toolsinbox

Hi to all. My first post here. What a great site. I have read a lot and have been re-inspired to finish my boat which brings me to this post and a few questions. I have owned several boats but all outboards this is my first i/o.
1989 21 ft scarab excell. fresh 454 with alpha 1 outdrive.
I have been told that with the engine I have, with close to 10:1 cr, possibly 350 hp or more, I would be wise to upgrade to a bravo. The research I have done tells me that is good advice in addition to increasing the value of my boat. Why do I not see the bravo three used more and talked about more here? Is it not a performance upgrade from a single prop setup? I am after as fast a boat as I can but nothing crazy. Just reliable and getting the best speeds I can within reason.
Is there a " rule of thumb" when it comes to the height of the risers to stop water from backing up? I have Kodiak alum. manifolds, with SS imco risers, 4 inch tips with internal flaps. Any input here would be great. Is it height above the tips? Height above the intake? not sure what I should be looking out for. If i cook this engine over somthing like that my wife will leave me for sure.
Longevity is important to me so I have been looking at imco lowers and they are intriguing to me. I see that they come in different heights. I understand that less in the water is less drag but what are the trade offs if any? What are the real benifits to hp lowers such as imco?
What are the differences between a standered bravo outdrive and the swept back or x drive?
Last question for now is am I right in a 1:50 ratio bravo drive for my setup? I know its a lot of questions so I thankyou all for your patience and input.
Cheers.
Richard.

jeffswav

Ok, welcome to the site. I am familiar with that boat and it is pretty fast for what it is. You are limited to HP by the drive. Don't think you are increasing the value of the boat by anything you do to it. It should be somthing that you want to do to make your boating experenct better. OK, lets face it ,do you want to go fast!! It will cost you a bunch of money so be prepaired to put more money into the boat than what it is worth. But, it is pretty cool spankin brand new boats that cost more than your own. Bravo 3's are for underpowered boats that want to pull up skiers. They are slower than a the Bravo 1,x,xr. I have not done a alpha/bravo conversion but I hear it is not that bad. There is a sweet spot for x dim and I am doing that as we speak. I am raising mine from 8" deep to 5" deep. From my research that is a moderate height for speed but not to high to get on plain. If you are to deep you are plowing if you are too high you cannot get on plain. I am not sure about the quality of your exhaust, I use the EMI exhaust with lone risers. A custom roller cam from RMbuilder would be your best bet. Good luck with your project and don't make your wife upset with your hobbie.

fireboatpilot

I'll try to answer some of your questions. First thing to consider though is how much time and money do you intend on putting into an older boat? The Alpha will do for awhile at least so long as you don't hammer it out of the hole. Your not making alot of HP but the TQ will kill the Alpha. To switch to the bravo, Good Idea, could cost you 3-5K plus labor. With that power the exhaust thats your using should be fine. Use some flappers on the tips if no internal flappers are installed but with 350hp reversion shouldn't be an issue. The Imco lowers about 4-5K would not be a benifit. Shorties raise the prop and potentially gain speed but lose a little handling. 1.5 ratio will be fine for you. Boats with big hp and spinning higher rpm's sometimes need to go to 1.36 ratios in order to get their boats propped correctly with limited pitch props available. Bravo 3's are used for heavier boats and pontoons where more push at lower speeds is needed. They take more hp to turn 2 props. Difference in Bravo 1's, X's, and XR's ect is the gears and types of tooth design. Swept backs are just the newer style. Don't get wrapped up in the newer looking stuff. Some of the old school stuff is still out there dooing the job just as well. Just like it was meant to do. I hope I've helped. Others will chime in and correct me if I've mis stated any things. We try to help here. Keep us posted on your project, Good Luck!

AIR TIME

I MIGHT HAVE A COMPLETE BRAVO 1 SET UP FOR SALE if my boat sells as a project for 3 grand on a trailer, thenthere will be hyd steering and k planes too.

wtfo

On a fairly light boat you might be suprised how well an alpha can take a beating - if you keep up the maintenence and don't do ramp wakes, hammer it out of the hole, etc... Also, for the cost of the aftermarket replacements a little over a grand, you can about afford to call it a wear item... maybe run it and see how it goes. Change the lube often and if you start seeing burnt, or metal shavings the writing is probably on the wall... just a thought.

spectras only

I agree with WTFO , and I would keep the slimmer Alpha drive myself.

Nice boat but before you know it you'll want to go upsize and will never get your investment back .Enjoy it the way it is.

toolsinbox

figured out how to use photo bucket
here is a pic of my boat.
The last two are before and after rebuild

http://i874.photobucket.com/albums/a...ox/Scarab8.jpg

http://i874.photobucket.com/albums/a...ox/Scarab9.jpg

http://i874.photobucket.com/albums/a...x/Scarab11.jpg

http://i874.photobucket.com/albums/a.../Scarab4-1.jpg

http://i874.photobucket.com/albums/a...install002.jpg