40cc crankcase smoke system
 

Hi Guys
I'm sure this question has been posted somewhere on RCU before but there are so many threats it's getting difficult to find the answer. A couple of guys at my local club have installed a smoke system utilising pressure from the crankcase. They have a D.A 50 and a D.L 50 (rear mount carby) and they basically tapped a nipple into the reed block to provide the pressure. A tube then runs from the nipple on the reed block, through a one way pressure regulating valve and into a dedicated smoke tank. They have fitted a servo operated switch between the tank and exhaust to turn the smoke on and off remotely. The system is very effective and provides a good thick smoke for around 40 seconds. They are using a 50 / 50 mix of diesel and brake fluid. My question is, on a side mount carby, such as a BCME 40, where do I tap a nipple to get the same result?. Do I tap it into the actual crankcase, and where abouts should it be tapped.
The system they used seems cheap, reliable and VERY effective - and adds very little weight. No additional batteries or pumps. If anybody has done this can you please let me know and maybe post a pic.
Thanks

RE: 40cc crankcase smoke system
 

You'd have to tap into the crankcase in a location where the nipple you thread in will not interfere with moving internal components, and where you will not weeken the crankcase. If there's a conventional backplate, I'd drill in the centre of it, and be sure to file the nipple flush inside. I'd avoid anything in the bearing area, or in the arc of the conrod.

Looks like the SPE40 is an engine with a crank bearing in front of and behing the cylinder, with a pto shaft stub out the back. That makes things more difficult. Don't weaken the mounting lugs or bearing housings.

The crankcase is an open volume, so the whole crankcase sees similar pressures at any given moment. It won't matter from that perspective where you drill.

Think about this though. For the cost of a smoke pump, you're voiding the warranty of and risking the integrity of your engine. You're running a gasser, and you're gonna be carrying a second tank for smoke. Is the 60 buck, 2 oz smoke pump really that big a problem that you're gonna risk your $300+ engine? I'm sure it could work OK, but what are you gaining, really?

I don't quite get it, I guess.

J

RE: 40cc crankcase smoke system
 

WOW !!!!

diesel and brake fluid

My gas planes smell like lawn mowers as it is !!!!
Ad some diesel and brake fluid....:)

RE: 40cc crankcase smoke system
 

Mate - you would be surprised at how good it works. It creates the thickest, whitest smoke ever. Only problem, it does leave a greasy residue and kills the grass. I don't know what long term effects it will have on their planes - one of them is composite.

Jburry - thanks for the info on the crankcase. Yes, it does have a crankcase bearing and shaft on the front and back so I will look at tapping somewhere where it wont compromise the case. I'm not sure what you don't quite get, but as i see it the cost is absolutly minimal, no additional battery or pump weight, good thick smoke (cheap too) and reliability over the more traditional pump type systems. I don't have warranty issues with the engine - there was never any (ebay). I guess the worst that can happen is it wont work.

RE: 40cc crankcase smoke system
 

Good luck! Let us know how it works!