I believe ever started with EB mods and now AMR but more manufacturers have these from own production like REDS and MAX, I do not know how far back but I have heard stories of people with Serpent Impacts running these backplates back in the 90's.

I have made some before for OS, Novarossi and a Picco boost and now I was asked to make 2 for a new Picco Monza. The dimensions given were exactly the same as de one of my Sonic/Picco PSS so I had the right example at home.
The plate is exactly the same as I have made before but with one difference, no flat spot for the piston but a groove. It was on my list for a next one so I made a little helping tool for that.

Instead of pictures and tekst, now a short movie:

Impressive work!
Will it work better with conical hole in center?

All shapes can be made, this was simply done with a mill bit with a rond tip.There is enough pressure build up to put a lot in the channels., now it is 8mm in diameter and 4mm deep, I can use a 10mm one and still go 4mm deep, that will giv a wider opening. But I must also prevent not to take a lot of material from the backplate to hold a high pressure. I have plans to make a lexan version, just to ee if the fow is shown.

Great work!

Thanks for that!

I always wanted to try to print backplates from PA with some glas fibers in it. It should be heat resistant enough.
EUmakers nylon with glas fibers
With 3D printing, it's much easier to insert some fancy channels...
What are your opinions?

Andi

The temperature on the lower part of the engine does not become very hot, so for that platics will work.
But there are many plastics that are not oil or chemicals (nitro) resistant and of course the rod will rub it so ik must also withstand that.

I have plans to make a lexan version. With 20mm thick lexan I can make it fit w/o touching (and so no needed polishing) the looking through sides.

Nice idea!
I think I'll try to print a prototype on the week end, shouldn't be too much work.

Andi

It occurs to me that the backplate obstructing the entryways to the transfer channels is a problem that only occurs with non-pullstart engines. With pullstart engines, the extra clearance required for the pullstart assembly to fit in the crankcase also prevents the backplate from obstructing the entryways to the transfer channels.

No it is not that. RTR engine makers just do not care the most optimized flow in an engine to get a good power and best milage. The racer wants to have any improvements, how tiny they can be.

I'm not disputing that this is an optimization. I'm saying it's an optimization that pullstart engines generally don't need, because pullstart backplates don't intrude into the crankcase as far.

HEs saying that the pull start isn't an optimization, its better in the engines without the pull start. Pull start hurts the engine, backplate helps

With pullstart you still have a rotating disc where no cut outs in can be made. That disc is on a same level as a normal backplate.

Again, many competition engines do come with a flat backplate, no channels or cuts at al and they are still fast. the work on those bacplates with teardrops and now these channels are more to better the flow in those side tranfer channels.

Awesome as always mate,
let us know how they run

I seem to remember reading somewhere that these plates have zero effect on power on the lower side of the engine but did help with returning to idle faster. Is this the case in your testing?