Four stroke Temp question
06-17-2014, 04:45 PM
#1
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Four stroke Temp question
I am using an inferred temp meter to check the temp on a Magnum 1.8 XL. What would be the expect temp range? What would you consider excessive after shut down? Are the temps typical for most four strokes?
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06-17-2014, 04:54 PM
#2
When tuned properly and cooled properly (cowling if applicable), the engine runs at the temp it runs at. The car guys are always using a temp gun and I always tell them to put it away. If it's getting too hot it's going to just quit on you. Checking the temp for reference is fine, but use that data for that only. Reference.
06-18-2014, 01:02 AM
#4
I usually put two fingers on top of the saito rocker boxes while the engine is running,depends on your pain threshold but how long you can comfortably keeps your fingers there.For me it's about five seconds and i judge everything else off that temp wise.
06-18-2014, 10:43 AM
#8
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Ditto.
Temp is a reference number for that engine only.
2- or 4-stroke, I lick my finger and see if I can touch the cooling fins for 2 to 3 seconds. If so, you're in the ballpark.
A pal was breaking in a piped Super Tigre .45 ABC last weekend, and you could hold the engine after full-throttle runs. The pipe and extra fuel it extracted kept the engine cooler.
It is cool to check temps during break-in, and see the engine drop 20-30 degrees when it's broken in.
Temp is a reference number for that engine only.
2- or 4-stroke, I lick my finger and see if I can touch the cooling fins for 2 to 3 seconds. If so, you're in the ballpark.
A pal was breaking in a piped Super Tigre .45 ABC last weekend, and you could hold the engine after full-throttle runs. The pipe and extra fuel it extracted kept the engine cooler.
It is cool to check temps during break-in, and see the engine drop 20-30 degrees when it's broken in.
06-18-2014, 11:04 AM
#9
I use the telemetry on my RC trucks but I only worry about the engine getting too hot if I see it showing 300F. Those engines are running 30% nitro 8% oil and just a tick rich of max power at 1/2 tank and turning 35,000-40,000rpm. If the engines quit, they're too hot. Needless to say, if they're tuned right and getting adequate cooling then they are running at the right temp regardless of boat, plane, or car.
06-19-2014, 02:51 PM
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Update. I ran the engine tonight and you are right, after adjusting the high and low speed settings getting it to run, and stay running, good the temp really did not matter. FYI it was about 130F. Yesterday I checked my OS 70 and 90 FSs at the field and they ran about the same.
06-19-2014, 07:27 PM
#11
130 is way cold, your temp gun is lying to you or you are running way rich. Some engines do run hotter then others. My YS runs much cooler then my OS. One thing to keep in mind is that when your engine quits because it got too hot you are greatly reducing that engines lifespan.
06-20-2014, 02:48 AM
#14
They have a high error rate because a lot of people are holding the gun a foot away. You need to get the gun as close to the target as possible and even then the temp reading should be taken at the glow plug. I used to have an infrared temp gun until all of my R/C stuff got stolen out of my garage. I never did replace the temp gun. I have found using a tach on 4-strokes and a pinch on 2-strokes to work really well on the engines I run. My 4-strokes tend to run just a few ticks rich (300-400rpm) if I lean them down from rich until they -just- clean out and run smooth. They will sometimes have a very occasional miss but I'm sure that's due to the high castor content of my fuel. Haven't had an overheated engine in years doing it this way.
06-20-2014, 05:34 AM
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I checked it on myself and I am running at 90F. The 130 was with the engine running it was 150 right after shut down so I guess the surface was cooler due to air flow. I do run my stuff on the rich side plus I run the 2/4 stroke fuel. It is Also why I need to run glow drivers on all my stuff. I am to the point of running it with the cowl installed. I will check it again.
06-20-2014, 06:31 AM
#16
I checked it on myself and I am running at 90F. The 130 was with the engine running it was 150 right after shut down so I guess the surface was cooler due to air flow. I do run my stuff on the rich side plus I run the 2/4 stroke fuel. It is Also why I need to run glow drivers on all my stuff. I am to the point of running it with the cowl installed. I will check it again.
06-20-2014, 08:01 AM
#17
Eddym,
To get back to your original question- nobody knows the answer. There are no hot or cold temperatures suggested by manufacturers. There are too many variables to even try to say. The accuracy problem is too great. And, how do you accurately measure every single time, and where do you measure from? Can't solve that. Also, you have prop sizes to deal with. Nitro content. Oil content. Shims or no shims. Cowls. How big are the cowl holes?
Your best bet lies in buying the Eagletree onboard telemetry system with an engine temp module if you have the money and if they still make them. You get other goodies that give you important info on inflight rpms, real altitude readouts, etc.
To get back to your original question- nobody knows the answer. There are no hot or cold temperatures suggested by manufacturers. There are too many variables to even try to say. The accuracy problem is too great. And, how do you accurately measure every single time, and where do you measure from? Can't solve that. Also, you have prop sizes to deal with. Nitro content. Oil content. Shims or no shims. Cowls. How big are the cowl holes?
Your best bet lies in buying the Eagletree onboard telemetry system with an engine temp module if you have the money and if they still make them. You get other goodies that give you important info on inflight rpms, real altitude readouts, etc.
06-22-2014, 03:50 AM
#20
06-22-2014, 05:33 AM
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I new this was coming. Yes I use on board glow drivers. Please do not revoke my Manhood Membership! I do know how tune an engine but am still learning. Here are a couple reasons I like a glow driver:
1. I hate dead sticks
2. When I get two the field I do not want to be tweeking my airplane I would rather be flying it
3. Safety, I figure the more I keep my fingers away from a running engine the better (disconnecting an external driver)
4. At my field I have long taxi to the end of the runway. We have already established a properly tuned engine will run cooler. It's aggravating to get all the way out or have to hold for someone else, just have the thing die.
5. We have paved runways and taxiways so I like to have aircraft slow to a stop at idle.
When I first tune the engine after install I tune it without the driver connected. So it's not so much for lack of knowledge but for redundancy and safety.
1. I hate dead sticks
2. When I get two the field I do not want to be tweeking my airplane I would rather be flying it
3. Safety, I figure the more I keep my fingers away from a running engine the better (disconnecting an external driver)
4. At my field I have long taxi to the end of the runway. We have already established a properly tuned engine will run cooler. It's aggravating to get all the way out or have to hold for someone else, just have the thing die.
5. We have paved runways and taxiways so I like to have aircraft slow to a stop at idle.
When I first tune the engine after install I tune it without the driver connected. So it's not so much for lack of knowledge but for redundancy and safety.
06-22-2014, 06:12 AM
#22
In response to your list; 1) if you tune it properly without glow support, it should not dead stick on you unless your plug burns out or you run out of fuel. 2) if you tune it properly without glow support at half tank, it should run slightly rich with a full tank and run at peak at the bottom of the tank. 3) use a remote glow driver. 4) if it dies after a long taxi to the runway, it's not tuned properly. It's too rich. 5) I don't understand how an on-board glow driver will allow an aircraft to come to a stop at idle. My flying buddy who also flies 4-strokes has no issue with his plane not moving at idle, and his engines are inverted and uses no glow support.
I just think those things are bandaids and just add more weight and complexity to something that doesn't need it. But that is solely my opinion. When I was new to 4-strokes, I learned to tune them 300-400rpm rich of peak and they run like Swiss watches once they are broken in well and the ring has seated. My engines run a lot hotter than 90-130F but they're running just a few hundred rpm under full power.
I just think those things are bandaids and just add more weight and complexity to something that doesn't need it. But that is solely my opinion. When I was new to 4-strokes, I learned to tune them 300-400rpm rich of peak and they run like Swiss watches once they are broken in well and the ring has seated. My engines run a lot hotter than 90-130F but they're running just a few hundred rpm under full power.
Last edited by 1QwkSport2.5r; 06-22-2014 at 12:42 PM. Reason: Edited to run in the time alotted.
06-22-2014, 12:26 PM
#24
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By running the on-board glow driver you are running your ignition timing as far advanced as the plug will allow which means you have to run a richer needle yet and in the process burn more fuel and run a shorter flight. Radials and multi-cylinder engines excluded here, they sometimes benefit from on-board glow but "smart" drivers that back off the plug heat at higher rpm.
In response to your list; 1) if you tune it properly without glow support, it should not dead stick on you unless your plug burns out or you run out of fuel. 2) if you tune it properly without glow support at half tank, it should run slightly rich with a full tank and run at peak at the bottom of the tank. 3) use a remote glow driver. 4) if it dies after a long taxi to the runway, it's not tuned properly. It's too rich. 5) I don't understand how an on-board glow driver will allow an aircraft to come to a stop at idle. My flying buddy who also flies 4-strokes has no issue with his plane not moving at idle, and his engines are inverted and uses no glow support.
I am really not trying to be an ass, really.. I just think those things are bandaids and just add more weight and complexity to something that doesn't need it. But that is solely my opinion. When I was new to 4-strokes, I learned to tune them 300-400rpm rich of peak and they run like Swiss watches. My engines run a lot hotter than 90-130F but they're running just a few hundred rpm under full power.
I probably look like a total jerk, but I learned a very different way from a different angle and have had great success doing it that way. To each their own though.
In response to your list; 1) if you tune it properly without glow support, it should not dead stick on you unless your plug burns out or you run out of fuel. 2) if you tune it properly without glow support at half tank, it should run slightly rich with a full tank and run at peak at the bottom of the tank. 3) use a remote glow driver. 4) if it dies after a long taxi to the runway, it's not tuned properly. It's too rich. 5) I don't understand how an on-board glow driver will allow an aircraft to come to a stop at idle. My flying buddy who also flies 4-strokes has no issue with his plane not moving at idle, and his engines are inverted and uses no glow support.
I am really not trying to be an ass, really.. I just think those things are bandaids and just add more weight and complexity to something that doesn't need it. But that is solely my opinion. When I was new to 4-strokes, I learned to tune them 300-400rpm rich of peak and they run like Swiss watches. My engines run a lot hotter than 90-130F but they're running just a few hundred rpm under full power.
I probably look like a total jerk, but I learned a very different way from a different angle and have had great success doing it that way. To each their own though.
06-22-2014, 12:39 PM
#25
And for the record, I do not claim to know everything and never have said I did.