Eagle SGX

[bigriggr]

I have a Eagle SGX with a mac 67. I was told the optimum engine temp should be 200. I tried the smallest stinger bushing for the AB pipe, no change. I record 72-75 on the gps. CMDI says I should be running in the high 70's to 80. The engine temp I have is only 100 after any given run. How else can I raise the temp or is this matter even affecting my performance?

Bill

 

[shoboat]

Bill,

What pipe and how long are you running? And what propellers are you testing?

We need a little more info. The CMB black Fat 67/80 pipe works very well on

the MAC-67 @10.5". H-32 propeller works very well also @5.29" of cup. FYI,

A H-48 is really a reduced 1667 propeller.

Don,

This set up worked great on my old SG-67, did the SGX differ that much?

Thanks,

Mark Sholund

231.590.3023

 

[Don Ferrette]

I have a Eagle SGX with a mac 67. I was told the optimum engine temp should be 200. I tried the smallest stinger bushing for the AB pipe, no change. I record 72-75 on the gps. CMDI says I should be running in the high 70's to 80. The engine temp I have is only 100 after any given run. How else can I raise the temp or is this matter even affecting my performance?

Bill

Before you start messing with changing props try restricting/reducing the water flow first. You can either put a zip tie right after the water outlet on the rudder or take a small 1/8" plastic vacuum "T" fitting and add it line after the rudder to bleed off some of the water. I personally prefer the T fitting as sometimes you can blow the water line off from too much back pressure if you are restricting the flow alot with a zip tie. Once you determine how much restriction you want you can make it more "permanent" by doing things like filling the brass nipple at the rudder with solder and then drilling it up to the size you want to reduce flow.
The best pipe I found on the MAC67 was the 67 parabolic @ 10.75" with the internal baffle drilled out to match the stinger i.d. The CMB fat belly pipe, while good on the CMB's, proved too inconsistent on the MAC67 and 84 motors.

As far as props go I found the H32 not to work that great on the SGX, once you get the head temps up try an H38 with about 4.9" cup or a 1667 cut down to 64mm with about 5.6" cup.

 

[Don Ferrette]

Don,

This set up worked great on my old SG-67, did the SGX differ that much?

Thanks,

Mark Sholund

231.590.3023

Yeah, the SGX didn't like the H32 and the fat belly pipe got really inconsistent in hot weather. Depending on what Bill already has for a prop I'm sure you could hook him up with the H38 or cut 1667.

 

[bigriggr]

Thanks Don and Mark, so it sounds like I do need to get this temp up to around 200. Here's more input. The pipe is the new barstock AB67. Measuring from the center of the pipe (the fatest diameter) is 10 1/2" following the angle of the pipe to the center of the engine. Or, 10 1/8" from the center of the pipe straight across to the glow plug. The props CMDI sent me are 1657 w/5.5, haven't been running them. The prop I religiously run is from Mark, H-38 w/5.29 pitch. I also have a H-38 w/5.65 in the box. There was one hot Michigan day here last year I hit 80 mph, but can't seem to find that anymore. I like what I read already about the water restriction. That tee would be a good test, or maybe drilling a 1/16" hole in the rudder brass nipple. Anymore test and tune input would be appreciated.

Bill

 

[Don Ferrette]

Thanks Don and Mark, so it sounds like I do need to get this temp up to around 200. Here's more input. The pipe is the new barstock AB67. Measuring from the center of the pipe (the fatest diameter) is 10 1/2" following the angle of the pipe to the center of the engine. Or, 10 1/8" from the center of the pipe straight across to the glow plug. The props CMDI sent me are 1657 w/5.5, haven't been running them. The prop I religiously run is from Mark, H-38 w/5.29 pitch. I also have a H-38 w/5.65 in the box. There was one hot Michigan day here last year I hit 80 mph, but can't seem to find that anymore. I like what I read already about the water restriction. That tee would be a good test, or maybe drilling a 1/16" hole in the rudder brass nipple. Anymore test and tune input would be appreciated.

Bill

Bill you may have just answered your own question- "There was one hot Michigan day here last year I hit 80 mph, but can't seem to find that anymore." Get yourself a 1/8" vacuum T and add it in line right at the rudder. If you go to a hobby shop that is big on planes they may stock the T's for use pneumatics on landing gear retract systems. Put the T in so the flow from rudder to motor is in line. In other words the bleed off port is 90 degrees to the path from rudder to motor.