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DLE 55 squish tolerance?

Old 03-06-2018, 11:28 AM
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vertical grimmace
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Default DLE 55 squish tolerance?

I replaced the ring in my DLE 55RA with a bowman, and I needed to replace the cylinder gasket. I was sent the wrong set, so decided to leave the gasket out entirely and use Yamabond to seal the case. What would be the minimum head clearance to avoid damage? I kinda checked it doing the solder thing, but not sure I got it completely right. The thinnest it came back was .5 mm.
Old 03-06-2018, 03:23 PM
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CK1
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.5mm and is a good squish on a single 60cc or under.
.85mm is good for larger engines 85cc and up . The lower the stackup tolerances of the piston rock , crankpin and wristpin freeplay the lower you can go with the squish . You can go less than .5mm , all the way down to zero but it would be unlikely that an DLE engine is that tight in stack up tolerances
Old 03-06-2018, 06:06 PM
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Thanks for the reply CK1. I will get some runs on it soon. The ring seems to feel much better than stock. looking forward to experiencing the difference.

I am going to try something new this time around as well. (for me anyway) I bought a Telemetry module for my A9 Hitec radio. I think I found a good place to mount the probe. Right next to the exhaust exit at the engine, on the muffler. I have heard exhaust gas temps are the most important, while the plug area of the head is usually the hottest. The plug area has no good way of facilitating the probe. But the muffler works great, as I can get the probe right in the exhaust gas. Thoughts on this?
Old 03-06-2018, 06:19 PM
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While cylinder head temperature (CHT) is somewhat related to exhaust gas temperature (EGT) they are not the same. EGT will be considerably higher and I'm not sure that reading will tell you what you really want to know about how the engine is being cooled. Also, what are the limits on the temp probe? Will it tolerate the higher EGT.

If it were mine, I think I'd stick with measuring CHT and find a suitable location for the probe near the base of the plug, usually on the back side.
Old 03-06-2018, 06:28 PM
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The probe limit is around 450 degrees I think. I could possibly drill a small hole in the closest cooling fin. I will look at mounting options. So I take it is more important to monitor CHT than EGT? I can always get another probe. I have 4 temp ports on the module, I assume for a 4 cylinder situation. So if I wanted to add EGT later it would be easy.

My engine mounting situation is not terribly hot. But it is scale, and somewhat enclosed, but I am not too concerned about it over heating.
Old 03-06-2018, 06:41 PM
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CHT is more appropriate to determine engine cooling capacity . EGT would be more useful for tuning diagnosis but not really relative in our performance range and with little useful comparative data , not really practical. CHT is most accurate when measured at the base of the sparkplug . That being said if using CHT only to check the cooling effect of cowl ducting you can place the sensor where easiest to mount as your only looking for an over decrease in engine temp achieved with cowl changes .
Old 03-07-2018, 07:07 AM
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CK is giving you spot on advice. A probe for exhaust gas temp would need to be safe to 1400 degrees F.

I mount my Aurora 9 CHT probe tight to the cylinder at the rear between the first and second cooling fins. (Fins closest to the spark plug.) You can hold it there with a piece of silicone glow fuel line wedged in place. 300F would be a good max CHT.


AV8TOR
Old 03-07-2018, 04:33 PM
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Thanks for the info guys. THis will be a big help.

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