I am currently building a top-Flite P-51D that I bought off this forum (60 size not the giant).

I am wondering which 120 size 4 stroke engine to use. I only have experience with 2 strokes, the biggest of which is a OS .46 FX-H heli motor.

I am leaning toward a OS 120 Surpass, but don't know if I should get the pumper or not. I have never used one of these and don't know if they are REALLY necessary, or just complicate things..

Also, the supercharged YS 120 caught my eye, but I have never owned a YS before.

So... what do you guys recommend, since I value your input .

Thanks.

I have built two TF P-51 and the P-47 all with OS 120. Each has been mounted inverted with on board glow. The onboard glow is just a personal preference, ease to start, better idle etc. The P-47 has the 120111 pumped version the P-51's are the nonpumped. IMO the pump is of no real value and it can give you fits, costs more,adds weight, no increase in power that I can tell. The OS 120 nonpumped are great and I would highly recommend them for the P-51. I turn a 16-8 and the plane just hauls AS_ !!! Its a perfect fit.

Thanks for the reply.... any more comments?

I originally had the OS 1.20 pumped on my P51. Had too many problems so I removed the pump. It was the older version. Mine is side mounted and has ran without a burp for many years now.

My preference is the 1.20 over a .91. It seems to have that extra power that I need. I love doing slow flybys and then punching the throttle and making it into a victory roll, climb, and split S and the 1.20 has no problem pulling the plane for this maneuver.

It also sounds really cool as it flies by.

Scottrc...Thanks for the reply.