What RPMs should I be getting WOT?

[Cotay]

I noticed last year that I was getting low RPMs WOT while boating at Union Valley Reservoir just south of Lake Tahoe. I attributed this to the altitude (4,870 ft.). Yesterday we got better results at Millerton Reservoir just east of Madera/Fresno. My WOT RPMs for both engines for both engines was at 9,800. Is this normal? I've read that WOT should be around 10,200 so this isn't too far off, but if I wanted to check if I'm sitting on a potential problem. Both engines run fine after I changed the spark plugs and rechecked the gaps on my starboard engine that had been running rough after the plug change. We had two adults and two of our kids. Wife is pregnant with our fifth child so we probably had 500 pounds of people and a fully loaded boat with gear, coolers, etc.

 

[Andy S]

My port engine shows 10,000 and my starboard motor shows 10,200 at WOT.

Do you have High Output engines? Mine are HO engines but not sure if that would make a difference in WOT rpm. I would bet your engines are fine and you are getting everything you can out of them.

 

[Cotay]

Thanks Andy. This is a non-HO boat but I'm also not sure that makes a difference. I'm wondering if the load in the boat has any direct relation to the RPMs...I'd expect maximum speed to be impacted, but I'm not so sure RPMs should be impacted at all. Maybe this is just normal variance in engines off the production line. At no time did I get the sense that anything was "wrong" with the engines, so maybe I'm just getting "about" what should be expected.

 

[Bruce]

Both of my engines max out at 10,200 but top speed is 46 mph. Mine is an HO.

I believe that non HOs top out at a lower rpm.

 

[Andy S]

Both of my engines max out at 10,200 but top speed is 46 mph. Mine is an HO.

I believe that non HOs top out at a lower rpm.

My dream-o-meter shows 54 mph at WOT with just the wife and I and a full tank of gas, GPS shows 50.8 mph. This was done at 360' elevation and calm water on the lake.

 

[Bruce]

My dream-o-meter shows 54 mph at WOT with just the wife and I and a full tank of gas, GPS shows 50.8 mph. This was done at 360' elevation and calm water on the lake.

I believe the fastest GPS speed I have ever seen with our SX230HO was 47 MPH. But we have the bimini up much of the time which could account for a few MPH. I have considered new impellers and housing to see if it bumps up the speed but all I would gain is a few MPH that I really have no use for.

 

[Marvin willis]

Both mine are 10,200 and I dont drive fast that often but I can constantly hit 52 with gps. Unless I'm slalom skiing I don't ever get over 8000 rpms

 

[Andy S]

I believe the fastest GPS speed I have ever seen with our SX230HO was 47 MPH. But we have the bimini up much of the time which could account for a few MPH. I have considered new impellers and housing to see if it bumps up the speed but all I would gain is a few MPH that I really have no use for.

I am with you, it is rare I am running faster than 40 mph. Only when water conditions are perfect is when I will run faster. For me I would not spend the money for the possibility of only a few extra mph.

 

[Marvin willis]

I like to enjoy the ride so I average 25 mph. I get passed by skiffs

 

[OperationROL]

I am at 715 ft. We get anywhere from 48 - 52 mph at WOT. With my Solas impellers port turns at 10,100 and starboard turns at 9900-10000. With OEMs both turn at 10,200 - 10,400. I have never seen another turn more than 10,200 except mine for some reason.

 

[Pewaukee Dave]

I notice an imbalance when the boat is weighted to one side or the other.

 

[maboat]

Both of my engines max out at 10,200 but top speed is 46 mph. Mine is an HO.

I believe that non HOs top out at a lower rpm.

I have non-HO and they run at 10,200. My top speed is also 46.

 

[maboat]

Thanks Andy. This is a non-HO boat but I'm also not sure that makes a difference. I'm wondering if the load in the boat has any direct relation to the RPMs...I'd expect maximum speed to be impacted, but I'm not so sure RPMs should be impacted at all. Maybe this is just normal variance in engines off the production line. At no time did I get the sense that anything was "wrong" with the engines, so maybe I'm just getting "about" what should be expected.

At low altitudes you should be getting 10,200 max RPM. Aside from higher altitude, Spark plugs is #1 reason for coming up short. Since you already changed/checked those, the next thing would probably be the air intake path. Check or replace (or remove) the air cleaner and test. Also make sure your your air inlet channels to the engine compartment are clear of any obstruction.