounces of fuel (allow proper cooling between 10 running intervals)
3) After step 2 then run motor up to full throttle only long enough (few seconds) to set full speed needle (max rpms less 1/4 turn rich)
4) Adjust TX setting to achieve a reliable idle of 1900->2100 rpms
5) Go fly

Following this initial run-in procedure has increased my performance longevity and reliability immensely with the 160s and 170s I have competed with over the last few years. Also like others have recommended I suggest you upgrading to fuel containing 30% nitro with 20% or greater low viscosity oil to achieve ideal performance and lubrication.

My setup with the DZ 160 consisted of the following:
CoolPower Heli blend 30%
OS Type F or YS glo plug
APC 16.5X12 2bld @ 8500 RPM
APC 15X11 4bld @ 8800 RPM

I really think you need to enlarge the vent exit holes, give it a try. that prop seems to little for that engine.