View Full Version : REX 91 3D 3N / H9 combo any one using?

04-04-2010, 12:09 AM
Hi Guyz,

I just bought this engine last week and did the breaking in yesterday.
Yesterday the whole afternoon I was trying to set this thing properly with no luck.

it's rather too reach or too hot, and never could be able to get the power i need out of it.
a very simple tic toc with maximum stick management would let the engine bog easily.

Im not satisfied at all, I even wrote to Helidirect if there is a way to return this engine.
I dont know how such engine which still needs too much testing in the factory is already selling in the stores.


04-04-2010, 12:36 PM
What needle settings/shims/% fuel/etc. are you running? Break-in proceedure used? A little detail goes a long way....


04-04-2010, 08:25 PM
I am interested also. I have the same engine in my 700 and I am either hanging or bogging with no power. I run wildcat 30% with 4mm shims. When I start my flight the motor seems rich and when I land the motor is hanging

04-05-2010, 03:58 AM
PM Luca(user name - ininverno). He'll help you out with your questions on this engine. You can also check the NR91 owners thread here: http://helifreak.com/showthread.php?t=176478

I've just installed mine and can't wait to start her up. Out of the box it is a work of art and I've heard nothing but great things about this motor. I've seen it at the field on another pilot's heli and it has awesome power, which is one reason I chose it. One thing Luca did mention was that the carb really needs to be pressed tight, compressing the O-ring onto the engine while you tighten the clamp.

Also, it doesn't hit it's max HP until 16,500 rpm, so about 2012rpm on the head with 8.2 gearing. The engine has been tested and has been proven to be a great engine. Do you have the V1, or the V2? The V1 has the round cooling head and the V2 has the sides squared off.

Let us know, we'll be happy to help you in any way we can.


04-05-2010, 02:28 PM
Its a work of art outside the box but not when in the heli .

Im using cool power 30%
First tried with 0.4 shims than 0.5 because of the high temps.

Im not trying to fine tune this thing.
its wayyyyyyyyyy far away from the nearest competitor to it.
it fells like I have 30 engine in the 700.

If other ppl are having luck with this engines looks like mine is defective.
I am using OS number 8 as recomended and already had 3 burnt plugs because of the hit issue.

Im not trying any more to work with it, i just did 6 flights break in and three flights testing and tuning ( if we can call it tuning )

04-06-2010, 06:21 AM
What are your current needle settings?

04-06-2010, 01:27 PM
I cant remember any more,

i think it was 2.5 on the high and 2.8 on the mid.
with very low power and high temps.
when I say high i could here the remaining fuel in the engine was making like boiling sounds.
and lost 2 OS 8 plugs due to overheating

04-06-2010, 04:38 PM
Hi can I understand the situation??
If you over eating the engine maybe you destroiy him???
wath is your situation??
I thinks your engine have some trouble.

Have you check the inside of the engine? everithing is OK??

Also please try to be more precise in your explain, if you desire support I will do, but be precise.

Chek and let me know.

04-16-2010, 02:28 PM

I shipped the engine back to Helidirect.
When I removed it from the heli, I checked inside the engine and looks like there is something wrong with the piston.
It's like melt or broken from one side.

As I told you since the first day when I did the break in there was something wrong with the engine.
It was rather too reach or too hot.

I did 7 flights break in with the high and mid needles set to 3 turns and half out.
after the break in I tried to tune the engine but the most time I closed the needles were 2.5 turns both but with very high temps.
When I go back to 3 turns out it was too reach.
Please keep in mind that I know very well how to tune an engine.
i tune mine and my friends engines all the time .

I saw Lukas flying the same engine in the latest video, I wished mine had the half power of that.
looks like my engine had a manufacturing issue.
so bad luck :arggg:


04-21-2010, 04:21 AM
Hi Guy's

Thought you all might like to see the N91 Engine in action.
Here are three video's I found on YouTube of 'Lukas Riva'
dialing in the N91.

The engine looks to be producing some good power.
Once the Engine is fully run in hopefully he will post some more.

Mine did take 18-20 Tanks to fully loosen up and become a wild beast. :D :D

Anyhow here are the Links