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28 viper 454 need more speed


28 viper 454 need more speed

Old 01-25-2004, 09:32 PM
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Default 28 viper 454 need more speed

I have a 28 viper 454 310hp low hours single step hull runs 50 mph should i replace engine or put whipple or pro charger on would like to see 65-70 mph its my first time posting i love reading all the articles apprciate any info boat hopefully stepping stone to 31 sonic or ????
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Old 01-25-2004, 10:17 PM
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Hey Automan:
If the 454 is still low in hours and fresh, a whipple charger with an intercooler and a good set of marine headers should get you to 70. Just don't forget to check your outdrive ratio , should be 1.5 or 1.36 and reprop the boat for the increased power at the prop. Don't forget to pull the ripcord if the waves are big!!
Good Luck!
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Old 01-26-2004, 12:46 AM
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I would not recommend trying to make that much power from that engine. The 310 hp engine has a cast crank and 3/8 rods. In order to attain the speeds that you are looking for, you would need to gain between 250-300 hp, based on the formula of 12-15 hp per mph.Give us a call if we can help you any further. We would be glad to answer any questions that you have. TMP
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Old 01-26-2004, 02:06 AM
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The big question is how much do you want to spend????

Best option would be to build another engine and keep the the other as a backup or for when you sell the boat.

Like tmp said, that engine is not a good candidate for an SC. It may work for a while, but will end up in pieces.
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Old 01-26-2004, 05:43 AM
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From experience... I tried to work up a base 454, not the mag and first time out.. crunch when the crank and everything upward. IN MY OPINION... you would need to tear the block down completely and build it up to get something reliable and in the power range you want.

Other options are to find a bigger power plant, 502/415 or 500 or 496HO take out engine. They're around and can be had for a good price. The 500 will cost you, even in a take out. The 502/415 would be a good motor to build upon. Outside of mercruser engines are a lot of builders with big hp engines at a fraction of the cost for mercruiser. Not sure how a non merc setup will do for resale value since your looking at moving up soon.

Just my thoughts....

You may also want to post this under the tech section, might get more attention and more options.

Good luck!!!
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Old 01-26-2004, 09:00 PM
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also i have a bravo three on this viper it sounds hopeless should i just leave it alone and trade up i have low hours around 30 boat has lot of good stuff merc k planes McLeod electric seats gaffrig gauges halon system mechanical trim indicators quick & quiet exhaust
not sure what to do i own my own auto shop so not completely in the dark raced some cars in my day new to power boating the viper was picked as the price was right not much known about viper seem to be idle right now thanks to all who have responded i appreciate your input
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Old 01-26-2004, 11:08 PM
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sell the 310 for 2000.00 or so and find a 502 for 6000 , should pick up 10mph approx
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