I tried building a couple DIY analog style setups before finding this little unit. First was a hall effect paddle wheel setup specifically made for boat nav/depth units. Looked good on paper, but once connected a sine vs square wave signal issues kept if from working. Wasn't looking to build a wave converter on top of the wiring job, so scrapped that one. Next was a pressure based rig, also didn't play out well.
The biggest problem with any boat speedo is accuracy. Your standard old school marine speedo gauge units work off water pressure, or as above, a spinning wheel. Typically only accurate within 10-15% or so. New ones use a GPS to feed a dash speedo, but those wouldn't work with a ECM VSS either. The Dmax E60 ECM uses a high res 160k pulse per mile I believe, while some others GPS based units I testes were like 8 or 16k per mile. I could have adjusted the pulses with EFIlive, but once I found this piece and spoke to an engineer there who explained they built it to work with about any signal type ever used, I said ship me one and I'll let ya know. Within 20 minutes I had it wired in and ready to test.
What's also nice is it has a calibration mode that puts out a 60mph pulse signal for testing. When I compared it to a handheld GPS, it was within 2mph out of the box. I quick calibration in EFIlive and that puppy is spot on at any speed. I've refered a few LS engine swap guys to this unit also, they said it worked fine in their swaps too. Checked my setting in EFI;
{H0101} Vehicle Speed Sensor Pulses per Mile 127359.375000 Pulses/Mile
{H0102} Vehicle Speed Sensor Pulses per Revolution 40.000000 Pulses/Rev
$200 sounded pricy when I was doing this setup also, but after testing some cheaper ones, I can say it's worth every penny. Takes a thumping in the boat, high moisture local, and has done great. Battery drain was also a concern since it's always powered on. But it has a sleep mode built in and doesn't seem to have any noticeable drain when parked all winter...
Best,
-K
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