454/7.4 PCM or Mercruiser

[88Supra]

Re: 454/7.4 PCM or Mercruiser

88Supra,

Are you trying to tell us how to set up an "old school BBC" for marine performance? Or are you trying to setup a Comp boat for top speed? I can't believe I am still asking these questions. I am certainly capable of being the dense one. Just take a look at Dockside Chat; I couldn't understand a simple request regarding an address change :facepalm: Butttt, If you want to go 50, you need another boat. If you want more horsepower for whatever reason, then good on ya. Or, if you want to find the best combination of power, hole shot, speed etc with prop changes, then I can kind of understand that. I'd drop pitch and get this thing wound up a little more. Why you think 3800 RPM is a good WOT target is odd to me too.

With all that said, it's just not clear (to me) what it is you want.

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What carburetor, What propeller, what rpm and what degree of timing is optimum for a 88 Supra Bravura straight drive low compression 454?
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Well lets recap; just by Browsing the forums here on iBoat, Horse power TV and not to disagree with anyone but, I've improved hole shot & speed by 7 miles an hour with prop changes and a little fine tuning. All WITHOUT drop in pitch but, increased pitch from 14X12 to 14X16. Most would think; get this thing wound up a little more, Right?!!! Not a small block and definetly not a performer. 3600-3800 RPM is a good WOT target and is odd to me too But, tork drops off before 3800 and I find 3600rpm is where max tork is made for this perticular application seemingly peaked. So, putting these assumptions to the water has proven to me max speed has been accomplished through max tork and contrary to popular IO believe Max excelleration sure hasn't suffered but, I don't have anyway to measure.
All said and done... Subject Boat Seem's to have hit a max hull speed barrier 44mph +/-2mph, Right?!!
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What carburetor, What propeller, what rpm and what degree of timing is optimum for a 88 Supra Bravura straight drive low compression 454?
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RV cam would be the next step for improved speed and or reduction transmission???
...and redo all the aforementioned.
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At least the right Cam would sound cool!

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Complicated world here in Competiton Boat ownership, Not trying to tell anyone except, to give the current parameters to the best of my knowledge and what I've tried.
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[Tail_Gunner]

Re: 454/7.4 PCM or Mercruiser

Supra you have your info wrong Provide a link to the engine you are talking about and this will be easy to clear up.As to this tourqe thing geez what yr and vintage of engine are we talking about that's the first step. By the way QC has a grasp on engines that is well founded if you want to get your head around this start with the engine.

This reminds me of post yr's ago where a eng type wanted to prop his engine for max tourqe say 3500 and leave it at that...

While were here post some mid engine props that are top performers in alum only