Glen-L.com

hi, i've decided to build the 17' gentry runabout but i'd like to figure out what engine to use before i start building it. i don't want to put a big heavy and inefficient cast iron v-6 or 8 in it. the engine that i've decided would work perfect is an EJ253 which is a 2.5 liter 4 cylinder boxer engine used in a 99-05 subaru forester. it generates 166 pounds of torque at 4000 rpm. it is a well made engine and has a very strong block, and since its a boxer engine it will have a lot of room inside the hull as well. the reason i want to use this type of engine is because it probably weighs a third of a typical marine engine and if i can make it light it won't need 200+ hp to get up to a good speed.

so, is this a good choice of engine or not? and if not, why? i've searched the web and it seems the only engine people ever use is a chevy small block for some reason.

also, if you have any info for me on choosing an appropriate transmission that would be helpful. (gear ratios, brands, etc) i'm going for durable and cheap and probably old used.

thank you very much for any help you can give!

--jake



-----------------other info---------------------



gentry hull weight is approx 900
estimated weight of drive train and misc 900
total 1800
max torque 166
10.8lbs per 1lb torque or .09222 ft lbs per 1 lb weight

somewhat educated guess of top speed 55



four winns h180 dry weight 3400
horse power 190, top speed about 40
17.9lbs per 1hp or .05588 hp per 1 lb weight



.09222/x=.05588/40

.09222*40=.05588*x

3.6888=.05588*x

3.6888/.05588=.05588*x/.05588

66.01=x

x=top speed of my boat
40=top speed of four winns h180 with 190 hp


however, friction or drag increases exponentially and also my hull may have more initial drag than the four winns h180. therefore i'd give a safe estimated top speed of my boat at 55mph.

half of the excitement is the beautiful sound of the SBC engine makes it a go fast boat just idling
would not be right having it sound more like my Hoover

-Billy

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(insert witty phrase here)
Billy's Belle Isle website

Unless you make your own exhaust manifolds, I don't think any exist. Also no marine type carbs, alternators, starters, water pumps and block fittings for them.

That's some of the reasons to go SBC.

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As Conan the Barbarian says, " It's not how hard you can hit, it's how hard you can get hit and remain standing".

upspirate came up with a link to an aricle in Wooden boat magazine about marinizing a Subaru engine :

Subaru on Craigslist

Customer Photos lists a Tiny Might built by Michael Sabin powered by an L-81 Subaru direct drive 96 hp engine with a water-cooled exhaust and fresh water heat exchanger system. No pics of the engine installation ... You may be able to contact the builder for installation details.

TINY MIGHT by Michael Sabin (12-00)

A Forum search will bring up several posts but they yield very little 'direct' information :

Forum Search for keyword SUBARU

Here's a little nugget :

Here's the article. Scroll down to The Drive System :

Marinizing a Subaru 1.800 cc engine (4wings.com)

Hope this helps !

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Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod : http://www.boats.chelseacoachworks.com

thanks for the info mr hot rod. the links on that other forum post didnt work becuase they must be rather old but thats ok, in my mind its not a terribly complicated thing to convert this engine to marine use. as for the headers, i know its not "safe", but i will just use the stock ones with some heat deflection shields until it goes past the risers which i will have to make myself. then i will have the water from the cooling system injected into the pipe after the riser so it will be cool enough to use the rubber exhaust tubing. as for the "radiator" i'll use two heater cores in parallel to increase flow and encase them in a sealed copper box and pump fresh water into it and then to the exhaust.

as far as the starter and alternator go i will just use the ones that come with the vehicle and make sure that there aren't any fuel leaks by replacing all injector 0-rings and misc seals along with venting the fuel tank through the deck. i will use the complete wiring harness and engine control ECU on the engine in water tight compartments. carburetors are not my thing because they decrease the engines available power and decrease fuel mileage. also a carburetor will release fumes which will settle to the bottom of the hull and cause a possible fire.

i know that my engine won't sound like a v-8 and i don't want it to. if i can't get the exhaust to sound "good" by changing the diameter of the pipe, mufflers, etc i will instead make it very quiet so that the main noise you hear will be the water hitting the hull. i know that most people (especially older people) take a lot of pride in their small block chevy engines and other misc american made engines, but i am only 25 and i am an ase master tech who works on all sorts of vehicles and have found through experience who makes a quality engine and who doesnt. this of course is just my opinion.

so, i will go along with "marinizing" this engine and begin building my boat whenever i find the time. when/if i complete the project i'll be sure to post pictures and whatnot.

--jake

hi Jake-
you have hit upon why you are building your own boat. it can be built to fit your needs/budget/dreams within reason and still perform.
...where you asked for opinions (from an older person ) thought i would at least give you mine so you would have more than someone posting telling you to "go for it".
as you can see from HR's post above it has been done before - so do so just safely.
looking forward to seeing pictures of your progress.
-Billy

_________________
(insert witty phrase here)
Billy's Belle Isle website