Engine Misfire on descents - Whats wrong?

Engine Misfire on descents - Whats wrong?

Post by Simon D » Mon, 02 Aug 1999 04:00:00



Heli people

Here's the scenario:

Shuttle Z-TS
Irvine 36 F1 engine (a few weeks old - had about a gallon through it).
Hatori 333 pipe
Main needle  1.5 to 1.75 turns open
Model Technics Contest 10 (10% nitro) (and also Contest 10  with 15% nitro)
Enya No. 3 plug

Runs fine in all circumstances (fff, power ascents, hover), BUT...

rapid descents with -5 to -7 degrees pitch and idle up ON (about 40-50%
throttle) the engine misfires (sound "crackly")

Seens to be cured by running very rich, but fuel consumption is unacceptably
high (also too much smoke!).

(my guess - should I have more throttle??)

I want to do loops but not if its going to misfire at the top!!!

Any ideas anyone?

Thanks
Simon D.
Colchester UK.

 
 
 

Engine Misfire on descents - Whats wrong?

Post by MArmitstea » Mon, 02 Aug 1999 04:00:00


Quote:

> Heli people

> Here's the scenario:
> Shuttle Z-TS
> Irvine 36 F1 engine (a few weeks old - had about a gallon through it).
> Hatori 333 pipe
> Main needle  1.5 to 1.75 turns open
> Model Technics Contest 10 (10% nitro) (and also Contest 10  with 15% nitro)
> Enya No. 3 plug
> Runs fine in all circumstances (fff, power ascents, hover), BUT...
> rapid descents with -5 to -7 degrees pitch and idle up ON (about 40-50%
> throttle) the engine misfires (sound "crackly")
> Seens to be cured by running very rich, but fuel consumption is unacceptably
> high (also too much smoke!).
> (my guess - should I have more throttle??)
> I want to do loops but not if its going to misfire at the top!!!
> Any ideas anyone?
> Thanks
> Simon D.
> Colchester UK.

Simon,
       I have tried 10% Nitro in an Irvine F1  (but with a fully tuned
pipe) and i could not tune it properly so that it wouldn't tend to
overheat ,whilst also maintaining an even balanced clean running mixture
across the whole throttle range ,from a full to 1/4 full tank.At first i
thought it might be the Enya no.3 (which i also was using first) that
was too hot a plug ,but i tried colder plugs too but it didn't cure the
problem completely either.You will find it is fine when flying around
using 3/4 to full throttle with a rich main needle setting but tends to
overheat in the mid range after prolonged hovering and will "buzz"  or
misfire when making descents or buzz high idle when hitting the throttle
hold unless both the top end (main needle) and the idle
(transition/tickover) needles are set quite rich.

Try a different heat rating of plug or drop the nitro content by using
Sport5 instead of Contest10.During the colder months you may be able to
move back to the Contest10 but during the last couple of weeks
you'll probably find it runs like shit on 10% unless setup very rich.The
F1 is a high compression engine and runs really too hot on nitro levels
above 5%.You could increase your throttle  % 'tage to get more fuel
through at the troublesome throttle range but it will just increase your
overall fuel consumption.

Martin

 
 
 

Engine Misfire on descents - Whats wrong?

Post by Donovan R. Do » Mon, 02 Aug 1999 04:00:00


Evening Martin

        Further to what you told Simon, does the Irving 36 F1 prefer just
straight FAI fuel?

Thanks
Don Dow
-----------------------------

Quote:

> > Heli people

> > Here's the scenario:

> > Shuttle Z-TS
> > Irvine 36 F1 engine (a few weeks old - had about a gallon through it).
> > Hatori 333 pipe
> > Main needle  1.5 to 1.75 turns open
> > Model Technics Contest 10 (10% nitro) (and also Contest 10  with 15% nitro)
> > Enya No. 3 plug
> > Runs fine in all circumstances (fff, power ascents, hover), BUT...
> > rapid descents with -5 to -7 degrees pitch and idle up ON (about 40-50%
> > throttle) the engine misfires (sound "crackly")
> > Seens to be cured by running very rich, but fuel consumption is unacceptably
> > high (also too much smoke!).
> > (my guess - should I have more throttle??)
> > I want to do loops but not if its going to misfire at the top!!!
> > Any ideas anyone?

> > Thanks
> > Simon D.
> > Colchester UK.


> Simon,
>        I have tried 10% Nitro in an Irvine F1  (but with a fully tuned
> pipe) and i could not tune it properly so that it wouldn't tend to
> overheat ,whilst also maintaining an even balanced clean running mixture
> across the whole throttle range ,from a full to 1/4 full tank.At first i
> thought it might be the Enya no.3 (which i also was using first) that
> was too hot a plug ,but i tried colder plugs too but it didn't cure the
> problem completely either.You will find it is fine when flying around
> using 3/4 to full throttle with a rich main needle setting but tends to
> overheat in the mid range after prolonged hovering and will "buzz"  or
> misfire when making descents or buzz high idle when hitting the throttle
> hold unless both the top end (main needle) and the idle
> (transition/tickover) needles are set quite rich.

> Try a different heat rating of plug or drop the nitro content by using
> Sport5 instead of Contest10.During the colder months you may be able to
> move back to the Contest10 but during the last couple of weeks
> you'll probably find it runs like shit on 10% unless setup very rich.The
> F1 is a high compression engine and runs really too hot on nitro levels
> above 5%.You could increase your throttle  % 'tage to get more fuel
> through at the troublesome throttle range but it will just increase your
> overall fuel consumption.

> Martin

 
 
 

Engine Misfire on descents - Whats wrong?

Post by MArmitstea » Tue, 03 Aug 1999 04:00:00


Quote:

> Evening Martin

>         Further to what you told Simon, does the Irving 36 F1 prefer just
> straight FAI fuel?

Don,
    What is FAI fuel?

    I use 5% Formulae Irvine,which is 5% Nitro ,Klotz oil and a small
percent of castor,oil content is about 18%.

Martin

 
 
 

Engine Misfire on descents - Whats wrong?

Post by Donovan R. Do » Tue, 03 Aug 1999 04:00:00


Morning Martin

        No nitro, 20 oil and 80 ***. At one time to compete in FAI events
that was the required fuel to use.

cheers
Don Dow
---------------------------------------------------------------

Quote:


> > Evening Martin

> >         Further to what you told Simon, does the Irving 36 F1 prefer just
> > straight FAI fuel?

> Don,
>     What is FAI fuel?

>     I use 5% Formulae Irvine,which is 5% Nitro ,Klotz oil and a small
> percent of castor,oil content is about 18%.

> Martin

 
 
 

Engine Misfire on descents - Whats wrong?

Post by MArmitstea » Tue, 03 Aug 1999 04:00:00


Quote:

> Morning Martin

>         No nitro, 20 oil and 80 ***. At one time to compete in FAI events
> that was the required fuel to use.

Don,
     Thanks,i've only heard it referred to as castor or synthetic
straight .

So back to the original question,basically yes but i use 5%.I know some
have gone as high as 10% and above but it's a high compression engine
and doesn't really like it.

Martin

Martin

 
 
 

Engine Misfire on descents - Whats wrong?

Post by Simon D » Tue, 03 Aug 1999 04:00:00


Thanks Martin (and others)

I'm going to go back to 10% (I've got about about 4 galls to burn) and play
with mixture and throttle curves.  Then I'll try some 5%. I'm also going to
speak to Irvine support and see what they say about fuel for this engine.

Simon D.


Quote:

> > Morning Martin

> >         No nitro, 20 oil and 80 ***. At one time to compete in FAI
events
> > that was the required fuel to use.

> Don,
>      Thanks,i've only heard it referred to as castor or synthetic
> straight .

> So back to the original question,basically yes but i use 5%.I know some
> have gone as high as 10% and above but it's a high compression engine
> and doesn't really like it.

> Martin

> Martin