[/QUOTE]keep in mind that this Lowrance unit will fit in the 2 1/8" hole and give you the display for MPG for $125 at BOE;
http://www.byownerelectronics.com/st...at=2996&page=1
Just wonder how good they are?
Since my Navman 210 crapped out, been looking to get MPG & GPH in the same dash hole.
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The Lowrance unit is the same thing that BRP offers as one of their I-Command Digital gages. If you're running an E-TEC, it's an easy plug-in, just 1 cable to the EMM, and then all sensors and gages just hook in to network cable with T-connectors; gets fuel flow from engine computer. Needs speed input from NMEA compatible GPS antenna or paddlewheel sensor. They also mention Suzuki's on Lowrance Installation guide which you can download, so should be compatible with those motors. Not sure it will work with other motors - you'd have to ask Lowrance; they do have a separate fuel flow sensor you can buy.
I have the I-Command set-up and it's pretty neat for setting optimum trim. I can usually improve mileage by about .5 MPG by tweaking throttle, power trim and trim tabs. My E-TEC seems to be most efficient at about 2700-3000 rpm, around 25 mph and 5-5.5 gph; still over 4 mpg all the way up to about 4000 rpm however. (It interesting that this is about the same optimum cruise speed/mpg that Boating magazine got on a 140 I/O Seafari test back in 1969! Running angle went from 3.5deg/10mph to 2.5deg/20mph to ~1 deg @ 25+mph, so I've concluded that 20-25 mph speed range probably gives least wetted surface/drag and is therefore the most efficient speed for the 20' hull.)
Another and possibly cheaper option, if you just want to know fuel flow rate and gallons used, is Floscan. They've been making fuel flow meters for over 30 years - good aerospace quality stuff. I installed one years ago when running an old carbed 115 V-4; at 23-25 mph it burned 8-10 gph! At idle it burned 2 gph - I-Command says the E-Tec burns 0.2 gph at idle! Needle on Floscan meter doesn't even come off the peg at idle - have to goose the throttle to even tell if it's working!