What is a flow meter

[Todd]

Haven't used an eagle tree, but the max temp on their temp gauge is 450F, which isn't going to cut it for the exhaust on a gas engine. When I was racing karts we'd tune the carb to get the exhaust at the header to 1200F. 1250F and you were on the ragged edge, 1300F and you were going to be melting pistons.

Paul it reads higher than that. Have the setup on my 1/5 scale truck. 1000 to 1200 deg F is the norm with it.

If you want to use the temp gauges that come radios. Than those are real low. Been awhile I wrote them down but seemed Futaba was 400 F and Airtronics maxed at 275 F. I Called both manufactures and told them I needed higher than that. When they said you will not see that kinda temps. I told them it was for gas engines.

They than said sorry we will not be doing anything higher.. So I got the Eagletree system instead of a new radio.

Todd

Quickdraw

 

[TraceyJacoby]

Tracey, Next time your coming to Huntsville let me know and I'll bring a flow meter and my note book and show you about them.

Bzubee,
I'm working on planning a trip in about a month. I talked with Bill Zuber, at the Atlanta spring nats, about becoming a Huntsville member. Thank you.

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[Glenn McClintic]

John thanks for the detailed message. Really interesting. A schematic would be great. I'm guessing you flow a fixed (known size) orifice to calibrate, and then go ahead and flow the engine. Wish I was near Alabama.

 

[John Beardslee]

Mr John Beardslee,

Thank You for sharing your wonderful story about the historical introduction of flow meters into the world of rc boat racing. I enjoyed it.

I just got home from the Atlanta spring nats; im a little tired. I had a great time for the first time in 35 years. I look forward to learning more.

Be well.

Sent from my SAMSUNG-SM-G891A using Tapatalk

Here's the old drawings and info that we sent out with the flow meters or info for those who wanted to build their own. You could probably substitute an air pump for the propane tank or an air tank. I personally use one of the large dial flowmeter that Boris Mazor built. The large dial is easy for old eyes to see.

scan0002.pdf scan0001.pdf

Thanks, John

 

[John Beardslee]

John thanks for the detailed message. Really interesting. A schematic would be great. I'm guessing you flow a fixed (known size) orifice to calibrate, and then go ahead and flow the engine. Wish I was near Alabama.

Glenn the flow meter is great for twins to get the engines close to sync. to start with and then run the boats both twin and single until I'm happy with their performance and then flow the needle/needles and record the number. I chart everything from pipe, pipe length, prop, water temp, air temp/density and I flow my water lines as well and have an adjustable flow control for my water (manual)

Glenn see the sketchs in the previous thread to Tracey

Thanks, John

 

[Andy Greene]

After a recent move I found my old style propane flow meter Herb Stewart gave me before he passed,neat old piece.

 

[PaulHail]

Haven't used an eagle tree, but the max temp on their temp gauge is 450F, which isn't going to cut it for the exhaust on a gas engine. When I was racing karts we'd tune the carb to get the exhaust at the header to 1200F. 1250F and you were on the ragged edge, 1300F and you were going to be melting pistons.

Paul it reads higher than that. Have the setup on my 1/5 scale truck. 1000 to 1200 deg F is the norm with it.

If you want to use the temp gauges that come radios. Than those are real low. Been awhile I wrote them down but seemed Futaba was 400 F and Airtronics maxed at 275 F. I Called both manufactures and told them I needed higher than that. When they said you will not see that kinda temps. I told them it was for gas engines.

They than said sorry we will not be doing anything higher.. So I got the Eagletree system instead of a new radio.

Todd

Quickdraw

Thanks for the clarification, I was going by what I saw on their website. So do they have a small dia thermocouple you put in the exhaust header to get exhaust gas temps, or do you wrap it around the header?

 

[John Beardslee]

After a recent move I found my old style propane flow meter Herb Stewart gave me before he passed,neat old piece.

Andy is it in a metal box with a handle on top?

Thanks John

 

[Glenn McClintic]

Wow thank you. That's super interesting. Looks like you flow gas through the Flowmeter and then through the Carb. The Magnehelic measures differential pressure (dP) between the pressure in the line and atmospheric pressure. I can see that as flow increases the dP goes down and vice versa. I suspect that using compressed gas would be nice because it's always dry where an air pump could push some (small) percentage of water through the system if it's really humid.

I bet that using modern day microchips you could measure air density, density altitude, humidity, etc. and compensate to correct for those conditions. But I bet those old meters we're really good - just kinda big.

I actually found the Magnehelic and Flowmeter on line.

Thanks so much for the information.

 

[John Beardslee]

Glenn we would adjust the tank valve to set the magnahelix to read 40 as a constant and the flow change is read on the flow meter as you change the needle.

Thanks John

 

[Glenn McClintic]

Oh...ok. That makes me think about the system differently. So you have a regulator on the propane tank and adjust until the magnahelix reads 40?. Then adjust the needle and record reading from the flowmeter.

Does the magnahelix reading change while you're adjusting the needle or stay relatively constant? i.e. Do you have to adjust the needle, then reset the gas pressure to 40, adjust needle again, then adjust to 40 again...etc?

Thanks. Does anyone have one of these meters they would be willing to sell? For some reason, this is all really fascinating to me.

Glenn

 

[John Beardslee]

Glenn most of the first ones we used an adjustable valve at the tank from a Bernz-a-matic torch that we modified to a fuel line nozzle, so we could control the amount of propane to keep the magnehelic at 40. Later we used a regulator on the propane tank, that helped a lot to give a more constant rate of propane to the magnehelic and subsequently more consistent flow readings. The system did not compensate for weather conditions but if you kept good notes/data of your running conditions it was possible to replicate performance. The overall size of the units compared to the new units like Boris Mazor's or the newer units from Dave Roach was what moved me to switch to the newer style when I started back racing a few years ago.

Thanks, John

 

[Mike Rappold]

I don't see a thermocouple probe offered by eagle tree. The problem is that as far as I know the smallest diameter high temp thermocouples are 1/8" diameter. Not a big deal in a 1 1/2" or larger header in regards to disrupting flow, I would be concerned that in a 7/8" header that the flow disruption would be to the point of robbing some engine power. If someone made a 1/16" or 2mm diameter probe, I think you'd be good to go but I don't think such a beast exists.

Paul,

The Eagle Tree logger (black box data logger version) comes with an RTD type of temperature sensor. This is intended to measure cylinder head temp by wrapping it around the head of an engine. The RTD sensor is only good to about 450 deg max. In order to measure Exhaust Gas temperature, Eagle Tree offers a thermocouple expander board. This allows you to connect a type K thermocouple - which goes up to something like 2000 deg. The expander board allows for two thermocouples. The type K thermocouples can be purchased from other companies that specialize in industrial type ones.

I am using a 1/16" diameter thermocouple to measure exhaust gas temp in an 67 and 90 nitro application. The end of the thermocouple extends into the center of the tuned pipe to read the gas temperature. I have the thermocouple located right next to the tank pipe pressure tap. I have not found a smaller diameter than 1/16" that would work for the application. I am sure they exist - just have not found yet. The thermocouples I am using come from a company called Pyromation.

I chose to locate the EGT sensor at the center of the tuned pipe (widest section) vs in the header to minimize flow disruptions - as you mention above.

Hope this helps.

Mike

 

[Terry Keeley]

Hey Mike: What range of temperatures are you seeing?

 

[Mike Rappold]

Terry,

Usually between 550 - 650 deg F once everything has warmed up.

Mike

 

[Terry Keeley]

Cool. Wonder if it would be as hot as a fuel car (1800-2000F) near the exhaust port?

 

[Todd]

Paul

I am running the expander board with one for exhaust temp and the other for head temp. My fault for not saying this earlier.

Todd

Quickdraw

 

[shoboat]

Glenn,

I have two propane flow meters if you would like one.

They are old school, but still work very well. I have a

Gen 2 Boris meter also. I am going to try one of Kevin

and Dave’s new meters. They will compensate for different

air density conditions.

Let Me Know If You Are Still Interested?

Mark Sholund

 

[Glenn McClintic]

Mark

Yes I would like one to use, and learn about. I have a Boris meter too and I use it but the old school stuff is interesting.

Let me know what you want for it and your PayPal. It's fun running boats learning about this hobby.

Thanks

Glenn

 

[PaulHail]

Cool. Wonder if it would be as hot as a fuel car (1800-2000F) near the exhaust port?

That might work for a 3 second run on the quarter mile, but aluminum melts at 1220-1250F depending on the alloy so for heat racing you need to tune to a temp that will allow your piston to last.