Alpha 1.84 vs 1.50 - opinions please!


Well-Known Member
So here's the scenario...
Now that my powertrain swap is in full swing, I'm looking to the Alpha 1.84 drive unit. It used to get wound up by the 175 HP of the stock motor (and it didn't push a 23' pitch prop very well).

There's a rebuild shop that will re-manufacture this from stem to stern for around $900 including regular wear parts and painting , decals etc... OR, there is a 1.50 Alpha available in perfect shape (factory, and not a mark on it) for about $750.

The new motor should make around 220 - 250 HP which is similar to the lower rated V8's that use the 1.50. (I don't think the V6 will match the torque though)

I have decided that the HighFive is the prop of choice and have acquired a 21" pitch version. I have some nibbles on available 19" pitch versions too. (I will have both)

So, If I switch to the 1.50 will my 220 HP 4.3 be able to spin a 21" pitch ? If it can, I estimate WOT to be around 52 mph (assuming 10% slip). The 19 should hit 47.5 mph under the same circumstances (4,400 rpm).

On the 1.84 side the 21 is estimated at 42 mph and the 19 at 39 mph. I'm sure the motor can turn the 1.84 with no troubles.

If I go to the 1.5 and gamble, I can sell the 1.84 for similar $. If I stay with the 1.84 I will rebuild it and I'm down $900 (but with a sure thing).

And now the age old question.... Do I stay...or do I go?
Last edited:


Well-Known Member
Yes Nathan i realize that...
But, now the motor is so much stronger...220 - 250 HP as compared to the anemic 175 HP it was. It's in V8 territory for sure.
I wiill not be able to get torque numbers until its been run on the dyno....


Well-Known Member
It is 18' LOA (same as my old Donzi) and is 85" at the beam.
I don't have the weight but she feels a little lighter than my Classic 18 2+3 Donzi but in the same ballpark I think...
The Donzi had a 260HP SBC Alpha at a 1.50
This is a 220- 250HP 4.3L V6