YS91 OR OS91

[furywife04]

Hi guys i just got a new raptor 90 and i would like some feedback on what engines you guys are running. Can't decide what i want to use. Thanks

[GM1]

I have both and prefer the YS as it is pretty much set and forget. The OS runs fine and makes good power but is a little fussier to needle.
Gordie

[claysmith]

YS runs better, OS looks better. Which is more important to you?

[WillJames]

OS does look better. :) Don't forget your viper head!!

[SKYBLUE]

Are you guys talkin about the new PS version for the OS91?

[Spitfire_mk5]

Say YES to YS :D

[capebob]

I really like my YSs. I am fortunate to have three of them and they all run well without any modifications (Viper Head). Now if I could figure out a way to get more than nine minutes out of a tank I'd really be happy. :lol:

[wes22]

Well I'll take the os side, I have an os with a kline, no ps. The kline makes more tank pressure than the PS does. Viper head and a carb mod done by omi and it runs awesome. Put it next to a ys and it has more power. YS is alot easier to set the needels on though...but OS does ahve more power though.

[Buzzin Brian]

YS here for me as well. Plenty of power, and they run oh so sweet. Not much fiddeling needed to get them to perform very well. That is what I am running in my Raptor 90, and I love it. Oh, and it is running a MP2 for exhaust. All in all I have 4 YS big blocks, and I have been happy with every one.

[Todd Marsh]

I see why the YS engine manufacture has such a strong following. It is a slightly cheaper product price wise (not by much), easy to keep tuned, and just works well by just installing, & 'setting & forgetting'. I bought the OS.91SXH C-Spec/PS engine with OMI viper head, simply because I have had great luck with OS engines/products in the past. Also something I cannot verify myself, having never owned a YS, but it does seem the longevity of the OS ringed engines is quite lengthy to say the least, & I had heard opinions the YS piston/liner/con-rod had inferior usable life when compared to OS, allthough the YS'S ran GREAT until that time. I know the earlier versions of OS91 had crank balance, & also some fuel delivery problems, which probably slowed sales dramatically when the first OS/YS 91's hit the market initially.

I would be interested to see some hard data that the Klein 'regulator' actually produces more fuel pressure than the new OS C-Spec/PS which has a exclusive fuel PUMP. I am guessing the OS/PS has a fuel return line at the carburetor, due to the fact fuel pressure is in fact too high at times, due to the addition of the new pump, and thus needs a release/fuel-return valve for the positive fuel pressure thats being delivered at a rate it cannot consume. Apparently the YS regulator works great & perhaps the Klein does the same for the OS, but I am predicting higher fuel pressure is being generated by the OS pump VS either the Klein or YS regulators.

[corey11]

id go with the YS 91...i REALLY love mine..and it has TONS of power...O yea, i can get 12 minutes, and 36 seconds....yes that is right... of constant 3-d..and no, im not running the engine really lean or anything. I have no mods done to it either...i simply have ViperHead on it...And i know the viper head doesnt had much time to flying...What my set up is a 8.45 gear ratio, and a 1550 head speed.

[Buzzin Brian]

Corey, your headspeed in one of the things contributing to longer flight times. Most tend to run 1750-1800 on the head for aerobatics. Which does tend to use more fuel. That being said, I find the flight times to be acceptable with my YS 91's. :D

[corey11]

well, he never said he wanted to use a 1750 head speed...so i said what i can get with a head speed...i can get prety close to 10 minutes on a 1750 head speed

[Clintstone]

I like the OS PS with the Viper Head @ 24 thou (shims )and the stock PS @ 12 thou that is plus 4 thou over the stock config. Runs smooth and powerfull with a wide tuning band.

[Fredrik aka. mrNoodles]

YS :hug:

[angelob]

I'll vote for YS also. Why spend extra $$ to add a regulator to a C-spec? In my opinion the C-spec PS with the perry pump looks like a band-aid fix vs the YS with the tried and true fuel pressurization system that has been in use in YS engines for years.

The YS isn't as pretty as the C-spec though... :D

Angelo

[WillJames]

Clint had by far the finest running motors of the weekend. Thanks for tuning motors for the stupid Clint. ;) Mine is running a WHOLE lot better!!

Clints PS on his #1 bird will pull and hold 1870 RPM Headspeed on full power and collective climbouts time after time on a hot day. :) It is all in the tuning, I used to think my PS's sucked.

[furywife04]

Well guys thanks for all the replys. I just ordered my new ys91 :D

[Buzzin Brian]

Great choice! I knew YS would win. It always does! :nanabobo