Quote:
Originally Posted by Vezo, Part II
. . . Worst part of first days with new ride is the tach is not accurate. Comfortable cruise, tach said 58 revs, and I knew this should be about top. Stayed away from it all day, finally running at 42, then 4, and at 38 she was JUST about to fall off plane!?! Thinking I had the wrong prop, I was disappointed all day. So with little traffic, I headed in the HB canal, and put her to the pins!!! Ran even better that the 99 175! Look down at tach and I'm spinning 72-7400 rpms! Yeah right. Never hit a rev limiter and she sounded perfect. She's quick!
Now I'm thinking of pulling every gauge and possibly mounting 94sv in this custom fabbed dash panel from PO. Pics to follow.
Vezo, Part II
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Michael,
I believe the rev limiter on that motor is set at a little over 6000 rpm, so your tach is indeed way off. I wouldn't waste time screwing around with that analog tach! Even if you get it on the correct switch setting, analog tachs are notoriously inaccurate, so it could still be off by 200-300 rpm! That's too much to accurately select the right prop. I'd recommend getting a 3.5" I-Command gauge or if you're gonna buy a fancy NMEA compatible chart plotter, just hook it up to that. If you have the system check tach with the lights on it, you may already have the Engine interface cable that you'll need. Here's a link to the
Installation Manual that will show you what's needed.
I believe you said that motor was actually a 2007 model? If model no. is DPXSUC, it's the same as mine, so the optimum rpm range is 5300-5500. Gillie's right, I think it's mounted too low, so need to correct that before considering a prop change. I'd raise it a couple holes and try to get a pic of the AV plate when you're up on plane. Plate should be above solid water when at cruise. Put some black electrical tape on top of AV plate because that white plate is hard to see if it's under white water! (See second pic below) I've since raised it another 1/2 inch since 3rd picture was taken. I've picked up at least 100 rpm and 1-2 mph since I raised motor almost 3 inches from where I had been running it for years. That's enough that I can now turn a SS 4B 14.5 x 15P BRP Cyclone prop up to 5400-5450 rpm. It evidently has more cup than the larger 4B SS 15x15 PowerTech prop I've been running for a couple years because the "smaller" Cyclone turns about 100 rpm slower at WOT, but gives 1-2 mph more speed! It's a very efficient prop with good stern lift, and cruise MPG is over 4.0, at least 0.25 mpg better than the PT prop at the same mph.