ORIGINAL: KevinS
I put the APC 8x8 prop on and shortened the header by 1 inch per directions. I leaned the engine out as much as I could on the ground, but upon launching it barley got off the dolly, not near as much pull, and in the air it was way slower then the 9x7 prop, probably only around 100mph. Any ideas? I can't lean it out any more it will shutoff on the ground before I even get it in the air. Richening it of course, just lowers the RPM. I am getting some smoke in the air, so its not too lean. It doesn't even sound like its getting as high of a RPM with the 8x8 as I am on the 9x7.
What RPM are you getting on the 8x8? You have the west 50 VI correct? My engine with the 8x8 didn't like it when I cut the header shorter, with the header stock length, (assuming mine was the same as everyone else's) on 15% nitro with an APC 8x8 I get 21,500 on the ground. That combo give me about 190mph in a slight dive, about 170 in level flight. Make sure you're running a nice cold plug, I use the OS R5's I believe they are, they are an RC car plug. Also, I put the large diameter fuel tubing on it, the medium just didn't seem to let the fuel flow as well. Also, make sure your header and pipe are close together but not touching, you don't want much more than a 1/16" gap between the 2. Make sure the prop is balanced as well or you'll lose a lot of RPM's.
On my West 50VI in my Whiplash with the custom header that weston made for me I somehow manage a wicked 24,000RPM off that engine. Philly baby and I have discussed it and cannot figure HOW that engine is doing that much RPM but it's awesome. It just screams, makes the one on my magnum sound quiet LOL