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Thread: 1st Post, Want more speed.. HELP

  1. #1
    Chillin The Most
    I need some info. I have a mint 1995 Rinker 236 Captiva Cuddy, about 125 hours on original 454 carb. 300 Hp motor, 21 pitch SS mirage quicksilver prop. It runs 63 mph @ 4600 rpm.It also has Baja SS corsa through hull exhast. I don't need the fastest boat on the river, however what do I need to do without spending a fortune to get this thing running around 72-75 mph. My local Rinker dealer says it can't be done. I told him he must be crazy because HP means speed.
    Any suggestions would be greatly appreciated.

  2. #2
    ratso
    Dude...Money=Speed. Make the commitment to the money first...Then you get there.

  3. #3
    Chillin The Most
    I know money = speed. I said 72-75 mph, although 80 mph would be nice as well. Money isn't really a problem, but I don't want to get $20.000.00 tied up in my motor like I've read on some of the other threads where some people have 800-900 HP motors. What I would like is for some of you experts to tell me how much it will cost and what I need to do to achive 72-75 mph & the same to reach 80 mph. Thanks for the reply! Waiting to hear more!
    Mike

  4. #4
    Havasu Hangin'
    Any other guys going that fast with that hull?
    Maybe the dealer was trying to say that your bottom (the boat's, not yours- sorry) was not designed to go that fast. There are alot of boats out there that no matter how much HP you dump in, they still drag like an anchor is out. For example, some boats have a little hook built in the bottom to smooth out the ride...
    Also, with boats that wern't meant to go that fast, funny things can happen. Maybe the balance is not set up for the hull to fly. Maybe a chine walk develops.
    Either way...I'm assuming that's a fairly heavy boat, so you'll need ALOT of money...er...HP (torque) to get to 75MPH. According to my unscientific intuition, a blower and 150+ ponies are in your future for 10MPH. Also, you may need better steering...
    http://www.planetsmilies.com/smilies/happy/happy25.gif

  5. #5
    crmax
    you will need to change your heads from oval port to square new cam intake and carb, 23" or 25" prop should get you close to 70mph however the rods and crank in that motor are not the best and you have to keep your rpms under 5000 for sure. you may need to do some upgrades to your steering. as far as your hull goes it should make it. make sure you dont wax or paint the bottom and adding trim tabs if you dont have the will help. if you do alot of the work yourself it should cost $2000-$3000

  6. #6
    Costello
    Why don't you try just one thing at a time? That way you would know what's really working without the heavy investment. Here's what I would do right away and I think you will be impressed with the gains. Go to an MSD distributor and box, and change the intake and carb. You don't even have to buy these parts new if you want to really keep it on a budget. I would also agree with Crmax on some trim tabs,. In fine, I would agree with Havasu Hardcore on the hull design. If this is the Rinker with a cuddy that I am thinking of, I'm impressed that it does 63 mph right now, that's pretty damn good! Again if this is the style of hull I'm thinking of it was NOT really made with high performance in mind, but rather comfortable pleasure boating. This further supports my "one step at a time" approach and HH's theory about not taking it beyond it's limits, and keeps it pretty affordable at the same time. If you do end up changing the heads later, you'll already have a carb that can run with the bigger heads and the proper ignition.

  7. #7
    Chillin The Most
    Well thanks for the info. I guess I will have to do the old spend and hope theory. As far as the hull design, it is made for high performance. I've seen two of them on the water and a guy on shore with a rader gun clock them at 90 mph, but these guys won't tell you a damn thing. I know they got a ton of money in them but they won't share any info. I don't need to keep up with them though. Just interested in another 10 mph.
    Thanks,
    Chillin
    [This message has been edited by Chillin The Most (edited March 17, 2002).]

  8. #8
    hulshot
    chillen, oval port heads for you will work fine, you wont be spinning over 6000 rpm. Oval heads will work up to 6/6500. They should help by producing low end torque. If I was in your position on a buget, which most of us are anyway, I would sugest cam, carb, intake, ignition and an upgraded exhaust. you dont need to go radical just get some combos that work, ie... MSD, Gil risers or any after market riser and possible manifolds, good aluminum dual plan intake, 750 carb, and maybe a hydrolic roller cam with a mild lift and duration to keep the power where you need it, 2/5000 rpm on a 108 ceterline. One thing is your motor may only have 8.0:1 compression, if so you could opt to bump it to 9.1/9.5:1 and still run mid grade gas if you chose to. all this may cost about 3500, for new stuff if you shop around. just another opinion.

  9. #9
    Chillin The Most
    I don't mind spending 4 or 5 grand. One person says oval port and one says square port heads, hey everyone which is it?
    Mike

  10. #10
    hulshot
    chillen, oval port heads generate greater low end torque than rectangle port heads. the ports are smaller so the head can generate more velocity through the ports at a slower speed to help the torque. rectangle ports need some assistance at lower rpms due to their large volume runners, they are great for spnning 6/9000 rpm where an oval cannot get enough air through the smaller ports for high rpm running. Think about this, why does GM put oval and penut port heads on big trucks, To generate the best low end grunt to haul the weight. You dont see them spinning 6000+ rpms they dont need it, they will generate sometimes over 500 ft lbs of torque at about 25/3000 rpms. hope this sheds light on your head delima.

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