ForrestC

Havasu Hangin, I'm turning 4600 to 4700 RPM with the 27"p props, but there is a 300 RPM mis-match between the props (the port side turn only 4400 RPM now). I guess this happened since they weren't built at the same time. I'll have him tweak 'em and match 'em for about 4800 RPM. Prior to the 27" I ran 24"p Volvo-Penta Ultra props and they would turn 5600 RPM but wouldn't hook up on the top end (high % of slip). I wanted to bring the RPMs down a little to increase the cruising range, and that's why I went with 27"p as a starting point. On thing I find with prop testing on the Volvo Aquamatic setup is that they have more prop slip on the top end than I've found on Mercrusier setups. I'm keeping my fingers crossed that the nose-cones will help reduce the prop slip at full speed. I'm sure that matching the props will help as well.

As for steering, no external steering - just Volvo power steering on the inside. When I go to the next out drive setup, you can bet it will get external hydraulic steering. I tie bar the two drive together using a stainless-steel hiem-joint tie bar from a TRS setup shortened to 30" and attached where the 280/290 steering torque compensation trim-tab was removed. It works fine and doesn't drag in the water.

No one that I know makes one, but you can build a solid external steering attachment point on a Volvo Aquamatic drive. A few of years ago I built a stainless-steel steering-ram attachment plate that bolts to the top of a 280 drive using three of the drive-cap bolt-holes for a friend of mine's X-18 Donzi. Basically, it's a piece of 3/8" stainless plate cut to cover the top of the drive with a hole in the middle to allow access to the screw-dipstick, and three holes for the three cap-bolts. It used three stainless-steel spacers that fit tightly into the recess of the out drive cap where the attachment bolts go. These spacers, which are about an inch long, raise the stainless-steel steering plate just high enough to clear the drive's cap. You can accurately locate and weld the spacers on to the plate or just bolt it all together using ARP stainless steel bolts.

The best way to go about designing the plate to insure that it will work with the steering ram that you have, is top build the plate out of 1/4" plywood, to mock it all up to make sure the steering doesn't bind at any angle, before you commit to having it cut out of stainless-steel plate. If you can't find any stainless steel spacers at you friendly fastener shop, these stainless-steel spacers can be found in many automotive disc-brake calipers. The trick is to find the correct caliper repair kit at the auto supply. Bring your magnet - some are more "stainless" than others.

Havasu Hangin

...that make sense. I was wondering how a custom plate would sit on top of the cap, and still fit flush in the cap bolt holes.

I heard Speedmasters in Florida was making a plate for the tie-bars, so I called them. He wants $100 for one, but I'm not sure if it will work for a ram.

Well, I hope the nose cone helps your slip. Those lower units are pretty blunt, and may be causing your problem. The pic below is what mine looks like with the cone installed.

candyman35

ForrestC,
Nice boat!
I stopped at Greg's shop but he wasn't in. His Dad says the boat runs low 70's but didn't have exact numbers. I know he runs a GPS Speedo so the numbers were pretty accurate. He did not have Wolff build his engines. I'm 90% sure he has Merc drives on the boat. I told has Dad to have him check the board. He is not a member yet!!! I'll stop by next week and see if I can talk him into checking out the board.

Dan

traviss

I have a 383 in my 18' powerplay... I built it over the winter and now have 55 hrs on it.. its around 400hp.. my stock 350 mag spun a 21' at 4500 for 58.6 mph and now with the 383 it spins a 25' at 5300... for at least 72-73 mph

Preuni

traviss, what kind of heads you are running? Vortechs?
What exhaust and cam?
Andy

Kent Perroux

Forrest,

the hydromotive nosecones will make a difference on the volvo 280. I picked up 3-4 mph on my 18 Donzi with it.

Blowout is significantly reduced also and you will be able to trim higher.

KAAMA

I talked to Wolff today and he said those 383's that he built for that 27' Magnum make about 375hp each and push the boat from about low to mid 70's.

traviss

Yes..I am running the vortech heads... screw in studs.. guideplates... guides machined for high lift cam... springs to match cam..

roller cam is 222/230 duration.. .509/.528 lift on a 112 LSA.
( I used 1.6 rockers so mine is acutally .543/.563 lift..)

Exhaust is all aluminum EMI's... with the riser water going out dumps in the transom instead of going out the exhaust..


Travis

ForrestC

Kent / Havasu, UPS just delivered my two Hydromotive Volvo nose cones, and Havasu, it sure looks like it going to take a little doing to get 'em installed properly and faired in. Did you guys need to clean up the inside of the nose cone to get a tight fit? The reason I ask, is beacuse when I hold it in place it against the lower unit, there seems to be a few gaps here and there. Also, what kind of filler did you guys use to fair it in?

Preuni good luck with the 383. From my experience, the 383, even with a mild cam and (or) 76cc smog heads from yester-year, is much stronger, smoother, and in may cases quieter, than the equivalantly setup 350. I also have an 18 Donzi with a big and heavy TRS outdrive and a budget-built 383 (76 cc 441 heads, UEM Claimer flat tops, and a Crane H-272-2 cam), and I can honestly say that this engine is the best all around running engine that this Donzi ever had in it. With a 23" pitch Mirage prop, it has incredable bottom-end and mid-range, and a 66 MPH top end. With any luck, I may be trying a 24" pitch 3-blade Hydromotive prop soon. You have to remember that this is a heavy, short, 24-degree bottom boat with a giant outdrive. Hay, I may need a nose cone on this boat's TRS outdrive as well!

Havasu Hangin

Forrest- When I spoke with the guys at Hydromotive, they made it seem like it would be a piece of cake- far from it.

I saw the same thing you saw- the cone does not seem to fit very well. I had BIG reservations when installing, because it seemed like it was not made for my bullet, and you have to get it perfectly straight. I even had to start over one time.

I took the drive down to the metal, and even did some grinding on both the cone and the bullet to get a snug fit. For lining it up, I had the drive upside down, and eyed it off the skag. Also, I eyed it from above using the centerline of the top plate in relation to the shaft.

It still didn't look snug, but that's what Hydromotive told me to do. I then used the Sea Goin' Poxy Putty that came with the cone to tack it on. More grinding and sanding...also be careful to keep the putty off the drain plug on the bottom.

Before backfilling, I also took some material off the sides of the cone, to streamline it a little, and make it easir to fill.

I used some 4x4 Bondo for backfill. What a pain- I was not as good as I thought at body work. Took me 4 tries to get it right. I've heard there are better fillers out there- after 2 seasons, I have a couple hairline cracks in the filler at the bottom. I have been told that this is from flexing- if I had welded it on, then I may not have the small cracks.

Good luck!

BTW- I'm going to WPM on Friday to get the wing plate made for my external steering- thanks again.

Preuni- my engine made 457HP with 10-1 pistons, the same cam as Travis, and ported Edelbrock Performer RPM heads (on dry headers).