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Snookerd 03-27-2019 08:30 AM

With the 17 pitch prop, you should be able to get above 5750 rpm’s. Your motor is mounted to low. I’m at the highest mounting hole and have no cavitation in tight turns and getting on plane, etc. I have an 18.5 pitch prop and can get higher rpm’s then you are getting with your 17.

Bigshrimpin 03-27-2019 07:24 PM

Quote:

Originally Posted by striper56 (Post 262645)
I took the boat for a ride here are the stats. WOT 5790 at 25 knot I was burning 9.79 gph 18kts 6.75 gph. it has a 16 X 17 prop. what do you thing? Should I try to get closer to the max RPMs 6100


Something is very very wrong with this setup.

26% prop slip at cruise is really really bad.
29% prop slip at WOT is WORSE.

Are you sure you weren't towing the dock.

Ed 03-27-2019 08:05 PM

The C-10 gauge has an endless array of options on how you can set up the pages. Most people either don't know they can be changed or don't know how to change them. The new gauges due out soon are not as powerful (option wise) but are more user friendly and visually appealing.

striper56 03-28-2019 06:48 AM

I am going to take it for a ride today and double check my original stats.
Ed. The marina that installed the motor didn't have the new gauges. But it will be connected to my Lowrance GPS by the end of the week.
Bigshrimpin not sure what 26% prop slip at cruise or what 29% prop slip at WOT means.

kmoose 03-28-2019 08:05 PM

Did you get the TX or the AP? Either way something is bad wrong. As Danny said, the motor is way too low. That motor should spin an 18.5x 16 with no issue and you should be seeing 38-40 knots WOT lightly loaded. Have them mount the motor all the way to the top.

Bigshrimpin 03-28-2019 09:33 PM

Explanation
https://www.go-fast.com/prop_slip.htm

"Slip is never a negative number, and will range from 5% on a light cat to 25% on a heavy workboat. Most hi performance applications will be between 7 and 12 percent."

25% - 30% slip at Cruise and Wide Open Throttle (WOT) puts you into the work boat (Barge) category.

The 3.6L V6 models use a 2.29:1 ratio. (I made the assumption you have the 3.6L w/2.29 ratio when calculating the slip)
The 4.0L V6 models use a 2.08:1 ratio. (if you have the 4.0L with the 2.08 ratio, slip numbers increase to 33% and 36%)


Your prop is a 17P

Plug the numbers into the prop slip calc below.

Prop Slip Calc
https://www.go-fast.com/Prop_Slip_Calculator.htm

CaptLloyd 03-29-2019 09:13 AM

Something is not right. I get 6200 wot, 41 kts with my 20P light load. I can cruise 26 kts at 4400rpm with a full load.

striper56 04-11-2019 07:42 AM

I finally got out to run the motor last nigh and to get accurate information. This is what I found with a half tank of fuel and one passenger with the 17 inch prop.
3500 rpm 20 knots
4000 rpm 25 knots
4500 rpm 31 knots
5000 rpm 34 knots
5750 rpm 39 knots
5900 rpm 38 knots

One thing I noticed when running the boat with a 2-3ft flowing swell, is the motor would go from 25knts to 21knts then back to 25knts after 30 to 60 seconds.

DoozleD 04-12-2019 08:18 PM

back off on the pitch...?

kmoose 04-14-2019 03:16 PM

Quote:

Originally Posted by striper56 (Post 262917)
I finally got out to run the motor last nigh and to get accurate information. This is what I found with a half tank of fuel and one passenger with the 17 inch prop.
3500 rpm 20 knots
4000 rpm 25 knots
4500 rpm 31 knots
5000 rpm 34 knots
5750 rpm 39 knots
5900 rpm 38 knots

One thing I noticed when running the boat with a 2-3ft flowing swell, is the motor would go from 25knts to 21knts then back to 25knts after 30 to 60 seconds.

Motor is way too low.... we have all been through this on the Suzuki. Do you have the 250AP?


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