Open Firewall

[LEE]

Hi fellas. I am putting in the tank to my Edge 540 and because I am using the rear carb Ryobi, I had to cut a big hole in the firewall including some others (see LEE in the galleries section). My question is, should I put in another firewall further back to block off the motor box from the inside of the fuse? What about pressure buildup in the main fuse if I don't?
I was thinking of a simple baffle so spitting from the carb won't go into the radio compartment, but should this be airtight?
Thanks for the help :wink:

[Cecil Marshall]

Hi Lee:
My 4*120 has a Ryobi in it and I hd to put a 1 1/4" hole in the firewall so the "carb" could breathe....I put the tank below the platform that was made for it(to use a bigger tank) and thus have an open area that goes right into the fuse..

I haven't put a deflector or anything in it and so far it is still dry inside..

What I did add was a "scoop" on the top of the fuse to "ram air" into the fuse to "feed the carb" ....

My Ryobi (with standard ignition) turns an 18x8 Dynaflight prop at 7400 rpm...
I'll try to post some pics of my setup.........

[Cecil Marshall]

Hi Lee:
My 4*120 has a Ryobi in it and I hd to put a 1 1/4" hole in the firewall so the "carb" could breathe....I put the tank below the platform that was made for it(to use a bigger tank) and thus have an open area that goes right into the fuse..

I haven't put a deflector or anything in it and so far it is still dry inside..

What I did add was a "scoop" on the top of the fuse to "ram air" into the fuse to "feed the carb" ....

My Ryobi (with standard ignition) turns an 18x8 Dynaflight prop at 7400 rpm...
I'll try to post some pics of my setup.........

[Cecil Marshall]

Oops :oops:

[LEE]

Ok, I get it, I get it :!: :!: Speaking of ram air, is it worth the effort to build an air scoop to the carb? I thought these works better in still air so you don't get fluctuations with changes in airspeed :?:

[Cecil Marshall]

Lee:
I don't get carb fluctuations, but before I opened the "firewall" and put on the scoop, I was turning 7000 rpm.. After mods. , I got 7400 rpm on an 18x8 Dynathrust..
With the B&B mount, the back of the carb was only 3/16" from the solid firewall,and with the cowl on I seemed to lose rpms..

[Cecil Marshall]

Another

[LEE]

Thanks Cecil, I guess I won't worry so much now :wink: What did you attribute the rpm increase to, the hole in the firewall :?:
Just got my Hitec digital servos in, now I can get some final installation done..Yehahh 8)

[Cecil Marshall]

Lee:
Before I cut the hole and with the cowl on, I could only turn 6800 to7000 rpm.. After I cut the hole and with the cowl on and the scoop, I get a constant 7400 rpm on the ground....
It seems to work for me....You'll get to see it this summer at your fun-flys...