Is dynafocal better .

Please offer your opinion or facts regarding is dynafocal better than conical mount. If so, why ? What is the difference/ merit of dynafocal 1vs. 2 . I am considering a new balanced engine and need to pick the best mount for my -3.

nothing wrong with the conical but the dynafocal is better. the way the loads and stresses are transmitted to the airframe are a lot better and give a smoother operation. the dyanfocal 2 was designed for the IO-320-B1A on the PA-30. that engine used a long hub prop so to compensate they changed the angle of the mount on that engine and it became the dynafocal 2 mount.

bob burns

Dynafocal IS better. The extended centerline of the mounting bolts converge at the center of gravity of the engine thereby minimizing vibration being transmitted to the airframe.

The Dynafocal 2, as already stated, was designed with a different angle because with a long prop extension, the CG of the engine moves forward.

Dynafocal 1 is far more common at least on RV's as far as I know. Your engine version determines which mount you will need.

Bevan

If you are buying a new engine you will be having Dynafocal I. I'd be surprised if you can get either type in a new engine. I believe Vans has stopped making the other engine mounts on some models, but I think they can direct you to someone that makes them.

If you are rebuilding the engine you can have Divco convert the case to Dynafocal I.

I've had both a conical and a dynofocal 1 engine on plane and the D1 is smoother, as mentioned above, due to the focal point of the mounting bolts and the mounts. The conical mount surprised me by sagging a good bit more than expected in 250 hours. For some reason, the D1 engine hasn't sagged nearly as much.

If you get a good deal on a conical engine, it can be converted to a D1 but it has to be disassemble first. The good news is, the procedure is only a couple hundred bucks.

Lord mount optimize conical?

Kelly et al,
Thanks for the input and Kelly's encouragement. I have a help request into Lord regarding best choice for conical mount and no response in one week

Van's sells them at a decent price, cheaper than a lot of the competition anyway, still expensive. The bolts, too.

Dave

Not sure if you have already made decision but...

in my case I got a screaming deal on a used R22 O-320-B2C complete with accessories.

After much discussion the swap to a Dynafocal mount was going to be expensive, so i decided to have the engine prepared for Conical mount installation and converted the carb to center mount, installed a mechanical pump, put on a few more goodies and now have an "experimental" engine that with good maintenance(on condition) will run a Long time all for around 9K Canadian.

So with that in mind and compared to the cost of a new engine at 27K +(USD) it appeared that the conical engine mount would run smoothly... at least in my mind. LOL

My research and investigation suggest that the difference in smooth ride did not equate to 18K dollars and so went ahead with the B2C and conical.

I strongly suggest the Lord Mounts from Vans, they are expensive but I had purchased the cheapies from Aircraft Spruce to hang on my engine stand while building the plane and when the Lord mounts arrived at 900 dollars Canadian I could see the difference clearly and i am glad i ordered the Lords now.

The fun of building a plane eh? Good luck on your decision.

FWIW My conical mount

allowed my 0-320b3b to sag 1/8" on first engine start and in the ensuing 300+ hrs hasn't moved a bit. As for smoothness I haven't noticed any excessive vibration.