271 fastech plaining
#4
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Joined: Aug 2007
Posts: 676
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From: Greensboro,NC
I removed my silent thunder and changed my manifolds to Aluminum and made no noticeable difference. Between the two you are maybe cutting 100 lbs. The silent thunder weighs around 50 lbs. I put a 700hp motor in my 271 Fastech and it leaps right on plane now. The boat just needs more power. Jeff Wurl
#5
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Joined: Nov 2008
Posts: 965
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From: East Lyme, CT
I removed my silent thunder and changed my manifolds to Aluminum and made no noticeable difference. Between the two you are maybe cutting 100 lbs. The silent thunder weighs around 50 lbs. I put a 700hp motor in my 271 Fastech and it leaps right on plane now. The boat just needs more power. Jeff Wurl
#8
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Joined: Sep 2006
Posts: 4,002
Likes: 3
From: Tonawanda NY
#10
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Joined: Jan 2011
Posts: 3,066
Likes: 8
From: Ocala, Fl
I have studied this deal over the years with 4 Formulas that I have owned and found that they are all "big assed girls".
What works well is to run big tabs but especially go with a higher numerical drive gear and get your top end with a "deeper" prop. An example of this would be a regular 1.5:1 gear ratio with a 19" pitch vs a 1.65:1 gear and a 21" prop. I know it souds whacked but it works. The 1.65 ratio comes out of the hole quicker and still maintains the top end. It has to do with the ineficiency of props at low hull speeds vs. prop efficiency at higher hull speeds.
Any other experience with this?
What works well is to run big tabs but especially go with a higher numerical drive gear and get your top end with a "deeper" prop. An example of this would be a regular 1.5:1 gear ratio with a 19" pitch vs a 1.65:1 gear and a 21" prop. I know it souds whacked but it works. The 1.65 ratio comes out of the hole quicker and still maintains the top end. It has to do with the ineficiency of props at low hull speeds vs. prop efficiency at higher hull speeds.
Any other experience with this?


