Getting some performance out of this thing...
 

Hey guys, what would I need to do to get my 29 with twin 350's to around 85 mph? All I really know is that I'll need hydraulic steering. I'd like to stay away from superchargers if possible. I thought about stroking them to 383 and getting some aggressive head and cam work but I have no idea if that will do it. I have about 25K to spend. I also need help about headers and what the Bravo 1's can handle. I'd like to stay away from having to do much to the outdrives because I know that can get really expensive in a hurry.

Thanks,
Dustin

are your 350s mpi or carbs

His boat is a 02 so they are MPIs if it is original. Dont know why you want to stay away from huffers? Whipples would reliably get you close to your goal and stay within your budget including the hyd. steering.

Yeah, reliability was my main concern. I have just always assumed that if you could get the same power with bore and stroke it would be more reliable. However, I wouldn't be opposed to the idea if I knew that owners have had success with them. That's kind of why I wanted to ask here first before talking to a builder.

Your power will be more reliable (IMO) with chargers. You'll have to build and RPM the hell out of those small blocks to get them going that fast. RPM's kill motors... Chargers will help get the power up and keep the R's down... Run 'em if you can afford 'em!

how fast are you running now? figure you'll need aprox 200hp per side to get 10-12 mph. Bore and stroke won't get you 200 hp so I hope your already running over 75!!

will the rest of the engine hold up to the added power of chargers does it strain the rest of the stock parts on the small blocks

Guy near me tried to do the same with a P-29 T/350's, spent a ton and got near 80. Never did bis with the builder (good or bad) but it was a nice package and should've performed better...

It's all stock, 67 mph on the GPS and each engine has 220 hours. I've been reading some about the Whipples and it does seem like the technology has gotten a lot more advanced since I last cared to do any research, I guess I should expect that things can get a lot better in 10 years. One thing I didn't think about at first is that no matter what the hardware costs, I imagine that the labor charges would be much less to install the supercharges than bore/stroke. I do have a set of Revolution 4 23 pitch props. A friend of mine gave them to me after he sold his boat and put his old props on it. I didn't install them because I knew my boat didn't have enough power to turn them as his had twin 525's.

If your stock running 67 on 300hp SBC then you'll need to get them to about 650-700hp each to hit 85......pushing 700hp would likely kill the drives quickly unless your real careful.

FYI: A whippled 500efi barely makes 700 so you've got your work cut out for you.

1st you need to find out if your motors are cast cranks also what beam do you have is it close to 8'? if you have 25000 to spend, thats good for headers and either building your sm blocks to 500 hp or 600 with blowers, being a 02 29 that should get you to 80 to 85 with a drive height change either 1'' or 2'' shorties.I bet a pair of 671 blowers would work and save money. cause 67 does not sound right and you should be able to tyrn those 23 revs stock. check your prop shaft height from bottom and post it should be 4 to 5 '' if its 7 or more you are loosing speed there. that 29 was a light boat don't you have a step also, remember theres 02 boats with heavy big blocks running 78 to 85 with carbed or injection 500hps or 525s in the 35 to 38 ft. .

for small blocks theres a few guys that are good with them I would think 4 to 5 grand for na rebuilds/ each blowers 3500 to 7000 plus 3000 to freshen up each motor, headers 4500 to 7000 for both motors, 2'' shorties cases two sets 3600 or6000 with new shafts, so na motors,headers , drive cases=16000 low side high 24000. blowers low side =21,000 high side =31,000 plus .

This might be one of those times where the saying "if you want a faster boat, buy one" comes into play. I don't know how in love you are with the boat you currently have, but you could likely find a 29' - 31' with hydrolic steering (another cost you're going to have to fork out that AIRTIME didn't factor in... at least I don't think he did) and big blocks that you could build up to 85mph much cheaper than your current build/boat.

Just a suggestion... I know I see built boats all the time with $10 - 50K dumped into them that barely sell for more than a stock boat.

I know that I would love to have a faster boat, and I can afford one. However, it doesn't make sense for me to dump that kind of cash into my current vessel so I'm avoiding it as much as possible... you'd never know by the two 500Hp 502 blocks on engine stands in my garage, but I keep telling myself... "those AREN'T for the Baja... those AREN'T for the Baja..." and I'm hoping to actually believe that before I do something rash!

:coolcowboy:

It would probably be like cramming 10 pounds of s**t in a 5 pound bag but:
http://www.offshoreonly.com/classifi...o33211-en.html

How does the saying go? There is no replacement for.....displacement.

i have a 350 . 30 over mag carb set up on my 22 scarab at 8 lbs of boost on my procharger on my second season with an alpha drive still going strong. boat straight hauls ass. but if your going to go the supercharger route make sure you get headers i have stainless marine on mine. also my thunderbolt ignition wouldnt work had to go msd . my boat runs in the mid low 70's depending on load and water.

i like the procharger set up better over the whipple twin screws are so hard on the drive lines from the fast tq curve.

plus the whipples with intercoolers are quite pricey also the whipples make more heat than centrifugal blowers do, but at the end of the day its all about personal preference.

ltsp is correct all you can get out of that stock 29 is 67-68 how much mph would you gane if you raised the props up 2'' one thing i tried my k planes had stops in them would't go up far enough boat was always running with some tab haven't got the results yet til weather gets better but hoping to gain some mph we'll see. engines are a little tight with 7'6'' beam

Yeah, I' have thought about just buying another boat but if I went that route the one I would want would cost about the same as my house. I could afford it but I don't like the fact of having another 15 year loan. The 02 is paid for and is in excellent shape so putting 20-25K into it doesn't really seem like that big of a deal to me. I'm not really worried about resale after the mods, I didn't buy the thing with the intention of making money selling it. All that being said, the 85 mph was just an arbitrary figure. I'm going to go with the superchargers and see how it does, I mean, after that it should run a hell of a lot better and if it gets to 80 instead of 85 it's not going to break my heart. I've been trying to do some research on headers but I'm getting a lot of mixed results. I've heard from some people that the superchargers need the back pressure from a exhaust manifolds but common sense tells me that headers always offer an improvement in performance. BTW, I put the Rev 4s on it yesterday and tried them out. 62 mph at 3900 rpms. It hurt top end quite a bit but for what its worth it did seem to have better acceleration.

good luck with the chargers i think the 29 is a great boat let us know how you make out with the upgrades and when do you think you will be finished your project

I have done the pro charger route and you will see 77 to 78 out of that set up I also did some head work and a bigger cam the best I saw was 82 with a 3 blade prop that boat goes slower with a four blade than a three blade plan on spending a lot of money on the bottom ends of your motors they are all cast and will break after time been there done that if I had too do it all over again I would buy a bigger and faster boat It took a sh!t load of money and I will never get it back out of it I also took the super chargers off the boat and now back to some what stock motors they dynoed at 410 a side with the better heads and bigger cam still playing with props but I should turn a 25 three blade and get about 75 to77 I would think. Super charger are for sale to buy one get one free

I did prochargers on my 98 twin 350 29 scarab. Best before was 67mph and best after was 80. Most of the time high 70s. Ran mine three years with zero problems. Loved them, very efficient. 26 pitch to start with and 28 after. Great cruise speed of almost 50 mph at 30000 rpm. I did haave stainless marine headers and thats it.

Prochargers do make some power, but the Whipple set-up is way better engineered. Talk to Dustin at Whipple and he will let you know definitely wether you need to swap exhausts or not.

I understand where you're coming from, but for my money I would look into something that is already done like this one:

http://www.offshoreonly.com/classifi...o26308-en.html

Has the hydrolic steering and superchargers already, it's a bigger/better boat and if you sold yours for a reasonable price you should have much less into this one that your current rig built, not to mention that the ceiling on this boat is much higher if you want to juice up the speed down the road.

It's one thing to not plan on making money on buying and selling a boat, but it's another to throw away a ton of cash trying to go fast for 2-3 years. It's not uncommon to do and if you want to get over 85-90 it seems that throwing away a ton of cash is inevitable, but I would try to mitigate it as much as possible...