Locate a PROPSHAFT DYNO in Midwest???
10-20-2015, 04:59 AM
#33
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That's something I'm worried about with prop shaft dyno. The water. I have thru hull pickups and just at 1800-2000rpm I can pull a strong garden hose half shut. The headers get hot when on the hose with no load. With a load would be horrible and I have stelling dry's. If one of them go Im up ****s creek
What a fustrating issue, I know that you have checked everything about 5,6,7 times now on the motor and drive side. I also know that the problem is present in neutral which makes some of what I am thinking irrelevant, assuming you have verified the actual trim angle and drive height is equal on both sides? You did let a little secret out in this post that I don't think you mentioned before are you sure the water pick-ups are in the exact same position and are not spoiling the water to the drives. It is possible that your issue is not with the motor that is low on RPM's, it could be with the so called good motor that is high on RPM's. People much smarter then me will know better what that does.
One quick test that I can think of that might show this is to run the boat a degree or two off centerline both directions to see if it changes anything. I know that doesn't explaine the drop in neutral but it could certainly be playing a factor while underway and loaded.
Last edited by Questofpower; 10-20-2015 at 05:17 AM.
10-20-2015, 06:14 AM
#34
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Thanks for the response. You could be on to something and my thoughts weren't far off this yesterday. I will know more hopefully Thursday but when I put the drives back on swapped I did make some adjustments to the tie bar. I thought The neutral differences could be a fluke and unrelated and here's why: initial carb accelerator pump reaction vs throttle lever position. I noticed the port (just off idle) doesn't respond as fast cable wise as the starboard. Like an initial slack in cable. When I checked the cables before the first checkpoint was about an inch up at which point they are about equal. Before that the starboard cable reacts faster. Maybe because of the shorter cable. I tightened up as much slack as possible in port cable but this tells me that likely the neutral tests have all been inconclusive. At least that's my theory there. Regardless both the carbs have definitely been going full throttle. That has been tested many times and the levers have plenty of room left when the carbs are buried full open.
Last edited by Eliminated572; 10-20-2015 at 06:17 AM.
10-20-2015, 07:15 AM
#35
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Running the new slip numbers the starboard engine at 6000rpm is at 7% slip. The port would be at -1% slip at 5500. I don't think the one is aerating. Looks like the higher reving engine is right on.
10-22-2015, 11:44 PM
#36
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I have a prop shaft dyno (land and sea). I've done a lot of boats up to 750 pshp. It won't hold much more than that. Just doing a sweep test only takes about 8 seconds so cooling is not a big issue. If you need to run an extended load test then it's an issue. I'm in central Texas so it might be a little far for you to drive, but I've had several people tow that far to find a problem.
Bob Lloyd
Bob Lloyd
10-23-2015, 02:13 AM
#37
like here-
http://www.offshoreonly.com/forums/g...-pictures.html
Not quite what you want, This uses a Stellings extension box. Shows real time HP and TQ while driving.
http://www.offshoreonly.com/forums/g...-pictures.html
Not quite what you want, This uses a Stellings extension box. Shows real time HP and TQ while driving.
10-23-2015, 09:07 AM
#38
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Well, I swapped the drives and also adjusted toe to 1/8" in. Also adjusted the port throttle cable a bit. Not sure what exactly to say because the problem didn't chase to the other side. It basically went away. AFR was mid 12's all the pulls. Very confused and don't know exactly what fixed it BUT I'll take it! Also posted this on other thread....
