sp123

for you guys that have had a sonic much longer than I, I just had a question. I have twin 8.2 merc engines. the factory says the red line is 4400 to 4800 rmp. I can tack 4600 at wot. I was wondering if anyone had a similar setup and what would be the best rmp to just drive around and for how long would you run at wot. I have finally gotten to 20 hrs, had all fluids changed and do not want to break anything just yet.. any advice would be appreicated. I took it out last sunday and ran for a while at 2900 cruising at approx 40 mph... but looking for more info..always had outboards...

Plum_Crazy

Not a lot of the new 8.2's out there yet to compare with, especially in a Sonic. This may be more of a General Q&A question.

I imagine optimal cruise RPM would be around 3000 RPM. You really have to pick it by where the boat feels and sounds like it's running easy.

You don't say what the conditions were when you ran 4600 RPMs. However, I like to set up my boat with HO's to almost hit the rev limiter in cool temps of 55-60°. You can lose about 150 RPM in 90° temps. As for running WOT, I usually don't do it for more than a minute or so. Also, the factory states the "Full throttle RPM" is 4400 to 4800. The rev limiter should be even higher than that. I know on a 496HO the range is 4600 to 5000, but the limiter is 5150.

26sonic

am i correct in saying that your 8.2l engines are not ho's than? my 02 31sonic with 496 ho's runs at 5,000 rpm wot . with 26p bravo1 props and am currently having a set of labbed 28p bravo 1 props made by cutting edge propellers .

sp123

thanks for your responses... I was running at 4600 rpm on a 78 degree day with extremely calm seas.... around 2800-3000 rpm the engines were very smooth so I kept it at that range. I was courious as to how long I could push it at wot. I only opened it up for about 20 seconds... but it ran great. and you are correct 26 sonic.. they are not HO engines. Thanks again.

GO4BROKE

iTrader: (1)

Merc manual for the old 502 mags stated no more than 15 mins WOT. If the new 502's are built like the old ones, you can beat the crap out of them and they will be fine. Valve train was the weakest link, and even that took a couple hundred hours to break. Just keep the oil clean an full and run them the way you are comfortable. I wouldn't change props yet. On a cool day with a light load you may make it to 4800.

sp123

Thank you very much for the info.. I have to say that I am very happy with this boat. Since I got it in the water this season my daughter and I have been out every weekend and she is looking for boats to race on the bay.. something she never did before....I can't tell her we might get beat... but in RI there are not too many that run 70 and up so it is all good. I appreciate all the help from the other sonic owners as I have had boats since age 13 but never an i/o, always outboards..... I am also very happy with the fuel consumption we have been out several time and after filling the tanks once we pulled it out today filled it and did not use anywhere near the fuel as I thougt we would... I did not go by the gas gauge as they seldom reflect an accurate reading...... the new 8.2's run great... and the sonic plows through the waves...