Most economical way to get 300 HP out of a 91' 350
11-03-2011, 09:58 PM
#11
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In today's market you're better off keeping your boat healthy and save your money to get a boat already powered like you want it. To get a boat that size to perform you need to have about 800~1000 ft lbs of torque in the water.
11-03-2011, 11:39 PM
#12
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I have twin 1991 Merc 5.7's producing 260hp according to Merc. The outdrives are Alpha one gen II are good for up to 300hp so this is my limit. I would like to get 300hp out of both engines at a lower rpm 3500-4000 than the current 260hp at 4200-4600 since I don't cruise in that rpm range (fuel economy). I would like suggestions on the most economical way to get this done. Pulling both motors is not out of the question but keep in mind it cost around $400 to pull a motor. I was thinking that head and exhaust work may do the trick with a possible cam change. But would like to hear from people who may have already been down this road.
Thanks all.
Thanks all.
http://www.summitracing.com/parts/NAL-12558060/
11-04-2011, 06:03 AM
#13
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Gold Member
Trying to get much more speed out of a 10,000 pound boat with twin small blocks and Alpha drives is a recipe for pouring money down the drain. It's going to cost more than you're willing to spend to get much more speed out of it and the drives will give up the ghost when you get enough HP. Oh, and wait till you see what happens to your resale value. Leave it stock and be happy - and reliable.
11-04-2011, 08:33 AM
#14
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If the 500 hour motor builds good compression and doesn't use oil, do a leak down test and see if it needs a valve job. The motor would be a bit down on power if the heads are ready to be freshened. Otherwise, I would leave it be.
