496 hop ups
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I have kicked around the idea of CMI or Lightning headers for the reported 30-40HP you might get. But, I also heard you might have to re-map the computer system to adjust for the flow. If that is the case then I will leave mine stock. My boat is light and fairly fast so I dont really need the extra $$$ spent on the upgrades. I did drop about $600 in prop work though. That help out tremendously.
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4,219 Posts
I waited and found a USED set of red Lightning headers WITH oxygen sensor port for 496 application. I was all set to buy new and this set came on here for sale. I haven't put them on yet, but that is your first step. Before you add anymore air IN, you have to be able to get it OUT.
I also have new in the box - Scorpion 1.75 roller rockers. Going to rollers will free up 10-15 hp that is being used to rub the stamped rockers against the stop of the valves, as well as the base of the rockers against the pivot balls. Going to 1.75 ratio will increase the valve lift slightly for better cylinder filling. Probably another 10-15 hp there.
Other than that, you can switch to full synthetics front to rear (including drive). Dyno tests show there is 10 hp there. I've already done this and gained a MPH.
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2,129 Posts
1) exhaust (dana, cmi, lightening, emi)
2) Contact Dustin at Whipple for a remap
3) rockers (check out beer30)
4) prop (get it labbed)
5) get more air to the motor...
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4,219 Posts
The heads are the biggest issue - or at least the area for biggest gain. You don't HAVE to go RAYLAR. You can have a good shop open up the stocks and upgrade the valves. A few guys here have modded the stock heads with excellent results. The Raylar heads would add the benefit of cutting out some fat. You would shed almost 100 pounds.
I also have some CompCams beehive springs to update mine with when the rockers go on. I have the conversion studs and all. Better control of the valvetrain should really help the motor. The stock valve springs are really weak and barely adequate for constant 3000-5000 rpm use.
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1,922 Posts
X2. Before my whipple, we picked up 2mph with the stock motor by simply opening the hatch 2" when running. I was amazed.
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3,136 Posts
should have did it the first time, it's just a little more OT
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4,599 Posts
Right on track with the 525 and a regular Bravo would live behind it if you were gentle with it.
Seriously, 100 lbs in a boat? Put less ice, water, and other refreshments in the cooler and a few less gallons of gas. Unless you're talking about running a drag boat through the traps, 100 lbs isn't going to make any noticible difference, especially in a big v-hull wave crusher like your Sleek.
Personally, I'd leave the 496 alone and run it and run it and run it. The more you mess with it, other than bolt on stuff like headers, the more you're asking for problems as you're running outside of the parameters it was designed for. Not to mention, you're talking about huge amounts of money to see 3-4 mph... I suppose it's all relative though.
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