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Volvo 280 to volvo dps

J

jmm4jmc

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I am currently re powering from a 350 to a 383 stroker, and I currently have a Volvo 280. I have an opportunity to buy a good used VP DP-S (off a 1998 boat) complete. Are there any concerns I should have with this swap? I'm assuming the dp-s transom shield is larger, so the transom just needs a larger hole, no filling. And what gear ratio would I need with the DPS?

Also another option I was thinking was to add a DP lower unit if that is doable with the 280.

I appreciate any advice and feedback.

Thanks,
Jim
 
jmm4jmc said:
  1. I am currently re powering from a 350 to a 383 stroker, and I currently have a Volvo 280.

  2. I have an opportunity to buy a good used VP DP-S (off a 1998 boat) complete. Are there any concerns I should have with this swap?

  3. I'm assuming the dp-s transom shield is larger, so the transom just needs a larger hole, no filling.

  4. And what gear ratio would I need with the DPS?

  5. Also another option I was thinking was to add a DP lower unit if that is doable with the 280.
Click to expand...
Jim, my suggestions here.

  1. Jim, I know that this is off topic somewhat...... but there are a few "Do's and Don'ts" when building a 6.3L (aka 383 cu in) for Marine use.
    First and foremost, I would strongly suggest that we NOT build a 383 with the GM style full dished pistons.
    Build a quench into your combustion chamber by using a quench style piston, and with a correct quench dimension (approx .038" for a Marine build).

    This is a simple change to the piston selection, and several points of attention given to the piston deck height and compressed head gasket thickness.
    This requires no other engine modifications.

  2. Your Volvo Penta 280 drive is among the AQ series family. The VP DP-S (off a 1998 boat) is a gimbal system drive.
    Your AQ series transom cut-out is too large for a Gimbal System drive.

  3. Jim, it's just the opposite of that. The AQ series transom shield, and the cut-out, are larger than the SX or DP-S.
    In my opinion, the design and geometry (main suspension fork/pivot tube) of the AQ series is superior to the later Gimbal system Volvo Pentas.

  4. Again.... in the AQ series, the normal SBC V-8 ratio would be 1.95:1.
    However, with a good quench built 383, and depending on the hull size, the 1.78:1 ratio can be used.
    This ratio gear set is slightly different.
    The 1.78:1 "drive" gear is a bit larger, and the two "driven" gears are a tad smaller.
    This makes for more gear tooth contact at any given time......, and believe it or not, it makes this gear set a tad stronger.
    Since the 1.78:1 is taller, it helps take advantage of the greater 383 engine torque.

  5. Yes..... any of the AQ series (250 and on) can have the AQ series Duo Prop lower unit added.

NOTE: the vertical shaft tapered roller bearing "race" has a control shim pack above it.
This shim value must be re-calculated and adjusted when changing any lower unit to another Intermediate housing.




.
 
Last edited:
RicardoMarine said:
Jim, my suggestions here.

  1. Jim, I know that this is off topic somewhat...... but there are a few "Do's and Don'ts" when building a 6.3L (aka 383 cu in) for Marine use.
    First and foremost, I would strongly suggest that we NOT build a 383 with the GM style full dished pistons.
    Build a quench into your combustion chamber by using a quench style piston, and with a correct quench dimension (approx .038" for a Marine build).

    This is a simple change to the piston selection, and several points of attention given to the piston deck height and compressed head gasket thickness.
    This requires no other engine modifications.
  2. Your Volvo Penta 280 drive is among the AQ series family. The VP DP-S (off a 1998 boat) is a gimbal system drive.
    Your AQ series transom cut-out is too large for a Gimbal System drive.
  3. Jim, it's just the opposite of that. The AQ series transom shield, and the cut-out, are larger than the SX or DP-S.
    In my opinion, the design and geometry (main suspension fork/pivot tube) of the AQ series is superior to the later Gimbal system Volvo Pentas.
  4. Again.... in the AQ series, the normal SBC V-8 ratio would be 1.95:1.
    However, with a good quench built 383, and depending on the hull size, the 1.78:1 ratio can be used.
    This ratio gear set is slightly different.
    The 1.78:1 "drive" gear is a bit larger, and the two "driven" gears are a tad smaller.
    This makes for more gear tooth contact at any given time......, and believe it or not, it makes this gear set a tad stronger.
    Since the 1.78:1 is taller, it helps take advantage of the greater 383 engine torque.
  5. Yes..... any of the AQ series (250 and on) can have the AQ series Duo Prop lower unit added.

NOTE: the vertical shaft tapered roller bearing "race" has a control shim pack above it.
This shim value must be re-calculated and adjusted when changing any lower unit to another Intermediate housing.




.
Click to expand...

Thanks Ricardo

1. I appreciate the mention, I am working the correct piston and quench into the build per your previous advice here.
http://www.marineengine.com/boat-fo...inless-prop-for-Volvo-280&p=437796#post437796

2. & 3. Ok, sounds like the dp-s idea is out, don't want to fill.

4.currently my 280 single prop is 1.6:1 and I'm assuming your 1.95:1 recommendation is for a dp application weather it's a 280/290 dp or dp-s, basically a VP duo prop in general.

5. So when I'm looking for a used 280/290 dp lower unit is there anything I should look for, avoid, etc? Other than shimming.


Thanks for the valuable info.

Jim
 
jmm4jmc said:
Thanks Ricardo

1. I appreciate the mention, I am working the correct piston and quench into the build per your previous advice here.
http://www.marineengine.com/boat-fo...inless-prop-for-Volvo-280&p=437796#post437796

2. & 3. Ok, sounds like the dp-s idea is out, don't want to fill.

4.currently my 280 single prop is 1.6:1 and I'm assuming your 1.95:1 recommendation is for a dp application weather it's a 280/290 dp or dp-s, basically a VP duo prop in general.

5. So when I'm looking for a used 280/290 dp lower unit is there anything I should look for, avoid, etc? Other than shimming.


Thanks for the valuable info.

Jim
Click to expand...

1.... Good move!

2 and 3..... Yes, and the AQ series is actually a much better drive.

4... Yes, the SBC DP ratio would be 1.95:1 ......... or...... with more torque, and if the hull is not too large/heavy, the 1.78:1 ratio.

5... you are not limited to a 280 DP or a 290 DP.
Any of the AQ series DP's..... clear up to the DP-C, DP-C1, DP-C2 and so on....., will work.
When you get into the "C" series, the vertical shaft becomes shorter. This requires the longer p/n 3852268 spline coupler.

This is what the AQ series lower Duo Prop unit will look like.
These exit the exhaust via the housing outlet.... not thru the prop hub.





You will not be able to use the later DP-S style Duo Prop lower unit.
These are completely different in some regards.
These exit the exhaust thru the prop hub.




.
 
Here's an AQ series DP "C" model.




This is an older 270 top view.
Whether 250/270/275/280/285/290/SP/SP-C single prop lower units...... or any of the Duo Prop lower units, the tops of these will all be extremely similar.
This one is being shown with the vertical shaft tapered roller bearing race sitting over the roller cage.
(normally, this race remains up inside of the Intermediate housing, and seldom catches up with the lower unit as it should have when being sold)

 
RicardoMarine said:
4... Yes, the SBC DP ratio would be 1.95:1 ......... or...... with more torque, and if the hull is not too large/heavy, the 1.78:1 ratio.




.
Click to expand...

Ricardo... how well do you think the dp 1.78:1 ratio will work? 26ft boat is about 4k dry and hull is fast and doesn't take much to get it on plane. I just see more used 1.78's out there and better pricing than the 1.95's.

Thanks,
Jim
 
jmm4jmc said:
Ricardo... how well do you think the dp 1.78:1 ratio will work? 26ft boat is about 4k dry and hull is fast and doesn't take much to get it on plane. I just see more used 1.78's out there and better pricing than the 1.95's.
Click to expand...
Jim, the 1.78:1 ratio will be too tall for a 5.7L SBC. You'll need the the 1.95:1.

If you were to build yourself a good quench built 383 SBC........ the 1.78:1 ratio would likely work OK.
 
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