Triple 500 HPs to twin 575 SCIs
06-12-2015, 01:46 PM
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Triple 500 HPs to twin 575 SCIs
Alrighty folks, new to the forum, and hoping to be welcomed by a flood of knowledge, lol. Got a 95' 43 scarab with triple 500 HPs from the factory. Transom is needing to be replaced, so 
Since everything needs to come out completely and be redone, my guy Derek at Top Gun Marina, LOTO, who thusfar I would recommend to anyone, is suggesting a twin setup replacement. The boat actually already has 2 575 SCI's in the rear from the result of 2 blown motors that were in it when I bought the boat. The 3rd center motor is still the original 500 HP. Boat actually tops out now at a lower speed than from the factory, but it's not propped right and with the difference in HP who knows what's really going on back there. We're thinking that with the weight loss of the 3rd engine, transom assembly, outdrive, 5 ft driveshaft, and the increase in HP (dyno'd at roughly 600 hp) of the new motors, propped right of course, the boat should be able to reach it's factory speed of 73 with twins instead of trips. Factory HP would have been 475 X 3 = 1425HP, dry weight 12k, new setup would be 2 X 600 = 1200HP, roughly 10,300k dry weight if my math is right. SO........... what does everyone think? Let the flood of knowledge pour! Thank you in advance for the advice
Since everything needs to come out completely and be redone, my guy Derek at Top Gun Marina, LOTO, who thusfar I would recommend to anyone, is suggesting a twin setup replacement. The boat actually already has 2 575 SCI's in the rear from the result of 2 blown motors that were in it when I bought the boat. The 3rd center motor is still the original 500 HP. Boat actually tops out now at a lower speed than from the factory, but it's not propped right and with the difference in HP who knows what's really going on back there. We're thinking that with the weight loss of the 3rd engine, transom assembly, outdrive, 5 ft driveshaft, and the increase in HP (dyno'd at roughly 600 hp) of the new motors, propped right of course, the boat should be able to reach it's factory speed of 73 with twins instead of trips. Factory HP would have been 475 X 3 = 1425HP, dry weight 12k, new setup would be 2 X 600 = 1200HP, roughly 10,300k dry weight if my math is right. SO........... what does everyone think? Let the flood of knowledge pour! Thank you in advance for the advice
06-12-2015, 06:36 PM
#3
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Problem is, with a 43 scarab, twins, and regular style bravos, coupled to anything that will make it run respectably, will probably eat drives. A friend has a 46 Black Thunder, with 575 mercs. It eats up XR's.
The coolest setup though would be going to a twin stagger setup. It's getting a new transom anyway right. ??
The coolest setup though would be going to a twin stagger setup. It's getting a new transom anyway right. ??
06-13-2015, 01:57 AM
#4
Charter Member # 55
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Talk to Ed at Lake Ozark Marine about the costs of this. He was in the process of converting his trip 42 Fountain to twin staggered.
I think your costs to do it the right way will quickly add up to much more than you think.
I think your costs to do it the right way will quickly add up to much more than you think.
