More HP

[Kopasetic]

What the easiest way to increase HP, I've got an '87 Chris Craft Scorpion with 350/260 HP and Alpha 1 drive. Now that the boat is away, I'm trying to budget for spring, ideally looking for bolt-ons, any ideas, carbs, ignition, etc, where do I begin. Love this forum, thanks in advance

 

[mkast]

Re: More HP

Bolt on a big block and a Bravo 1.

 

[Bondo]

Re: More HP

Originally posted by mkast:<br /> Bolt on a big block and a Bravo 1.

Ayuh,..........<br /><br />That'll Easily fit in a $10,000.00 Budget...............<br /><br /><br />Kopasetic,..... I suggest alittle Seat Time in the Archives here at iboats,...........<br /><br />Your application is Near it's Upper Limits from the factory,.........<br /><br />Any Real, Noticeable Improvements in Your HP picture is going to come with an Extreme Expence...............<br /><br />You'll do better by Tuning,+ Tweeking the setup you Have to get It's Best,..........<br />And be Happy with It,........

 

[Weirdwalt]

Re: More HP

Dont listen to them gropasetic. They're wrong wrong WRONG! A Bravo III would be best behind that big block.

 

[mkast]

Re: More HP

Originally posted by Weirdwalt:<br /> Dont listen to them gropasetic. They're wrong wrong WRONG! A Bravo III would be best behind that big block.

I have to admit... I laughed!

 

[QC]

Re: More HP

LOL @ WW. But wrong, wrong, wrong, the Bravo 1 would be faster . . . And before it blows up, the Alpha is even faster than that.<br /><br />Kopacabana,<br /><br />1) Listen to Bondo<br /><br />2) You could try through the transom exhaust, you might pick-up 5 bhp and about .2 MPH; not 2, .2 . . .<br /><br />3) Listen to Bondo

 

[Weirdwalt]

Re: More HP

Hey! I didnt say faster, I said better! But hey while were spending mopeasetics money why not just go all the way?<br /><br /><br />

 

[QC]

Re: More HP

That's right, HE was looking for speed, you're just spending his dough. Got it.

 

[Haut Medoc]

Re: More HP

It sure is purty though

 

[FreeBeeTony]

Re: More HP

hey Bondo......how about the Vortec conversion we all know and love....

 

[Bondo]

Re: More HP

Ayuh,............. If 1 of those fell off a truck in front of the house,...........<br />I'm Sure I could be convinced to install it in My Boat,...... Even if it Isn't Black.........

 

[Kopasetic]

Re: More HP

Thanks guys, I've got through hull exhaust now, top end is around 40 mph, I guess it is OK. Just always looking for more, Good responses though.<br />Regards

 

[rodbolt]

Re: More HP

bondo<br /> the boys in black are working on marinizing the chysler V10<br /> while I am spending other folks money lets spend a bunch.

 

[pbv]

Re: More HP

Read in a boat mag a while ago inexpensive adds to get a little boost in hp. Two mentioned where less restrictive/larger flame arrestor and synthetic oil. comments?

 

[Weirdwalt]

Re: More HP

Man that V-10 be an awesome marine engine. So would the Ford Triton if they could keep the spark plugs in the heads.<br /><br />PBV those "tips" might get you .1 to 1 mph. I really doubt you would even notice a difference.

 

[Bondo]

Re: More HP

Originally posted by pbv:<br /> Read in a boat mag a while ago inexpensive adds to get a little boost in hp. Two mentioned where less restrictive/larger flame arrestor and synthetic oil. comments?

It takes Serious HorsePower to make Any Noticeable Differences,.............<br /><br />You can spend all the Time,+ Money you want on these Trickets & Tricks,..........<br /><br />You're Not going to See, or Feel Any Difference.........<br /><br />Roughly,..... You can figure for every 20Horsepower Added,.....<br />You'll Gain 1, maybe 2MPHs,......... That's It......

 

[SeaRay24Sorrento]

Re: More HP

Start with looking into Vortec heads and if you have FWC, Edelbrock or others make a nice aluminum marine carb/intake manifold setup along w/ a K&N flame arrestor. Take the rest of your bugeted $ and save it for gas! This winter that is the route I'm going, along w/ building the engine to a 383 stroker. Can't wait to blow up that Alpha outdrive this spring!

 

[paulie0735]

Re: More HP

You really need to ascertain how healthy your engine is before you going throwing ‘go faster bits’ at it! Do a compression and leak down test. If it comes up ok, that is within 90% of original epecs and all cylinders are fairly even than you have a reasonable base to work with. If it all comes up ok and depending on your budget than a Hi-Performance inlet manifold and carb will help. As will having the distributor re-graphed to suit your application and premium petrol. The factory setup at 260hp is near enough to the limit with standard parts. These engines were designed to run hard all day and stay reliable, any changes you do is going to tax it and the leg!! The above suggestions should get you around 280hp from a healthy 350. Going the cam and head route will shift your power peak up the rev range. It will give you more speed if its propped correctly but you may find it lacking a bit of bottom and midrange which is where you need the power most.<br />If you’re dead keen to go faster than buy a faster boat, in the long run you’ll save a lot of money.

 

[FreeBeeTony]

Re: More HP

Hey Paulie..........I recently converted my SBC to a Vortec........why would different heads move the power peak up the rev range?

 

[Weirdwalt]

Re: More HP

Ya know Dopeasetic, I've thinking of building a stronger motor to turn the next prop set up from mine (From a 6 to 7 Stainless Duo props). I have a stock 5.7 just like you. So first things first in order to build what you want you must first start with a good foundation. If the 5.7 you have already is a 4 bolt main, that's great. If not you might try finding one. I tried, and not much luck. You can certainly buy them but we are trying to stay within a reasonable dollar figure. E-Bay lists a few and there's even a '72 block for sale. <br />Then you have to worry about heads. Vortecs wont work on the older 4 bolt blocks, but you might be able to find the old 2.0 intake heads that will. <br />You can convert a later motor to 4 bolt main with a relatively inexpensive kit, but you will have to pay a machine shop to drill those for you. No matter since you should be using a machine shop anyway for other things. But it sounds like you were asking about the bolt on route for a little more hp. The problem with that is on an automobile you will feel 20 hp in the seat of your pants, but on a boat it's barely discernable. Boat engines work so much harder than auto engines. Will all the water drag you need 50 hp just to notice any difference. You say you're getting 40 mph, I imagine you were hoping for 50. That will take a massive horsepower increase which I suspect your wallet isnt capable of. All the bolt on auto tricks will get you maybe 1-3 mph, and then maybe you'll pick up another 2 mph by experimenting with props. So there you have it. An easy 1000 dollars for maybe 5 mph. If you're propped wrong now you might get more. <br />We never did ask you what your current performance is, and we should be ashamed. What is your current top speed and what rpm are you hitting? Perhaps you can get a performance improvement with a prop.<br /><br />Do not change camshafts. You run the risk of water ingestion if you don't know what you are doing. Do not install automotive carburetors or distributors. Do not install large bore carburetors, that will cause a performance loss.<br />Free tips you can try are:<br />Advance timing a few degrees and run premium fuel.<br />Make sure the carburetor throttle flaps are opening all the way at wide open throttle. On the water have someone watch the secondary mechanism and make sure it opens. <br />Prop should be no more than 3 blade, steel is best for top end. Prop should be clean with no dings.<br />Check your hull for 'hook' at the back where the transom meets the hull and make sure it's flat. Check the hull for water intrusion. Don't laugh, it happens a lot. The hull starts soaking up water and the boat picks up weight and lots of it. It's more common than you think. <br />Once you've verified all those items you can experiment with props which is where your money is best spent. A prop shop will usually let you try out props for a nominal fee, usually 25 bucks. Sometimes over propping will get you a good mpg at cruise, and underpropping gets the engine up beyond rated wot and you pick up a few extra mph. Not really recommended but it's your boat. <br />Still not happy? Yank the engine out and build it from the ground up and gain 50 hp, or go the big block route and gain 100. The Scorpion is a heavy boat, but I think you ought to get better than 40 mph. I assume compression is okay?<br /><br /><br />