footchopper

I want to add a few bolt-ons to my boat to try to squeeze a few more MPH's out of it. I have posted a few questions on the forum about this topic. I'm going to consolidate the information and see if what ya'll think. By the way it is a Formula 252, 7.4L (carb'd) w/ Bravo 3. Can hit 53-54 mph on GPS. It has 28P props (kind of dinged up) with no through hull exhaust. These are the upgrades I've thought of or have been told about so far. Looking at trying to top 60 mph.

1. New exhaust manifolds w/ through hull exhaust (any suggestions?)
2. Labbing props (BBlades)
3. Air Gap Intake
4. Holley 4150 Carb (what size?)
5. Hotter Ignition (any suggestions?)

Would love some feedback.

At some point, in a few years, will probably repower and switch to a Bravo 1, but in the mean time.

DMOORE

Have you thought of just putting a small blower on it. There are many used setups in the classified, and spam section. No reason to run a bunch of boost. It could add 75hp easy, which is more than you will see with simple bolt ons, and those heads. It would get you to 60, and that is about max speed for the B3. Just my $ .02.



Darrell.

rssteiny

For starters with a 28 pitch prop what is your rpms and whar gear ratio is that drive. to pick up 6 mph as your after it will take more than exhaust , carb , intake you would most likly need better heads and cam then add the other stuff.

footchopper

Great question on the gears, not sure. How do I find that information? 4400 RPM's As far as a blower goes, I've thought about that, that is a really good option.

rssteiny

4400 means your over proped have you tried a 26 to get your rs up around 4800 where they should be. the 28 will work if you build more hp.

jeffswav

It sounds like you have the 330 with cast internals. A blower would on that engine would probably not last long. Swap out that Bravo 3 for a Bravo 1. What is your budget?
If you want to do it right Bore & Stroke it to a 489 or 496 with forged internals. Get a set of large oval heads with bigger valves. New intake and carb. Get aftermarket exhaust with long risers and add the through hull, I use EMI with long risers, Imco, Dana, CMI are all good. Call RMbuilder and have him set you up with the Cam and Valvetrain. That will get you 500 very usable reliable HP. OH, I forgot to tell you I use the DUI ignition, so far so good.

psychoboater

If you want to do it right Bore & Stroke it to a 489 or 496 with forged internals. Get a set of large oval heads with bigger valves. New intake and carb.

to do this it would cost the same maby even less to sell your motors and buy a set of 454's 450 hp or 502's 450 hp and drop them in. I have been looking into this same thing. like steiney said you are not proped right and if your props are messed up even a little bit it will scrub speed and r.p.m

AIR TIME

get a b1x drive, I just sold a brand new one for 3642.00 it was for sale for months at 3800, but there were some used b1x drives for sale for 3500.00 that would be the 1st stop you might pick up 4mph. in the long run get rid of the motor or use it for a back up. theres a few custom motors out there for under 10,000 grand. headers are a must stainless marine is a good choice they last forever and the dry sets are the balls. good luck

getrdunn

iTrader: (7)

I respect all the above and yes there is the question how much do you want to spend? There are many different things you can do and have a lot of input that can help you in your decission making. If you want to get the biggest bang for the buck find a 525SC blower set up used for around 2,000.00 and figure and extra 500.00 to axcessorize it and go have fun. I only say this because it is quick simple and instant. It would be an ideal situation only if you perhaps plan to do a stroker engine or some other type of build down the road. You may even get luckey and have no issues at all. I know there have been several people who have done the same thing even on this board. Do a search and contact them. Keep in mind if you so chose to go with the blower set up I would certainly start your next build with a 4 bolt main and good forged internals, stroked or not stroked. Otherwise look for a good used 496 or 502. With a good upgrade build to be worth while with what your starting gets very expensive. Been down that road several times myself. I went from what was just going to be a freshen up a couple of 454's this year to building 496's. To be honest I stopped counting how much I have put into them. If your any kind of a gambler - find a blower set up. Keep in mind though the fuel consumption is much greater and if it grenades you'll have an early start on your next build or purchase. So in a nutshell what I'm saying is to go blower with keeping your eyes peeled for another complete bigger cube engine with good internals or at the very least start gathering some goodguy parts. You can always off the blower down the road or hang on to it with all the other bits and pieces it may have caused.

LOL........

Good luck and keep us posted!

John

stevesxm

well... all the motor discussions above are valid i suppose but from where i sit i think your approach is backwards.

if i were you i would look at real world hard data that i knew to be true and compare that with motor combinations that i knew to exist. you describe your boat and its performance and lets say those numbers are accurate. ok... exactly how much faster do you want to go ? you say " top 60" so lets say you need 6 or 7 mph faster.

first obvious question. do you know any boats like yours that do that ? for real on gps... not beer talk... if so, what is their combination ? that is real world data. now you take all your numbers for boat weight and type etc and plug all those in to a number of various calculators that are floating around...

that gives you the theoretical hp increase you are going to need.. does that agree with your observed data?

drag vs speed vs hp is a cubed factor. at 55 mph you need a LOT more power to go just a little faster. thats the number you need to know . if everything says that to go another 5 or 7 mph you will need another 125 hp, then that is a piece of hard data that you can use when selecting your path to financial ruin.

this forum has , maybe, 500 threads that start with " i just spent $ 5000 on new exhaust, new intake , new ignition and some magic beans and im supposed to have an additional 200 hp now but i don't go any faster... why not ?"

try not to be another one.