496 upgrade?

[blythebound]

i've got a 21 ultra stealth with a fuel injected 496 and to be honest with you i want it to go faster. what would you guys do to make this power plant perform better? i'm open to all suggestions, you guys know a hell of a lot more about boats than i do. should i save up some money and replace the motor or are there some bolt on accessories or work that can be done to get it to run better. the reason i want an upgrade is i got my doors blown off over the weekend by a similar boat and i'm not in to loosing although it's what i'm best at. cheers

 

[Flat Broke]

The absolute worst thing you can do is say, "I want to go faster." The reason being is that you can never reach faster, because no mater the gains you make, you'll always want to go faster. It sounds like philisophical fluff, but it's an important concept when addressing performance modifications. Rather than faster, define exactly how fast, and how quick you want the boat to be (within the weight and performance constraints of the hull).

Once you decide how fast/quick you want to be, it's a lot easier to determine what you need to do. I don't have any first hand experience with that hull, or the 496, but as far as 20/21' jetboats go, you're going to need around 700hp at or below 6k rpm and a properly setup pump to get near/into the 80s.

I know John West had rigged one of the 22' Stealths with a pretty stout engine as a jet (it had a leather interior and was a maroonish color if I recall), so getting the numbers and setup on that boat would be a good starting point for figuring out the performance potential of your boat.

Chris

 

[Riverbound]

The absolute worst thing you can do is say, "I want to go faster." The reason being is that you can never reach faster, because no mater the gains you make, you'll always want to go faster. It sounds like philisophical fluff, but it's an important concept when addressing performance modifications. Rather than faster, define exactly how fast, and how quick you want the boat to be (within the weight and performance constraints of the hull).

Once you decide how fast/quick you want to be, it's a lot easier to determine what you need to do. I don't have any first hand experience with that hull, or the 496, but as far as 20/21' jetboats go, you're going to need around 700hp at or below 6k rpm and a properly setup pump to get near/into the 80s.

I know John West had rigged one of the 22' Stealths with a pretty stout engine as a jet (it had a leather interior and was a maroonish color if I recall), so getting the numbers and setup on that boat would be a good starting point for figuring out the performance potential of your boat.

Chris

This boat?

This one has a 750 HP 572ci Derberry motor, set back pump, etc. I have been in the boat mid 80's

 

[Flat Broke]

That is the boat I was thinking of. Out of curiosity, how hard does it pull from 60-80? Any word on the top speed? I think I remember seeing this boat in a picture sitting in the driveway across from wherever Zach picked up his DCM in Parker (Your place I'm guessing?).

Blythebounds 21 Open bow would need a little more power to pull the same digits, but 80mph wouldn't require insane (or at least what we consider insane today) hp.

Chris

 

[Riverbound]

That is the boat I was thinking of. Out of curiosity, how hard does it pull from 60-80? Any word on the top speed? I think I remember seeing this boat in a picture sitting in the driveway across from wherever Zach picked up his DCM in Parker (Your place I'm guessing?).

Blythebounds 21 Open bow would need a little more power to pull the same digits, but 80mph wouldn't require insane (or at least what we consider insane today) hp.

Chris

It's my buddy Gordo's boat, Im pretty sure the picture is from his driveway in Havasu. It accelerates pretty well. I know we ran neck and neck at about 85ish with 5 people in each boat. I dont think it has been any faster than that.

 

[blythebound]

thanks for all the input. i guess i should of asked, what are the steps i should take to make the boat perform better. i've got some money to put into it but i don't want to waste money. what i should of asked is, what would you guys do with a fuel injected 496 to help it perform better.

 

[Flat Broke]

I hate to sound like a broken record, but you still need to define a performance goal, or you will probably end up wasting money in the long run.

There are aftermarket heads, exhaust manifolds, intake manifolds, and camshafts available for the 496. But doing one or two independantly may not get you where you want to be. The pump and the motor have to work together, and once you get above 600hpish, you should start looking at beefing up things in the pump/driveline. As an example, a set of Dana exhaust manifolds with risers will run you around $3000-$3500ish, that's a good chunk of change, but they may not net a speed increase by themselves.

The quick (and probably most cost effective in the long run) solution would either be a Procharger 650 hp setup (if you've got a mag HO), or if you want more HP, sell the 496 complete and have a professional build you a 700+ HP deal.

If you're just looking for a couple MPH, you may look into the jet drive itself for efficiency, and possible setup tweaks if you have a shoe/rideplate setup. If you have pictures of the rear of your boat, and the intake of the pump, there might be some free speed hanging around there you could be pointed towards if you're willing to do some testing.

Chris

 

[blythebound]

the boat ran 61 on a gps a couple weeks ago with just me in it and low fuel. i guess my goal would be 70. anybody have any experience with the procharger. the motor is a HO so it sounds like a good fit. sorry for my vauge question, just throwing it out there for suggestions. thanks for the input.

 

[Flat Broke]

No worries on the question. The only reason I harp on setting a goal is because in cars and boats I started off with the "faster" idea, and only wasted money until I decided to set a goal and build to it.

It sounds like you'd ideally like to pick up an honest 12-13mph, so that you could hit that 70mph mark in slightly more "normal" conditions (a passenger or two, and more than fumes in the tank). I'd say you need to start looking for options that will get you into the 650-700hp range. I don't have first hand experience with the procharger, but it's a popular enough upgrade that you should be able to get some good input here or on other boards.

I say, spend the summer researching and enjoying your boat as is, then pull the trigger in the off season.

Chris

 

[blythebound]

keeping the boat as is for the summer is a great idea. i will do some research on the pro charger and i bet that's the way i end up going. if i could gain 10 mph i would be pumped. it's a pretty heavy boat. any idea of the cost of the pro charger maxed out. if i'm gonna do it i'll go with the max kit.

 

[Flat Broke]

I haven't thought along the lines of forced induction for a while, but I started thinking about it, and sure enough Whipple has a kit for your package too.

http://www.whipplesuperchargers.com/product.asp?ProdID=1149

There's some MSRP pricing on that page, so at least you'll know one mfg's answer.

For the life of me, I couldn't remember who the other big 496 player was besides AZ Speed and Marine. The name was Raylar. They do naturally aspirated mods for the 496, but honestly by the time you open up one of those engines and start doing pistons, cams, heads, etc; you might as well just sell it complete and have a profesionally built large CI NA setup.

Good luck with the research and planning.

Chris