I have a Evo 45gx that is rear carbed and i plane on putting it on a GP 330s extra 27%(if i can get the engines ICU working) My question is that the planes instructions call for the engine to be spaced out 6 3/4 inches. Because the carb is in the rear of the engine and with the standoffs it puts the engine to far out. The prop will be way in front of the cowl. My question is this can i cut a hole in the firewall that will allow the carb to go back into the engine box. I know that alot of the gas engines are rear carbed how do you guys get around this problem.

Cut a hole for the carb to fit. The firewall might flex more so stronger corner bracing where the firewall glues to the engine box sides might be needed. If your engine has a small foot print for engine mounting, spreader bars might be needed. Lots of folks can post pics of their way of spreading the torque loads across the firewall with standoff mounts made from wood that will eliminate firewall flexing. This pic shows one way to do it but I don't recomend it for your first time. It's a good mount if you pay attention to bending forces and watch for harmonic vibrations. Solid wood standoffs transmit less flexing torques and vibration.

You can cut the firewall......but liked mentioned above you need to reinforce the firewall.

Pics show an MVVS 58 Pro mounted in a QQ Yak and an MVVS 45 mounted in an Xtreme Composite Edge, the 45 mounting is a propriatary mount available from MVVS the Yak mounting is one I made myself, these help spread the load over a larger area and isolates some of the vibration, no other mods to the firewall where carried out.

Mike

Sorry just re-read you post you are using an Evo not an MVVS clone, (Evolution) I did not know that Evo made a 45 where did you get it from?

Mike

From a flew club member that is going to an 85cc. Thay don't make the 45 anymore i think. They moved to the 50 but my 45 looks like your mvvs! How do you like your 45, what prop ,what size, weight plane?
I just read you post again you said Evo not an MVVS clone Evolution. I have an evolution i thought that MVVS and evolution were the same? Is there an evo engine?

"Is there an evo engine?"

Yes, there is. Engines look very nice. Not too much info on how they run though. I believe they are made in Spain.