Cox Product Engine Hop-Up
11-11-2004, 10:09 AM
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Cox Product Engine Hop-Up
I have a standard .049 Cox product engine that I want to use on a glider pod. I am going to install a TD cylinder and piston. My questions are:
1. Do I need a special TD glow head or can I use a standard one?
2. Will the addition of a teflon reed valve have any effect of performance?
Thanks!
-Barry
1. Do I need a special TD glow head or can I use a standard one?
2. Will the addition of a teflon reed valve have any effect of performance?
Thanks!
-Barry
11-11-2004, 10:31 AM
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RE: Cox Product Engine Hop-Up
Barry,
How old is this engine? Is it one of the newer "Sure Start" engines with the funky little choke and the gray backplate? If so they have the newer porting and even with the twin slit exhaust are pretty darn good out of the box. Otherwise screw the TD top end and play with the head gasket count. Just get the setup what will let you run the biggest prop at the best rpm because with a glider you need the pulling power and not the speed.
Later,
Tim
How old is this engine? Is it one of the newer "Sure Start" engines with the funky little choke and the gray backplate? If so they have the newer porting and even with the twin slit exhaust are pretty darn good out of the box. Otherwise screw the TD top end and play with the head gasket count. Just get the setup what will let you run the biggest prop at the best rpm because with a glider you need the pulling power and not the speed.
Later,
Tim
11-12-2004, 01:08 PM
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RE: Cox Product Engine Hop-Up
The TeeDee cylinder will definetly help a bit. But probably not as much as you think. The standard twin bypass product cylinders pump out a fair amount of pep as is.
The choice of glow head comes down to how much nitro you are using and how much you play with the compression ratio via adding gasket washers. On a TeeDee I have I found that with 35% nitro the engine ran "hard" with the high comp head and actually blew out the plug seal after a 1/2 dozen runs. I switched to the middle comp straight cone shaped head (rare these days I'm afraid) and it ran much better with more power, easier starts and generally made the sun shine brighter in the sky. So use the hi-comp head by all means but I suggest you start with about 3 head gaskets and try it for a few runs then remove one and try for more runs and then remove another and try... etc until you find the happy medium. Watch for it starting to kick hard against your finger when starting and sounding laboured when running and a lowering of the rpms from too much compression. If you later change the nitro content then you'll probably need to retune the compression.
The new clear mylar reeds work great as I'm sure the teflon one does too. The reed choice probably doesn't affect power that much but it'll make a big difference in the ease of operation.
The choice of glow head comes down to how much nitro you are using and how much you play with the compression ratio via adding gasket washers. On a TeeDee I have I found that with 35% nitro the engine ran "hard" with the high comp head and actually blew out the plug seal after a 1/2 dozen runs. I switched to the middle comp straight cone shaped head (rare these days I'm afraid) and it ran much better with more power, easier starts and generally made the sun shine brighter in the sky. So use the hi-comp head by all means but I suggest you start with about 3 head gaskets and try it for a few runs then remove one and try for more runs and then remove another and try... etc until you find the happy medium. Watch for it starting to kick hard against your finger when starting and sounding laboured when running and a lowering of the rpms from too much compression. If you later change the nitro content then you'll probably need to retune the compression.
The new clear mylar reeds work great as I'm sure the teflon one does too. The reed choice probably doesn't affect power that much but it'll make a big difference in the ease of operation.
