I'm nearing completion of my 3rd Weeks Special, this one gets a gas engine (toc 3mm 52cc) the plans show a g38, quadra 42, or equivilent for engines, there is no mention of a an engine box, plans show engines bolted directly to firewall.
The 3mm TOC engine I have specs for an engine box for cooling airflow but I'm afraid it may set the position too far forward not sure what I'm going to do with it, this is my first gasser, Is it that the old school gassers didn't require that much cooling there for mount directly to firewall? Maybe use some standoff spacers or bulid a box I guess.

How much does the plane weigh? What is its wingspan and wing area? You may be way overpowered with a 52cc engine. What is the distance from the firewall to the cowl and what is the distance from the standoffs to the propeller hub? Dan.

18-20lb, 78" wings, 1650sq" area, 64" fuse, I do not have the engine in hand yet, The cowl I have yet to build, (scratch build plane)) The question was all I see of todays kits is engine box box box box, the plan I build from indicates q42 mounted directly to firewall NO BOX, to provide adequate airflow. I added some cowl baffling to my last build custom to the Saito 300 that powers it. I have to get the engine in my posession before I can proceed, been just going by engine photos thus far.
Just not sure if completely understand the importance of an engine box.

A motor box is a much more secure method of attaching an engine. The standoffs create a cantilever effect which is susceptible to vibration. The longer the standoffs, the more the vibration. You will notice it most at idle. Make the box with 3/8 inch aircraft plywood with plenty of hard wood triangular stock and 3 hour epoxy. If you do not have room for all of this, then you are stuck with the standoffs. Dan.

Are we talking about the Pitts biplane here?

I had a friend that flew one with a G62 in it and loved it.

Yea here's a picture of one I built with a Saito 300, liked it so much that I've built another that will have the gasser engine.
I'm thinking of fabricating a mounting cage similar to whats on this Saito only out of alluminum.

I have never heard anything but good about how this plane flies...

Well he must like it, it's his third? To each is own.

Here's what I have done most recently. 3/4" popular from Lowes drilled through to accommodate bolts. 1/4" aircraft ply firewall just large enough for engine mounting, the outside is wrapped with 1/8" ply to prevent flexing.

Lol yea I know , the obsession started after flying the first one I built from a Miles's kit fresh from the basement of his house.
I'm getting really fast at building them from scratch, I've made all the templates and with each build I get better at it, incorporating new techniques and mods to make each one unique.
I really have no desire to fly any other plane and hopefully one day I'll be able to make it do summersaults like Miles Reed did, god rest his sole.

To answer your question. No you do not an engine box for cooling. It was devised as a way to allow various engines to be used on a single design. Miles designed that plane for the avaiable engines, at the time. If youe engine fits the cowling mounted on the firewall, great. Some builders move the firewall to accomodatre engine of choice. Stand offs and boxes can also be used if you need to extend the engine out to match the cowl. Just make sure it as strong and secure.

Thank you, Planning to provide enough space for air circulate through and out, probably no need to build a box, it's a 3/8 firewall laminated from three 1/8" pieces of aircraft ply.

I've adjusted the firewall to provide a little air runoff, the last thing I want to do is cook this engine from lack of airflow around the fins, still not sure how I'm going to bring freah air into the cowl, I painted some of the areas to be cut out but don't like the position. Give me your ideas please.