DOHC or SOHC?

It's a lonely room, Carl. The EJ22 is a few inches narrower, hence my choice.

The ej22 has only 1 cam on each side, but four valves per cylinder. That means it breathes just fine. The airplane guys say they easily get 160 hp out of them in that application with just a standard regrind.They appear to be turbo-able as well, just in case you're insane.

 

With the 2.2 you're looking at only 20 pounds more than a type 1 engine over your rear wheels. I believe the bigger engines weigh a bit more.

 

Obviously, if you really need more than 300 hp you'll be needing the four-cam....

David, is that 'few inches narrower' front to back, side to side, or top to bottom?

 

Ed, I certainly don't need massive horse power. Totally stock FI EJ will pleas the dickens out of me!

Narrower as in side to side. As mentioned in my Word Document that I sent you about my conversion, I noted that my older IM frame rails were only 29" apart and the EJ22 engine takes up 28 1/2" of that. Peter Venuti has a beautiful conversion and I'm going to take a longer look at his this year at Carlisle. I'll still stick with a single Weber 32/36 progressive carb on my next conversion though.

Yeah David, we'll both be intently looking at Peter's conversion. I followed him for nearly 200 miles last year in Gordon's Carlisle caravan,... it's dignified with a great burbbling exhaust, and torquey smoooth...Envious!

 

 

I had a '96 Outback with the DOHC EJ25.  Had lots of miles on it (196k) and was due for a timing belt change.  Takes special tools to hold the cams in place so the valve springs don't spin cams when the old belt is removed.  If the cams spin the valves mash the top of the cylinders bending the valves - NOT cool.  Coupled to an automatic and the AWD, it was not a very economical car.

 

Sorry to butt in here but am thinking of putting my new stroker in my TD and going Subi in my speedster build so... David - do you mind sending me your conversion info as well? thanks for any help - dlschu42 at comcast.net

Dale (schu) check your email for the info. Marksbug...You've asked three questions and made four statements. In that order, here's my reply 1) because I had one on the shelf 2) compared to what ?  3) didn't have any and don't know anything about them 4) would it beat 39 US mpg with the type of driving I do and the setup that I have ? 5) could you now predict what extra power they could provide ?  6) torque is good...could you also provide what extra torque they could provide ?  7) what is everything in your world...same as mine ?

 allrighty then, for the most part yes they will, but no you dont have them on your shelf I understand that.my vw baja with the big air grabing fenders gets close to what you have there.and if you want more info , the hot vws'&dunebuggies mag had a comparason test between the duell singles&the duel idf type carbs about 3 months ago, I know your isant a duel but I did have a single on mine befor going to idf type of carbs and there was a big differance in all of it.power, torque&mpg. there arnt a lot of progressives that work real well, as most dont know how to tune them for the app. a IR system will always out perform a common runner system if there tuned right & set up right. the size of these motors is perfect for this type of induction.and your not diluting the charge to the other cylinder or steeling from it either.try it youl like it.

Mark...you've probably forgotten more about engine builds than I'll ever know but try to envision my picture. I buy a 1915 engine from a lad near Baltimore to replace the stock 1600 I drove from Idaho to Ontario, Canada and it comes with a mid mounted Weber 32/36. I messed with a couple of jet setups and got it running pretty well. It was easy to tune...even for a klutz like me who hates tuning carbs. 10,000 miles later ( in five weeks of mostly highway travel and a bit at home ) the cam lets go on one lobe and I pull the engine and do a home brew conversion with a Soob EJ22. Not wanting to get into FI and having said carb on the shelf, I rip all the FI stuff off the Soob manifold, install the same Weber carb mid mounted again but on the Soob manifold, don't even change one jet and guess what ? The thing starts easily, idles fine, runs smoothly up through all rpm ranges and seems quite happy to run about 65 mph all day with stock VW gearing. I did 12,000 miles on it last year. With it running so well with this "back yard" setup, I'd consider myself stupid to change anything. Your mileage may vary. I'm sure anything can be improved if you throw enough time and money into it. Ever heard about the law of diminishing returns ? ( It's a lot simpler than gun laws..  :-) )And no, I won't try it.

gladd it worked for you,Is it jetted right I cant say.I would of probably stayed with the FI.or gone to what I said,I dont know what diminishing returs is, is that a throttell return spring of some sorts? you need a good one of those no mater what. I do like power, lots of it.And good millage too.But I realy dont like working on stuff&having to mess with it so I dont ( thus the reason I usualy bulid everything from new parts, new cases new everything )some combos work great, some work better, some dont work worth a crap,and some dont work worth a crap because of the tuner or owner.gladd your is working to your satifaction,I was just wondering why, not meaning to offend you if I did.I do realize there are many types of drivers that have many types of driving habbits, in many different types of driving conditions. And most all want something different in thier driving expearance, some dont care at all ,some do.

Nope

 

 

 

 

 

Carl, I have a SOHC EJ25. I honestly do not remember the reason I went with the single overhead but I spoke with John Steele about it at length and we both agreed it was a better choice for what I wanted. He really liked the SOHC for my particular set up. There was a tangible performance based reason at the time of the decision, but I don't remember what or why. Maybe the SOHC gave me more useable power where I wanted it and/or cruised better? Maybe I'm making that up and those are bits of info from a completely different conversation? It wasn't a price issue as they were within $100 of each other if I remember correctly.

 

At the same time he did my install, he was simultaneously throwing a DOHC in a different customer's car so it certainly isn't a blanket statement. I bet if you call his shop, he could explain it in under a minute. Sorry I couldn't be more help.

Colin,

 

Your post (experience ) was very helpful...an evaluation and conscious choice to go SOH instead of a DOHC reinforces the opinions I'm picking up that for reliable cruising the SOHC is more than adequate and potentially less complicated...and lord knows, I don't need 'complications'!!!

 

Nobody has offered an opinion that a NA DOHC is a wiser choice. I suspect it would be if the goal is tearing up asphalt in a tubo version...that's simply not me. Steele must have concluded that its not you either.

I've considered going Subaru power twice, and both times I've shied way because of the fabrication involved.  Somewhere down the road I want to buy a dune buggy and spend my retirement years converting it to Subie power.

 

Carl,

 

I run a Fuel injected EJ22 with a SOHC.  Its a new Delta cam with a low grind so it has plenty of torque.  Colin is running a EJ25 with a SOHC and I have read some of his post and it sounds like his car flys.  Here is a quick video of a Sunday drive in my 2375 pound Intermeccanica.  Second gear start from about 10-15 MPH.  It goes down the road just fine.  How and where are you going to drive your car? 

 

 

Marty, did you miss something?

Yep, it's there now

Marty,

 

EJ22 non turbos appear to be as scarce as hens teeth. There's a large selection of 20's and 25's though.

 

How am I going to drive it?...Marty, until my butt hurts!!! at 10 to 15 mph over posted speeds, and short sprints at 80 or so just to feel invigorated.

 

Low grind and Delta cam? Jeez I wish you hadn't put that in my head.

 

 

Aaaa JEEZ, MARTY

 

After watching your video maybe I'll revise my 'short sprints' from 80 to just shy of 100mph

 

Will I need a Delta cam and low gring for that???

Carl, glad I could help. Marty definitely brings up a good point that I'd like to reiterate. You can see it in his video and you can hear it from me. There is no power shortage with the SOHC. None.

 

A quick search yielded a few quotes that stuck out to me. I can't vouch for the source or the accuracy of the statements so this could be complete misinformation but they do come from a discussion on the North American Subaru Owners Club forum and everyone seemed to agree. Here they are.

 

"The difference between the DOHC and SOHC is not all that great. The SOHC is simple to work on, where the DOHC requires a bit more attention to detail during timing belt changes or headgasket changes. I would go with a SOHC motor for that reason alone."

" I know there's been various discussions on both engines. My impression is that the SOHC is basically superior, but there may be cases arguing both ways. With some modifications, the SOHCengine has no problem with top end power."

And last but certainly not least because like you, I'm not interested in any difficulties:

"The DOHC were known to have head gasket difficulties."

David-

 

That's an amazing testimonial. I always wondered why you did the progressive (as it's pretty universally hated by those "in the know"), but I love the fact that you just jumped in with both feet and did something pretty cool.

 

I'm the retro-grouch, as you well know. My main hang-up is not the air-cooled/water-cooled thing, it's the analog/digital thing.EFI is functionally superior in every way, but interests me not in the slightest in a speedster.

 

I'd love to see somebody do what Mark is proposing- SOHC Subaru, dual Dellortos, tri-Y header

Thanks Colin...your comments and Marty's video have slipped me off the decision fence onto the SOHC side.

 

Damn, I just wish he hadn't mentioned a 'Delta cam and low grind"!!

You have to be careful with putting a turbo on a NA EJ25. Most of those have an open deck case which means no support around the top of the cylinders. The turbo cars had closed or semi-closed decks (EJ257) for extra support.

 

Yeah, on EJ25's make sure they get new head gaskets. If you don't know how old they are, assume they're the old defective versions.

 

They say the SOHC heads flow better than the DOHC.

does somebody make a support for the top of the cylinders for the unsupported version? Isant any body running the dells or webber's on the subys'?hmm.I woud of thought they were when they didnt go FI.

Ron O...there is virtually NO fabrication involved. If you've just mounted a forward oil cooler, it's no different to run a forward rad. Everything else just bolts on. You've pulled an engine and you'll just bolt it back on. Hook up the fuel and wiring. What is it that makes you think too much fabrication.?  .....Oh....where to put that heater core...ah, and explain the heat to the Bride....that's it. :-)

I make the choice based on what the desires for the engine are. The newer SOHC engines feature variable valve timing and drive by wire throttle, both of which I love. The SOHC heads flow within 5% of a DOHC, but most people don't realize that they do not achieve full valve lift on both of the valves per cylinder in stock form. The SOHC engine is a 4 valve cylinder head, but the second intake valve only lifts .150" and is there to aid in swirl which promotes fuel economy.

 

Thats at least how it works in stock form. Some witch craft can change that intent. My 270HP JR28 can be based from a SOHC engine and I feel that the SOHC engines have benefits that people have not found, only because they haven't looked for them.

Jake, when you say "newer" are you referring to subie engines with a numeral identity suffix? (example: EJ253 instead of EJ25L)

Basically any engine 2006 and newer. The codes don't mean much at my level, all we use them for is sourcing a gasket set :-)

Carl,

 

Glad to hear about your interest in the Subi.  As mentioned I have the EJ22 SOHC.  I chose this engine over the EJ25 because I wanted a noninterference engine(I can change or break  the timing belt and not worry about slapping the pistons with the valves) .  I have Delta cams as well but the opposite grind as Marty so my car doesn’t start making its real power until 2800rpm. The engine is still fuel injected running the stock Subi computer.  When I was looking for an engine I shied away from the EJ25 because it is an interference engine and also because reading the Subi forums I found varying info about dependable years for the engine at the time and while the lure of HP in the EJ25 was tempting I found I could get plenty out of the EJ22 so to me it seemed like a safer more dependable choice. Both Marty and my Engines where professionally rebuilt by CCR in Colorado, they sourced the engine and ECU from a donor car for a few bucks more it was well worth the money to me.

 

Can you tell me are you considering a rebuilt engine or are you interesting in grabbing a good runner from a used vehicle? I have read about a lot of people who go used and have great luck while saving a lot of money.

 

Feel free to PM me and we can talk until your ear is soar  pvenuti(AT)comast.net

FWIW I have a complete EJ22 engine with wire harness, body harness and etc that I'll sell cheap.. I base my engines from the EJ20 and EJ 25 platforms and this one was only bought to use for measurement purposes.

Jake, can you explain the advantages of drive by wire throttle? Is it feel, or performance advantages too.

Here's a site worth checking out if you're thinking of converting:

 

http://bb.bbboy.net/vwengineconversions

 

Here's another one:

 

http://www.rjes.com/index.html

Marty asked:  "Jake, can you explain the advantages of drive by wire throttle? Is it feel, or performance advantages too?"

 

Let me take a stab at this, as I was involved in this a little with a small company in Beaufort making small, multi-fuel engines with full ECU:

 

The biggest advantage I can see is far more control of the fuel/air mixture under all conditions.  The Engine Control Unit manages everything about the fuel mix.  If you have a standard butterfly throttle, the ECU has to have a throttle position sensor to tell it (roughly) how much demand is being asked of the engine, and it also needs an incoming air sensor for density of the incoming charge (air), sometimes how much air is flowing, incoming air temp and so forth.  Lots of stuff going on and a big chunk is mechanical (the actual throttle movement).   There is also a certain amount of tactile feedback from the throttle to your foot, but that is usually caused by the tension of the throttle return spring and the pedal return spring, unless you get a big cough back through the throttle and can feel it with your foot (and that stuff is NOT supposed to happen).

 

OK, so in a "drive by wire" set-up, you may or may not have a throttle involved.  On my diesel and on the drone engines we were involved with, there was no throttle - the engine gets full incoming air all the time (which varies in volume with engine speed) and speed is governed by what RPM you wish to maintain and how much fuel you feed to the cylinder(s) - more fuel, more speed.  If there is a conventional throttle involved, it is actuated by an electronic (sometimes vacuum assisted) servo, controlled by the ECU (but mechanical throttles seem to be going away).  The same incoming air sensors exist to know what the incoming air charge looks like (which was important for our smaller engines to know because they are used in flying drones) and the ECU keeps the air/fuel ratio within a spec programmed into it for various outside conditions and power demands.

 

Follow so far?  Good......So the "gas pedal" would be connected to a "pedal position sensor" (yup, that's what it's called) which then just tells the ECU how much arbitrary demand is being asked for from the engine and it then opens the throttle butterfly and/or shoots enough fuel into the cylinder to satisfy that demand while maintaining the air/fuel ratio it "sees" from it's internal map (soft-programmed in - that's how people can re-program their operating characteristics with a laptop).  The "feel" at the pedal is simply the pedal return spring.

 

OK, so what's the difference in driving the two?  The biggest that I can think of would be no "bogging" under over-rich fuel conditions (like when you stomp on the 'normal' gas pedal, temporarily flood the engine and it slows briefly, then clears itself and lunges forward).  Since the ECU maintains roughly 14.7/1 air/fuel mix at all times (it doesn't, but just assume it does) then you can't make it bog.  Otherwise, you should get a little snappier performance, a bit better gas mileage and you never have to worry about jets when you're driving through mountains (or flying at different altitudes, for that matter) because it adjusts for this 100 times a second, automatically.

 

So, the two-word answer to your question is:  Mostly Performance  

(But now you know why!)

 

How'd I do, Jake?

 

gn

Jake,

 

I'm interested in your EJ22.

Sent you a PM via this sites dialog

 

Carl

I LOVE the drive by wire throttle.. I hate broken throttle cables and the DBW arrangement is so smooth and allows for better pedal modulation.

 

Its one of the reasons why I prefer the 2005 and newer engines as the foundation for my conversions. I even equipped my test cell with a DBW throttle for not just the OEM ECU harnessed engines, but also those that use Electromotive stand alone systems.

 

Carl Berry, I am not here much so email at jake@rabyenginedevelopment.com to begin dialogue for the EJ22. 

Gordon, that would explain why a more modern engine gets a little better gas mileage around town even when your getting on it some.  At cruising speeds I assume this all settles down because I get up to 39MPG when not hitting the throttle hard. 

Gordon---thanks for that information---it's a keeper and I printed it and put it with

other lessons learned here.

 

Does it feel like the SOC site has gotten a lot better in a few ways lately?  It sure does to me!  I for one hopes it continues in this direction!

DBW throttle also allows for load based actuation of the variable valve timing portion of the modern engines. Thats where the crisp throttle and better MPG really wake things up.