Upgrading VP SX drive to DP questions

[gcope63]

I am looking at replacing my 2001 VP 5.0Gi SX outdrive with a DP outdrive. My reason for the change is to increase performance at higher altitudes and better use what hp I have. I have discussed this on another forum (trailerboats) and their recommendation was to change the outdrive gear ratio from the 1.60 I have now to either 1.76 or 1.95 and stick with the stock SX. Which do you guys think would be a better way to go? I do about half my boating at less than 1000' but the other half is much higher at around 7000' and the 5.0Gi at that altitude is kind of dog and at this time I am running a 15" High Five to get any kind of ability to plane or do any water activities. At the lower lakes I run a 19" High Five and it runs great and will get up 50+ mph on the speedometer.. Another possibility is upgrading the engine to the 5.7GXi which would bump the hp from 250 to 320 but is pretty expensive..

Thanks for your help

Gary

 

[Don S]

Re: Upgrading VP SX drive to DP questions

ratio from the 1.60 I have now to either 1.76 or 1.95 and stick with the stock SX.

No, you don't just change the ratio. You MUST change the lower unit to a DP style with 2 shafts. It will have a 1.95 ratio, the 1.60 is for a single prop. The 1.75 ratio is for a Big Block (7.4 and 8.1) engines.
The DP will help at altitude also. But at 7000' everything will be a little more of a dog, but the DP will make a big difference over the single prop.

 

[gcope63]

Re: Upgrading VP SX drive to DP questions

Sorry, I guess I wrote it wrong. What I was wondering is which would be the best way to go, change the gearing on my SX drive or upgrading to the DP drive? How much should it cost to change over to a DP drive?

Thanks

Gary

 

[Don S]

Re: Upgrading VP SX drive to DP questions

Go to the DP.
It will be like driving a completely differnt boat ............. MUCH better.

 

[mcleaves]

Re: Upgrading VP SX drive to DP questions

Go to the DP.
It will be like driving a completely different boat ............. MUCH better.

I can vouch for this in a HUGE way. Lower planing speeds, time to plane cut to about 1/3. I can load the transom with people and have no trouble getting on step. About 4 mph on the top end.

The only way to really understand and appreciate the value of a DP is to put one on a boat that had an SP.

And Don you are right, it's like going like adding cubic inches. As for fuel economy, I actually use a LOT more fuel. I guess that happens when it allows you to use your boat more often . That is a good problem to have though. I used to dread long trips in short chop and wouldn't make them since I needed to stay in the 20-24mph range to stay on plane, and some days it just beats the crap out of you. Now I can stay on plane at 15-20mph a 5k lb boat loaded with gear and people. Those trips are a treat now!

M

 

[gcope63]

Re: Upgrading VP SX drive to DP questions

Okay, Do I have to change the entire outdrive or only the lower unit? I have heard both.. What should something like this cost?

Thanks

Gary

 

[Don S]

Re: Upgrading VP SX drive to DP questions

All you have to change is the lower unit.

 

[gcope63]

Re: Upgrading VP SX drive to DP questions

Is there a certain model of DP drive I need? I have heard there are a couple of models of DP. Also, do you know of a good place to get one online?

Thanks

Gary

 

[mcleaves]

Re: Upgrading VP SX drive to DP questions

"http://www.dougrussell.com/Products/index.cfm?fuseaction=ProductDetails&ProductID=169&Category=2&Brand=22[/URL]

"http://www.dougrussell.com/Products/index.cfm?fuseaction=ProductDetails&ProductID=170&Category=2&Brand=22[/URL]

 

[gcope63]

Re: Upgrading VP SX drive to DP questions

Is this something that can be changed by an average mechanic at home?
Also, what do you think would be a good propset to start with? My boat weighs approx 3600lbs dry so with a full tank and a load of people the total weight would be around 5000lbs.. I want my first set to be something setup for 1000' or less. After this I will work on the higher alititude set.

Thanks

Gary

 

[mcleaves]

Re: Upgrading VP SX drive to DP questions

Is this something that can be changed by an average mechanic at home?
Also, what do you think would be a good propset to start with? My boat weighs approx 3600lbs dry so with a full tank and a load of people the total weight would be around 5000lbs.. I want my first set to be something setup for 1000' or less. After this I will work on the higher alititude set.

Thanks

Gary

If you can remove 3 bolts on a plastic cover, remove 6 nuts holding a drive on, detach a cable and make sure a small gasket stays in place when you slide the drive back on you are in business.

Now, there are some maintenance items you need to do while you have the drive off (check the gimbal bearing and engine alignment, as well as inspect and grease the ujoints).

So yes, unless you don't know the difference between a screwdriver and wrench you probably have the skills.

Even if you didn't want to do it, it's only about 30 minutes to do the swap. A shop won't cost much.

it's really simple.

M

 

[rodbolt]

Re: Upgrading VP SX drive to DP questions

to convert from the SX to a DP simply requires a lower unit with the compatible gear ratio.
unlike merc volvo like to change ratios in the lower.
drive removal is not required make the change.
you wil find prop sets are rather pricey,especially if ya like them shiny stainless ones.
just make sure you use new orings at reassembly and other than buying the lower and prop sets its painless .
nice thing about MPI motors, they tend to compensate for a change in barometric pressure.

 

[mcleaves]

Re: Upgrading VP SX drive to DP questions

drive removal is not required make the change.
you wil find prop sets are rather pricey,especially if ya like them shiny stainless ones.

You are absolutely right.. My bad. I forget we were talking about swapping out the lower.

There is one IMPORTANT thing to note though. Some of the early SX drives had the recess in the upper a flat surface in the lower. At some point there was a flat surface in the upper and a recess in the lower.

The consequence is that if you ended up with an older upper and a newer lower, like I had on my 1995, you have two recesses trying to mate. The standard o-ring is too small. You will need what is called a "quad ring" instead of the normal o-ring for sealing. It basically doubles the thickness of the ring to compensate for the doubles sized gasket space.

So if you swap the lower make sure you get the right sealing components. I was told but my VP shop they stopped making the quad rings and what was out there was all you could get. I bought their last two and tried to order more but they couldn't get them, from several sources. I am not sure how many years the upper was like this, but at least 94 & 95.

M

 

[gcope63]

Re: Upgrading VP SX drive to DP questions

Okay, you've brought up another question. You said that I will have to match up the gearsets? My drives gearset right now is 1.60 and the DP's all show gearsets up around 1.95. Do I have to replace the gearset in the upper drive along with replacing the lower drive?

Thanks

Gary

 

[Don S]

Re: Upgrading VP SX drive to DP questions

One more time ................ YOU ONLY HAVE TO CHANGE THE LOWER. The uppers are the SAME.
You do not have to do anything at all to the upper.
You MUST have a 1.95 Dual Prop Lower, the 1.60 is a Single Prop lower.
They are NOT the same. The ratio for a DP or an SX is complete different.

 

[mcleaves]

Re: Upgrading VP SX drive to DP questions

One more time ................ YOU ONLY HAVE TO CHANGE THE LOWER. The uppers are the SAME.
You do not have to do anything at all to the upper.
You MUST have a 1.95 Dual Prop Lower, the 1.60 is a Single Prop lower.
They are NOT the same. The ratio for a DP or an SX is complete different.

So what you are saying is you don't have to do anything to the upper. Or are you saying you don't have to do anything to the upper?

M

 

[Don S]

Re: Upgrading VP SX drive to DP questions

No, you don't have to do anything to the upper, BUT, you really have to do nothing to the upper. Got that?????
Man you are hard to teach

PS, can't put my split files back together .............. Waaaaaaaaaa

 

[rodbolt]

Re: Upgrading VP SX drive to DP questions

DonS
try intergrating the files with chrome plated muffler bearings lubricated with rum.
works

 

[Don S]

Re: Upgrading VP SX drive to DP questions

try intergrating the files with chrome plated muffler bearings lubricated with rum

Send rum, have the bearing.

 

[rodbolt]

Re: Upgrading VP SX drive to DP questions

bwhahahahaha,
OMG
that pic I gotta save
PM me your address and when I get back to the states it will be on its way
that pic is worth a bottle of santa theresa