R/C Tech Forums - View Single Post - Team Magic G4RS 2009
View Single Post
Old 08-09-2009, 04:46 PM
  #621  
blis
Tech Elite
 
blis's Avatar
 
Join Date: May 2008
Location: Brisbane
Posts: 3,478
Default A pinch about my engine experiences.

Yes, I admit in my early days I was heavily experimenting these techniques with low end engines. Firstly I believe the metalurgy of alloys is the key to good engines fundamentals. We use a composite of metals and they need to expand and contract with heat together.

Im 44, I owned my first nitro engien ona cox model aeroplane when I was a young boy. That was my first bad Nitro experience and I avoided them like the pague for many years.

Getting back into RC I was very paranoid over lifecycles of engines and my first engines were low end Hyper and LRP's. Expecting to blow them up while I was learning, I realised there's more to it than meets the eye.

I pinched my SH TM 1.5 sleeve using a GAS flaring tool. and I left it crimped for too long ( note for GTRMX - Try and make a guage for turns and TIME the crimp). As the alloys are maleable on the sleeve, the pinch may take a few minutes defrom. Might want to formulate a chart etc.

I could barely get the piston up past the intakes so I called an "ALL IN" grabbed the dremel and used a barrel disk and began to hone out my sleeve by hand. Believe it or not, I ground out and then polished it (not much) put engine back together and put on starter box and it fired first time and idled like a purring pussy cat.

Excited by my achievement I went out to track and realised how lovely it idled and how quickly it deteriorated under speed. A whole 3 minutes of fantastic run time, never before achieved with this engine. but for 3 minutes.

I assume the gap between the liner and block created by the pinch allows for room to expand. Combustion then escapes down the sides of the piston and the engines gets even hotter and it snowballs and stalls. Maybe at this point it's time to UP the oil content. Old schoolers told me to run rich and let carbon deposits build up to create a better seal. I only clean with solvent (not polish) the bottom outer of the liner and ports, the top of piston, button and the block. The rest of combustion chamber components I leave coated in carbon residue.

Having said all this, I dont think the alloys in those engines were anything close to those used in Italians engines. Ive very much considered revisiting this but would also want to try a simple electroplating technique to apply more metal to the outside of the sleeve to keep the titght fit.


Atm, I use an OS TG less than 1hp "Gas Touring club class here" and Two GRP Tuned one old and low on compression and one relatively new race engine. There was an article I read from one of the buggy runners and engine maintenance procedures. Warming engine up before starts, afterrun after use, cleaning techniques, bearing maintenance, run in methods, etc etc etc All the things to do at the end of a busy race meeting.

My club GRP had a bad plug that frosted after it created a stalactite/stalagmite of platinum from the dropped plug coil and a very pitted and frosted chamber. Cleaned it up, little compression left yet still runs merrily.. so LUCK does play a part.
blis is offline