hey it was on GPS .... well like i said ill be having the boat for a long time .. and have some money laying around .. the stock cranks in those magnum 454 EFI s? cant handle the 5 pounds of boost they would be running? aswell and same goes for the pistons and rods? do you need to do this all at once? I could see if I was running more boost but 5 isnt too much .. I tried to get ahold of cougar to find out about hull speed no such luck so far .. also the drive? what would I upgrade too? everyone i talked to so far said the leg on this thing is a good leg and would handle the hp from a supercharger? ill try to find the specs on it for you guys

also carbs?? its EFI

I'm not saying not to add the supercharger, just saying be careful, it may handle fine at 90 and kill you at 91. It's a small V hull, Just an opinion.

And if you want to keep it EFI that will cost MORE than carb's !! Because you sure can't use the EFI off your 454 on a blower set up . :eek: We are just trying to give you some free advice that a lot of us on here learned the hard way .:drink: OH to be young again .

Might not have been hard but it sure was EXPENSIVE!

Man, I'm spendin thousands now just trying to squeak out 2-3 more mph. If you want to do more than 75mph, get a bigger boat. Even if you don't hurt yourself or someone else your gonna ruin the comfort and usability of the boat for example, cutting up the hatch to install a scoop and not being able to have the honeys lay out on the back.

thanks guys
 

haha they aint laying on the hatch anyways lol ... well with the EFI i thought all you have to do is get it programmed? thanks alot for the advice guys im just trying to work all the bugs out im thinking of starting this in september .. for a winter project.. just want to know what to do first etc.. im sure there has to be someone out there that has messed with this hull or something similar at 75 it feels fine .. and i know with more hp i could keep the leg trimmed down more .. im sure it would handle 85 fairly easy ..

PS thanks for helping out the youngster lol im 25 getting old now

Find a 454 mag or 502 with the good internals add a EFI Whipple to it and be done! Cheap NO but would be the most reliable IMO.

I had a merc 6.2 done over the winter with head swap, cam, and piston change along with a EFI Whipple took boat from the low 70's to 89 and am still working with props and mines an 18' Donzi Classic, in that size hull every 10 mph past 70 feels like about 25! I've spent the last 5 years getting the boat dialed in with steering, shorty, and some other small moods in preparation for the bigger power along with nearly 400 hrs of seat time, just dropping in a bunch of HP in a fairly new to you boat without learning how it responds is prolly not a good idea.
If you really wanna run those speeds take baby steps and really learn the boat and it's limits, your friends and family will thank you later for it!

Steve

The internals from the 454 mag EFI are good for the whipple system. Whipple comes with it own intake, fuel pump and injectors. You may need to change fuel line, water seperator and pickup in tank. Depending on the year it is and if it has MEFI 1, 2, or 3, Dustin Whipple can reprogram it. You may have to upgrade the ECU but Dustin can hook you up with what is needed. How many hours are on the motor?
If you add any supercharger, I can not stress enough about installing new head gaskets. Cometic are what I would use, but I have used Felpro and not had problems. Even if it doesn't have many hours the stock head gaskets will not hold up, and you will be replacing them within a year or 2, but could cause more damage when they blow out.
Sounds like to fun winter project. At 20' that thing will be a rocket.

Some good advice by 28Eliminator, as well as the other guys. Don't forget to upgrade the exhaust valves to a high grade alloy like inconnel or the Ferrea Super Alloy. Lots of threads on here that touch on the need for this. Also, with EFI, stick with a shop that has a lot of experience with EFI superchargers. Get the mapping wrong on this and lean it out and bye bye motor.

The stock Bravo will probably handle the power in a light boat if you use common sense. However, a light boat like that will have more tendency to get the prop out of the water, and the loading/unloading/loading is what kills drives.

Rule of thumb is take your initial estimate for the upgrades, double it, and then multiply by an additional 20% for all the little clusters that will bite you in the ass. Remember, BOAT is an acronym for Break Out Another Thousand, and this is especially true for the high performance variety.

hey
 

thanks alot guys great advice .. sorry for any confusion this is a 454 EFI magnum motor with good internals .. can someone provide me with some links on where to buy the whipple or supercharger as well as the exhaust valves? sorry for the conufsion also ive been driving this boat for years my uncle owned it before me and ive been running it for a long time aswell as running a boat all my life .. my dad has a 19 ft modified tunnel from cougar with a 2.5 racing merc ive been running since i was 13 lol ... thanks alot guys seems like im heading in the right direction .. also for hours the motor is at 450 right now and it isnt hard ran hours at all ..