R/C Tech Forums - Four stroke in a 1/10 scale

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Four stroke in a 1/10 scale

Hello all,
I have recently undertaken the project of attempting to put a four stroke engine into a nitro chassis. I have chosen the magnum xl .52, an aircraft engine, and for now I am putting it in a simple chassis that I belive is a knockoff from a very old company. I have had no problems with fitment or drivetrain so far, but I cannot find a good starting solution. I bought this engine used, but it seems to have only been through break in so it has great compression, making it hard to turn over. I have tried using a bump box, a belt, and even attaching an old electric spur gear to the flywheel and turning it with a brushed motor to start this thing, but none are getting enough grip to turn this thing over with any consistency, and I have not been able to get it started. I have spent hours trying to figure this out but I have gotten nowhere. I am open to any suggestions but I don’t want to spend stupid amounts of money to get this thing going. Thank you!
P.S. yes I know that four strokes don’t have enough rpm to make these cars fast and that they overheat and all the issues that come with this build but please humor me all I’m asking for now is help with starting.

A bump box is probably gonna be your only option. What may help is turning the flywheel clockwise bumping against compression. Then put it on a fully spooled up bump box. A high torque motor is gonna be required here. FWIW - the Ofna 10250 starter box uses the same motor that the Hobbico .90 airplane starter uses. The torque is very good if you use enough battery voltage. If you’re using a 12v lead acid battery or 3-cell lithium battery, you may not have enough power to start the engine. Bringing the voltage up to 14-16v will give better results.

I use my Hobbico .90 starter to start a 1.20 4-stroke engine, so a similar sized starter motor will do the trick with enough voltage.

for my 4 stroke aircraft engine.. my bump box was 16 volts. (14) 1.2 volt cells.

and yes.. reverse rotate engine .. to get a running start on the compression

There’s a guy on here with a thread that’s still going about his progress building 8th scale with a 4 stroke engine, it’s from mxwrench.. seems like he’s taken this venture on for a long long time (2004) and still is trying to figure it out. You may get some good ideas or you may take the route most have and settle on the idea we are long ways out till this hobby goes 4 stroke! I for 1 watch and read that thread because it’s interesting but in no way do I see it possible to make a modern day airplane engine useful in nitro cars, something needs to be developed specifically for our cars to run close to a 2 stroke. Here’s the thread.

https://www.rctech.net/forum/offroad...pment-126.html