Ej20G vs. EJ20k

BXSS · Post by **BXSS** » Tue Jan 16, 2007 7:27 pm

Hello,
I've recently purchased a '94 LSS & after installing a FMIC (31"x12"x3"!), a 3" TBE, & walbro fuel pump I think I broke the ej22t while setting my FCD. The symtoms look like AIC problems (750-500 idle) but my vacuum has gone from a rock solid 19mmHG to 15-16mmHG, & compression has dropped from my baseline of 180x4 to 180x3 + 160 for cyl #2. No CEL on before or after the drop in compression. While looking @ possible replacement motors I noticed the ej20G has a coil on plug ignition & the ej20k has a coil pack. Is one of these motors better that the other in terms of ultimate potential, & which one of these will drop into my LSS (running on the lss harness & ecu) with the least possible problems?

Post by **Legacy777** » Tue Jan 16, 2007 7:43 pm

What boost level did you hit when you were trying to set your FCD?

BXSS · Post by **BXSS** » Tue Jan 16, 2007 7:46 pm

12.8 psi on the greddy profec b's max boost recall.

Post by **Legacy777** » Tue Jan 16, 2007 7:57 pm

Hmm....that shouldn't have been enough to kill the engine.

Did you try the oil trick when doing a compression check to see if it's lower or top end that you're losing compression?

BXSS · Post by **BXSS** » Tue Jan 16, 2007 8:06 pm

I have not tried the oil trick yet, but I also thought the boost(vf11) was a little low to kill this engine. I did hit boost cut a couple of time while setting my FCD, but I thought boost cut was designed to protect the motor, not kill it. I was going to squirt a little oil in the grumpy cylinder over the weekend, but it has been raining here so I have not had a chance yet. I suspect a bad valve, but want to rebuild @ my own pace thats why I'm considering ej20g's & ej20K's.

Post by **Legacy777** » Tue Jan 16, 2007 8:12 pm

Yeah....you shouldn't have cooked the motor at fuel cut.....I've bounced off of fuel cut several times.

I think others should be able to give you some insight on the ej20g's & ej20k's.

BXSS · Post by **BXSS** » Tue Jan 16, 2007 8:24 pm

Yup, I was curious to see what I could get out of the car with the stock turbo, once maxed on the stock turbo I was going to put on my 16G & additional injector controller & see what I could get out of the single cam heads, I guess curiosity killed the LEGACY....

555BCTurbo · Post by **555BCTurbo** » Tue Jan 16, 2007 11:48 pm

It sounds like you have a vacuum leak...

As far as the EJ20G v. EJ20K...

The EJ20G is closed deck, the 20K isn't, the 20K heads flow a bit better...but in all honesty, I would go with a 20G any day of the week.

Matt Monson · Post by **Matt Monson** » Wed Jan 17, 2007 12:34 am

Actually,
The Ej20G was only closed deck through the early 90's. There is much debate about when it actually stopped, but I have seen 1993 engines that were open deck and recently dismantled a 1995 WRX-STI EJ20G that was open deck. For years the rumours were that for 94-96 STI's stayed closed deck. The only thing I can verify for sure as closed deck that late is the STi-RA models.

There are a couple of versions of the EJ20G out there. The first one is the 89-93 Legacy/Liberty engine. It was the first of the turbo charged EJ series engines and was a good engine. Most of them were closed deck. They used a weird "stub rocker" with HLA valve actuation design and a really steep combustion chamber peak.

The second generation of EJ20G's went into the WRX starting in the 93 and running through 96. The heads were redesigned on this engine with the valve actuation now being directly on the bucket with HLA's under the bucket. It was an improvement, and the combustion chamber design improved and it's volume went down. As stated above, these were all open deck with few exceptions. This doesn't mean these engines should be avoided. Open deck is nothing to scoff at.

The Ej20K was the 97-98 JDM WRX engine. The import market engines did also start to get called Ej20K's but they were really still Ej20G's internally, though they did get the under intlet manifold change that you saw with the JDM EJ20K's. The JDM engines in manual trans spec were the ones that were rated at 280ps from the factory. This is really a matter of tuning and turbo size. The other engines can handle this power level just fine. These engines were also wasted spark, and no longer coil on plug.

For a 1st gen Legacy, I would favour the Ej20G's as well. The reason for this is how easy they are to install in our cars INCLUDING the ECU and coil on plug ignition. It's a very straight forward swap with only a handful of wires needing to be messed with. Whether you go with the Legacy or WRX variant depends largely on price and availability. The Legacy ones are often a little trickier to deal with because they use an AWIC, but they also don't require a new hood scoop. It's really up to you.

I could go on, but I have rambled enough. If I have raised questions, shoot away...

555BCTurbo · Post by **555BCTurbo** » Wed Jan 17, 2007 12:43 am

Yes...as Matt pointed out, I forgot to clarify...(gee that never happens lol

)

I meant to say I would chose the Closed Deck (as in 89-93 Leggy Motor) EJ20G over the 20K, other than that it is a toss up I'd say.

BXSS · Post by **BXSS** » Wed Jan 17, 2007 2:15 am

I initially thought the problem could be a vacuum leak, but abandoned this thought once I tested the compression, a vacuum leak should not have had any effect on compression.

I have seen the EJ20G's for lower prices than the Ej20K's which makes them attractive, but the Ej20K looks more plug & play which makes it look good too. I really would like to have a motor that would run off of the LSS ecu & use its ignition.
Can the EJ20G be made to run decently this way (lss coil-pack, & ECU)?
As far as intercooling is concerned the car already has a FMIC, so any intercooler that comes with the engine will probably wind up in the parts shed. I eventually want to use the twin cam heads with a built ej22t bottom end, but do not want to get into wiring issues & potential problems just yet.

555BCTurbo · Post by **555BCTurbo** » Wed Jan 17, 2007 7:27 pm

20G is more plug and play...you would have to do a lot more wiring for the 20K

Look at it this way...I did an EJ22T to EJ20G swap in 11.5 hours once...it ain't that hard

Matt Monson · Post by **Matt Monson** » Wed Jan 17, 2007 7:40 pm

I agree that the Ej20G is the way to go. Regardless of the fact that the Ej20K is delivered as a wasted spark engine, one needs to think ahead. More and more the tuning tool of choice for these cars is becoming the PowerFC. It's sooooo much easier to put an Ej20G PowerFC into the car than it is to put in an Ej20K based PowerFC. This is because of connector compatibility. Ej22T and Ej20G plugs are identical. As was allued to, when it comes time to wire it properly (running it on an Ej22T ECU is a stopgag measure and temporary at best, and ill advised at worst) it will be less than a dozen hours to get it set up for the complete EJ20G based conversion with the COP igntion...

BXSS · Post by **BXSS** » Wed Jan 17, 2007 9:41 pm

OK - so the EJ20G is more plug & play with the SS, but what has to be done in order to convert the ignition system to coil on plug, & get the EJ20G ECU to run the car?

Are there any forseeable problems, or considerations that will have to be made when doing this conversion in an automatic SS ( My car is auto & based on my past with subaru manual tranny's I do not want to change ), such as using an auto ej20G ecu, will there be any issues with the starter....

Matt Monson · Post by **Matt Monson** » Wed Jan 17, 2007 9:56 pm

The engines don't care if a car is auto or not. The ECU's do care. If you are temporarily using an Ej22T ECU, nothing will change. You will just need to put your intake manifold harness onto the Ej20G and zip tie a coil to the manifold of the Ej20G. I am not sure if you need the Ej22T TB or not. You probably do since the TPS is on it. You will also want to switch the Ej22T IAC over to the EJ20g. They are ever so slightly different and people have reported compatibility issues with mixing and matching. Better safe than sorry.

All of this might require you to lengthen a few wires on the manifold harness. A few items like the IAC and the coolant temp sensors are in slightly different places.

That's about all I can think of off the top of my head. Maybe someone else who has done this will chime in as I have never done it without using the Ej20G ECU and wiring, and definitely not ever on an auto car...

BXSS · Post by **BXSS** » Wed Jan 17, 2007 10:09 pm

Will an automatic ej20g ecu be able to communicate with a ej22t tcu? Can an ej20G TCU control the ss's 4eat?
Will I have to minipulate factory signals with an E-manage or something of that sort to keep the tcu happy & maximize the 20g's potential?

What is required to get the ej20g running off of its own ecu?

Matt Monson · Post by **Matt Monson** » Wed Jan 17, 2007 11:28 pm

hmmm.
This is a very interesting question. I will have to do some digging and get back to you. I would guess that the USDM TCU is probably the same and most of what it wants to see isn't coming from the ECU anyways. But I can't say that for sure. Let me look over the wiring diagrams and see what I can see. If you bought a complete EJ20G auto swap, it would very likely get the JDM TCU as well. If the pinouts are the same, you just plug it in, even if it's a different unit (like different shift points for example).

As for the other question, you just have to wire in the coils and the 4 channel ignitor. There's a handful of threads about the conversion. There's different parts you can use depending on if you can get the right ignitor or not. I am in the middle of helping Legacymax do one right now. IIRC, it's adding 4 wires and making about a dozen splices...

BXSS · Post by **BXSS** » Thu Jan 18, 2007 12:07 am

A dozen splices + 4 wires does not sound bad at all.
When considering ej20g's are there any I should stay away from?
I would like a closed deck block, but that would probably mean an older mechanicals & electronics.

Matt Monson · Post by **Matt Monson** » Thu Jan 18, 2007 12:36 am

personally, I favour the 94-96 WRX EJ20G. It's the better head design and most of the parts for the heads are the same as USDM DOHC Ej25 heads from '96. Try and find the HLA's or other bits from the 89-93 Legacy heads in the states. I was recently in CCR with my old Legacy Ej20G heads. I consider CCR a very knowledgeable and experienced Subaru specific shop. They had never seen those heads before and didn't know where to find things for them...

BXSS · Post by **BXSS** » Thu Jan 18, 2007 3:40 pm

Are ej20g parts like timing belt/tensioner, water pump, etc. the same as usdm WRX or 2.5RS parts?

mr soul · Post by **mr soul** » Fri Jan 19, 2007 11:32 pm

Did I read on here somewhere or another forum that the 20G IAC supply air nipple points down where as the 20K points horizontal or something to that effect?

IAnybody know?

Matt Monson · Post by **Matt Monson** » Mon Jan 22, 2007 6:10 pm

mr soul wrote:Did I read on here somewhere or another forum that the 20G IAC supply air nipple points down where as the 20K points horizontal or something to that effect?

IAnybody know?

Yeah, it's something like that. I would have to look at the 2 parts to remember which does what, but they are different...

206er · Post by **206er** » Mon Jan 22, 2007 10:47 pm

a little semi-highjack....
how much power can a 94-96 wrx longblock take?
and how similar internally are they to the ej20h from the same era? ie does ej20h=ej25d? I'm thinking of picking up one of the super cheap ej20h's to mess with, chucking the TT and ej20h wiring.

matt, you say that even CCR didnt know what to do with some early liberty ej20g heads? bummer. I guess its not that surprising given their company's focus. are there ANY options for refurbishing some of these stateside?

Matt Monson · Post by **Matt Monson** » Mon Jan 22, 2007 11:20 pm

206er wrote:a little semi-highjack....
how much power can a 94-96 wrx longblock take?
and how similar internally are they to the ej20h from the same era? ie does ej20h=ej25d? I'm thinking of picking up one of the super cheap ej20h's to mess with, chucking the TT and ej20h wiring.

matt, you say that even CCR didnt know what to do with some early liberty ej20g heads? bummer. I guess its not that surprising given their company's focus. are there ANY options for refurbishing some of these stateside?

I've got an Ej20H sitting in my garage right now. It's for sale if you are interested. I was going to part it out to make more money, but I could use a quick sale. PM me an offer.

To answer your question, EJ20H heads are IDENTICAL to Ej20G WRX heads. The WRX heads get tapped for the second turbo, but they seal it off. Both heads are HLA's under the bucket. I have yet to pull them apart and check casting numbers and whatnot, but everyone that I have spoken to has told me they're the same. The only thing I can't verify is cam grind, which is part of why I bought the engine.

If you had Ej20H heads that you wanted rebuilt, you would use '96 Ej25 components. Max, who used to work for CCR, is going through a personal set as part of his swap. (see other thread here)...

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed Jan 31, 2007 6:51 pm

On a related note, what would it take to run an EJ20G Power FC meant for a '93-'96 WRX on an EJ22T.

Mainly, it looks to me like I would have to mess around with the ignition pins/wires to compensate for the use of WS instead of COP.

If I am thinking about it correctly, wouldn't it just involve splicing the #2 cylinder ignition pin to the #1 cylinder ignition pin and replacing it with the #3 and #4 ignition pins. Basically making the wire running to the ignitor see both the #1 and #2 COP signals instead of just the #1 and the #3 and #4 signals instead of just the #2.

For those of you looking at a pinout, moving so that B44.9 and B44.10 connect to the wire for F47.10 and B44.7 and B44.8 connect to the wire for F47.9

Does that make any sense?

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Ej20G vs. EJ20k

Ej20G vs. EJ20k