SEI outdrive question

[carlos515]

Hi All,
I am pondering between purchasing a new SEI 116 drive or a rebuilt Mercruiser drive. The 2 will cost the same roughly . My question is are the SEI drives good with a 230hp 5.0l engine? I am looking at 1.47 ratio. My gimbal housing is alpha 1 gen 2. The dealer told me that it had a 1.81 or1.84 ? mated to it. When I purchased the 20foot Sunray there was no outdrive , nor motor.

Thanks,
Carlos

 

[alldodge]

Get the SEI, it comes with a better warranty

 

[Rick Stephens]

I would think a 1.47 is pretty steep for a 230 HP 5L motor. I thought 1.62-1.64 was the standard with that motor. Guess it depends on how light your boat is.

 

[achris]

I'm with Rick, 1.62. A 1.47 will require a propeller right down at the bottom end of the sizes available. I'd even go as far as thinking seriously about the 1.81. That would push you up another couple of inches (in propeller pitch) and be a bit nicer to drive. You may find that boat is a little stern heavy, consider a 4 blade propeller...

Chris...

 

[carlos515]

Thanks ,
What is the breakdown of the gearing? 1.62 = 1 motor rev to 62 prop rev? My boat weight is 2600lbs , not sure if dry or wet.
I was hoping to use the boat for water sports , tubing , wake boarding etc. My young lads will using it more than me so handling would be important. My horsepower will be more in the 240-250hp range .

Carl

 

[matt167]

5.0L would get a 1.62 or a 1.47 from Mercruiser, but the tipping point was 200hp or over.. I would agree that a 1.62 would work better. You can run a higher pitched prop, rather than a prop with more slip

 

[Rick Stephens]

Thanks ,
What is the breakdown of the gearing? 1.62 = 1 motor rev to 62 prop rev? My boat weight is 2600lbs , not sure if dry or wet.
I was hoping to use the boat for water sports , tubing , wake boarding etc. My young lads will using it more than me so handling would be important. My horsepower will be more in the 240-250hp range .

Carl

1.62 is 1.62 revolutions of the motor for every revolution of the prop. Actually stated 1.62:1. Hence a 3.0L motor, with less torque, get 2 revolutions of the motor for every prop revolution. 2.00:1 or 1.98:1.

 

[achris]

Thanks ,
What is the breakdown of the gearing? 1.62 = 1 motor rev to 62 prop rev? My boat weight is 2600lbs , not sure if dry or wet.
I was hoping to use the boat for water sports , tubing , wake boarding etc. My young lads will using it more than me so handling would be important.

1.62 revolutions of the engine to 1 revolution of the propeller.
If you are planning on water sports, it's recommended you drop down a further 2" (prop pitch) from the prop that gets you to the recommended rev range, so this would definitely push me to the 1.84:1 drive ratio.

My horsepower will be more in the 240-250hp range .

??? What does this mean? Have you been modifying the engine? If so, please read this -> Why more 'horsepower' might be a BAD thing.

 

[carlos515]

When I rebuilt the engine I put flat top pistons and a new cam. The cam is a marine mild cam close to stock. I kept the build close to stock but my hp guessing is probably off.
Class I camshaft. Good idle quality. Low rpm torque and mid range performance. Will work with stock or slightly modified engines.
Basic Operating RPM Range:
1,000-4,500
I was looking at more torque than hp gains when I put the engine together.

 

[Rick Stephens]

My horsepower will be more in the 240-250hp range .

Unless you made a major change, 2 barrel to 4 barrel with intake to match, or better flowing heads, like Pre-Vortec to Vortec, something like that, you will have have trouble justifying much if any change in power output.

 

[carlos515]

Thanks all,
Ok like I figured , my hp rating is off. The motor stock was 230hp
So 1.62 or 1.84 for a drive. With proper size and pitch of propeller .
A 4 blade would get me better pull at low speed? ie, hole shot?
What rpm do most see when pulling water sports ?

 

[achris]

Thanks all,
Ok like I figured , my hp rating is off.

Possibly.

The motor stock was 230hp

Non-vortec heads, 4bbl carb? You didn't give us the serial number, or even the year... We're all just guessing without knowing what you have.

So 1.62 or 1.84 for a drive. With proper size and pitch of propeller .

Bingo.

A 4 blade would get me better pull at low speed?

Yes.

ie, hole shot?

Yes. They also improve stern lift, which means being on the plane quicker, and the boat will be more responsive to the drive trim angle (I call that a win!)

What rpm do most see when pulling water sports ?

Depends on how fast you want to pull your water toys...

One thing about 4 blade props, there's no such thing as a free lunch. All the very nice benefits do come at a cost. You will lose a few knots off the top end. I went from 41 knots with a 3 blade to 38 knots with the 4 blade. Given where I use my boat, that's a zero cost investment for me. But your mileage may vary.

Chris...

 

[carlos515]

Thanks,
motor serial was b409807
1986
The loss of a few knots at top end is not a deal breaker for me. So I will play with Mercruisers prop calculator when time comes .

Carl

 

[achris]

... SEI 116 drive ...

That's a Gen II replacement. You need a SEI-106 to replace your Alpha One.

 

[carlos515]

My gimbal is a Gen II 0D753918 . Yes I truly bought a project boat .

 

[Rick Stephens]

Also note that in '86 horsepower rating was at the flywheel. Your HP at the prop is closer to 200.