Diagnosis Nitro Fuel burn residue

[scott]

Hi Forum readers,

I have a relatively new 1/8 scale Nitro Buggy not my first and not the last, i have been running differant fuels all at the 15 and 16 % nitro with either 18 or 20 % oil blends in the 8 port 21 size engine (Force). I have run the engine in on this fuel and have put some 4 litres or approx 1 gallon of fuel through the motor now.

The engine is starting to produce good power now and i have noticed that when i pulled the glow plug out to check the piston surface and the glow surface that instead of the shiney clean looking finish which i expect is normal , i found a brownish burnished look which is what i am asking the forum for advice.

Has the fuel that i have used maybe got a low grade residue forming caster and synthetic mix or is it possible that it has run a little lean in the tune mix.

I have always got a white smoke trail. I did run approx 4 or 5 tanks continously yesterday and was driving it hard. Maybe this is a lean out at the high end :shrug:


I would like to know what your learned thoughts are on this.


Cheers.

 

[Tarant]

it is better to stay with one type of fuel and stay with one type of nitro% and oil%,

What temps are you running?

 

[scott]

Didnt take my temp probe with me yesterday, what temperatures would you recommend upper of 120 degrees centigrade ?.

I used the temperatures for the run in, but was caught up with the fun this weekend and didnt check just the touch test it was a little hot at one stage. Maybe answered my own question.

 

[Tarant]

between 135C and 100C is were you want to be.

 

[vbgagnon]

coloring on top of the piston is normal. All mine have tha brownish/blackish "glow" to them.

 

[emu67]

Ah...I'm glad that someone has said that the brownish/blackish glow is normal. I have that in my sh .21 motor, too. It's been run on 20% monstor fuel for about 3 gallons and runs fine.

 

[OFNA buggy basher]

Me to. Happy to hear it. My hyper 8 port its starting to get the brownish tint. But i wasn't worried because i get a nice thick blue cloud of smoke all the way through the powerband. I learn so much every day on this forum. I dont know what i would do without you guys.

 

[RcTire]

when i started racing i used blue thunder and it turned the piston all kinds of brown colors...I started using Rocket Science in my new motor and about a gallon through it and it still looks new

 

[scott]

Thankyou for the fully encouraging response,
I had the day off as my rostered day off had some spare time left this afternoon and took the buggy to the park, it started first pull and performed better than yesterday.

When i got home i ran the fuel out of the system and cleaned around the glow plug by holding the buggy upside down and spraying some metholated spirit into the heat sink to clean any crap. took the glow plug out it was blackened around the base, i got a cotton bud and wiped the centre of the piston which appeared to show the shine of the metal. unreal. I didnt take the temp probe so i have set the hi speed needle at 1/8 th leaner than the factory setting. the engine transitioned better than when i thought it was going well yesterday