Os 91 sz-h engine good for 3D?

[Heliboy8613]

I just bought an os 91 sz engine from Jeff fassbinder a week ago. Im into 3D flight and realized this engine is made for f3c it is the non pumped version will it be ok for 3D or did I mess up? All I can think of is to get a regulator for it and run it off muffler pressure. Id rather not spend the money for a regulator. My understanding is that without the regulator the engine can go lean in high stress manuvers? What do you guys think I should do?

[Thestructured]

Sounds like you're new to nitro.

Muffler pressure = noregulator
Regulators are for crank pressure.

Regulated vs muffler pressure engines = the difference is the consistency of fuel delivery, but not power. Yes, for constant hard flying, regulated engines are going to be more consistent to some degree. Muffler pressurized engines are not bad at all though and nothing to worry about, especially if you're using a header tank. There is also less to go wrong with muffler pressure, where as regulators can get stuck, and check valves can go bad, more points of failure.

Judging by various videos on youtube, this is about what you can expect as far as 3d performance from the SZ. It's not going to be good for harder 3d but it's ok for mild 3d like in this video. I don't know what flying style you have, but if it's going to be harder 3d then I'd recommend an OS 105 HZ or HZ-R, or a YS 91 srx, YS 91 sr, YS 120srx, or YS 96srx. Any of those can handle hard lying no problem.

Raptor 90 SE (3 min 22 sec)

T-Rex 700N at MascotNQ (5 min 1 sec)

[Heliboy8613]

Thanks for your reply! Yes im fairly new to nitro. Ive only had a gaui nx4 so far and I loved it other than that ive flown a lot of different helis from the trex 500 up to the trex 700e dfc. I rushed into the 700dfc at that time so I got rid of it quick cause it scared the $hit out of me. I finally feel confident flying a 700 Looks like ill be ok for a little bit im really into hard 3D but im more of an advanced intermidiant flyer if that makes sense haha. Ill be upgrading to an os 105 before long.

[Luis Murillo]

If you can get your hand on a o.s 91 speed 3d you would love that motor. Easy to tune, and looooots of power. Match it with a hatori muffler made for that motor and you got a strong, powerfull and quiet engine. I had the os muffler made for that motor, same power as the hatori just a lot more noisy.

Im using that motor on the sab nitro 700 and it rocks.

[Heliboy8613]

So the sz has 3.3 hp and the hz has 3.4hp? As long as that sz has about the same power im ok with that!

[Luis Murillo]

o.s 91 HZ-R speed 3d is 3.6hp. Problem is they discontinue this engine and are hard to find.

[Thestructured]

Despite nitro motors having similar horsepower figures, there are torque differences that you won't see on paper. Going from an os 91hz (3.4hp) to the os 105 hz-r (3.75hp) was a pretty big difference despite only being .35hp more. The thing pulls like a freight train.