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Repowering from a 485 mercruiser

iceknight66

Contributing Member
Hi there, Im looking to update my 22ft game fisher boat, I am currently running a 485 mercruiser sterndrive, When converting from petrol to Diesel, will the diesel in the same hp out perform the petrol? Or should I go a lot more HP? I currently get 17knt cruise and a 22knt top speed, Ideally I would like something a bit quicker!, I was looking at the steyrs, wich would be comparable In weight I would guess,.


Any Information would be greatly appriciated
 
You love this boat enough to spend that kinda money on it ? that 485 is a version of the 170 isn't it. 4 cylinders correct ? Really cheapest way to power that boat is to buy a donor boat with the package you want and transfer everything over.
 
Yes based on the 4cyc 470, when I say Gamefisher, Its an australian version, based on a bertram, over here a doner boat woulld be worth 35 thousand ish, when I cann buy a small diesel here for around the 20-25ish new.
 
485HP diesel with a reduction gear in a 22 foot boat? You will be doing about 50 at 1400 rpms! I looked at a 58' Hatteras with twin 475HP Turbo Cats and I thought that was overkill. Plus good luck getting an outdrive that could handle the power that cost less than $30K.

Just stick a 4.3L you will be just fine.
 
i don't know if the 4.3 will bolt up to his bell housing, and the inner transom plate. The flywheel is different also i think cause it's a ford based motor that 170 or whatever version you have.

It's not a direct change out is what i am trying in my own inept way to post.

My first post is the cheapest way to repower.
 
485HP diesel with a reduction gear in a 22 foot boat? You will be doing about 50 at 1400 rpms! I looked at a 58' Hatteras with twin 475HP Turbo Cats and I thought that was overkill. Plus good luck getting an outdrive that could handle the power that cost less than $30K.

Just stick a 4.3L you will be just fine.


485- As In a Mercruiser that I already Have In It, I want a 200Hp diesel Or simmilar,
 
Hey we all want what we want, i say you go around once in this life and if you have the money go for it.

I for one am not gonna try to talk you out of it.

Mercruiser cummins diesel ?
 
Was tossing Up on the Idear of a new mercruiser diesel, Was originally thinking the Steyr, But got a price yesterday for a 200hp one, $37500, Everything Is so exp here In aus, And the boat already owes me 65grand, Might look Into the mercruiser range tomomorrow, Dont really wanna spend much more on this boat :(
 
Any Idear on what a unit over there would be worth, Motor,leg,Harness, ? say something around the 200hp?

I'd thinking maybe I'll just get one from the states and have It shipped over, I remember the smallest CMD engine here was around the 27grand mark last year when I enquired..
 
Been looking all over the web for you, perked my interest.

Can't seem to find a price here in the U.S on the web.

You guy's down under seem to be f--ked when it comes to price of things.

If you go to the website i posted they have dealers all over Aus.

If you want i will make inquires here can't promise anything but i can call around.

You want the drive also? In other words you want the complete package, motor drive and anything else that will be needed, to install, a complete package?

It's the way i would do it, and whatever you have on the boat now you can sell, try to recoup some money that way.

You will probably need new cables and all, maybe a new throttle, complete everything ?

It's 7:35 AM here in NJ, i am one state over from New York city if i can't find it here it here it can't be found anywhere.

If i find it i will get the phone number and email address from the co. and post it here for you to be in direct contact with the co.

I'll try.
 
I would definatly go the Complete package, Cables ect I could get them over here, Being Incidentals I dont mind paying that little bit extra,

If you could find out from one dealer what a package would be worth that would be Muchly Greatly appricated, Looks like they do a 180hp model, That would be sufficent, I dont expect nor want you calling 100 dealers for me just a figure would be good to think about,

I've dug some last years quote out, 140hp one was 27 grand, for the unit, No fitting ect Included,

Us In Aus get screwed over with prices :(
 
CMD would the way to go for a complete package. The inline diesels will likely be longer length, and will require a fuel return line to the tank.
 
Tell me more about the boat and year, its 22 ft, and based on a bertram? bertram variants I know of aree 21ft or 23 ft.
similar boats are 21 ft carribean reef runner, or 23ft carribean crusader.
both from International Marine melbourne, same as bertram.

PS, dont increase pwr and torque using 485 leg. you may break it. also consider ratio.
Mark.
 
Not one single place has one i can go look at it. I can order one from a bunch of places but not one place has it in the store.

This indeed what Bond-o posted, " Ayuh,... You're treading into Unknown territory..."
 
"When converting from petrol to Diesel, will the diesel in the same hp out perform the petrol?"

maybe some one can post power/touque chart for the 485, you can then compare to the new engine options.

As to perfomance of the new engine, your the best judge as you know your own boat, and you can guess from pwr/torque charts.

My boat is a bertram derivitive, is one foot longer than yours, cruises 25 knts, tops at 36 Knts. At normal cruising , trolling for beakies it uses 13 l/h.
Uses a bit more if you want go around at WOT, But I find theres not enough flat water around sydney for that. Mark.
 
Not sure If this pic Is going to work, Wish I had your speed Tuna_man, I get around the 22knts flat out and a 17knt cruise, Although Ive worked out Im using somewhere around the 6 liters an hour for 6.5knt trolling speed.

boat.sized.jpg


PS: Im the White fellah In the back ;)
 
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I sent a note to vic marine tech, he said he had a diesel conversion for the 470, are you interested?

You could save a packet on a new cummins/merc package. Mark.
 
Generally when comparing gas vs Diesel and/or converting, the performance pretty much gets to...
1) For the same cruise, lower top
--or--
2) For the same top, higher cruise.

HD marine diesels by and large run happily at 90% of WOT RPMS, while gas engines should be limited to 80% of WOT RPMs.

For a given HP, diesel are usually heavier than gas engines.

With a smallish boat (for diesel) I'd probably shoot for the same cruise speed with better fuel consumption and better life. I don't know about your particular Bertram clone, but with the factory Bertram 25 I/O I used to own (the rag top), if I stood at the stern, (all 100 kilos of me) water ran back in the scuppers. If yours has the same "design feature", I'd be very careful about putting a powerplant in the stern that is much heavier than what you have now.
 
Experimenting with sand bags down the back to get the deisred effect, almost decided on a 310hp marine diesel, with a bravo. Unit comes In at about 500kgs, About 150kg hevier then what i have now
 
I rang Julius at Vic Marine Tech, seemed a nice person. He had a lot to advise, too much to post here. I told him you were a mate in my fishing club..BBGFC.

He told me about a Qld company that did petrol to diesel conversions kits, sounded promising. approx $15000.

Also offered to import the CMD package for you if you want to save some cash on local distributors.

Also suggested best upgrade for you, if you didnt get stuck on diesel, was the Merc V6, which your leg should handle after ratio change in top box.

Ring Him.

Ph: 61 (3) 9852 3295

http://www.victorianmarinetechnology.com.au/
 
My advice...forget diesel, get a 2nd hand chev V8 Mercruiser alpha package. youll get better than the speed figues i quoted as mine is a bit bigger boat.

Youll pick up a good 2nd hand around $7500.

I just put a 1997 5.7L TBI Alpha II in a mates 22 ft Haines, all good. goes like the clappers, good fuel figues.

On fuel, a mates Cruise Craft Rover 660 (22ft), with a 470, use more fuel than my 23ft Carribean with a 350V8 alpha package.. he was not impressed when were both re-fuelling after following each other around the ocean one day, a few years back...
 
I'll give him a call thanks :), I thought about the V6 then decided agianst It as Im doing 200hours a month on average. And some trips see a 600kay turn around, So I think I should definatly go to diesel,

I'll give him a call tomorrow, and go from there/


Cheers.
 
When I repowered my 1969 23 ft Chriscraft Lancer ( If Bertram had made a 23 ft here in the USA, this would have been it) which came with a 283CID 185 HP (4 bbl) engine with a 350 CID 260 HP engine ( 2bbl... a FWC MERC 5.7L MIE TKS) both cruise and top increased nicely and fuel consumption (miles per gallon) improved.
 
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