Hello

New on this forum and a restarter at modelflying
after a period (15 yrs) of non activity (kids etc )
Flew last with a laser200 with a OSFT160 boxer.
(still have it) Want to start slow again and now building
a Piper Cub (70''span or 1850mm) and also have a Pt-19
ARF(span 58"or 1450mm) waiting next . Want to fly both
with a 4stroke and as I want to keep spending money to
a minimum but do want a good quality engine I'd like to
get 1 engine which can power both. The piper manual
tells me it can be flown with a .40 2 stroke . Does not
give me an equivalent for a 4stroke. The PT19 also to
be powered with .40 to .46 2 stroke and up to .52 4str.
I would like the Piper to be able to do some aerobatics
like loops and rolls but should also be able to fly slow.
I was thinking of something in the order of a .60 4stroke.
Is this oké or is it too powerfull or heavy for the PT19 ?
Someone said to go safe on power and go for a .70[X(]
This could maybe be oké for the Piper but the PT19 may
get to nose heavy (I'am not worried about power as that
can be controlled) So in short what would be the minimum
displacement for a 4stroke for the Piper and the max for
the PT-19. Both about 2,5kg (5,5lbs) take off weight.
Any advice on engine size and brand will be appreciated.

Thks
Yetvart

for a 5.5lb model a 72 4 stroke will be fine. If they plane can handle a 46 2 stroke a 70sized 4 stroke will be fine.

Recently I did quite a bit of investigating 4 stroke engines. The result of all my investigation was in favor of Saito. This was for several reasons. First of all, they make only 4 stroke engines. It is there sole business. Second, I like to design as well as fly. There have been times where I wish I had used a bigger engine. Saito solved that issue by making many sizes in the same case and mounting holes. The 65, 80 and 91 are the same case. The 72 and 82 are in another case. Last but not least, the 120, 150 and 180 are in yet another case. So if you are having questions as to which engine for what plane, you might find a group you can live with. Also if you are looking for some real good information on Saito, go to this site:
http://saito-engines.info/

For a few extra dollars the saito 82 will do the job, Theres no replacement for diplacement!!!!!

O.S. 70 Surpass or Saito .72. You will be happy with either one. There is enough wing on the Cub and PT-19 so that the extra weight of a four stroke won't be a problem.