B8M upgrade questions

[Damocles]

Hello All !

I have a very stock B8M with a MAC (and a prerotator) that need some extended maintenance.
In the same time I would like to make some modification.
1. Add a horizontal stabilizer in the prop wash.
2. Change the ignition to CDI
3. Port the engine
4. Replace the boat tank with a removable foil shape tank on the mast, higher than the engine, or something similar to the Gadget.
5. Add some sort of a exhaust
6, Rotor speed gauge, Head cylinder temp gauge, RPM gauge
7. Something comfi to sit on.
9. A coat of paint


I also read about having a 5' teeter bar instead of the 2' makes a good difference (Don't know about this one).

If anyone has suggestions or reason for not doing a mod, please do mention it.

 

[Timchick]

I added a horizontal stab in the prop wash on my KB-2 by bolting the Air Command stab pieces to the top of my rudder. It was a perfect fit and I liked it. I never flew the gyro before I added it so I couldn't compare the flight characteristics with and without it.

I also found some expansion chambers and had them jet-hot coated and installed. I had to change the jets in my carb quite a bit after adding the exhaust.

For a rotor rpm gauge I used a cat-eye bicycle speedometer with a magnet mounted up on the ring gear. Worked great and it was under $20. On the photo of my instruments the cat-eye is the second one up from the bottom.

Instead of trying to mold a fuel tank around your mast why not install a seat tank? They make seat covers for them so they are comfi to sit on.

 

[dabkb2]

Hello All !

I have a very stock B8M with a MAC (and a prerotator) that need some extended maintenance.
In the same time I would like to make some modification.
1. Add a horizontal stabilizer in the prop wash.
2. Change the ignition to CDI
3. Port the engine
4. Replace the boat tank with a removable foil shape tank on the mast, higher than the engine, or something similar to the Gadget.
5. Add some sort of a exhaust
6, Rotor speed gauge, Head cylinder temp gauge, RPM gauge
7. Something comfi to sit on.
9. A coat of paint


I also read about having a 5' teeter bar instead of the 2' makes a good difference (Don't know about this one).

If anyone has suggestions or reason for not doing a mod, please do mention it.

I would do the math on disc loading before adding 3' of rotor. It could help with lift, but could slow the rotor to dangerous low speed.

Porting the Mac could help, but if done wrong might cause hot spots and even if done right the increase will be minimal. Polishing is what I did to mine and it only lowered the temps by 25 degress.

If you can find some expansion chambers that were made for the Mac, I would highly recomend them. I beleve that adding exaust pipes, even if they are not expansion chambered will help. Maybe not with more power but will make the Mac last longer. I have no numbers to support this but it makes sence to me.

I would replace the boat tank with a seat tank. It should bring the gyro to within a 1/2" of CLT and have less drag.

Just a couple things that I have found, but they might help.

 

[Mike484]

You may be able to get a little more help if you post some pictures of what you have.