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Old 03-16-2019, 12:28 PM
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Default VP performance suggestions

Hello all. I know VP isnt a "performance engine" in offshore but after asking all over the net I just cant find any help so this is my last shot. Ive got a 21' Caravelle Interceptor with a 5.7Gi. I would like to do cam, heads and rockers. Its a GM Vortec based engine so the hardware isnt complicated, its the electronics that are. Do any of you know of a place offering computer re-work to optimize the mods? Thanks
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Old 03-16-2019, 01:09 PM
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You are very limited on the fuel injection system and the ECM calibrations. I would leave it stock. I would focus on props and the bottom of the hull. Also takening some weight out and or moving it around. Also balance of the hull while running in some chop can provide better handling and speed.. All of this is going to cost you alot less except if one was to blueprint the bottom of the hull.

Production boat bottoms many have hooks and rockers that can slow the boat down. Alot of production boats put in a hook in place so the hull will plane faster and persay stay planted in the water . . Cavavelle is not going to be a fast boat and is more so suited for small lakes and or river boat. No offense to you but back in their day many of these boats use to come thru my shop and so did Volvos.

You always could get rid of the injection / ecm and install a really good flowing intake manifold and custom carb dialed in and that surely could add 10 to 25 hp depending.

Last edited by BUP; 03-16-2019 at 01:15 PM.
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Old 03-16-2019, 06:46 PM
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Bup,

I understand everything your saying except the "hook" but know enough about boats to get the principal. That said, I have raced and tuned fuel injection vehicles for years and know what a good heads and cam can produce as long as the injectors and fuel map are robust enough to handle it. Helped a friend build a LT4, basically my engine, for his Vette years ago and a simple PCM re-calibration was amazing! This should respond the same so Im really hoping to find someone who can provide the info or help.

I hit 60 even on GPS with a new cheap 21p alum 3 blade. She was very stable and even handled the lake boat wake chop better at that speed than at our cruising of 40. I cant attest to the design of this hull but have driven and been on a lot of boats in my time and am here to tell you this little boat can take a lot more power and speed.

Thanks for your input.
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Old 03-16-2019, 08:34 PM
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What does it use for a computer ?
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Old 03-16-2019, 11:45 PM
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It either has a MEFI 3 or MEFI 4 or E controls and if it is E control you are not going to be able to recal anything with that nor gain anything period not matter what you do. The fuel mapping, ignition and timing is all done from the OEM and is locked.

If its a Mefi 3 or MEFI 4 you will need to buy software for remaping and that is not cheap either.

If I recall the 21 interceptor came out in 99 or 2000 or 2001 ? Those all would be MEFI 3 ,-- 2002 thru mid 2005 was MEFI 4 and late 2005 thru 2009 NON cat engines was E controls

Changing cam and or heads and or intake or all of these combos with your EFI ECM without proper recals plus using 02 sensors is going to net zero. Thats why I brought up the carb / intake install. It takes 15 to 20 hp to gain 1 mph in a boat. Just saying

LT car engines alot easier to remap and tune plus bolt ons is a hole lot easier to gain noticeable speed than a boat ever will. Prob 100 time easier.

Last edited by BUP; 03-17-2019 at 12:14 AM.
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Old 03-16-2019, 11:53 PM
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at 70 mph you will need trim tabs and full hydro steering. 70 mph is a whole new ballgame, New that cost alone is 5 to 6 K for decent stuff, Not including install

How fast do you want to go ? Just asking

Last edited by BUP; 03-17-2019 at 12:06 AM.
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Old 03-17-2019, 10:10 AM
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You're doing 60 with a cheap prop and a 5.7 liter engine in a 21 foot boat. I'd say that's pretty good. You could easily spend money and pick up a few mph but you need to put a value on mph. I've read many stories about boat owners who dump big money into boats and achieve a couple of extra mph but is it worth the effort?

Beyond that, if you ask anyone on here about BUP they'll tell you he knows what he's talking about. Very knowledgeable and helpful guy.

Sorry if that's not what you want to hear but consider all opinions before jumping in and spending money.
Good luck.

RR
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Old 03-17-2019, 01:08 PM
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Sounds like Center consoles only again here. ugggg.

OP- Supposedly you have a mefi # something.if your mefi is one that is programmable you can get software to program your computer at MEFIBurn.com

Sorry about the naysayers. This place used be a performance site for every boater. Now it's mostly 'don't do it's' buy a center console. LOL LOL LOL

Last edited by SB; 03-17-2019 at 02:06 PM.
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Old 03-17-2019, 01:20 PM
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Really appreciate all the reply folks. Im just a tuner at heart and anything I can make faster, I always try. I think I would like to get 70mph just for the hell of it. Ive only seen a few boats on our local lake that can do much more than that. I probably wouldnt take it on the river that fast, the river can change its temper too quickly.

Its an 04 btw.

Bup. I knew the mentioned hardware mods wouldnt even be worth it if the comp would compensate. Im now thinking maybe the Edel or Holley Pro Flow systems. They are very tune able.

I think Im going to hold off until I get a new prop. leaning towards a 4b 21p stainless. See what that nets and where the rpms are and go from there.
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Old 03-17-2019, 01:22 PM
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Originally Posted by SB View Post
What does it use for a computer ?
I dont really know anything about it except that its says Volvo Penta on it, proprietary? Ive tuned on cars and trucks forever, never marine so thats why Im here.
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