Formula 233 Registry

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i have a 83 233 that im looking to put a 400 hp small bock in what kind of speed am i looking at? my goal is around 70mph+. from what i have read as long as i prop it right i should be able to get high 60's with this hp. is that true? this is just going to be a temp set up i plan on doing a 500+hp big block with a bravo and a surface drive conversion in the future but for now im just trying to get in the water and get going. my friends are running 55-65mph in a few foot smaller boats with around 260-300hp. so just doing my math running this kind of power all though im in a slightly bigger boat i should be able to keep up? also what prop does any one recommend i was thinking around a 22-23 my friend is running a 20ft baja with a stock 260hp small block and hes hitting around 65-70mph with a 21 pitch prop at wot. does any one have any advice for me on this?  my plan is to run a true classic in several local poker runs here in san diego. i want to play with the people in the 100,000+ boat range and make them go wtf when im next to them. also does any one know what kind of power i can run threw stock manifolds i am running them threw transom. i dont want to buy headers because this motor isnt looking like a long term set up.

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hi 82 formula. good to see another speed freak on this forum!         last question first. in my opinion, if you're going to build a serious performance engine, exhaust should be your FIRST upgrade. not only is the stock stuff restrictive, but if you're running a big cam (high duration high overlap) you'll have a reversion problem at low rpm's (i e sucking cooling water back into the engine thru the exhaust.) in my stainless marine exhaust, the fully- jacketed tailpipes mix water with exhaust 6"in back of the transom. i'd say stick with a pretty much stock engine until you're ready for the ' killer' motor.       as for speed, don't know what  your boat weighs, but my '79 233 interceptor weighs 5480 lbs (according to the buc book) and has seen 68 mph on gps with a borrowed spinelli 4 blade wheel. (pitch around 23 "- you never know for sure with a spinelli)  for power, i have a built .030" over 454 putting out maybe 500- 525 hp (not sure, never dyno'ed. ) good luck- hope this helps!                                                                                                                                     
hi richard it helps alot. as for the caming of the engine i learned about that with my last boat which was a 73 south wind jet boat. i was running a 560hp 402bb that was built. for the exhaust i went with a set of hyperf logs to risers, i had a couple friends running bassett's that with the wrong cam would have a major reversion problem. i know the "logs" or manifolds restrict you a little on power they have less of a problem with reversion. are you running a alpha or a bravo drive? ive read that your pushing it to push more then 350-400hp threw an alpha. i have seen a couple people talking about running 600hp threw a alpha so i am planing on a 400-450hp small block. i looked on i  boats and they say my boat ways in about 4150lbs. depending on how the motor runs i was thinking a 22-23 pitch prop should push me around the 70mph mark. i am also glad im not the only speed freak on here ether.

It takes a lot of horsepower to drive a 233 over 70mph.  They are very heavy.  I think you might save a lot of time and money if you save up for the killer motor.  I'd recommend you go to a bravo for reliability.  I'm using Alpha's but I'm very careful with them.  You'll need 23" or more.  Engines are nothing but air pumps so good exhaust is critical.  Good luck and keep us posted.

has any one used a surface drive on a 233 before? if so how did it do?
i agree with david-- it takes alot of hp to make these pigs fly!! as for my 233, i'm not running alpha or bravo- i've got an old TRS drive. from what i understand, the drive's pretty much bullet- proof (at least if weight equates to durability.) my weak link is the trans (shorty- style merc- rated for 330 hp.)the guy i bought the boat from 15 years ago told me his trans guy said "don't bust it out of the hole"-i never have. i assume you currently have an alpha on your 233- there's no way it will live behind a built big block. as for a hot smallblock, a friend of mine had a 19' caribe with a 400- 425 hp 350 alpha (a boat much lighter than our 233's) that ran in the mid 80's. he always ran the best synthetic oil he could find (i think it was redline) and always started the boat in gear to eliminate the gear clash of shifting. his alpha lived for probably 8 years- not too bad!! as for converting to bravo, from what i understand, the verticle distance between the drive input and output shafts is 1" more on the bravo- putting the prop deeper in the water (not good for increasing speed.) the only other alternative is to go with a 'shorty' lower unit or redo the transom and raise the drive. as for surface drives, i have no experience with them- never even SEEN one on a single engine boat.for more info you might want to try "offshore only .com" (you know- where the guys with the $100,000 plus boats hang out!) hope this helps.

Good evening Richard!


I was just browsing through some of the various threads on this site and I stumbled into this one.  The "Surface Drive" portion of this discussion is what caught my attention.


I too am a speed freak but I plan on "Settling" with this particular boat.  I am planning on running this boat offshore and along the Colorado River and Lake Havasu.  With this in mind, my goal is to build the hull to ride smoothly through rough water.  That being said, top speed will most likely be second or third on my list.  Rough water handling and durability are my primary goals.


With regards to the single engine surface-drive installation, I remember "Schiada" built a single-engine 21' River Runner years ago.  I think this hull was set up with an Arneson drive but I cant remember which drive they used.  I recall the speed and handling to be pretty good though.  If you enjoy performance boats and know anything about Schiada, you know that they build their hulls as good if not better than anyone else in the boating industry.  They are rock-solid boats and they are capable of handling whatever amount of horsepower the lucky owner can afford.


Sorry to go off on a tangent; it was just an interesting topic in your discussion.



82 Formula:  What was your decision?  I'm looking at building a 500-550hp 383 stroker due to engine block weight and cost of performance parts.  Also thought it would be interesting to let you all know Ford has an Aluminum 302 block that would make an ideal performance engine for our rigs.

Originally I was planning on finding  a reman Bravo one and have instructions to do so but didn't realize it will drop 1" lower if that's the case I will be replacing the transom and at 30 years old it's probably not a bad idea.  Can someone help educate me on the exhaust.  I live in Minnesota where it's illegal to run a switch to change from hull through so I have to do one or the either.  Personally I don't want to listen to that noise for 1/2 periods at a time on open water.

Surface Drive system would let the 233 operate reliably with a High HP single engine.

As mentioned, the Bravo attachment system could work. Running twins in these hulls eats up a lot of room, (V8 twin) and not as efficient.

X Factor could play a part as well. I have a TRS, and one factor is the prop tech is better now, so maybe the TRS could get out of the water a bit. But you still have 2x 90deg power changes, and a Bravo would be expensive to run at that power level.

Of course...the drives are all rated at Tq, not HP. So I you jack up your max RPM to 5500, then the drive gets it easier. So does the engine.




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