Volvo DuoProp on a C18

[AVickers]

Couldn't resist...

I just bought a Volvo DP/C DuoProp drive and transom plate -- w/ trim. I really wanted one for my old C18 (trim mostly, but the duoprop would have been way cool...). Anyway, it came up for sale here in my home town so I just up and bought the thing. (What a moron...)

It was on a '92 19' Glastron w/ a Chevy V-6. Geared 2.3:1. Anybody know what props would go on this for a V-8? I hope it's not too low to be useful. If so, at least I've got a trim-ready transom plate and some trading stock to get what I may really need...

Oh well, when I get my next old 18 (Classic or X-boat), I'll be ready.

[MOP]

I think it will be hard if not impossible to find props that will work, an idea would be to go on Ebay or just shop for an SX drive of the right ration and sell the Dou probably for more than you will pay for an SX. The other alternative is to change the gearing which would be more expensive.

[oldLenny]

What you have is the 4.3 gear set(2:32) in there. You would need (for a 350) either the 1:78 or 1:95 by my way of thinking.

The DPX (way more slippery drive) runs down to 1:47, :59,:68,:78.

Also, the DPX is available on MANY new performance boats now as a drive option.

Here is a foreign language link to gear sets and info.

http://www.kvartet.spb.ru/ru/volvopenta/gas_aqu.html

[AVickers]

I have a DPX (1.5:1) that I'm going to install on my 454 Mag C22 this winter. Way cool drive -- but a HUGE transom plate.

When I looked at this DP/C, I was looking at an almost bolt-in replacement for a Volvo 280 or 270... Thus, a relativly easy update for a mid-seventies C18 or X-18 w/ a Volvo Drive. Just think, an old Donzi C18 w/ no porpoising (trim control) and no paddle-wheeling or torque steer (dual props).

No hurry, since I don't have a '70s C18 or X-18, so I have time to stumble across a gearset or a lower unit that meets my needs... (Or maybe I can build that small block Chevy to turn six grand to get those props wound up where they need to be.)

Does anyone know the pitch equivalents for the A-, B- and C-Series Volvo Props? I think I need Cs, but they only go up to C-7. The As go to 10 and the Bs go to 8.

But what do the numbers mean??? (The year model 2000 C22 w/ the DPX drive was equipped w/ E-4 props from Donzi. These props have a 29" pitch.)

[oldLenny]

From what I have been "told" the "A" sets are for diesel, low rev applications, the "B" is for high rev, gas applications, and "C" is a stainless version of the other two. The others, D,E,F are for DPX and specialty applications.

You CANNOT mix the applications, as in use an "A" set-up on a gas motor, AND you CANNOT mix the numbering between the same set. eg: B-6 forward with a B-4 inner...

Some of these sets have 4 blade forwards combined with 3 blade inners and all are matched sets.

I have been told that you simply need to give hull weight, engine horsepower and revolutions, and then they can ball park you a set. From there, you simply move up a number or down to achieve your results. There is no pitch cross-reference to these props as they vary a lot from inner and outer on the same set-up.

I got all this from a VOLVO tech today. Funny, tho, how the Blackhawk is able to put numbers to their props...also, you will want the 1:78 - 1:95 ratio for the V-8 application.