differance 91AC and 110FZ
 

Hi guys,
I aquired a new in box YS 91 AC and 110 FZ and was wondering if there is much differance in power between these engines? I currently run a 14-10 MA Simalar prop with an older 91 AC in a warbird and get great performance. I want to put my 110 in a warbird as well, what would be a good prop for top speed and all around performance?
Regards,
Frank

RE: differance 91AC and 110FZ
 

The differences are subtle but there are some that are major for the first and most important its a larger displacement. 1.10 vs the 0.91....As for operational its the same basically. I would say depending on the fuel you choose you could likely go to a slightly larger prop. Maybe a 14-11 or 14-12. Again it depends on the circumstances. You should really look into the APC props as they are much more efficient that anything else out there. The other molded props tend to flatten out as they run up and they also flex a bunch. This means that the work of the engine is not getting transfered to the air efficiently. You might see a huge performance increase going to the same prop in an APC.

What ever you do try to run the 91 and 110's up above 9000rpm say 9200-9500 is my target. You can load the 110 a little lower say 8800 but I would not try to run the 91's down this low in the rpm range. They just work too hard and can create more heat...but 8800 is OK on the 110's I prefer higher. 9200-9500. The first 110FZ on 30% heli Cool Power will turn a 14-12 at 9500-9600 at my Arizona 1000ft above sea level.


Less nitro means use less prop, going to sea level will give you better performance. Going up in elevation to say Denver area at 5000ft you will have to lower the prop load to get the desired RPM

Troy Newman
Team YS

RE: differance 91AC and 110FZ
 

Thanks Troy for your quick reply. On other question, I heard some people just run a small header instead of using the full muffler which gives them a few hundred rpms because of less restiction and is said to sound better?Also does the 110 use a check vavle as the 91?
Regards,
Frank

RE: differance 91AC and 110FZ
 

Yes plumbing setup is identical.

YS 110FZ infor here

http://www.yspartsandservice.com/pdf/FZ110.pdf


Straiight header yes you can do this. It is very loud this way and I mena very loud this way.

Part number is YSE0895

Troy Newman
Team YS

RE: differance 91AC and 110FZ
 

Troy/Frank,

If I may...... In Sacramento we're racing warbirds with these motors on 20-30% nitro and APC 13x13N props. The RPM's are a little higher than Troy's recommendation of 9.2K-9.5K, but for the most part I've found that the motors will turn this prop about 10K-10.3K on the 30% fuel and they seem to run very well...... this is using the header set up as well.

Hope this helps.

Jimmy Skids

RE: differance 91AC and 110FZ
 

No problem jumping in Jimmy,

I like to have lots of folks involved. We can all learn from what other guys are doing. It makes the forum better. It also gives YS users a place to share their experiences and such. We just don't to turn this place into a gripe forum. And your input is not doing that. I appreciate the help and advice in the forum as well as others.


Yes the 10-10.3K is on the high side for sure but it suits the application...I would suspect at those rpms there might be a few more failures or parts. That is working them pretty hard. But in a pylon racing application motor work is a common thing. I don't know have specific experience with the engines in that application but I have heard they are awesome in those racers.

I would not recommend this type of use for every day every flight for engine longevity but its all a matter of how you choose to run them.

I remember a few years ago the hot engine for War Bird racing down here in AZ was the 120SC on 30-40-50% nitro and it was making huge power in the Top Flight 60 size war birds like the P-51 and P-47.

Troy Newman
Team YS

RE: differance 91AC and 110FZ
 

Recently, the hot engine for Warbird racing in AZ has been a YS 1.20 bored out to take a 1.40 sleeve making it a 1.34. It also has some mods to improve breathing. Running on 80% nitro, it is an awesome engine.

Only problem is that after about 30 heats, a minor problem occurs:

RE: differance 91AC and 110FZ
 

That IS impressive!

We used to back off the nitro a bit when the piston began coming out of the exhaust;).

I see you went a step beyond:D.
----------but until then they sure do run sweet[8D].

RE: differance 91AC and 110FZ
 

NICE!

I know on the DZ series of engines the case has continually been beefed up to hand the extra power.

That is what you guys found I'm sure.

I bet if you ran them docile like on some 30% the engine would last a little longer...been thats not racing.

Thanks for the picture

Troy

RE: differance 91AC and 110FZ
 

Man...You were going so fast you blew the paint off the front of your aeroplane!! Kewl...:D

RE: differance 91AC and 110FZ
 

Wait a minute. 80% nitro + 20% oil = 0% methanol. What am I missing here?
42

RE: differance 91AC and 110FZ
 

>>Wait a minute. 80% nitro + 20% oil = 0% methanol. What am I missing here?

80% nitro + 18% oil + 2% methanol.
Engine will not start with this mix but will run once you have the fire lit.

Personally, I don’t go above 65% nitro because of the start/run and high speed needle setting problems but other guys do. Also, I probably get 40 heats before the jug blows off instead of 30. :D

RE: differance 91AC and 110FZ
 

I'm almost afraid to ask how many jugs you have lost, but my morbid curiosity needs to know.

RE: differance 91AC and 110FZ
 

The deal here is that they bored out the case to accpet the 140 piston and sleeve on the 120 engine....This combined with the extra power of the high nitro is what is causing the failures.

I have run 40-50% in 120SC and they will handle it really well. But changing the wall thickness on the case would make it weaker at the same time you are making mucho power with the higher nitro turning really high rpms...all it takes is an air bubble, or a little lean or run it out of fuel...the detonation can just eject parts and pieces. Especially if they are running 10, 000 rpm

Troy Newman
Team YS