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  #1  
Old 10-16-2004, 10:04 AM
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Upgrade the Predator to an MCX?????

I know just enough about engines to get myself into trouble. It appears to me that the main difference between these engines is the intake manifold, EFI, and throttle body. Now I have a lot of components from the Corvette sitting in the garage and was wondering if this might be possible. I have a program, LS Edit that lets me get into the PCM for the Vette and was also wondering if this will work with the Mastercraft PCM????? Just looking for some input.
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Old 10-16-2004, 12:00 PM
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First, it's still under warranty. If you modify it, your warranty is history. Second, the 'Vette has a closed loop system, the boats don't. The ECM on the boats can be used on a car (like with the GM Performance Parts crate motors) but you would need to recalibrate (with correct fuel mapping and advance/retard) if there are any different air/fuel requirements after the mods are done. The TBI calibration is not the same as the MCX, but a dealer could be able to update it for you with the understanding that neither they, nor Mastercraft, are liable for any damage to you or the boat. Beyond the intake, EFI and throttle body, without seeing the actual specs on the rest of the motor, it's impossible to tell if it will be the same.

If I wanted to use spare 'Vette parts and not void my boat motor's warranty, I would be tempted to find a used 5.7L motor with the Vortec heads, roller lifters and rockers, find a shop with a dyno to test it so I would be sure it wasn't running too rich or lean and was developing the power I want in the right RPM range. Then I would probably do something goofy, like put it in a car or pickup that would never have had a motor like it in its wildest dreams.
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Old 10-16-2004, 12:10 PM
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Hmmmmm sounds a little more complicated that working on the LS1. With the car, I can throw it on a Dyno, hook up A/F meter and start re-mapping the fuel curves. OK.......how about some different exhaust manifolds?
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Old 10-16-2004, 12:16 PM
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Read my edited post, first. The exhaust couldn't have much less backpressure than on a boat. You won't get an improvement form that. Do you want more speed or do you just want to have more power for the sake of it?

The LS Edit only lets you do so much with the fuel, too. They know people will try the high and low extremes so they make it hard to go out of a range that's safe for the motor. Again, the car is closed loop and the boats aren't, so if you hook LS Edit to a boat, it's going to throw a bad O2 sensor code and may not let you proceed.

The dyno you put it on has the motor in the car, tested at the drive wheels, where in marine dyno testing, they mount the motor on the dyno and test it, usually without the trans. One of the main tests that us mere mortals don't usually have access to is testing for in-cylinder temperature, intake air flow volume and temperature, emissions and frictional resistance of the motor.
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  #5  
Old 10-17-2004, 10:29 PM
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Hey, Jim, just out of curiosity, any ideas for squeezing some extra horsepower out of the 351 HO? Not that I'm seriously considering it, but winter is approaching and I've got to have something to ponder.
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Old 10-17-2004, 10:38 PM
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Go to a speed shop, preferably with their own machine shop. Otherwise, some NAPA stores can do the work and some have pretty good gearheads working there. Intake manifold, cam, porting and polishing all help it to breathe better and that's what gives you more power. A motor is basically an air pump, after all. More in=More out.
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Old 10-18-2004, 10:30 AM
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Very good. Food for thought. So what kind of potential horsepower increase are we talking about?
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Last edited by east tx skier; 10-18-2004 at 10:48 AM.
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  #8  
Old 10-18-2004, 11:48 AM
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Mag, just my but I wouldn't even consider doing anything to the engine as long as it's under warranty. My guess is that if something went wrong they would point to your mods and say it was somehow related to the problem. After the warranty expires you can go wild with it (if you want).
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  #9  
Old 10-18-2004, 12:04 PM
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Jimn,
Does the Magnuson-Moss act apply to boat manufacturers?
If it does, would it not allow a guy like mag to do what he wants or does it specifically apply to aftermarket parts rather than modifications such as the ones mag mentioned?
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  #10  
Old 10-18-2004, 01:56 PM
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I don't know of anyone who allows mods on anything and have the warranty stay intact. "Only authorized personnel may perform service on this equipment", or words to that effect. I don't remember the Magnussen-Moss Act anymore. What does that state, or should I look it up?

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