1971 Donzi Classic 18 power....

**FUJIMO** · 01-29-2017, 04:08 PM

Originally Posted by Classic18

...........
I guess beyond the steering parts that are on the transom bracket and the steering pump on the engine, I have not thought about what I need in terms of a steering system. I would be interested in your thoughts on what might be a good average system that would get the job done though

External Bravo Performance Steering System, consists of a top mounted Bravo drive stainless steel steering cylinder & mounting plate. 9" stroke cylinder with clevis rod end(bolt/nut/washers attachment kit for clevis end) & two 90 degree 1/4" male pipe x 3/8" SAE male flare chrome brass fittings threaded into the cylinder. Two short high pressure -6(3/8")cylinder hoses & hose ends(3/8" SAE). I recommend Eaton-AeroQuip 2651-6 black hose material, and fittings. Attached to two 1/4" female pipe x 3'' long stainless transom thru-hull hydraulic fittings, via two more of the exact same chrome 90 degree fittings. Use TefGel, which is a white Teflon based thread lubricant, at all the hydraulic thread connections. This completes the outside portion of the steering...

**FUJIMO** · 01-29-2017, 04:21 PM

...Two of the same steering hose assembly's from the inside of the two thru-hulls, up to the three-port full hydraulic helm. Two of the same 90 degree fittings on the inside of the thru-hulls, pointing to the starboard side rig tube. A third hose assembly from the helm back to your existing engine mounted power-steering pump, via a -6 "Banjo" fitting at the pump, "powers" the helm. Chrome fittings optional inside the boat. Fill with Dextron ll, lll, or lV automatic transmission fluid. Start & idle for a minute. Turn wheel back & forth a couple times. Stop engine. Top off with more fluid. Start & run for another minute. It self purges. Done. You can use the boat at this point. Micro bubbles congregate to the highest point in the system after a day or two. Recheck fluid level then.

**FUJIMO** · 01-29-2017, 04:39 PM

...Transom end of external steering cylinder is mounted at outdrives(and engines) crankshaft center line. Thats at the level where the drives input shaft comes through the gimbal/transom plate. Extend 9" cylinder to half of its stroke(4 1/2") & thats where you mount it to the transom.

**FUJIMO** · 01-29-2017, 05:22 PM

...typical single cylinder external installation... This particular vender is Zeiger.

**FUJIMO** · 01-29-2017, 05:46 PM

Mayfair brand externals...

**Classic18** · 01-29-2017, 05:50 PM

Seems I have a system that works internal to the hull ...it should work for my application, right? What's the advantage of the external setup?

**FUJIMO** · 01-29-2017, 06:00 PM

**blacktruck** · 01-29-2017, 06:02 PM

Originally Posted by Classic18

Seems I have a system that works internal to the hull ...it should work for my application, right? What's the advantage of the external setup?

Safety, Safety, handling, saves your existing steering and gimbal etc. You will feel a huge difference in how it steers, no play, way better. And, looks cool!

**Classic18** · 01-29-2017, 06:02 PM

Very nice setup!!

**FUJIMO** · 01-29-2017, 06:15 PM

Originally Posted by Classic18

Seems I have a system that works internal to the hull ...it should work for my application, right? What's the advantage of the external setup?

Not if your putting 450 horses in a 18 Donzi. You can use the standard MerCruiser steering if you want. I wouldn't get in your boat though. Bravo gimbal rings break on standard Bravo's. That's why they offer stronger Bravo transom plates from MerCruiser for Bravo's with engines in front of them with your horsepower. Among other reasons. Here's the bottom line. What your proposing is dangerous. That's just my opinion. You rig things right, with 450 horsepower, or you don't do it at all. Even then, 18's are unpredictable. Keep the boat at 300 horsepower or less, and you can piece it together on the small budget you have, and be much, much, much safer.

**Classic18** · 01-29-2017, 07:30 PM

Thanks for the thoughts. I had no idea the ring has issues with breaking. I am reconsidering my powertrain based on the feedback I've received. I need to figure out how much power I need to hit 70mph....it's likely much less, maybe 375-400. If I need external steering I'll include it.

**cali kid** · 01-31-2017, 10:43 AM

Originally Posted by Classic18

Thanks for the thoughts. I had no idea the ring has issues with breaking. I am reconsidering my powertrain based on the feedback I've received. I need to figure out how much power I need to hit 70mph....it's likely much less, maybe 375-400. If I need external steering I'll include it.

I have an '08 mercruiser mpi mag horizon, 300 hp,dry joint, complete drop in bravo package,low hours, I would sell to you reasonable.

**Classic18** · 02-04-2017, 05:00 PM

Originally Posted by FUJIMO

You think an old school high horsepower 2-bolt main small block will take jumping in & out of the water, the way those old Donzi 18's do? I don't know. Agree with the heads/compression thought. But he will have to spend some money. No matter how you choose to attain a "dependable" 450 h.p., you will be spending some money.

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Have been out of town and doing a bunch of rereading and thinking about all the comments on this thread. I really appreciate this feedback and take it seriously..

I'm going to limit the boat to 70mph....and I'm thinking I might be able to take my 1991 2-bolt main 5.7 Mercruiser and do the fast-burn heads, a performer intake and go with it. The lower end was good coming out of the donor, unless its recommended to redo (and if so with what hardware)? I would like to run 6000 if I can. Bolt this to the Bravo One with a TBD prop.

XstreamVking mentioned the "reversion" I know I might sound uninformed, but what is that?

I should be able to keep the transom-mounted steering, or should I get the recommended external system above. It makes great sense, but only want to do what is needed to be safe.