QSM-11 EGT installation questions

[fixinbones]

So I just purchased the Tiara 4700 with QSM-11 715hp engines that I recently surveyed.  I want to install EGT gauges before I run the boat and I was wondering if the Smart Craft 1.0 could display the temps without having to install a separate EGT gauge for each engine?  I was also wondering where the thermocouple probe and fitting installs into the exhaust system?   I’ve searched around but couldn’t find any info on the above. Thanks 

Topic

[fixinbones]

Yes, the twin engine option has one gauge that displays the temps for both engines

[Steve Lewis]

That is what I think.  I do not know it for a fact though.  I would call SBMAR parts department and ask the question and they can get it sorted.  They are very helpful.  I called in for a different reason and they helped me pretty quick.  

[fixinbones]

So it sounds like if you order the twin engine then there’s one gauge that shows the temp of both engines?

[Steve Lewis]

I have the space and I like the symmetry of the two separate gauges on the dash.  Personal preference.  

[fixinbones]

Thanks for all your help Steve.  Just curious why you ordered two single kits instead of the twin engine kit? 

[Steve Lewis]

Fixinbones,

Don’t worry about the “K” type probe.  The correct one is included in the kit and the instructions included are very well written so you get the wire color correct.  The Kit includes the gauge, the wire and the probe.  What you need to specify when ordering is the length of wire you want, the fitting size(which for you is 1/8 npt) and the correct voltage.  The voltage has to do with the bulb that goes in for back lighting.  The probe generates the signal that is run up the wire to the gauge so there is no need for power at all unless you want the gauge backlit for low light situations.

I would not make an assumption that the entire boat is 24v.  I would want to know that for a fact.  The nice thing about Tiara is that you can go to their website, get the Customer Service email address and send them an email with your hin number and they will tell you exactly what you have.  Sea Ray does that as well.

We have a mix of 12 and 24 on our boat.  Primarily it is 12 but our bow and stern thrusters are 24.

When I ordered the EGT kits, I ordered two of the single engine kits.  I ordered a rather long length of wire so I have the extra coiled and secured in the engine compartment.  Better to have too much than not enough wire length.  The installer attached the power leads to the 12v buss for the electronics behind the dash.  When the starboard battery is on, the gauge lights are on.  At some point I will change that or put a switch inline.  For now having the light on when the battery is on is acceptable for me.

[fixinbones]

So is the gauge kit that Tony sells all I need for a QSM11-715?  It asks to choose  a 1/4” or 1/8” probe fitting size and Clark mentions needing a  K type probe. . 

[Clark Leighs]

Examine and measure it for lengths.      Better too much wire than be short 6″  because  you assumed.    There may be obstructions.

 

You can always cut the leads if they are too long.   Even then I would still leave some slack and tie it up in a coil.

1 user thanked author for this post.

fixinbones

[fixinbones]

I’ll probably get separate gauges.   Where do you tie in to get current for the gauges?  I assume the Tiara is all 24volt.   Also which size probe 1/4” or 1/8”?  Yeah my engines are right below the helm.   I would think 20’ of wire would be plenty.  Is there any drawback to getting the 30’ length just incase you have to run the wires around stuff?

[Clark Leighs]

So you understand what your thermocouple is actually doing   the actual probe is itself a voltage producer  , not a resistive device.     That voltage is read by the EGT guage to produce the temperature readings.

That voltage is produced as a reaction between two different metals which are basically welded together at the sensing point/tip. 

Use of wires other than  the same will/skew the results so be sure to get enough lead length. 

Your probe will be a ‘K’ .     I will warn to pay attention to the wire insulation colours or you can reverse the polarity of the voltage in which case the meter will not work .         RED IS NOT POSITIVE  for a K type.

Instructions should warn you of this.

There are special  plugs and receptacles to add the proper wire if needed but even they have to be purchased for the K type  thermocouples.      If I remember correctly they are yellow but ask to be sure.

 

1 user thanked author for this post.

fixinbones

[Gene Fuller]

You can even order different length wire depending on your needs(It’s a special low impedance wire to carry the signal).

The impedance is unimportant since the signal is DC and the current flow is very small. What is important is the matching of wire types. Every junction between two wires of different compositions is a thermocouple in itself. It is necessary to ensure that erroneous temperature signals are not created by adding random (usually copper) wires to extend the lead length.

The connections at the gauge head can have the same problem, but it is normal that the gauge head effect is already properly compensated.

The bottom line is that home-brew solutions can lead to inaccuracy.

[Steve Lewis]

The kit comes with everything you need, even the probe.  You can even order different length wire depending on your needs(It’s a special low impedance wire to carry the signal).  As I recall the layout on the 4400/4700 the turbos are up front in the engine compartment and the helm console is a short run up from there.  I am hoping Tiara did a better job than Sea Ray with the conduit that will get the wire up  through to the helm.  The one thing you will want to do is use anti-sieze on the threads of the probe.  That way you can take them out without fuss if need be.  Its a rather easy install.  I had the electronics guy install the gauges and run the wire since he was going to be doing that for the other stuff I was having done at the time.  I did the probes and connecting the wires.

In my opinion this EGT info combined with your fuel flow is invaluable.  It will help you dial in your setup and inform how you run your boat in various conditions.  I am keen to see what if any changes to EGT I get now that I have upgraded cylinder heads.  It has been a rather expensive off season for “Just Us”.  But we are “Done” with the big stuff and ready to stretch our cruising legs here in the Great Lakes.

1 user thanked author for this post.

fixinbones

[fixinbones]

Thanks Steve.  Gauges look great .  Does the gauge kit that Tony sells have anything else besides the gauge and wiring, do you need to purchase the thermo couple  probe separately? 

[Steve Lewis]

https://www.sbmar.com/wp-content/uploads/2015/11/QSM11EngineDrawing-with-ZF325IV.pdf

Rear view.  #14  It might be under some heat wrap.

As for your question about joining the signal into the Smartcrap harness…..  This again is my own opinion so take it for what it is worth.  I like having an independent analog gauge that is in my line of sight.  It saved my hide this past season.  My port EGT went over 1000F when the norm is about 750.  Broken clamp as it turns out.  Easy fix.  You know your own operational tenancies.  I do not want to have to toggle through screens to see mine.  Mine are on the outside of the OEM clusters and are in my line of sight.  See attached.  Just one man’s opinion………

[Author]

Replies