Really need your help with 350 mag replacement engine??
 

I've read a lot of posts on engines and I'm just have trouble coming up with a plan for this boat...

I bought a 1989 Glastron CSS-19 and I turned it into a project boat, not by choice, it's just started with a soft spot on the floor and then some cracked exhaust manifolds, then I take the interior out to get it redone and decided to pull the motor to give more room in the stern to work... sooo since the motor is out What the hell, why not put a fresh engine in.

The boat has a 350 Mag that says that it is a 270HP motor. This boat stock is said to have a speed of between 60-65mph and I have never had a boat that goes this fast, would it be unsafe to put a new engine in that has 300-350 HP?

And my main question is, dollar for dollar what is the most bang for the buck in replacement engines that are out there. I have skills do do the work myself as far as taking an engine a part and replace cams or heads so I could really use some good advice on an engine. I don't need to be the fasted boat on the water, nor spend the bank on a motor, would like one that would run a long time, but have a little more spped then stock.
Would this be some kind of crate motor or...??

Thanks very much for your advice,

Dan

If you have Alpha drives becareful on how much HP you add. I had a fountain with twin 350's and alphas and never had a single problem in 7 years of operation. (500+ hours)

Merc long block. Stay away from the crate engines as you will be dissapointed. Been there done that. Long block from merc will run you around 3200 with a 2 year warranty.

Write Glastron, and ask them. I did the same when I was looking at a 1980 Glastron Carlson CV-27. It still has the original inline 6, I wrote Glastron and they said the best ballance size/hp would be 305's.

The boat came with a 350 mag that is stock, and going to a 305 would be less power then I have now. There is such a debate over the Chevy crate motor at about $1600 and the Merc at $3200. From what I've read that the head gasket are SS and the freeze plugs are brass are the two main differences between the two, oh and the cam profile. The boat has the Alpha One. I also bought a set of the Alum GLM exhaust manifolds. Still would like to get a new motor at the best price, but which one?

how about a nice low hour 6.2 motor? They are 320HP I believe, and efi. I am sure you can find one somewhere

What about freshening yours up, and going with a few mods, like cam, intake, carb, and good exhaust manifolds??

These guys that sell you a crate engines lie. For example , offered for sale at a "marine repower center" are gm long block base motors , 350 275 hp , 4 bolt mains , roller cam. Sounds good right? That motor will have less hp than the merc 305! Warranty , yeah right , good luck there. If you can get a build sheet ( you never will ) and see that the correct marine cam is in it and the right size and material valves, I might for a minute think about it. Then I'd wake up! Do it once and do it right , believe me , been there with twins. The gm crate motors will not make the power the mercs do. If you want to go through the motor and do the mods you may end up with a nice package but you will have more in it than doing a merc block. Buy the crate and your headaches will begin from little things like the timing cover will not fit under the circulating pump to the final test run and you find you'll have to drop 2" in prop pitch to get the pos to wind up in rpm and probably lose 6-8 mph in speed. Mild Thunder has a better idea than a crate.

I would have reputable marine shop build you a nice shortblock and then you can add your choice of heads, cam, valvetrain etc... I went this route over the winter.

1980-85 4 bolt block, forged internals, balanced, 10.0-1 SCR, AFR 190cc heads, XM276HR cam, Performer RPM, 4150 750CFM, HP exhaust manifolds. I am very happy with the performance and way it turned out. It made 426hp on the dyno with dyno headers. I figure in the boat with the manifolds it will be around 400.

http://img131.imageshack.us/img131/8...tandvj1.th.jpg

Turn your 350 mag into a 383 you can get 425 hp out of it on pump gas 9.3 comp. prices have come way down on the cranks and you can get a good set of rod for under $ 300.00:D :D :D

Man!!! 425HP in that little 19 footer?? I not sure if the block got cracked in the last freeze so I would hate to tear it down and waste time on it. I started to read on the difference between the boat and car engines and most say that the SS gaskets and cam change is it. How much HP would be safe on this boat?

Here is a link to the boat


http://beta.communities.msn.com.mx/G...to&PhotoID=658

That's a good looking boat and would be pretty quick with a worked over small block. You can easily gain 100hp over stock with the right parts. As to being safe, there are plenty of 19' boats running 400hp. PlumCrazy on this board has a 19'
Baja with a potent 383.

Marine motor differences are mainly the headgaskets, brass core plugs, cam etc... I've often heard marine engines should be set up a tad looser than spec but i've always built mine around standard spec with no problems.

If you have any reservations on a cracked block either replace it or have it tested before using it for a new build. If you want to go this route let us know as we can spec all the go fast HP parts you'll need.

As to the Alpha drive. They are rated at 300hp but many including myself have made them live long lives with much more. My 1992 Alpha has outlived 3 350-400hp small blocks in my 22' Challenger. Having a light boat always helps.

To keep the Alpha alive ......

Add a drive shower and synthetic oil
NO stiff arm hole shots. These are not jet boats
Wait until you get moving to go WOT
If you get the prop out of the water get off the throttle under reentry, coming back in WOT will either strip the gear teeth or break the driveshaft.

There is a reason Merc engines cost more...........they are worth it.

I'm sure Merc are good engines but I see a lot of boats that are a few years old that say they have new motors in them and they had Merc's to begin with.

I would like about 300hp and a bit more, but 300 would be fine. If I had one built I would use inconel valves, roller cam(marine grind) standard pistons. From what I hear, it is the valve train that takes the most punishment. Would a Vortex motor be a better start?

One other thing is that if you look at the link on that site and check out the rear of the boat i would like to run the exhaust straight out the rounded area at the bump rail with chrome tips. (I thing it would look great to see them there) The angle would be very slight and would a tip with the built in baffles keep the water out? Also, would the boat be to loud for normal use?

Merc's are the only way to go for a drop in, they are better.
If a newer boat has new engines, it was likely a power upgrade.

What is right for you, depends on your plans for using this boat.
Salt or fresh, lots of at idle cruising, skiing, long WOT runs, wave jumping, short blasts across the pond, or re-sale?

To build your own engine would not be all that difficult or expensive. If you are in fresh and don't use lots of gas in the season(or it's a non issue) , I would lean towards building a stout aluminum headed 350 or 377/383.

If you do more no wake zone cruising and some water sports and are more concerned about fuel consumption, I would look for a drop in MPI.

My own boat is getting a pair of re-man 383 MPI's with Bravo 1 Drives which I bought prom Pro-Tec Marine. My firsts plan was to build a pair of killer 383 carbed engines, but by the time I priced it all out, the new re-man engines and drive combo's were just a couple grand more.

I can understand why you think the Merc "BLUE" motors are better because they are hand built, but why are the black motors better?

Dave

I mean better than a GM Motorsport crate engine for marine use

try
http://www.dereberyperformancemarine...k_Engines.html

reasonable prices and I have not heard of any complaints.

merc reman has a 383 that makes some good power

I'm just wondering about all the cam and engine size thoughts...

If a boat engine is under heavy load from an idle up to 5,000rpm and the cam is ground for the best torque down low, then a larger engine should work less then a smaller one as far as the load?( lets say a 400 SBC ver 350) More torque, right? So if you get a zz4 motor that makes torque higher and has more HP but at a higher rpm, would and engine like that run good if you changed the gears in the drive? What kind of problems would happen?

Here are some differences I've run across between Merc and GM crate engines:

Marine cam with low overlap, and wide lobe centers (pushes torque peak to higher rpm, while preventing reversion).

Stainless steel head gaskets

Brass freeze plug (some crate engines do have these)

Lower compression pistons (generally 9.4:1 or less)

Inconel exhaust valves to stand up to the constant high exhaust temperatures

Hard anodizing on aluminum heads to prevent corrosion

Better quality block paint to prevent corrossion

Bigger oil pan

Marine distributor

Marine carburetor or fuel injection

Full floating piston wrist pins (high performance engines)

******

I'm sure there are a bunch of other things, too (valve springs, retainers, etc). It doesn't mean you couldn't start with a crate engine, but it would be best to make a few changes before pressing it into marine service.

Michael

At least as of last year, the mouse motors (small blocks) and the lower performance big blocks did not have Inconel exhaust valves. I am not sure if they were even HD rated. Mercury's price for them was something like $8-9 apiece. Way too cheap for Inconel.

IMO I think a 6.2 (320hp) with a B1 outdrive should do the trick. I think they can be had with closed cooling if you are running in salt. Maybe a little pricey, but reliable, warrantied power and an engine that should last a long time.