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Old 07-10-2011, 05:44 PM   #1
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Default 2000SR3 Best way to add power w/o reliability impact?

My 2003 2000SR3 has the 5.0 litre carbuerated engine which was zippy and capable of 50+mph down at sea level elevations. Now I mostly run it at about 4500' elevation, and the ability to quickly pull adult-sized skiers out of the water is diminished and only the strongest skiers can survive the slow-motion ordeal.

I have tried different prop pitch combinations and even the best one delivers the above results.

Short of getting another boat -- my kids' solution -- what steps can I take to increase the power on this boat without seriously diminishing the reliability?

Is there a high-altitude electroninc ignition module, or would a new bigger carb do it, or...?

Any suggestions welcome!

Thanks
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Old 07-10-2011, 06:00 PM   #2
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I just put Smart Tab SX tabs on my 1900 SR to try and up the performance out of the hole. For a small investment (~$120 from amazon.com) they have done a great job of getting the boat out of the water quicker. They may compensate for your loss in power due to altitude.

-JP
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Old 07-10-2011, 06:15 PM   #3
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There seems to be a lot of info on the net about re-jetting the carb and adjusting the timing.

Check out: http://www.marineengine.com/boat-for...uretor-tuning&

You may want to talk to a local speed shop or mercruiser dealer to dial in the engine based on your altitude. Have you checked the spark plugs to see if they indicate a rich burn?

-JP
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Old 07-10-2011, 07:24 PM   #4
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first off..welcome to the zoo..

definitely look into rejetting the carb and retiming......that's your problem right there....at that altitude the carb can't breath enough air to make decent hp...so...you need to make it richer to fix the lean problem...also the air jets need to be replaced cuz it's not mixing enough air...

lets say your running 115cm air/120cm fuel jets at msl....you move to your alt. that your in now and it's running sluggish ...in order to get the balance of fuel/air mixture back to the levels it needs....your now needing something like 125cm air/135cm fuel.....to bring the burn ratio back into normal combustion range in each cylinder....

SP
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Old 07-11-2011, 04:14 AM   #5
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Default Smart Tabs SX first , new carb second?

Thanks Seapuppy and Countryme

I just read up on the Smart Tab SX and think I will order some now to install next week-end.

As to the carb advice, I had asked my shop and they told me since the boat came from California it is one that can't be rejetted...legally. I think they said maybe they could drill it out or something...so may be looking at that or a new carb AFTER I try the Smart Tabs.

Thanks for the advice and suggestions.

Mark
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Old 07-11-2011, 02:36 PM   #6
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Mark,

The carb can't be legally re-jetted - IF it's in Calif.

That said, if you do go that route, make certain the tech doing the work knows, REALLY knows, what they are doing. Changing jets is no big deal - can always go back, but enlarging air bleeds by drilling isn't easy to fix if they are made too big.

Keep in mind though that any engine loses power at altitude, regardless of how well it is tuned. So, while you may gain a little more power by bringing the gas/air ratio back in line, I would not expect the engine to make the same power at 4500' as it does at sea level.

Dan
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Old 07-11-2011, 03:20 PM   #7
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I'm an old Western snowmobiler, we usually figure 3% loss,per 1000' of elevation gain.

I think the same would hold true here.

So your losing around 13.5%

Also might add--your horsepower loss is a given, nothing you can do short of a super/turbo charger.

Your bad tuning at altitude can be fixed. Though in my experience, going up in elevation, you lose air, hence a rich condition, requiring jetting "down" not up.

My guess is your plugs are black and possibly fouled at altitude.
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Old 07-11-2011, 08:31 PM   #8
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Originally Posted by MPx5 View Post
My 2003 2000SR3 has the 5.0 litre carbuerated engine which was zippy and capable of 50+mph down at sea level elevations. Now I mostly run it at about 4500' elevation, and the ability to quickly pull adult-sized skiers out of the water is diminished and only the strongest skiers can survive the slow-motion ordeal.

I have tried different prop pitch combinations and even the best one delivers the above results.

Short of getting another boat -- my kids' solution -- what steps can I take to increase the power on this boat without seriously diminishing the reliability?

Is there a high-altitude electroninc ignition module, or would a new bigger carb do it, or...?

Any suggestions welcome!

Thanks
If you are running Alpha 1 or Bravo 1 drive (Single prop), you could always go with a VPP or Variable Pitch Prop offered by companies like Land and Sea (if they still make them). I owned a FourWinns 215 Sundowner with a carbed 350MAG/Alpha 1 G2 equipped with one. They are expensive but are real stump pullers for gettin out of the hole hauling skiers up. Some models offer as much several inches pitch change low at start and like an automatic transmission change as the blade load decreases giving you higher pitch. Along with rejetting and a little Octane booster 104 spiked in the go-juice you should get you "throw you back in your seat" type out of the hole acceleration. B.O.A.T.

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