Volvo outdrive--want to go faster

[Donzi Vol]

I'm running a 351 paired with a Volvo 270. As far as I can tell it's all original equipment. Either way, the motor runs strong, and the outdrive is solid. However, top speed is 48.5mph (gps) at 4800 rpm. It will rev to 5500 rpm, but no gain in speed. I'd like to see 60mph. Any thoughts with this outdrive? Not looking to make the switch to Merc power currently.

[thescooter]

try different props, i think you will find part of your answer. nick the scooter

[penbroke]

Props.

I've seen 56 gps with my 289 Ford / Volvo with an Ultra 24p.

I may have a 270 with a nose cone available in the spring but I don't know that the nose cone will help all that much at these speeds.


Frank

[zelatore]

I'm running a 351 paired with a Volvo 270. As far as I can tell it's all original equipment. Either way, the motor runs strong, and the outdrive is solid. However, top speed is 48.5mph (gps) at 4800 rpm. It will rev to 5500 rpm, but no gain in speed. I'd like to see 60mph. Any thoughts with this outdrive? Not looking to make the switch to Merc power currently.

Now more than ever we miss Randy...

48 sounds very low for that combination. I would guess mid 50's anyway.

Are you saying you hit 48 at 4800 rpm and then continue to pick up rpm to 5500 but with no increase in speed? That sounds like a TON of slip.

I know jack-all about these Volvo drives - does this have power trim? If so, I'd start there guessing you needed to trim it out quite a bit from where you are. If it's a fixed drive, as I think it is, maybe try moving the trim to a higher hole (?).

And of course the question everybody will be asking is what prop you're running now. And while we're at it, what ratio. But I'll let the prop scientist ask those questions...

Hope you're New Year's celebrations are going well!

[Just Say N20]

Vol, I ran my boat (16' 310 hp SBC, Volvo 290 w/power trim) with the big old aluminum prop. 5000 rpms = 47.8 GPS mph.

People who have seen this boat run by the previous owner swear it ran 62 GPS mph using a 19 pitch Grizz Solas prop. I have not run the boat since I bought the same prop 2 years ago, but even Grizz said it ran 62.

I would start with props.

[jl1962]

People who have seen this boat run by the previous owner swear it ran 62 GPS mph using a 19 pitch Grizz Solas prop. I have not run the boat since I bought the same prop 2 years ago, but even Grizz said it ran 62.

Nah - mid 50's w/ a 19" Solas - maybe a little over 60 w/ a 21".

I think Maddad has the fastest Volvo set up in his 18. He has big power, good steering and a 23" Solas.

Happy 2011!

[Donzi Vol]

Thanks for the replies, guys. Lots of good stuff to think about here.

Don, the first thing I thought when I started this thread was how much I miss Grizz right now. This was certaily his specialty. In fact I mentioned it briefly at our Chatt event back in August and he said something to the effect of "David, don't worry...we'll figure it out."

So the details are:
No power trim, unfortunately. I've thought about looking for a 280T, but would like to stay away from the investment if there's anyeasier way to get the speed. I do need to try it in the third hole, though. I keep forgetting to do move it up. It's in the middle hole now. I imagine that might give me a few more mph.

I don't know exactly what the prop is, as it came on the boat and I haven't switched it out. It's S/S and has 27 stamped on it. I'm assuming that's a 27 pitch. There is also a LOT of cup in it. I've thought about getting it labbed a little.

I also don't know the gear ratio. Again, came on the boat and haven't done much further with it.

[Donzi Vol]

Are you saying you hit 48 at 4800 rpm and then continue to pick up rpm to 5500 but with no increase in speed? That sounds like a TON of slip.

Hope you're New Year's celebrations are going well!

Yep, that's the situation. That's why I'm figuring it's something to do with the drive. I've been told in the past that these drives can reach a certain speed and then stop accelerating the boat due to aquadynamics (if that's a word).

As for the New Year's celebration...it was good. Pretty tame, but a fun time with friends. Hope yours was good as well!

David

[mphatc]

David,

Try to figure out your drive ratio and what precisely you have for a prop now, and then try a different prop. With a 351 H&M you should be around a 23p LH on that boat, but someone could have changed it to a RH rotation???

. . .there are several boats here running Volvo's that go over 70 MPH w/o trim . . . and I'll be running twin Volvos on my Magnum 27 and will be over 70 mph as well, thanks to Grizzly for getting me two Solas props.

Madad has a SBC in an 18 that easily runs over 70 MPH !


Mario L.

[Donzi Vol]

David,

Try to figure out your drive ratio and what precisely you have for a prop now, and then try a different prop. With a 351 H&M you should be around a 23p LH on that boat, but someone could have changed it to a RH rotation???

. . .there are several boats here running Volvo's that go over 70 MPH w/o trim . . . and I'll be running twin Volvos on my Magnum 27 and will be over 70 mph as well, thanks to Grizzly for getting me two Solas props.

Madad has a SBC in an 18 that easily runs over 70 MPH !


Mario L.

This is good news! Well now the obsession of gaining speed has begun. I will take some pictures of the prop and post them. I'm pretty sure it's a left hand rotation. As for the drive ratio, I've never crossed that bridge before, so how do I figure that out?

Thanks

[MOP]

You can try!!! May work if the cone stays engaged!!!! Put it in forward then put a chalk mark on the balancer pulley then put a line on the prop shaft with magic marker, bump the engine over two revolutions with the coil wire out. Now look at the prop shaft from the prop end so you get an idea of how much short of turning the two revolutions of the engine. Say you marked the shaft at the top which I do, if it is a 1:61 It will be short about 3/4 short of making it to the bottom of the shaft. A 1:5 will be at the bottom as it will turn 1/2 turn less than that of the engines two turns, 2:1 would make it to the bottom. The RPM's you stated with the possible 27" pitch has me thinking someone slapped a 4 cylinder drive on and propped it up.

[Donzi Vol]

You can try!!! May work if the cone stays engaged!!!! Put it in forward then put a chalk mark on the balancer pulley then put a line on the prop shaft with magic marker, bump the engine over two revolutions with the coil wire out. Now look at the prop shaft from the prop end so you get an idea of how much short of turning the two revolutions of the engine. Say you marked the shaft at the top which I do, if it is a 1:61 It will be short about 3/4" of making it to the bottom of the shaft. A 1:5 will be at the bottom as it will turn 1/2 turn less than that of the engines two turns, 2:1 would make it to the bottom. The RPM's you stated with the possible 27" pitch has me thinking someone slapped a 4 cylinder drive on and propped it up.

Thanks for the input here MOP. I knew you'd have some light to shed on the matter. I have a few questions, though.
As far as determining the gear ratio, is this something I can do with the motor winterized?
Second, if a 4cyl drive is on there, what do I need to be looking for in the way of new equipment? Will just a lower unit do it, or do I need to replace the whole deal?
Lastly, if replacing the whole outdrive, does it have to be an exact match to fit the hole already in the transom or is this an opportunity to upgrade...maybe to a duo prop?
I really appreciate the help. Still a bit of a novice on the drives.

[MOP]

Bumping the engine over won't hurt anything, as far as the drive if in fact it is a 4 cyl it would be easier to swap the whole drive. Your gimble housing will accept all the older style including the early duo's. Let us know what you find.

Phil

[Sweet little 16]

the lower determines the ratio. 200 thru 270 are pretty much interchangeable
if you could find someone with one of Grizzly's 23 props to try the 2. ratio might just work out for you
all volvo props are high in slip except for Grizz's some even get higher in slip the faster you turn them.
you numbers don't add up or that prop is a real POS if you can turn a 27 pitch to 5500
A) if your tach is right a 2 ratio drive your prop has over 30% slip you want to be around 10% or under
B) your tach is off 1000 rpm and the prop is a 21 not a 27 then you have a normal or common V8 ratio of 1.6 and the prop has a normal 15% slip like most volvo props
high pitch volvo props above 26 are very hard to come by and usually were merc type props that had volvo hubs pressed in them .
besides the method above you can remove the drive 2 side pins then the top bolt might be a good time to check the u joints and the boot that cover them . mark the input shaft and the prop shaft turn the input shaft til the prop shaft makes a complete turn then see how many turns the input shaft makes 1 and a 3rd its a 1.3 1 and a tad more then half it's a 1.6 , one a a tad more than 1 and 3/4 it's a 1.8 and 2 it's a 2
Randy will be missed and the work he did in this area (the old volvos) was a labor of love and is appreciated dearly by old volvo owners. there is alot of documentation here and on donzi.org about his prop testing
the 351 came in a few hp versions the most common was the 290 HM package but later versions were rated at 260 and 250 all of which were a little overstated. but with the right prop mid to high 50's day in and out can be easy.
if you can spin a solas 19 to 5200 rpm it will have you knocking on 60's door.

[mrfixxall]

mine boogies ,it likes the 3rd hole,should be good for 5-6 mph with the rite prop..try to find a ultra propp and send it to my prop guy..mine will go in to the 70's with the rite conditions..post a pic of your prop so we can determine what it is..

look where the shift cable goes into the front side of the drive,their should be a letter at the beginning or end of the serial number... B = a 1.61 ratio,C = a 1.89 ratio and D = a 2.15 ratio..