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Old 03-02-2005, 03:59 PM   #1
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Top end

Hi,
looking for some advice..
a Phantom 21ft with a 225 optimax, wht will it do top end-wise?
late 60's or??

Trying to ask the same question again
Can somebody help me with the idffernce in the racing engines and the Optimax/ and or 2 stokes - whats the difference??

What kind of reliability should I expect in the 2.5 Racing?
Service pricing etc..

How stable are the "Racings" from Merc. in comparison to the Optimax's?

Thanks
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Old 03-02-2005, 04:37 PM   #2
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P21 depending on setup will do around 70mph with a 225 promax

2.5 EFI's (racing engine) require a rebuild every 100 hours

i've had one on my P20 for around 9months but already had an injector fail at a cost of £500 however if you are willing to rev them they are a great engine and it pushes my boat to around 85MPH
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Old 03-02-2005, 06:37 PM   #3
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y did it cost £500 for a injector or did it run lean?
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Old 03-02-2005, 07:33 PM   #4
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Quote:
Originally posted by Taz
y did it cost £500 for a injector or did it run lean?
No dude it was just the injector, but these engines cost a fortune

By the time it was diagnosed, repaired, front end removed and internals inspected to make sure it hadn't done any other damage (cus when an injector fails you also loose oil)and tested the money soon adds up

that was a second hand injector too.
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Old 21-03-2005, 01:31 PM   #5
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thx.. went for the 225 opti.
What kind of tuning is available for this engine??
low cost??
medium cost??
expensive - I guess a PM 300
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Old 21-03-2005, 02:39 PM   #6
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If you think you can get 100 hours out of your 2.5 youre on borrowed time, 50 hours is the max, especially if run hard, I rebuild mine after 30 hours tops, the rings are usually on their way out by then. I have three of them in different states of tune, the harder you run them the less time they will do between rebuilds
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Old 21-03-2005, 03:33 PM   #7
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When you guy's say rebuild what do you define that as - re ring or more.
Any info on the 300Promax Regarding rebuild intervals
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Old 21-03-2005, 03:42 PM   #8
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What tuning is availbe for the Optimax - and what prices are we taking about..?
Exhaust? porting? ECU? ect...
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Old 21-03-2005, 04:08 PM   #9
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Quote:
Originally posted by Wacky Racer
If you think you can get 100 hours out of your 2.5 youre on borrowed time, 50 hours is the max, especially if run hard, I rebuild mine after 30 hours tops, the rings are usually on their way out by then. I have three of them in different states of tune, the harder you run them the less time they will do between rebuilds
Does the same go for the XR2 if not how long before that needs a rebuild?
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Old 21-03-2005, 04:09 PM   #10
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It all depends on how fast you spin it.
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Old 21-03-2005, 05:03 PM   #11
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normally 6,400 rpm can get it to 6,700 if its really flat!
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Old 21-03-2005, 05:09 PM   #12
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Re-ring is the minimum on a 2.5, also get the injectors cleaned, if run really hard a set of reeds is not uncommon. the reed holders are susceptible to cracking.
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Old 21-03-2005, 05:39 PM   #13
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Quote:
Originally posted by Wacky Racer
I have three of them in different states of tune, the harder you run them the less time they will do between rebuilds
What sort of RPM's do you spin your motors too dude?
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Old 21-03-2005, 05:44 PM   #14
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ANYTHING UP TO 8700 DEPENDING ON WHICH ONE I,M RUNNING
2.5,S DON,T LIKE IT AT 8000 RPM THE VIBRATION KILLS THEM EITHER RUN UPTO 7800 OR OVER 8200
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Old 21-03-2005, 05:57 PM   #15
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I guess that some sort of harmonic resonance thingy then is it?

I thought it was the single ring motors that are turning around 9000rpm that needed a rebuild after 20 to 30 hours but a motor spinning in the 7's would last a lot longer, like 70 to 100 hours.
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Old 21-03-2005, 06:16 PM   #16
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Quote:
Originally posted by Wacky Racer
If you think you can get 100 hours out of your 2.5 youre on borrowed time, 50 hours is the max, especially if run hard
It seems your right dude, I've just had a look on scream and fly and it seems that for side pinned pistons on a motor with big exhuast ports (like a 260) 50 hours is about the max before your risking the pin coming out.
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Old 21-03-2005, 06:17 PM   #17
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I run two 2.5's on my cat and we rebuild after 25- 30 hours, basically at the end of each season.
Pistons, rings the works
What you have to realise is that these are a specialist race motor and not recommended for recreational boating.
we rev ours out to 8300 maximum, they are standard 2002 280hp offshores.
On our ski boat we have a 200XS Optimax, much better motor for everday use.
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Old 21-03-2005, 07:53 PM   #18
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Quote:
Originally posted by Wacky Racer
If you think you can get 100 hours out of your 2.5 youre on borrowed time, 50 hours is the max, especially if run hard, I rebuild mine after 30 hours tops, the rings are usually on their way out by then. I have three of them in different states of tune, the harder you run them the less time they will do between rebuilds
well thats fekkin fan tabby dosey. more fekkin expense then. guess i should start and save for a rebuild now then. how much are top pinned pistons? or better still is it possible to see if i already have them by looking through the plug hole?
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Old 21-03-2005, 07:59 PM   #19
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Oy dont get nun a that troubel wi me aul trarkter motors yanows!, she jus rattles arn n arn she doos.

But then it do only doo 70
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Old 21-03-2005, 08:03 PM   #20
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Quote:
Originally posted by Jonny
Oy dont get nun a that troubel wi me aul trarkter motors yanows!, she jus rattles arn n arn she doos.

But then it do only doo 70
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