I've got two, unrun 20FPs on hand, one off E-Bay and the other from an estate. As you can see, they are different versions. I left the carb on one and placed a venturi on the other. My brother might want one for RC and I'll keep the other for stunt. Have I got the fuel feeder configurations correct or should I switch them around?

Dave Mo...

I've got two, unrun 20FPs on hand, one off E-Bay and the other from an estate. As you can see, they are different versions. I left the carb on one and placed a venturi on the other. My brother might want one for RC and I'll keep the other for stunt. Have I got the fuel feeder configurations correct or should I switch them around?

Dave Mo...

    I hate to even ask, but is the iron-liner engine drilled out/damaged for a larger spraybar, or is that the special Enya OS-copy?  I assume you have the mufflers.

     If all else was equal, I would use the ABC engine with the E-2030 muffler, and get a STOCK venturi and STOCK spraybar assembly, or the Enya OS copy.

      Brett

The "ABC" version is really ABN, correct? Either way, I'd let the iron version go fly R/C, and keep the AB* version for CL. I think the one with the ridge down bypass area of the casting (left side in pic) is the earlier version and probably the iron version? This is based on the early/late castings for the .35/.40FP. It would be interesting to find out why they bothered to make the change in the castings. I can't imagine that they needed to strengthen the case on a sport engine. Styling points for increasing sales?  Steve

The OS manual for the newer version says ABC 'like' construction. But I believe ABN is more correct.

    It's nickel, but it is of no real consequence for use in stunt. Arguably it is better for our purposes, break-in is easier and it at least as stable over time. And in any case, it's not a matter of comparing a "nickel" 20FP vs a "chrome" 20FP since there isn't such a thing, it is comparing a 20FP (of any construction) vs, say a Fox35 (of any construction).

     It is not a durability issue, both Paul Walker and I each ran our respective 40VF engines for *many, many* flights - more than most people have in their entire lives  - before it finally wore out to the point we needed to change it. My guess is at least 1000 and maybe more like 2000 on mine, presumably more on Paul's. At the 97 NATS, I was needling mine during qualifying, and went to tweak it a little faster - and it sagged off lean. That was all it had. But the flight scored 595 point and was 1st on the circle with some margin.

      So it's a moot point if something else might be "better", it's more than good enough the way it is.

In any event the newer ABN version is really similar to the LA series engines. I have run both the 25 FP (ABN) and LA on CL models, and I don't see any real difference in performance, on the test stand or in the air. I'm spinning the 25 FP (ABN) version at around 12K with APC 9-4 sport prop. Same as I run the 25 LA.

The 'bump' on the case sides is definitely the older version (iron / steel P/L). The older version is similar to the older OS Max engines. Need to run higher oil content.

     But otherwise, the iron-liner version runs pretty close to the ABC version, once you put the later muffler on it.

    I am a little surprised that you did not see any difference between the 25FP and the "new" 25LA, but it may not be obvious without flying it and/or running it with smaller props that you would normally want to use for stunt. The "old" 25LA was a decent-running engine but has marginally less power than the 20FP in a stunt application.

      Brett

I've seen ABN engines strip their liner. Not one I've broken in from new, One or two I picked up at a flea. Could be they were abused. LAs seem down on power a bit, compared to FPs. How much? Some. This is not a scientific comparison. LAs seem to wear out faster as well. The front bushing, for one thing, doesn't run all the way through the case of an LA. FPs do. The cranks on FPs are forged, the cranks on LAs are cast. Does it make a difference? Combat flyers, flying slow combat with LAs and FPs, usually prefer FPs. Could be there are less of them around. What you don't have and can't get, syndrome. Also, slow combat engines are set to howl. Fun. Stunt not run as hard. I've been running an old style FP20, cast iron piston, in a sport plane. Flite Streak. Holding up well. Do what I can to avoid an inadvertent over lean run. Not a good ideas for a cast piston, iron cylinder, engine. LAs were engineered as a lower priced version of an FP. Looks like. Plastic cover plate, cast crank, four headbolts. Is there a difference in durability and power. Depends.