opinion 383vs454
 

im thinking about rebuilding my 350 to a 383 since i have all mounts pullys ect already on motor or would i be wasting my money and should i just go with a 454? would the weight and power of the 383 save me vs the weight of a big block? thanks in advance. also its going into a 24' sleekcraft enforcer open bow.

whats the weight on that boat? i would guess somewhere around 3600lbs??? the 454 will give you the added torque and lower rpm power. the problem is the alpha drive behind the bbc. i run a formula 242 with 454 and alpha, and haven't had any problems (as most dont have problems with their 242's). my boat is significantly heavier than yours too. its all about the nut behind the throttles. if you're conscious about holeshots and airing the boat, you usually won't have problems. the added weight may become a problem for the boat too with the bbc. it may change the handling and reaction to steering. you will also have to have a complete 454 for all mounting and parts, which could get out of hand quickly. on the other hand, you have a good 350, and the stuff to do up a 383. those strokers can pump out some massive power and relatively easily make 450hp. the motor will be lower torque than the bb and a lil easier on the drive but still give you the wtfo power.

A mild/stout 383 is what I would do.. It's a small boat, you can ring 400 hp out of a 383 no problems.. Not to mentions everything for them is cheaper then a BBC... No hole shots, and actually drive the boat, don't leave the sticks to the dash when you air the boat, you shouldn't have issues.. We are currently doing a 355 on 12psi, going to run it through a alpha, on my 202 stinger to see how long it will last.. Ran a solid 2 seasons, beat the hell out of a alpha good, before it broke with a 400hp sbc, when it did, it was not the shaft breaking, it looks like it was caused by a existing problem that we never seen.. Just my op, but sb's will surprise you if you do them rite..

John jr

I would suggest a 383 with a light weight 12 pound flywheel. The lightweight flywheel will be much easier on the drive.
For the price of a changing to 454 you could buy small block aluminum heads, aluminum exhaust manifolds, aluminum circ pump (and of course an aluminum intake manifold) and with that 12 pound flywheel pull a bunch of weight out of the back of the boat. It will jump up on plane much faster than with a fat (Big) block!!!

Invest in a good roller camshaft and you will have something that runs like a big block but will be 100's of pounds lighter.
Dennis Moore

I recently just went through the same dilemma. I chose to rebuild my 350 Mag and utilize my EFI system, accessories and exhaust. The real killer is the amount of money you have to spend on exhaust once you use a big block. That added significantly to the build cost. The big block also presented unknown issues of fitment within the engine compartment.

I built a brand new motor (block, crank, rods, pistons, heads etc) and utilized my old EFI system, valve covers, GLM exhaust, accessories etc. I ended up with a 377 and installed a fairly stout hyd roller cam. The power increase is SIGNIFICANT over the old motor and I'm just in the initial tuning stages.

Some people use a 3.875 crank with a 5.85 rod and make it a 396.

well im sold then ill do the 383 it seem to make more sense to me. right now my boat only runs about 35-40 with the 350 i have it has about 350 hrs on it so i know she is gettin tired i have to run it at wot(4500rpm or so) just to get any where and that yeilds me about 35 mph. im looking to get the boat to run in mid50's to low 60's. im always easy on outta the hole take offs so i think i can baby the drive for a few seasons.

its a tbi motor so can i reuse the tbi? or do i have to switch over to carb or multi port injection?

ill look to do the light flywheel as well.

also what style piston should i use

That might take a lot of HP.

I second that motion

350 to 383 is night and day, but it will take a BBC with a blower to gain 25mph! I really think you'll like the 383

ok i was afraid of that i was gonna have to go big block to get some mph outta her what kind of speed increase do you think ill get with the 383?

Build a 383 right and that boat of yours will do hi 60's or 70.
Dump the tbi and carb it.
Dynoed my 383 at 491h/498t. Boat equipped w/ Alpha.

how long you been pushing it with that alpha tmdog? how big is your boat

also what prop sizes are you guys running on your alphas with the 383

What gearing is the alpha??


John

What HP are you running now ?

That seems like VERY low mph. Unless that motor is hurt I agree you are going to need A LOT of hp to hit 60mph.

Are you running an aluminum prop?

383 is mounted on a 18 Donzi and been running 400+hp for the past 4yrs. Alpha has a 1.5 gear and turning a 25 Hydro.
Building a solid and reliable eng. is critical and very costly. Did I mention costly.

gear ratio is 1.5 it has 300 hp boat is super heavy im running a 3 blade aluminum prop right now dont remember pitch off top of my head. it will turn 4500 rpm wide open all day long maybe its not proped right? goto a 4 blade?

If you build a motor big enough to go fast, the drive is going to scatter. A 425 HP 383 is going to run better than what you have, but still not fast. Your boat may start eating drives even with the 383, and a 4 blade would make it worse.

well ill prob just swap out the alpha to a bravo what would be a real world mph increase with a good built 383?

Aluminum prop flexes a lot and looses speed but 35-40 mph to me seems very low. Even if a stainless prop got you 45mph you'd need 550 hp just to break 60! Unless your current engine is hurt.

so i finaly checked speed with gps and boat runs at 45 mph turning 4600rpm thoughts on where to go now?

I agree 100% !

If your engine and tuning and prop is right on, I would not look to add 100hp as that won't do anything much.

300hp now at 45mph means you'll need a quazillion more hp to even think of getting into mid to upper 50's.

Before throwing $$$ at the present combo for now, I'd call Sleekcrafter and find out what your boat runs with a 330 7.4L and a 385hp 7.4L. This will answer the question if feasible to up the power or not.

300hp at 45mph. yikes !

NO MATTER WAHT....TOURGE IS TEH KEY..NOT HP ..so any BB IS BETTER THEN ANY SB !!!!

hope that helps

sb is the yikes a bad commen? its a big heavy boat not sure on weight but shes a big girl. was full of 60 gal of fuel 2 full ice chest and 3 people.

yikes = ouch

300hp for only 45mph.

Means you'd have to step up power a ton (okay, a schitload...lol) to gain another handful of mph.

Say if you had a lightweight 18-21ft boat with a good running bottom, the 300hp may be running 65 or so mph. If so, then an extra 100hp would mean you'd run alot more addt'l mph over the 300hp baseline. Starting at 45mph means that your boat doesn't want to run fast and will be a lot more resistant to running faster.

=====================

Could you beg/borrow some of the more normal stainless steel props to see what it really can run as is ? Aluminum usually costs a bunch of speed.

If you could run say 50-55mph with boat as is, then adding more power would be more worth the results.

Sorry...sometimes hard for me to type my thoughts.