Volvo Penta DPX Q&A
 

Hey all - looking for some info about Volvo Penta DPX duodrive performance. I have a 27 Eliminator with a stock (non-EFI) 502 and E3 props on my DPX. Running 66MPH @ 4k RPM. What do you have with yours and what are you getting as far as performance? Thanks!

I ran the same speed in my v-bottom 21' boat @ 4500 rpm, 1.68:1 and E2´s.
Small block with 400 hp.

The outdrive is moving to my new (old) 28' boat but the engine will be replaced by a bigger one.
No idea on what speed to expect from the new boat, might hit the water this summer if all goes well - it´s to early in the project to know yet.

I think Volvo sold the DPX drive with a 600HP engine at one point. Has anyone exceeding that power level with the drive that you know of?

There is an Arrow 830 over here that had about 700 hp with an dpx outdrive, I believe that they broke the outdrive once when landing at full throttle doing about 70 knots.
You are correct in that Volvo sold the dpx drive with a 540 cui motor, 560 hp at the prop shaft.

Which DPX do you have, earlier R or later A? The As are a little stronger as they eliminated a mid housing, going to (2) pieces from (3). On the Rs, the upper/mid was a weak link. On all of them, the pinion gear is prone to failing once you get past a couple hundred hours. The other thing that was a MAJOR killer of them, was being used in high x dimension/surfacing applications. Last thing, is keep an eye on your props, as the rears especially, had a tendency to develop stress cracks in the blades.

I had the DPX 600 setup for 11 years, and as far as driveability/reliability, I would take them over a Bravo anyday

That is some great info - thank you for sharing. Not sure which I have as far as R or A, I have put a couple pics here - its on a 1998 model. The x dimension I am also not familiar with, but here is also a pic of the boat. Its a air entrapment hull (cat) - Thanks again for all the info! Love to learn.

no pics for now apparently :)

You are not allowed to post URLs until you have at least 10 posts

The Rs have a (3) pc housing and are kind of ugly/angular on the upper. If the drive is original to the boat, based on year I would guess you have an R. The As are a little prettier, have a (2) pc housing which is sloped/rounded on the upper.

got it. based on that description I have the ugly older one :) when I bought the boat the lower had broke instantly. sourced a new old stock lower from doug rusell and it was a different gear (1.58) versus the one I had. Luckily they mated ok and the service center said no problem, just not sure how affects gearing.

There are DPX-S (and S1), followed by DPX-R and then later on DPX-A.
I have a picture of the differences of the drives but I'm not allowed to post any pictures yet.

I just had my picture restriction removed I think.

Here is mine. When trailer running it, I have 2 threaded open holes on the lower. One at the rear pointing towards the front of the boat, and one on the bottom of the lower pointing straight down. Water in either comes out the other it appears. Should both be open like that for normal use?

https://cimg4.ibsrv.net/gimg/www.off...1b994a1fa5.jpg

Were the E3s what came on it? Given your 4k rpm, that was likely affected by ratio change. E2s would help you get your rpm up closer to where you likely want to be.

Your drive looks to be an R (definitely not A) although like 1800T pointed out there were earlier S's. I generally dont mention them as they were/are few and far between based on everything I gathered over the years. The S's dont share many of the internals that the Rs and the As do either.

Correct on water inlets. Duel pickup as you described. Unless you are having problems, leave them alone

More great info - made me want to go look at the lower I bought from Doug Russell, as I could not recall if had a sub letter. Turns out It was an S lower (but who knows maybe they work with everything)

https://www.ebay.com/itm/Volvo-Penta...-tel:rk:1:pf:0

Is there a recommended place to get a set of E2 props - would like to try and see if makes a difference in MPH and plane speed - thanks again everyone for all the info.

The S, R, and A lower housings are all the same, so yes, they bolt right up. As for the props, I would keep an eye out for a used set on ebay or such. New prop sets are not cheap and since you dont know exactly what you will end up with performance wise its a bit of a risk.

I like these volvo drives way better than any other DP on the market.

My knowledge on volvo drives outside of the DPXs gets a little more limited. I think your answer depends somewhat on what you are going to apply the drive to. Volvo made a DPR drive for a while which was very stout. The DPH drive is also supposed to very strong. One of the things that made the DPXs and Rs desirable over all other Volvo drives, they are the (2) that had the built in hydraulic steering which was a very nice feature. The Volvo drives across the board al shift better than bravos, in my opinion. I feel Volvos engineering and machine work is better than Mercs and that contributes to a better/more durable drive overall.

What I can tell you about the regular DP drive, is my next door neighbor has a 22 Chris Craft Launch with a DP, which he runs pretty hard for what it is, on a regular basis and he put almost 800 hrs on the drive, without ever having to do ANYTHING, other than change oil

a question for the dpx savy - can you run mixed props? i.e. E3 rear and E2 front - would that be like splitting gear ratios or just not work?

No, you can´t mix props. You need to change both props if changing to a different size.

I have a different take on this. Yes, you can mix props, it is just a question of what the end result is. There is the potential for poor harmonics which could damage the drives and/or props themselves. This is not a given though. Plenty of guys mix prop pitches/diameters on duo-prop drives with good results, but applications are not necessarily similar, as in non-performance versus performance.

sometimes, there is only one way to find out..........

:)

My reply in this is what the VP prop guide tells you, I have no experience myself as to mixing props.

Understood, and not trying to "1 up you". Just sharing a different perspective.

I've mixed pitches on Bravo III drives before. As stated above, only way to know the results is to try it. I went back to a matched set as mixing did not have the desired outcome.

As someone who tried it and has real life experience what was it that made you try it and why were the results not what you had hoped for ?
BTW , I can , for example, see someone who wants to optimize their RPM range to exact factory specs and what they might run is a little bit too much and the next set down is too little or vice versa and therefore the reason for experimenting.

Trying to dial in WOT RPM with the hopes of a little more top end as well. I was in between prop sets as 26's I was hard on the limiter in ideal conditions but the 28's dropped the RPM too much. Tried a inner (larger) 28 with the outer (smaller) 26.

I like the real life testing . When you did that where did your WOT rpm go and was that the only switch you tried , ie; did you try the 26 front/28 rear mix ? .

I did not try the 26" forward with the 28" aft prop as I didn't think the diameters would play well together. It was in the early 2000's when I was messing with this so I don't remember where I ended up RPM-wise. I just know I decided to send my 26's off to Bronson Hill instead of running the mixed set. I believe Bronson added some cup to the props. A friend of mine and member on this site (Mentalpause) ordered a new 1998 Powerquest 270 with a 454MAG/Bravo III and he stated it came from PQ with a mixed-pitched set of props.

On another DPX note. Has anyone here had to bleed the XACT (external) steering. I want to have a leaking ram repaired but reading about bleeding is spooking me a bit

Or anyone have a factory service manual that may describe the process of bleeding the steering? thanks!

Self bleeding. Run the engine and just crank wheel back and forth, lock to lock several times and you should be good to go. The cylinders are pretty easy to rebuild yourself, if you have a bit of mechanical inclination. Hardest part is sourcing seals without paying and arm and a leg, and breaking the cylinder end cap loose can a be a B!Tc$.

I did, after some troubles, find a 3 pin, pin wrench that fits the caps very well, and made that job a whole lot easier.

Hadnt been back on here for ages, but wanted to say thanks. Self bleeding of the hydraulic system was indeed simple after rebuilding the rams. Time to service the drive oil, any special tips here? Only finding stuff on standard DP drives online - imagine about the same process?

Everything is pretty much the same. Remove the props and fill it from the bottom plug until it runs out the top. Be sure to run the Volvo GL5 rated fluid. Cheers,