61.6mph at 4800rpm but it cost me

handfulz28 · 11-27-2006, 12:56 PM

I figure that's probably about right for a '91 311 with 454MAGs and 23P Mirages, all bone stock and original. I wonder what the original performance specs were for the 311 with the various engine options? 330s, 454MAGSs, 502MAGs, packages with TRS drives?
That was with 3/4 fuel, one person. There was a good breeze out there but it didn't matter by less than 1mph going into or with the wind. I got her airborn too...going about 50mph@4000rpm I caught the second wake passing a small cruiser. I wasn't expecting to fly but I saw the revs pick up a few hundred rpm before I pulled 'em back...that was cool

And I had no idea how "twitchy" this boat handles. I've never driven an offshore, or a "fast" boat for that matter, but I wasn't expecting it to be so responsive to steering input. Man, anything more than a couple inches movement of the wheel and I would've been ejected! I was wearing my lanyard, and for the second time confirmed they work.
So it cost me the starboard bird emblem, which I think got rubbed off at the dock, and the starboard motor must've stopped moving water after I pulled the boat out to change props. I just changed the impeller on that side, and I ran the crap out of it for 1.5hrs doing a bunch of speed runs...ran flawlessly. As soon as I pulled away from the dock after the prop change, motor was running hot so I came right back. Ironic part is, I pulled a palm frond out of the port side lower unit when I pulled the prop off. It must've gotten sucked in through the hub when I was in reverse somewhere?
So at least my fuel pump and fuel line repair held. Now I've got to diagnose the cooling issue and get that done already. My 30 day exchange from Hydromotive is almost up!
Thanks,
Michael

RedDog382 · 11-27-2006, 02:36 PM

My '89 311 with 454 mags and 23 mirage props/bravo drives consistently ran 67-68 mph @ 5000 rpm depending on fuel/load and weather.

handfulz28 · 11-27-2006, 05:17 PM

Nice action photos!! Were those GPS or speedo numbers? A lot of people knock the stock speedo, but mine seems pretty darn close.
I've still got a bit of learning how to drive in front of me. I know very little about proper trim and tab settings; I'm still trying to remember and review what I've read here on OSO.
I've got a set of Hydromotive Q-IV X props on there now so hopefully I'll get to try those this week. I backflushed the oil cooler and blew a chunk or two, then it held perfect temp on the hose; hopefully those were chunks from the first impeller.
Thanks,
Michael

offthefront · 11-27-2006, 09:19 PM

you should see 65+ easily ....I have seen 67-68 constently on my 311 ..GPS .... I have seen 70 .... but that was very low fuel and just me ...and a lot of trim to get there . Also you should be able to run 5000 RPM without any worries .... I am running 23 Hydromotives ...I have been told by Throttle UP and BBlades that the VHulls have performed bettter with the B1 ( round Ear) props ...but never tried it ..m

Builder Bob · 11-27-2006, 09:54 PM

Quote:

Originally Posted by RedDog382

My '89 311 with 454 mags and 23 mirage props/bravo drives consistently ran 67-68 mph @ 5000 rpm depending on fuel/load and weather.

Is that boat racked at Pier 75?

f311fr1 · 11-27-2006, 10:01 PM

The best my stock 311/454 Mag would run was 68 MPH. Could always get a consistant 65. 89 model. The best with blower motors was 88 MPH. The 4 blade hydromotive props are the way to go.

handfulz28 · 11-28-2006, 08:23 AM

Here I was happy to get over 61, now I'm thinking I should've stayed out longer on the Mirages and kept playing trim/tabs. I had the drives out to 5 or 6 I think, but stopped there.
So what drive/tab settings should I shoot for to get over 65? I also hate to handicap myself, but these motors have 1105hrs now; I wonder if I'm giving up just a couple mph with "age"? Or maybe I just need to adjust/service the carbs and throttle linkage

The weather is still a bit breezy today, but I'll head out and see what she'll do...specially since we're down to about 1/2 tank now

Thanks,
Michael

offthefront · 11-28-2006, 11:57 AM

1100 Hours ? Holy Crap ....Maybe you should hold things at 4800 ....Definitely loosing some pop ....

ThirdBird · 11-28-2006, 12:08 PM

At 1100 hours you should be happy you're getting 61 mph!!! I agree with Offthefront, keep yourself at 4800 rpms, anymore and you may end up experiencing high energy metallic particle dispersion due to rapid disassembly!!!!

Those motors are due for a freshening, at least the heads. Be nice to it until you can get them done.

offthefront · 11-28-2006, 01:17 PM

Quote:

Originally Posted by ThirdBird

keep yourself at 4800 rpms, anymore and you may end up experiencing high energy metallic particle dispersion due to rapid disassembly!!!!

Thats Yankee talk for blow up ..........