Who would be interested in a unit that is custom designed to take inputs from 1-6 standard K-type thermocouples and convert those inputs into a useable 0-5 volt output that would be compatible with the "user defined" inputs on most datalogging units?

Datalogit, Haltech, Hondata and DataQ at least have this ability. The advantage is you will be able to see exactly what your EGTs are in reference to RPM, AFR, fuel pressure, TPS, Boost etc etc and then adjust both AFR AND timing based on the maps.

I am building a prototype now that will accept up to 6 K-type thermocouple and output the data to BOTH 0-5 Vout terminals (for datalogging and or 0-5 volt analog gauges) AND 10mV/degree C terminal, which can then be connected to an optional 1/8 DIN LED Panel with a 6 position rotary switch to monitor any of the 6 inputs.

The predicted cost for the full package (digital led gauge and support for monitoring up to 6 k-type thermocouples (one at a time) will be around $350 (dual led systems may also be available for about $75 more). I think just the datalogging amplifier/conditioner (no gauge output) will be possible for under $275.


These systems will work with ALL vehicles not just rotaries.

Right now I am just trying to get a sense of the interest level for a unit like this. The datalogit users group recently exploded with interest about EGT logging.

Thanks

 

Sounds GOOD... DO IT...

 

Why use K-type thermocouples? Just because every other EGT gauge manufactures use them?
There are RTD type EGT's out there for lots less and its way quicker to setup on a 0-5v datalogging system.

http://www.jimnel.com/rtd.html

However, Heraeus used to make RTD EGT's and they seem to not have them available anymore.

-PaulK

 

Paul

For certain uses RTDs rock (AIT, Fuel temp, Oil temp, etc) however their service range ends at 500 degrees C. Internal combustion gasoline engines routinely see EGTs in the neighborhood of 600-900 degrees C. K types give good dependability in the range necessary. Other problems exist in using a resistance type sensor, but the costs are much better than when using thermocouple setups.

Thanks for the comment though.

Jeff


To all:

My prototype (two input) unit is almost complete. I will update soon. I am also thinking of manufacturing these EGT amplifieers in kit form similar to the way Tech Edge markets its model of AFR units. Let me know if that is appealing to you.

 

Jeff,
Heraeus specifically made EGT RTD's rated at up to 1000C, but it seems like the company might not exist anymore. I had the sales brouchure on their sensor and they had addressed some issues why it was better than K-type thermocouples. If I remember correctly, it had something to do with a faster response time and specific construction to manage the thermal dissipation of the sensor body.
Also, those EGT RTD's were priced at $45 each.
But at this point, I don't know if they are available anymore. You are correct tho, I have not seen other RTD's rated for EGT use.

-PaulK

 

any updates Jeff?

Even any pics of progress or logs you have done testing

 

Bench test are complete and the Thermocouple test unit works well with the DataQ logger and the TE 2.0a AFR control/logger unit Datalogit tests have to wait until my the 1/8 NPT bungs are welded onto my exhaust manifold. I will update when everything is in place. I am going to mount and monitor both pre turbo and post turbo egts for comparison.

 

techedge wbo2 has the ability to datalog imputs such as egt's on a palm or a laptop, along with rpm, and afr's. i got the DIY kit and assembled it myself for under 250$.

 

[QUOTE]Also, those EGT RTD's were priced at $45 each


I've purchased brand new ungrounded K type thermocouplers for less than $20. They come with a metal sheath around wires as well.

 

http://www.plasticprocess.com/

Ask for the ungrounded K type sensor.
Part# BPKP-63672U

 

Jeff,
i am interested in a unit that would work w my dataloggit. good luck and keep us posted. also, i am looking for a sensor to log fuel pressure and engine oil temp. ( they may be currently available as though the last time i searched i came up empty.)
howard coleman

 

It was bad enough with EGO's and UEGO's, but EGT's are going to be even more lagged than that.

What kinda sampling rate are we talking about here?
You're still going to have to compensate for the "time shift" in the sensor lag.


-Ted

 

Ted

If by "sampling rate" you are refering to the polling of the "amplifier/linearizing/conversion (A/L/C) circuitry, the rate is based on the sampling rate of the datalogger and the computer driving it (eg. datalogit with a P100=about 7samples/sec or datalogit with a P3 1.2 gb = about 35 sample/sec). If you mean the polling of the T/C by the A/L/C, that number is a function of the speed of the A/L/C IC chosen. The A/L/C must read the T/C, then compensate for the cold junction temp, do an ice point calibration, linearize the output and finally amplify the output. For all intents and purposes, these calculations are instantaneous.


As to the question about "time shift" (I assume you mean the difference between the target temp is actually reached at the sensor and the time it is reported to the datalogger/gauge), the only thing I can say is that the "time shift" experienced by using a digital solution and a datatlogger or digital gauge is significantly lower than is experienced by the mechanical gauges most people rely on. The reason for this is that mechanical gauge must receive the T/C voltage from an A/L/C and then apply that voltage to the mechanical needle operating mechanism (usually a electromagnetic device) and then the needle has to overcome the actual inertia before moving to the new spot (all in all a very long time in terms of acccuracy). On balance a purely electronic system will reduce the "time shift" to a much shorter duration.


As to its usefulness, you know better than most of us that EGTs are best monitored in terms of trends. By monitoring large changes in the trend one can begin to isolate the cells in which problem timing may be occurring. Remembering that retardation of timing is never going to blow an engine (as long as Leading and Trailing are both retarded equally), you can verify whether the change in timing had a positive, negative or nil effect and move on accordingly.

Safe use of warning buzzers and lights are always set conservatively 50-75 degrees F below the chosen temp.

 

Here is most of my method for tuning Rotary engines equipped with separate EGT Type K thermocouples (one located in each of the exhaust manifold runners) and a Wide Band O2 system mounted as close as practical to the exhaust ports. (Because of WB O2 sensors sensistivity to heat, an NA system can have the O2 sensor mounted closer to the exhaust ports than in a turbo application which usually requires placement at least 6 inches post turbo). All these steps MUST BE LOGGED and reviewed, watching gauges is NOT an acceptable substitute. Use this information at your own risk.

Decide what your designated “safe” maximums are going to be for AFRs and EGTs. This is pretty much a question of how “risk averse” you are. Lower AFRs (mid to upper 10s at WOT under boost coupled with lower EGTs) are generally considered “safe” but conservative power producers. Higher AFRs (Low to mid 11s when coupled with slightly higher EGTs produce more HP at an increasing expense to engine lifespan).

First, set the timing for a "safe" but untuned condition (e.g. NO NEGATIVE SPLIT; turbo applications---make sure the Leading Ignition Timing does not exceed 12 degrees of advance under heavy acceleration up to the torque curve; etc. etc).

Next, set the AFRs to a fat safe map. Log both EGTs and AFRs.

Always remember that you are looking for trends in the EGTs and to a lesser extent, in the AFRs. There is always a delay between the time an event happens in the combustion chamber and the time the measurement of that event gets converted to an electronic signal by a sensor and finally reported on a datalog as a unit of measurement. That time is critical. Make your changes to fuel and timing maps based on the fact that the condition you see reported actually happened sometime earlier. (It’s really something like astronomy when you get down to it, y’know......the light we see from the stars is actually light generated a gazillion years ago and that star may atually be dead by now.


OK now read the logs---

A. If the AFRs are lean and the EGTs are high you probably want to add fuel to the maps at those points and re-log

B. If AFRs are rich and EGTs are high, you may be experiencing excess fuel being burned off in the manifold, try taking a little fuel out in those cells and re-log.

C. If EGTs are high and the AFRs are in the normal range, you may have a timing problem in that area and you may want to retard the ignition timing in the affected cells and relog.

D. If the AFRs are rich and the EGTs are low, you can take some fuel out in those cells and re-log.

E. If the AFRs are lean and the EGTs are low---well, this shouldn't happen except in two situations.......
1. Throttle tip-in ( in which case do nothing and you should see an immediate increase in AFRs above the throttle tip-in point) and/or
2. When EGTs are lagging behind the leaning out of the fuel. If you get this situation, look at the logs farther up and see if there is a trend towards higher EGTs, if there is then the WB is detecting the lean condition and you will expect temps to rise.

Remember that it is slow small steps that will allow you to take the motor to a safe tuning.

BTW do not forget that you are RETUNING the entire map and that Intake Air Temp compensation tables should be restructured if the Intake Temps are not stable between 35 and 45 degrees Celsius for the tuning period. . . .But that’s another story.......