magnum27

For some reason I just love black boats. I am finishing up my 27 foot Magnum starfire that I just gel-coated the entire boat BLACK. It just looks mean and intimidating.

phughes69

What kind of issues will Harry have with running the Speedmasters and this kind of power?

PatriYacht

He should save his money for the Conrad conversion. Speedy 2 lowers aren't any stronger than TRS. They sit lower in the water so there is no performance gain. The propeller choice is limited to cleaver designs that are very expensive. Leave the TRS and get a set of modern 5 blade props.

Cig35Mistress

Dear Laz:

Thanks for the reply - if you are a former Custom Engine Service guy you must know my very good friend, Tommy McMillen. Tommy is working in Stuart, Florida at present for the local Donzi dealer and has been a good friend for almost ten years. He always recollects his Custom Engine Service days and has been a big help with this boat. If you wouldn't mind, please give me whatever you can as far as the 496's you've built, my goal, and I know this is going to sound ridiculous, is to have a reliable, relatively big power application, that will have longevity as well. If you'd like to send it to me privately, feel free to e-mail me at [email protected]. Once again, I appreciate all of the assistance I am receiving on this board!

Har

Edward R. Cozzi

Your TRS drives were never meant for more than 525 hp and with as heavy a boat as your Mistress is, I'd be careful with hole shots. Stay with the lower compression unless you are planning to use aluminum heads. (More maintenance in salt water.). Remember the old Hawk 500's that usually stalled when you put them in gear? (Even though they idled at 1200 RPM in neutral.)? Well, if you use the cam you described, you'll be changing it before long.

Cig35Mistress

I fully understand the fact that my boat is 26 years old, and I am not looking to kill it, whether nailing it out of the hole or jumping five footers offshore at WOT . . .

My goal in building the engines is to have a boat that will cruise at a higher speed easier, rather than killing a set of smaller horsepower motors. With my original 454's I was turning roughly 4200RPM's on the tachs and barely seeing 45MPH on the GPS, although I think one engine was on its way out at that time.

As I mentioned, everything I had specified on the original post was per the machine shop proposal, and I came here to tweak it out! Also, Tommy McMillen, formerly of Custom Engine Service, has yet to go through this with me, so I am seeking his advice as well. Laz seemed to have some ideas that would work as well.

I'm sure with all of the collaborative help I'll be able to put together a dynamite set of engines! Thanks again for all of the input!

Har

KAAMA

iTrader: (1)

Try and design your engines/boat combo for TORQUE and to be as user friendly as possible---you'll be glad you did. I agree with what several of the others guys advice as well. Go with the better cranks. I think you'll end up being very sorry if you run 10:1+ comp ratio in your engines---especially with cast iron heads. Keep in mind the fuel octane ratings that the marinas normaly carry and that you may need 89 octane to get you home---so give yourself some cusion for error when it comes to comp ratio and remember that the gas is (or should be) the cheap part of performance boating.

I also agree that the cams you have your eye on are a bit too large. Of course you can do as you please, but I think you will appreciate good drivability/shifting, etc, while manuvering around the docks, boat traffic, currents, wind, etc. with a smaller cam than what you're speaking of. Besides, a smaller cam will give you better midrange, torque and throttle response---again, especially for a larger, heavier boat like yours.

I largest cam I would run for your engine/boat combination would be the Crane 741 hydraulic roller cams

Bowl/pocket port the heads

Switch from the single plane Dominator intake manifold to a dual plane like the Air Gap from Edelbrock or a comparable dual plane intake for such a heavy boat as a Cig.

KAAMA

iTrader: (1)

By the way, most of your engine mod efforts would be fruitless without a better breathing exhaust system vs the Merc cast iron exhaust manifolds which are very crude at best. I would run a full length tubular header if you can swing it. If not then one of the aftermarket hi-perf manifold designs would be the next choice such as the Stainless Marine exhaust system as you have mentioned.

cig1988

You may want to replace the heads. If they are the original, may be time to do so.

Cig35Mistress

Well here's the latest, I am going to opt for either JE #142980 flat top 8.7:1 pistons, or #145376 closed chamber dome 9.1:1 pistons or #141635 open chamber dome 9.5:1 pistons. Do you think there is a significant power loss between these applications? If so, is there something else to do that would increase power at lower compression?

For my next question, I am interested in the specs on the Crane 741 and I can't seem to get them online. I'd like to find a complete kit, cam, lifters, springs, timing set, etc. as the Comp kit that I mentioned. Anybody know a part number for that?

Also, I am looking a used set of Stellings big tube headers, I think they would work nicely on the boat with the engines I am attempting to build, plus they would unclutter the engine room a little.

I am trying to get everything built and sorted by November so that I can take the boat to the Key West Offshore races, is anyone here going?

Thanks again for your continued help!

Har