4bus

iTrader: (4)

Turned 5750 rpm at 97 mph this weekend on stock 4 blade bravo ones. Slip number isn't terrible. Engines got full roller cam upgrades this winter, but blowers got smaller pulleys so they are screaming. Wondering what people think about this high of rpm at WOT? I am sure I will lose a little when we get in the heat of the summer.

So, should I let her just rip? Can I bring my slip down without losing top speed? Would the next logical step be a 34 4 blade or a 5 blade xx pitch? Will propping up be harder on the drives?


Upgraded 575 scis, bravo xr spinning in, twin big step lighting, side by side, standard lowers stripped and knife edged.

Thanks

88bullet

iTrader: (1)

dude you got that thing rocking good!!!! 5 blades will be harder on the drive but should decrease your slip numbers. the quest for speed is very addicting. i have come to the conclusion that it costs way too much to squeeze every last drop out of it tho. i would rather sacrifice a couple of mph on the top end for a nice cruising speed and longevity of the motors with a lower rpm. BUT thats what 2 sets of props are for lol!! poker run props and daily driver props. i think you have the C-note in her with some prop work

4bus

iTrader: (4)

Thank you. It is still really cold out. If I can keep it in the low to mid 90's in the heat of the summer I will be happy.

I don't mid having two sets of props, but what two sets? Is 15 a lot of slip on the props I am running? Are you saying to work the 32s for optimal and purchase 5 blades for cruising?

Is that the new cig in your avatar? Is there a thread showing details of the new ride? I am lost on this new oso

88bullet

iTrader: (1)

brett at b blades will know what to do with your props better than me. he has done some nice work for friends of mine with great results. he will how to maximize speed and another set for nice cruising.

yes thats the new cig. there are some pics and stuff in the cig forums "taking a road trip" http://www.offshoreonly.com/forums/c...road-trip.html 572-750's and speedmaster #3's she runs pretty good. saturday june 8th you guys should come out to our little lunch run on the niagara river

MILD THUNDER

iTrader: (3)

So you've gained about 5mph so far with the upgrades?

As for the props, I'd prob leave them, see what you get when its hot, humid, and a few peeps on board with some gear. My guess is 5400-5700 is prob about perfect for your mills.

Esquire

I have a lot of experience with a similar set up on a 42 Lightning with staggered, upgraded 575sci's (intercoolers, cam change, smaller pulleys). 5750 is a lot of revs for that engine and the stock blower. I'd look for a set of 34P Bravo Ones and/or 32P Maximus to try. Both will get your rpms down and will help your cruise speed. Only problem is that in my experience, Bravo Ones start to suck at 34P and up. They just don't seem to perform as well as the smaller props, particularly out of the hole. The Maximus will likely lower slip and greatly improve midrange cruise, but they may cost you a couple on the big end, especially since you are running stock lowers. If you're planning on getting shorter lowers, the Maximus will probably be your best bet for an all around wheel.

4bus

iTrader: (4)

All time high last year was 92.7 at 5350 rpm, 60 degree air temps and cold water temps. Summer it would run 88-89. Its a little warmer than my all time high stock speed, but ya 5-6 mph is prob what I got. I still have AFR's from 10.8-11 WOT, so a little more work to do there as well Crazy how many ponies it takes to get the last few MPH out of these boats.

Going to be hot and humid this week, and this shallow lake warms up quick. I may go out Wednesday and see where I stand

4bus

iTrader: (4)

Lunch run huh? That sounds like fun. Lets see what we have for weather when it gets closer.

MILD THUNDER

iTrader: (3)

Dropping from 5600RPM to 5200RPM, will slow the blower speed down about 600-700rpm. I really don't think that will matter much when you're talking 10,000 rpm compressor speed. Ultimately, the best deal is going to a larger blower, like a 871, and run 5000-6000RPM blower speed at wot.

With good valve springs, and valvetrain components, 5600-5700 shouldn't be a issue for the engine internals.

4bus, 10.8 is a bit rich, at full kill. low 11's would be better. I wouldn't go much leaner with the small blower and throttle body injected setup. I think with port injection you could get away a tad leaner, as the cylinder to cylinder distribution is better. But, I wouldn't expect more than about a 10HP difference going from say 11.8 to 11.3 afr. I'd rather keep it on the safe side.

4bus

iTrader: (4)

Thanks for the tips! Ya it's rich everywhere still. 11.7-12.1 idle and cruising no boost, merc was way off with this tune. I haven't starting data logging or making changes yet, wanted to make sure I did not have idle, shifting, or any other issues before I started. Just rev limit changes so far. It drank 200 gallons of fuel already, I think we have the bugs worked out

8-71's and ASD7's are probably in my near future. I do have the good blowers, and I am at 78 hrs total so far on both engines, gotta get a little use out of stock before I send them down the road.