1987 scorpion w/ 454

[pipes]

Goodmorning.  I know that my scorpion 230 ltd is not a stinger, but this is the only forum that I found that has any knowledge on these boats.  I have a '87 230 with a 454/ 330hp,thru hulls, omc cobra outdrive with bennet tabs.  I have only found and seen one other boat with this setup.  Does anyone have experiance with this setup. I bought the boat and was told it had a bad head gasket and unfortunately it turned out to be a bad head.  So I have the 454 out of the boat and am in the process of a rebuild. It will be 425 hp motor with gobs of torque.  The guy I got th e boat from and the only other I have seen like this said that with the 454/330 the boat would top out at 58-62 dependinding on prop.  Here lies one of my dillemas.  I don't know what prop to start with and there is not one with the boat and can no longer get in touch with the original owner.  Any knowledge on theseon this boat would be greatly appreciated.
Thank you

[NWC]

I would get in touch with a good prop shop.  They should be able to get you a good baseline prop to sart.  There is one shop that I have heard of that has a loaner program where you can try several props to fine tune your setup.  Good luck with your boat and would love to see some pictures of what youre doing to it.

[stinger390x]

I agree with NWC to go see a prop specialist.
There are websites, such as Mercury , that have prop charts, but the situation here is that your setup is not stock...
The first thing I would do is get rid of that OMC and find yourself a good used Bravo. Parts are getting hard to find for OMC and when you do, they are dear! I had an OMC on my 210 many years ago and I had to change the ring gear on the drive every single year! (Not a good system) Universal joints are much stronger and a better drive system, especially for the torque that a big block will produce.
Back to the issue of the prop..... since you have a big block with lots of torque, I would recomend starting out with a 19 pitch and a maybe going to a max of 23-25 on trials. See what your rpm is and try to get the rpm to spin at WOT about 5300-5500rpm. Those big blocks should take the punishment with ease as mine spin at 5600 no problem.
A four blade would probably work well with that size boat but it would go good with a three blade too.
Another factor to consider is the X-dimension. If the drive is shallow enough you could even consider getting a "clever" althogh when I tried a set of those on my 260 they had no top end, but I think it was because my drive were too deep???

Hope that helps?

[jesse 314]

my sea ray had an omc outdrive and i really dont have too many complaints about it, it was the one right before the cobra. none the less, here in seattle we have a fantastic dealer that stocks tons of omc stuff. there name is seaway marine out of west seattle and they ship all over the country. so as i do agree that if you are able to upgrade, i would, but if not and you need stuff they are a fantastic outlet. reasonable prices as well. hope that helps

[pipes]

Just an update to this build.  Decided not to go with the big block for now.  The boat was originally a sbc boat and I happen to have a 375 hp vortec headed marine sbc (@ 5100 rpm) that was intended for a different baot.  I was thinking of starting off with a 19 prop and possibly working my way up to 21.  Any insight would be greatly apprec.  From everything I can read on these boats it appears that they will do 48-50mph with the stock 260 sbc.  I was hoping to see 55-60 mph with the fresh build.  As a general guide it seems that it requires 10 hp for 1mph gain.  If that holds true then 100 hp gain would give 10 mph which would put me were I would like to be.  Does that seem to be somewhat true.  I live on a lake that has a 60 mph speed limit anyway.  The boat will be used for wake boarding/water skiing/tubing and the occasional burst down the lake so I am a little confused on prop selection.  I was told the boat pulled almost 60 with the 454/330 in it and that weighed over 200lbs more. I know I am probably giving up some torque going back to the sbc but doesn't the weight differance compensate for that.  Let me know what you guys think.  Knowledge is better than guessing.

[NWC]

That sounds like a good plan.  Work to find the prop that gives you the balance between pulling and speed that you are looking for.  You might want to end up with two props.  One to get you out of the hole for skiing and a bigger pitch one for your top speed runs.

[stinger390x]

Glad to hear your going back to a small block. My 230 was a small block 260hp and it ran just fine.
The big block would probably scatter that drive!?!?!? Bravo's are built for anything over 400hp. Alphas will take some punishment but not for great lengths of time. As for that OMC you would tear the ring gear off the first time you opened the throttle?? I know mine was very weak. I changed mine every season!

You say you want to tow...waveboard, ski etc, then you need a prop with a good bottom end. Stay away from the 21-23 pitch and stick to a 19 tri blade for starters. You will get a better hole shot with a smaller pitch especially if your pulling a tube and some people.

[pipes]

Well I picked up a 17 and 19 pitch prop for the boat.  The 19 is a good used stainless unit, and thats the one I am going to try first.  With a solid 375-400 hp vortec headed sbc powering the boat how close to 60 mph do you think I will get.  I only ask because I have some poker runs to attend this summer and would like to keep up with my friends. Thanks

[Shekmark]

Have you run your Scorpion yet with even the original motor? Asking because I would love some info on how this boat handles. I am looking at an 87 with a big block Ford, supposed to be in good condition. I like the way they look but know nothing about handling etc.