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-   -   Where’s my speed at? (https://www.offshoreonly.com/forums/general-q/359112-where%92s-my-speed.html)

BUP 02-20-2019 02:52 PM

1989 Mercruiser came out with the 365 hp 454 carb and it was rated at the crank 365 hp. 1990 year was at the crank measured hp

1991 was the year they -- Mercruiser posted propshaft hp.

1.50 was the listed gear ratio for the bravo in 1990 and in 89 and 91 for the 454 / combo. I do not recall a 1.65 during THOSE YEARS. But of course later on more ratios where intro. .

RBeyer 02-20-2019 07:16 PM


Originally Posted by BUP (Post 4673589)
1989 Mercruiser came out with the 365 hp 454 carb and it was rated at the crank 365 hp. 1990 year was at the crank measured hp

1991 was the year they -- Mercruiser posted propshaft hp.

1.50 was the listed gear ratio for the bravo in 1990 and in 89 and 91 for the 454 / combo. I do not recall a 1.65 during THOSE YEARS. But of course later on more ratios where intro. .

The RPM sounds high like a Tach think that speed of 53 to 58 sounds about right spinning a 23 and 1.50 in the low 5000"s

MR.HAPPY 02-22-2019 03:17 PM

I owned the same boat-engine combo in a 92 model bought new & it ran 68 on the dream meter...
I think it ran 5200 Rs
Don't ever think we checked it with GPS...
Fun Boat!

veloc410 02-22-2019 03:53 PM

I had an 89 251 liberator stroked Ford 501, 1.410 ratio king cobra. 23 pitch, 5000rpm 60mph. 5000 lbs, slow hull. Drove the nose down.

Prestigeworldwideee 05-28-2019 06:05 PM


Originally Posted by MR.HAPPY (Post 4673882)
I owned the same boat-engine combo in a 92 model bought new & it ran 68 on the dream meter...
I think it ran 5200 Rs
Don't ever think we checked it with GPS...
Fun Boat!

yeah, my speedometer actually matches up to my GPS speed but I’ll stick to GPS so I know it’s right. So I changed the spark plugs out which I don’t think has EVER been done before.... so bad, so old. Got some new ones in, changed out the impeller and the water pump housing ended up cracking on me. So, won’t be able to test it out till possibly this weekend when I get the new housing. With the way the sparks look, I should be considerably faster with better acceleration. I’ll probably will replace the wires and cap as well... wires look like it wouldn’t hurt to change out.

SB 05-28-2019 06:20 PM

If they are Mercruiser/Quicksilver wires, the last two #'s in the part # printed on each wire is the year they where made. 3 boats the other year had OE wires from the 80's lol. so yeh, never replaced. Amazing.

Baja Rooster 05-28-2019 06:24 PM

If the easy things such as plugs have been overlooked it would be a good guess the carbs have been untouched as well. A proper tune up oughta make that feel like an entirely new boat.

Prestigeworldwideee 05-29-2019 08:28 AM


Originally Posted by Baja Rooster (Post 4688806)
If the easy things such as plugs have been overlooked it would be a good guess the carbs have been untouched as well. A proper tune up oughta make that feel like an entirely new boat.

very good point, I’ll have to take a look at the carbs as well. The spark plug wires are Mercruiser suppression... can’t remember the part number.

Prestigeworldwideee 06-08-2019 07:48 PM

Top end check in: ran the boat with the new spark plugs and saw a 7.4% increase in top speed! This boat just hasn’t been maintained the way it was suppose to be. The spark plug wires are original and made back in 1989! Gonna put new spark plug wires and a new distributor cap on. Top end speed aside, I’m sure this could use one for the sake of good maintenance. Ran 52.8mph last year and 56.7mph today and I might be able to even get a little more out of it since I don’t think the trim was fully down. I didn’t know at the time but I had bumped the power wire on the outdrive and it stopped working. I doubt I’ll be hitting 68mph but I might be able to hit low 60’s with the trim all the way down and new wires and a new cap.

phragle 06-08-2019 08:00 PM

Uhmmm you want to trim up...

Trimming up brings the drive up and the bow up.

In rougher water you trim down to get the bow to cut and keep the boat in the water...


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