Just a final check on outdrive choice

[carlos515]

Ok , i am ready for my out drive. I have an Alpha 1 gen 2 gimbal . 1991 era. It has been suggested before that I go with a 1.64:1 mated to my 5.7l. I can get a 1.81:1 for an excellent price. Would I be sacrificing anything other than a few mph on the top end?
Thanks,
Carlos

 

[Scott06]

Ok , i am ready for my out drive. I have an Alpha 1 gen 2 gimbal . 1991 era. It has been suggested before that I go with a 1.64:1 mated to my 5.7l. I can get a 1.81:1 for an excellent price. Would I be sacrificing anything other than a few mph on the top end?
Thanks,
Carlos

Normally the ratios were

5.7 - 1.47 drive
5.0-1.62 drive
4.3- 1.81 drive
3.0- 1.98 drive

unless you are at high altitude or have a small engine in a large boat I think you would want the 1.47 or 1.62 at the steepest. 1.81 you will over rev. These ratios allow you to use the typical prop pitch range of 17"-21".

You can prop around some as when I repowered a 4.3 boat with a 5.0 (190 to 260 hp change), I kept the 1.81 4.3 drive ratio and was able to pitch up from a 19" 3 blade SS to a 21" 4 blade. If I had a 5.7 I would be above 23" in pitch and run out of prop options.

What boat are you putting this in? Did you look at SEI drives that are Alpha aftermarket ? they are relatively affordable new

 

[carlos515]

Thanks Scott,
I am puting this in a 21 foot Sunray Bow rider with an 8 foot beam. Boat weighs 2600 dry.
I was told that the SEI drives were weaker than the oem drives.

 

[Scott06]

Thanks Scott,
I am puting this in a 21 foot Sunray Bow rider with an 8 foot beam. Boat weighs 2600 dry.
I was told that the SEI drives were weaker than the oem drives.

I would go for a 1.47 drive in that rig. My Sea Ray 200 (21 ft ish) is listed as 3200 dry, has a 5.0/260 hp, with a 1.81 drive I can hit the rev limiter with a 21" 4 blade Revolution 4 prop and a couple adults.

Your engine is a little more than stock too?

If you ask about SEI drives you hear good things, except with paint on it, lots of comments on how good the warranty is (which means something broke)...others on here who are professional mechanics have said decent things

@Rick Stephens I think has a SEI and can comment.

A new Merc alfa is like $3300 , I think a SEI is like $1800 so I would expect some difference, but you can buy two drives almost so pick your poison...

Either way do not put a 1.81 drive in it. Even with a 1.62 you will likely need a 21 or 23" prop. Do you know WOT performance with old drive/engine ( and what ratio)

 

[Rick Stephens]

I purchased an SEI when I had an Alpha 1 and a 3.0L on my boat. It was fine as long as paint chips don't bother the 'ell out of you. I'd do it again before I spent $3k. These days I have an Alpha 1 Gen 2 with a 4.3L in that boat.

The issue with the paint is possibly a big deal with someone who boats in salt water. Easily chipped paint will lead to high corrosion.

 

[carlos515]

Ok thanks guys,........Paint chips do not bother me. The rebuilt drives , OEM's cost the same as a new SEI. A new alpha 1 gen 2 is 7k so the dealer said. I will look at an SEI. Every thing is tripiling in price these days. Or at least in the great north.

Carlos

 

[Scott06]

Ok thanks guys,........Paint chips do not bother me. The rebuilt drives , OEM's cost the same as a new SEI. A new alpha 1 gen 2 is 7k so the dealer said. I will look at an SEI. Every thing is tripiling in price these days. Or at least in the great north.

Carlos

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