Possible Subaru Mud Boat Engines

[joel1847]

I'm new to Subarus but not new to wrenching on engines and my newest project is building a boat.  I was going to use a VW engine and found out that they have all but evaporated.  I then thought about a Mercedes diesel for the torque curve and availability, but the weight and size put the skids on that.  So I got to looking at Subarus and they seem to meet all requirements except one.  Which engine?  The boat is 18.5 feet long, roughly 8 feet wide at the top rails, and can displace up to 4000 pounds.  The hull will weigh right around 1000 pounds by the time I'm done and according to the designer, the hull can support  450 pounds for an inboard.  I'm hoping for 160hp and max torque being as low RPM wise as I can get.  Being a boat engine, I can strip the smog stuff off and reroute the intake and exhaust to gain some HP.  I would like to keep the engine as simple as possible being a boat motor and all.  I'm thinking 160hp to start with and then if I need more power I can add some goodies to it and hopefully won't sacrifice longevity too much so that needs to be considered.  I like the EA82 for simplicity but I'm not sure if I can get enough power out of it.  The EJ20 and EJ22 look to be about right, but looking at the EJ wiki page, there's a lot of variations and the power ratings seem to be all over the place.  Just looking for some pointers so I can start some educated research.

 

Here's a link to the boat and the basic Idea of what I want to do with the outboard setup.

 

http://www.blizzarddesigns.com/mudboat/mudboat.html

 

http://www.spirainternational.com/hp_galv.php

 

Thanks

 

Joel

norcal

[idosubaru]

EA82's are very simple and predictable, but low power. 

 

ER27 is basically an EA82 with two more cylinder -  6 cylinder with 145 hp and 156 torque i think.  it has more hp and torque than an EJ22. fantastic engines but uncommon and hard to find parts, though they're not needed terribly often. 

 

1998 or earlier EJ22 all the way - they're around 135-140 hp and readily available in most areas.  it's also one of the most reliable engines subaru ever made and very easy to work on and predict.

to get to 160 hp you'd need an EJ25, i'd aim for 2000 and up EJ25's (and 1999 forester/impreza RS).  Better engines and easier to work on. They have headgasket issues so buying a known good one (no significant prior overheating) , resurfacing heads and installing EJ25 Turbo headgaskets is a good preventative measure if that's a good fit for you.  

[idosubaru]

An EJ25D block with EJ22 heads might be something to look at - you get the displacement but simpler/lighter heads/timing belt gear and I think power is good on those, someone else will chime in. 

[joel1847]

I missed on one ER27, but I'm going to call on a couple more tomorrow.  Rockauto has most of the parts for the XT, so that's a good thing.   If that doesn't work out,  I'll start digging on what I can do with an EJ22 or EJ25.

 

Thanks for the info.  Might be a year before I get it all together and working, but I'll take pics and vids along the way and once it's running.

 

I'm used to working on engines that weigh 500 to 1200 pounds so working on something that I can move around without a chainfall or lift will be a new experience for me. :-)

 

Joel

norcal

[Scott in Bellingham]

all the EJ engines run Fuel Injected so you will need the harness from the car with the ECU , the EJ22 will be your most common easiest to get used parts, also DELTA grinds cams and you can get a low torque grind

[Numbchux]

Do you want to run fuel injection? All Subarus since 1988 are Fuel injected (in the US), so you'll need the ECU and most of the wiring from the donor car (which should be gone through and removed the unnecessary stuff). The early EJ22s can be converted to carb.

 

 

Stay away from the EA82/ER27s. Neither will give you the power you want. They are not simpler than the newer stuff, and parts are much harder to come by.

 

 

My recommendation would be an EG33 or early (2001-2004) EZ30.

 

 

EJ22 is a fantastically simple and reliable engine, but you probably won't get 160hp without sacrificing the reliability.

 

The EJ25s (either DOHC or SOHC) are rated for that kind of power, but high maintenance. And typical junkyard prices for known-good ones are pretty rediculous ($1500+).

 

There are a couple recipes for high compression engines, some using a mix of stock parts, and of course aftermarket. That may be worth looking into depending on your specific situation, but involves considerably more research, sometimes buying multiple engines, etc.

 

 

I've seen many excellent engine donor Subaru SVXs go for $500 or so. EZ30 donors (an option on 2001-2004 Outbacks) are a little less common, but they exist, and typically the parts you wouldn't be using are much easier to sell to recoup the costs (I bought my crashed fully-loaded 2004 for $1700, and only needed about $700 in parts to fix).

 

 

Externally, the EG33 is about 6 or 8" longer than an EJ 4-cylinder, whereas the EZ is only about an inch bigger. These are both fantastically reliable engines, they are more of a pain to work on in the car engine bay since they're kind of shoe-horned in there, but that all changes in a boat. They both make about 220hp, so considerably more than you were looking for.

[joel1847]

Okay, looking at the posts, and what's readily available in my area, the EJ22 seems to be the most logical choice.  To make up for the slight decrease in power, I think I'll run twin engines.  That will get my total power up, total torque available up and I won't have to run the engines as hard.  I could run the engines at half throttle and still have plenty of power in reserve if need be.  Doing twin longtails isn't that much more complicated than one.  Just add one linkage bar between the two.  Make a rear deck to cover the engines and it keeps everyone safe and you still keep deck space.  I think I can make that work easy enough and if you lose one engine, you can still limp home.

 

Thanks for the help.

 

Joel

norcal

[iceageg]

If you get an early "phase 1" EJ22 you can convert it to carburetor with a modified early 80s Ford Escort distributor.  If you are comfortable tuning a custom setup like that it would eliminate the need for the ECU and accompanying harness.  There are some threads on here on that topic if you want to investigate it.