engine query
 

my wife and son bought me a yellow aircraft a-4 for xmas, problem is the ramtec fan is set up for os-91. i was thinking of a k&b 1.0 but was told it will cavitate once airbornnothing against os, just too pricey!any advice would be appreciated.---henry

os91
 

The only enginge you should be thinking about putting in the Yellow A-4 is the OS 91..

Rossi, maybe , but for all round no hassle , no tinkering performance get the Os91....you WILL be money ahead----period.

My opinion from experience.......

Rod Springer

Engine for A-4
 

I would only consider a OS 77 or 91 for your A-4 project.The 91 is a stong running and dependable engine.Finding a tuned pipe that will work with the K&B 100 , is a problem.

Good Luck
Charlie Hissom

engine query
 

If it takes you a little longer to buy get the OS91, its one sweet running powerhouse, I love mine compared to an os77

engine query
 

Stay away from the K&B 1.0! You will have nothing but problems ( Broken Rods) A friend here had one in his Yellow F16 and broke several rods in it ( Including a RPM Rod!) It was never reliable!

Get the OS91 for it. Much better engine and you can get parts....

Engine Query
 

Follow these guys advice and get the O.S. .91. I would not recommend the O.S. .77 since it has been discontinued for several years. You might find a .77 on a swapshop or auction but good luck on finding parts.

Ducted Fan Engine
 

Nun45,
you can use the OS.91 and it is a very good engine-but if you want max.power and performance-get a Rossi .90 or 1.05-heres what you can do-use 3 head shims-if you don't like the Rossi carb,(although it is a good carb)-a OS.91 carb can be used-Break the engine in just like the directions say-use 5% nitro fuel with 8 ozs. of extra castor oil added to it- a OS.91 will turn a Byron fan rotor at around 19,500-20,000 rpm. The Rossi .90 will spin it at 22,000-a lot more power.



Jackjet

Re: engine query
 

Henry,

Nice plane...you have a good family to buy you such a great toy! :) I'm a little jealous ;)

O. S. .91
 

Have you checked with National Hobbies in GA? A few months ago I picked up an O. S. .91 there for around $255, which puts it in roughly the same price ballpark as the K&B. I agree with the rest of the guys... You can't beat the small-head O. S. .91 for ducted fan reliability. It's worth the wait. Good luck! (BTW, it sounds like you have a GREAT family.)

b/r,
Earl