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Old 09-04-2015, 11:13 AM   #1
Cracker jack
 
Country: england
Location: hertfordshire
Occupation: Roofer
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Boat name: Cracker Jack
Boat make: Extreme 21
Engines: 5.7
Cruising area: hayling island

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Location: hertfordshire
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Extreme 21 speed

Ring extreme 21 5.7 285hp what top speed should it be reaching
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Old 09-04-2015, 03:09 PM   #2
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Country: uk
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Around 60/65 mph depending on prop and load in the boat! That's what my one done!
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Old 09-04-2015, 03:40 PM   #3
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Around 60/65 mph depending on prop and load in the boat! That's what my one done!
60 if your lucky,they are a heavy boat,the V8 and drive weights around 440 KG

Which extreme 21 have you got???
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Old 09-04-2015, 04:09 PM   #4
Cracker jack
 
Country: england
Location: hertfordshire
Occupation: Roofer
Interests: boats jetsking
Boat name: Cracker Jack
Boat make: Extreme 21
Engines: 5.7
Cruising area: hayling island

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Old 10-04-2015, 10:06 AM   #5
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Location: hayling island
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Extreme 21 Sports (Ring) Boat Power Boat With Free De Graaff Trailer | eBay
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Old 14-04-2015, 01:11 PM   #6
Cracker jack
 
Country: england
Location: hertfordshire
Occupation: Roofer
Interests: boats jetsking
Boat name: Cracker Jack
Boat make: Extreme 21
Engines: 5.7
Cruising area: hayling island

Join Date: Mar 2009
Location: hertfordshire
Posts: 507
Can the 5.7 285hp have the ecu mapped ?
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Old 14-04-2015, 11:06 PM   #7
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Can the 5.7 285hp have the ecu mapped ?
Mapping of non turbocharged petrol engines really won't see much gain in horse power, may be 5% if very lucky. Despite the claims of people who sell the chips the only thing it will do is inject more fuel at cost of fuel consumption.

Significant gains can only be made on engines with turbo or superchargers, this is because if you can increase the boost pressure and get more air into the engine you are then able to burn more fuel and create more power.

With a non turbocharged engine one thing that does make a significant difference and cost next to nothing, is to make sure the engine air intake is breathing cool air as opposed to hot air from around the enclosed engine bay, or make sure the engine bay has plenty of ventilation. Cool air is denser and allows a more fuel to be burnt also increases adiabatic efficiency, can make up to 5% difference from memory.

Fresh fuel also helps too, modern fuel is crap and dependent on how it is stored (i.e. temperature and whether it is in a sealed container) looses its properties quite quickly. Just bought a Honda bike and the manual states:-

"For maximum efficiency, drain and replace fuel that has remained in your fuel tank for more than a month"

Your money would probably be better spent on decent prop setup, but then the ideal prop setup for max speed on calm water won't be the same ideal setup for ferrying four adults with a full fuel tank on a rough day, or water skiing.

Keep engine well serviced, cool air, fresh fuel and with right prop would have thought you should get 70mph on a good day!!
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Old 15-04-2015, 09:20 AM   #8
Cracker jack
 
Country: england
Location: hertfordshire
Occupation: Roofer
Interests: boats jetsking
Boat name: Cracker Jack
Boat make: Extreme 21
Engines: 5.7
Cruising area: hayling island

Join Date: Mar 2009
Location: hertfordshire
Posts: 507
Thanks
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Old 15-04-2015, 04:22 PM   #9
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FYI, i think that particular boat is a 97 not a 2000

it being the 21 used to CE certify them, in 98
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Old 15-04-2015, 10:04 PM   #10
Cracker jack
 
Country: england
Location: hertfordshire
Occupation: Roofer
Interests: boats jetsking
Boat name: Cracker Jack
Boat make: Extreme 21
Engines: 5.7
Cruising area: hayling island

Join Date: Mar 2009
Location: hertfordshire
Posts: 507
What is ce
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Old 15-04-2015, 10:20 PM   #11
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Country: UK
Location: Weston-super-Mare
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Boat make: Sunseeker Thunderhawk 43
Engines: Mercruiser 502s
Cruising area: Lyme Bay

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The CE mark, or formerly EC mark, is a mandatory conformity marking for certain products sold within the European Economic Area (EEA) since 1985.
the marking demonstrates design compliance with the appropriate EU directives.

Have got an Extreme 21 / 5.7 mpi / Bravo 1 & can just squeeze 70mph running a 4 blade 22x14 prop.
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Old 15-04-2015, 10:31 PM   #12
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Quote:
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The CE mark, or formerly EC mark, is a mandatory conformity marking for certain products sold within the European Economic Area (EEA) since 1985.
the marking demonstrates design compliance with the appropriate EU directives.

Have got an Extreme 21 / 5.7 mpi / Bravo 1 & can just squeeze 70mph running a 4 blade 22x14 prop.
To get 70mph in a 21 with a 22 prop you'd be needing to spin the motor to 5600
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Old 16-04-2015, 12:36 AM   #13
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Certainly not pulling 5600 rpm- more like 4800rpm.
Will check prop size.
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Old 16-04-2015, 08:42 AM   #14
Cracker jack
 
Country: england
Location: hertfordshire
Occupation: Roofer
Interests: boats jetsking
Boat name: Cracker Jack
Boat make: Extreme 21
Engines: 5.7
Cruising area: hayling island

Join Date: Mar 2009
Location: hertfordshire
Posts: 507
Steve this boat is 5.7 285 hp I just checked your profile to see pics of your boat and it says it's yours is 5.7 350 hp so it should've faster ?. Thanks
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