first 0% nitro experience

[Siam Heli]

After all your advices, I decided to try 0% nitro on my raptor. This one
sports the new TT.39 engine with the new TT muffler.
I bought that alcohol stuff or whatever it really is (it doesn't smell like
alcohol at all!), got some castor and - faced the first problem: From my
gasser I'm used to a 1:50 mixture but from somewhere I remembered figures of
up to 20% oil in nitro engines(?). That's a hell of a lot oil! But since I
wasn't sure, I gave it a try with 20% castor.
Started the engine. It came to life but only with 1/2 throttle stick. When I
took the glow bat off, it died. Right, not enough compression then! I'd
heard 0% nitro needs higher compression. After carefully grinding the
cylinder somewhat down I tried again: Same result, it didn't run stable at
all. It took me some time until I realized that all I'd ever heard about
meaningful needle range doesn't apply to this kind of fuel. Eventually I
ended up with both needles a hell of a lot leaner than they ever were before
(almost one full rev on both). And then it worked.
After some tweaking and two tanks spent in hover and occasional 'pull-ups',
I actually let it fly. Boy, what a surprise: That thing has power like never
before! I know this sounds unbelievable but it's true! It pulls 10.5 deg
pitch easily, whereas with the former 12% CP there was some strain already
with 9.5deg.
Now the question is: How long will it do this? What Beav mentioned about
discoloring on the exhaust became a new meaning to me. The exhaust looks
like ten years old - after 4 tanks. The piston (only had a brief look
through the exhaust window) seems relatively normal, perhaps just a touch
darker but not black.
What would be the best oil ratio? Is 20% too much? How was it in the old
days?
Still grateful for input!

Martin

[Paris]

Hi there

> ....... After carefully grinding the cylinder somewhat down ...

I think you mean cylinder-head!!


> meaningful needle range doesn't apply to this kind of fuel. Eventually I
> ended up with both needles a hell of a lot leaner than they ever were
before

that is normal in "less" nitro fuel


> That thing has power like never
> before! I know this sounds unbelievable but it's true!

of cause it's true,it has to do with "grinding the cylinder-head" (more
compression).
anyway,how much did you "grind" the head??
i grind mine 0.25mm (tt70,46fx)
that gives 13:1 compression ratio (mesured).
and the results are better than with 10%nitro before the "fix".
i just did it to "simulate" nitro,not to get them run better than
before,that's just a bonus.


> discoloring on the exhaust became a new meaning to me.The exhaust looks
> like ten years old - after 4 tanks.

had the same problem untill i used only synthetic oil in the fuel.(applies
to the next question too)

>The piston (only had a brief look through the exhaust window) seems
relatively normal, perhaps >just a touch darker but not black.

to get carbon deposits,you need more than 4 tanks.

> What would be the best oil ratio? Is 20% too much? How was it in the old
days?

i can't recomment a best oil-ratio (starting a flame-war),
i'm using 85% methanol and 15% synthetic oil (motul micro).
in the old days their were using sometimes more than 25 % oil!!!
newer engines are made with better and different metal now,and less oil can
be used.

regards
Paris

[Beav]

"Siam Heli" <econ@loxinfo.co.th> wrote in message
news:b1l945$5jr$1@news.loxinfo.co.th...
> After all your advices, I decided to try 0% nitro on my raptor. This one
> sports the new TT.39 engine with the new TT muffler.
> I bought that alcohol stuff or whatever it really is (it doesn't smell
like
> alcohol at all!), got some castor and - faced the first problem: From my
> gasser I'm used to a 1:50 mixture but from somewhere I remembered figures
of
> up to 20% oil in nitro engines(?). That's a hell of a lot oil! But since I
> wasn't sure, I gave it a try with 20% castor.
> Started the engine. It came to life but only with 1/2 throttle stick. When
I
> took the glow bat off, it died. Right, not enough compression then! I'd
> heard 0% nitro needs higher compression. After carefully grinding the
> cylinder somewhat down I tried again: Same result, it didn't run stable at
> all. It took me some time until I realized that all I'd ever heard about
> meaningful needle range doesn't apply to this kind of fuel. Eventually I
> ended up with both needles a hell of a lot leaner than they ever were
before
> (almost one full rev on both). And then it worked.

I think I might have worked things the other way round first (leaning the
motor before attacking it with a grinder:-), but if it's worked, then fine.

> After some tweaking and two tanks spent in hover and occasional
'pull-ups',
> I actually let it fly. Boy, what a surprise: That thing has power like
never
> before! I know this sounds unbelievable but it's true! It pulls 10.5 deg
> pitch easily, whereas with the former 12% CP there was some strain already
> with 9.5deg.

More likely to be the increase in compression ratio than the lack of nitro,
but again, whatever it is, it's good.

> Now the question is: How long will it do this?

How long is a piece of string? If you don't kill the engine by overcooking
it in these early days, it should carry on producing power like it is for
the foreseeable future.

What Beav mentioned about
> discoloring on the exhaust became a new meaning to me. The exhaust looks
> like ten years old - after 4 tanks.

Castor sticks to exhausts like shit to a blanket, so it's not a bad idea to
wipe it after every flight and to fit some kind of deflector to the back
end. As a point of interest are you running a muffler or a tuned pipe? If
it's a muffler, a pipe will give even more power, less fuel consumption and
a less critical needle setting too.

The piston (only had a brief look
> through the exhaust window) seems relatively normal, perhaps just a touch
> darker but not black.

It'll take a while for the piston to take on the look of a lump of coal, but
it's only an hours work to take the motor apart and soak the piston and
liner in either boiling biological washing powder or anti-freeze (be careful
with the hot anti-freeze). This brings both components back to their
original glorious aluminium and steel look and gives the motor a new lease
of power.

> What would be the best oil ratio? Is 20% too much? How was it in the old
> days?

20% is fine, although you could drop it to 18% when the motor is fully run
in. It's always better to have too much than too little. (Same with oil
too:-)



--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk

[Siam Heli]

Thanks a lot again. This NG is starting to become my most valued source of
info..;)

Paris: I indeed worked on the cylinder rather than on the head, which seems
to be the only way of doing it on a .39TT without using a machine shop.
How much I took of is somewhat hard to tell. With the means on hand I'd
estimate approx. .2mm. And no, I didn't use a grinder for that...;)

Thanks to Beav for the hints on cleaning the castor residue. Would have been
my next question....
As pointed out, I'm currently using the new TT exhaust that came with the
engine. A tuned pipe will follow, however, that needs further research
first as I have little input about the exact type that would be best for the
TT.39 . Also, I'm afraid that once this is determined I'll need further
advise in how to get the reso length right.
I'm flying on an GV1 and understand that this issue is critical...

With every day, in every way: This hobby is getting better and better!

Martin

[Siam Heli]

Just a last one: Is there any known substance I can safely add to my fuel
in order to dye it? With that clear alcohol my fuel level is kind of hard to
see...

Martin

[Beav]

"Siam Heli" <econ@loxinfo.co.th> wrote in message
news:b1o2d5$fbm$1@news.loxinfo.co.th...
> Just a last one: Is there any known substance I can safely add to my fuel
> in order to dye it? With that clear alcohol my fuel level is kind of hard
to
> see...

I've seen people use and RECOMMEND a food dye, (it's cochinile(sp) btw) but
having seen what it does to the inside of an engine, it ain't goin anywhere
near any of mine. There ARE fuel dye's available though, from Model
Technics, so they should be "gettable" either off the net or from a hobby
shop.

Pink's the colour to go for coz it's a nice gay one:-)


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk

[Lindsay & Sue Henderson]

Try leather dye as it is alcohol bases and you need less than a 1 ml in
ten litres to show good colour.
I have been using it for 6 years and without residue anywhere or lack of
performance.

Siam Heli wrote:

>Just a last one: Is there any known substance I can safely add to my fuel
>in order to dye it? With that clear alcohol my fuel level is kind of hard to
>see...
>
>Martin
>
>
>
>
>
>