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Wanna Max hp out of a HP500

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Old 02-17-2007, 11:41 AM
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Wanna Max hp out of a HP500

Hi I need to see if anyone could help me out here.I got a New HP500 short block..9:1 comp. blue printed and balance to 15000rpm.. tricked 502 cast iron heads, and A Holley strip domator manf. w/ Holley 850.

Now what I need to know is what kind of cam should I use ?
Now let me but the final ingredient in the mix.. ready its going into a 1988 Sonic 31 ss yes its going to be the a single motor in a 30ft 6500lbs boat..Im not trying to set a new Kilo record or nothing but would like to see 50mph.. my transom and stringer work is done by my Glass guy and He said im good for 2000hp hung a Imco Bravo1.

Well we see what comes up on this post of mine. I know that 90% of you guys are way more knowledgble than I could ever be so help this mad man out<<< to make it worst my full time boat is a 2000 Bayliner 285 w/ a small block... Im the KING of Under powered boats
Thanks
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Old 02-17-2007, 12:13 PM
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I am no "expert", but (1) engine in a 31' boat is going to be hard on that engine.
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Old 02-17-2007, 01:02 PM
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Hope when I had the Glass work done they needed 1 of my tired 330hp 7.4s to setup the drive geometry..so when it was done I put it in the water to try it out (this motor was very very tired blue smoke the whole time it was running) results:
it sat 4" higher in the rear
it planed in the same amount of time as the twins
3200rpm = 28mph
4500rpm = 39mph
Beat on her for 4hrs burned 70gals (twins would have burned 200gal)
She tracked good even with a sloopy gimble housing..

So Im hoping with about 500+ hp I could get my cruising speed up to say high 30s maybe 40s


Every1 involved it this project thinks Im crazy but they where impressed


now back to the cam shaft dilemia
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Old 02-17-2007, 01:39 PM
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Originally Posted by HotFastBoats View Post
Hi I need to see if anyone could help me out here.I got a New HP500 short block..9:1 comp. blue printed and balance to 15000rpm.. tricked 502 cast iron heads, and A Holley strip domator manf. w/ Holley 850.

Now what I need to know is what kind of cam should I use ?
You know all this weight is gonna be really hard on the outdrive?

Are you looking to but a blower on this motor, or stay NA? If you want NA, and 500-550 HP, just look to the 525 EFI cam, which is a Crane 168741, but on a 114 LSA instead of a 112, as the Crane is. Depending on how much work you had done to the heads, there is your high 500 HP engine. If you want, you can talk to some of the "custom" cam guys, but you are gonna be looking at only a few more HP which won't show on the water. Or just call Summit Racing and order the Crane.

You only asked about the cam, but of course you need good exhaust, intake etc. Plus you are going to have to do a bunch of prop testing to see which is correct for a boat that was designed for twin engines.
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Old 02-17-2007, 01:44 PM
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keep posting your next results! Curious to see your max speed. Hope it does not hurt too much (single engine 30 foot boat) your resale value...
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Old 02-17-2007, 01:50 PM
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Sounds like a good ideal. A lot less weight to carry, 1 less drive drag to overcome. Less maintance cost providing the motor is built right. If anything, the $$$ saved from not having to have a a second motor and drive can be put towards a beefier drive. Then you'll have your bases covered.

19yr old boat, I wouldn't be to conscerend about the resale aspect.
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Old 02-17-2007, 01:54 PM
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keep posting your next results! Curious to see your max speed. Hope it does not hurt too much (single engine 30 foot boat) your resale value...
I will thanks.. I couldnt give this boat away when it had twins. the market is so flat no1 wants a 1988 gofast. I fiqured its paid off so maybe when the Oil fields start to dry up Ill still motor around with the BIG sound and look like a millionaire.
I quess I like to be different.
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Old 02-17-2007, 04:11 PM
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Beat on her for 4hrs burned 70gals (twins would have burned 200gal)


So Im hoping with about 500+ hp I could get my cruising speed up to say high 30s maybe 40s


Every1 involved it this project thinks Im crazy but they where impressed


now back to the cam shaft dilemia
1) The most fuel you would have burned with twins would have been 140 gallons and you would have going a lot faster and covered more distance

2) I'm with Every1 on the crazy part
The single engine will have to work twice as hard and the drive will be stressed.

3) You need head flow numbers to maximize the combo. I would lean toward a smaller cam that makes a lot of torque vs more HP at higher rpms.
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Old 02-17-2007, 07:03 PM
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when i tested it with the tired 330hp I was using a 21p mirage prop. which my buddys though it would be to steep but it turn out to be pretty close for that motor/weight
Got lucky on that.
now this HP500 does any1 have the specs on this cam? Merc wont give out the specs and they want $1000 for it.not that Im cheap but if I could get a Crane for say 300 It would free up more money for other parts.pics at Boaterscove. com/sonic/index.htm
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Old 02-18-2007, 12:44 AM
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now this HP500 does any1 have the specs on this cam? Merc wont give out the specs and they want $1000 for it.not that Im cheap but if I could get a Crane for say 300 It would free up more money for other parts.pics at Boaterscove. com/sonic/index.htm
HP500 Carb cam is a Crane 169611 222/230 576/598
HP500 EFI is a Crane 169621 230/236 598/610
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