need only 1-2 mph quickly..(help)
 

here's the deal OSO bro's.. ME and a buddy both have Formula 312 fastech's his all stock 502 mag mpi's, 28 bravo-1 5100-5200rpm
,mine 454 mag mpi's. I run labbed 30 Bravo-1's, Offhore exhaust w/ss risres and a tweeked just a little ECM and vorteck breather. 5100-5200rpm We ran each other twice at Norris lake TN in 49deg weather and were dead even at 73mph, dead even. he had 2 people I had 3.. How can I gain just a little to pass him..? In theroy I should be beating him with the 30's but I'm not, I know you all know some tricks?
Help an OSO brother out,,,:coolcowboy:

Leave your 2 buddies, cooler and beer on the dock to watch.

Thats a no sh_tter

lose the weight

exactly....unload the boat..remove cabin seats etc...

Put on a blower:D

You could look into shorties or ask one of the cam gurus like RMbuilder what they can do for you.

Other than that, loose weight. Strip the cabin for anything that is easily removed.

Put in a bottle of nitrous for one run. When you are dead even hit the switch and waive bye bye.:boat:

:boat:

lose as much fuel as you can without running out and as others have said ditch any gear you can.

What gear ratio are you guys running? If you are running 1.5's, both boat's slip is pretty high. So, there is some improvement to be made there.

Are both boats showing the same speed on GPS?

JATO's on the sunpad.....

Good spotting Dave. Missed that completely.

Just did some number crunching.

With a 1.65 gear.

28" prop 73 mph @ 5100 = 11% good
28" prop 73 mph @ 5200 = 13% still ok, but some to be had
30" prop 73 mph @ 5100 = 17%
30" prop 73 mph @ 5200 = 18%

With a 1.5 gear.

28" prop 73 mph @ 5100 = 19%
28" prop 73 mph @ 5200 = 21%:eek:
30" prop 73 mph @ 5100 = 24%:eek::eek:
30" prop 73 mph @ 5200 = 26%:eek::eek::eek:

If you guys both run 1.5 gears, you need to get your boats dialed in + I'm not trying to be a smartazz or rude here, but honestly if running 1.5, whoever labbed your prop, did a bad job with those high slip numbers.

If you run 1.65 gears, you still have some speed left on the table.

On engines reving to 5000-5200 the norm would be to run 25" true pitch for the 70-73 mph speeds, with 1.5 gears.

I'm sure that they're running 1.65 ratios! Just an FYI, my Formula 292 SR-1 has a prop slip of 11% with stock Hydromotive QIV's A fastec hull IMO should have better slip numbers than a non-stepped formula hull.

Pretty sure that the 312's all came with 1.65 drives.

Run a duct from the engine hatch intake directly to your air intake and seal it off so you only take in cold air for the engines. Add a can of octane booster also.


You will pick up some hp there.

Next give Bblades a call.

Wannabe

And don't get any big splashes in that duct.:eek:

1) Lose as much weight as you can (especially fuel).
2) Weight you can't lose, move as far rearward as you can.
3) If you have a freshwater tank, drain it (they are usually far forward).
4) Roll up two towels and prop your engine hatch open with them - one to the left of center, and the other to the right of center. This will induce far more airflow into the engine compartment than any sort of quickie ductwork.
5) Make sure your throttle plates are opening ALL the way when the sticks are pushed forward (cable adjustment is often leaving a little bit there).
6) Forget the octane booster, unless it is incredibly hot outside - octane will not give you more power unless your motor is already retarding the timing to prevent knock.
7) We assume you know to raise your tabs all the way up out of the path of water. You may even want to temporarily take them off of the boat for the weight savings and potential tiny bit of hydrodynamic drag they may add.
8) We also assume you know how to trim your boat. Familiarize yourself with trim settings and watch the GPS.
9) Make sure your drives are properly toed in. Drives that are toed out add drag and give up speed.
10) Make sure your hull is clean. Waxing and rubbing magic salve on it really doesn't do much, but you can try a coat of good silicone based wax for a 2 minute micro-advantage.

11) You can experiment with a 2 degree bump in base timing. On back to back runs, don't touch your trim settings, and try it. Sometimes if your timing is conservative, you can pick up 5 hp or so. Other times, it pushes you into spark knock and your retard pulls timing out anyhow.

That's about it, aside from modifications or perhaps running exotic heavily oxygenated race fuels that are expensive and must be flushed from the tanks if any remains (although I presume you'd run it about dry and refill with pump gas after your face-off).

I've seen NuTec Special 4 add more than 25 horsepower to a 700hp motor with nothing but fattening up the jetting. I've seen it add 5 hp to a racebike (with similar fattening up the fuel setting). It's not what you want to run, though, since it will turn rubber to goo if you leave it in the system. VP Q16 is a similar fuel that does NOT attack your fuel system, and delivers 60% of the boost of Nutec S4. It's cheaper than the Nutec as well (NuTec S4/S5 was $15/gallon back in 2003).

I'm just rambling though - there's no way that it's worth the cost and hassle of spiking your tank with that stuff. You'd have to start with an empty tank, and put in at least 20 gallons of this stuff. Then you'd need to run it almost out and fill the tanks full up with straight gas and then run about 5 gallons of straight gas back thru the system...

MC

If your exhaust are the cast iron manifolds, swap them for some cast aluminum 496 take-offs. The 496's should flow a little better and they will save you a ton of weight. You should be able to find 2 sets pretty cheap...cheaper than good props.

As for props, find a marina that will loan props (with c'card down payment) and spend a calm weekday with a gps and a notebook and see if can find some faster props.

Keep equal number of people in your boats as your buddy has so he doesn't say you beat him that way. But, make sure they are petite lightweight hotties - less total weight and bragging rights all in one!

call me I can help

Gear ratio in my bravo's are 1.65 on Formula 312's
Yup- same speed on GPS,, dead same..

1.65 is the gear Ratio and they were done by Bret at B-blades.. so you would think he's the best to do the job..
I've asked a couple times about that as well,, slipseems high.
Maybe time for 5-blade props

Have had twin engine boats for 15 years,,Here's the odd thing.. I can have 1 person or 4 people, 1/8 tank of fuel or 3/4 tank.. Max speed is always the same 73,2-73.5, I have tried every trim angle, some K-planes, no planes, more trim/less you name it.. I think my prop slip is too high. I have a set of Bravo 28 and max speed is the same on those, I get more RPM and on plane quicker but same speed...
I guess I'll be selling my labbed 30's and my 28's to buy a good five blade F+++$$

How about a slightly different angle, you'll need camo gear and late night access to your buddies boat to retard his timing a few degrees... Taken straight from the book of "If you can't beat them honestly- CHEAT!.":lolhit:

Ok, now back to the helpful hints.

Guy has 454's.

How deep are your props sitting? Even with relatively high x numbers your B1's should work. If running 1.65's I won't say your lab job is bad, it was only if running 1.5. Nothing against Bblades. It's all good.
Just curious. What is Brett saying about your 17% slip? If I was you, I would talk to him about the QIV, P5, Hering 5 blades and the maximus. In other words, what you said youself. The 5 blade options or the QIV.
I know this might sound off, but maybe a ½" spacer could work too. Spacers does not always rob speed you know.

in my experience all lab props do for me is slip more I have never gotten more speed out of them. I agree that there may be some speed left in playing with the x-dimension. You are doing pretty good keeping up with boat with 502's your mods must have got you up to the 415HP mark.

Stepped hulls are not AS trim sensitive as a traditional vee, but trim angle and weight load should still certainly have a very noticeable effect.

If your props have been worked by somebody, then you need to get real life slip numbers on both sets of props and tell the guy you need more bite, etc. A good prop guy can hammer whatever you need into them. Sometimes a little more cup is all you need, other times it requires something more dramatic.

MC

I do too. The 496 exhaust bolts right up to the 454s - no problems. Been there, done that.

nose cones
 

I thought about nose cones,, Some say "no" unless your doing 70+ others say 80.. MAyby it will allow the water to feed the props better.. Problem is once you get them on I imagine it sucks taking them off..

You might want to check your plugs try going to a little colder
plug, bump timing up 1 or 2 degrees.
From your info,sounds like you need a prop rework.You might need more bow lift or more stern lift.
Have someone record your boat running at wide open throttle
from alongside to see how much wetted surface is in the water
When talking to your prop shop,the more info you can give them the better the end result.
To get 2 MPH look to the prop.

correct slip
 

In theroy if I could get 11% slip then I would be running 80..
But I think when you run a 5 blade you drop pitch,, thus speed but more than I have now..WTH,, This sucks.:grinser010:

Well, it does not really work like that. You will also loose some rpm's. If you can get your slip down to 11%, the 2-3 mph range should be within reach. But yes, start at the prop. I seriously doubt that a nosecone will give you anything. It will make your prop hook up more, but it will also create drag. Speed wise, you are nowhere near blowout due to speed and gearcase torpedo length.

Take off the flame arrestors. You might blow up but you will be a little faster.

Nitromethane:eek:

Who makes good 5 bladed props without a second mortgage on the house. Spent the jack having my 30's labbed but really didn't see anything. or maybe I need to try someone else on the labwork.

Cutting Edge 5 blades are great and the price is awesome!

I highly doubt you will gain speed with a 5 blade.

you would think if I could limit my slip numbers my speed should pick up. I'm around 17% now..and thats alot,

Yes, but there are other ways of reducing slip. I'm not saying it won't work for sure, it's deffinetly worth trying, as I said before. But it's on rare occasions that 5 blades give a speed increase on a setup like yours. I just can't get my head around the fact that the slip on that hull with B1 props can't be brought down. I know Bblades has labbed your prop, but have you talked to Brett about what else could be done. It might only need a little cupping. I think the hydro QIV and QIV-X could be interesting to try. Have you ever tried a set of non-labbed B1's in 30" and 32"? Then there is the last thing to try. Your friend has a set of 28's. You are both spinning the same rpm's and going equally fast. Try hes props as well. Something is apperantly working for him with the stock 28's.

THe 30's were mine first and not labbed, once Brett labbed I gained about 1mph, the biggest issue was one was running about 200rpm higher or lowere pending which one your talking about. They were able to even them out. The slip is whats got me,, Guess I need to call again.
What gets me is when I put my back up bravo-1 28's on I run about the same just higher RPM,,Thought about having those labbed and adjusted up.. but hate to dump the bucks in it and not do anything..Just getting my slip down to 13% would be great could put me at 75-76

Here's a current thread where a guy picked-up 2/3 mph that you may want to look into. Seems kinda off the wall to me:eek:, but it won't hurt to read it.
http://www.offshoreonly.com/forums/g...-skeguard.html

Nose cones will smooth the flow of water to the drives and lower the slip a few percent. However, lowering your rpm's may slow the boat down. Hard to tell without trying. :crazy: