24' Formula 242 speed with twin 260's
 

How fast will a 242 go with twin 350/260 hp go?

Personal experience with my own boats and talking to others through the years gets you an answer of around 65 MPH.

Typ. 65 MPH. Although I think the factory rated the package at 67 MPH. It's a heavy hull, so it takes a nice chop & a lot of trim to get it to dance. The 242 with twin 260's is a sweet package.

Checkout the configs and speeds I put together in another thread:

http://www.offshoreonly.com/forums/f...nfig-here.html

Mine (twin 260s w/ 2bl Rochesters) did about 54mph (actual is in the spreadsheet). After upgrading intakes and carbs (4bl), I hit 58.6. GPS. Just realized this week that my throttle cables aren't allowing the carbs to get to WOT! Correct throttle cable brackets should arrive tomorrow. Plan to test it this weekend.

Brackets arrived. New (used) 21P Mirage Plus props are on. Very excited to try it out tomorrow. Everyone says this boat should do 65. Best I've seen is 58.6. I'm really hoping to see 62 tomorrow! Will post results................
:boat:

so what was the verdict? how did the new props perform?

Test aborted. Port engine was cutting out above 3500 rpm. A "boatfreak" suggested it could be a bad coil. Received the new one today. Need to find time to install and plan to test. Still planning to post the results when I get 'em.

New coil fixed it. Boston Harbor today - best I saw was 53.7 @ 4600 RPM. I think the props are too big (diameter). Will drop back to the smaller diameter Quicksilvers and try to get the RPMs back up. Bottom line: I can't see how people get 65+ with stock 350s.

I think the best you're going to get is 60-61 MPH. My 242 with 525 hp BBC, and with aluminum intake, exhaust and heads ( so a light engine) my best was 68 MPH. You have the same HP but 2 engines and drives, so lots of extra weight and drag. For props, your best bet is a mirage plus, most likely 23 pitch. A 21 is never going to get you into the 60's. I run a 21 on the 242 but I'm spinning 5900 rpms. On my 292 with twin 330's I'm running hydromotive QIV's 24 pitch. On that boat I get 63 MPH at 4600 rpms. Hope this helps.

I can't see how people get 65+ with stock 350s

With less than half fuel load...one aboard....fresh tune...good fuel pressure...perfect trim, drives out with no tab and 2' seas with little or no wind.

Figure Mirage+ 21" pushing 5300~5500 RPM.....or a pair of old 23" Cleavers...but they suck for anything else but top end.