Phase II EJ251 into 95-98 Legacy questions

[janas19]

I have been researching this idea for a while and one person was able to swap a EJ251 into a 1990 Legacy. Is it possible to use the stock IAC valve and coil pack from the Phase I EJ22 and what modifications would that require? 

 

Swapping a phase 2 ej25 in an older legacy or impreza

[Numbchux]

Like that post says, there is nowhere for the IAC valve. That's interesting that once the car is warm, it will idle without it....

 

 

I have heard of people making a set of adapter plates to put the entire older intake manifold on the newer engine. Doesn't seem too difficult. Luckily once I got into the project, the EJ25D I was working on was in better shape than advertised, so I just sold the EJ251 and came out ahead.

[86BRATMAN]

ej18e throttle body is the missing link. It has an integrated iacv that functions exactly like the rest of the phase 1 divorced iacvs. You'll need the tps plug from the impreza harness because it's connector is different, you'll have to simply repin that. You'll also need a sheet of metal to make a small block off plate to bolt in between the throttle body and manifold, this will cover the ej251 iacv port in the manifold.

[janas19]

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Hey Numbchux and 86BRATMAN, thanks for the answers. I have been doing my own legwork on this and found some interesting answers. It seems that the 00-01 2.2 Impreza TB has the IACV and 3 pin connector. I believe it's possible to use that TB and splice the 00-01 IACV connector to my ECU harness.

 

 

Another question is about the ECU. The 95 ECU is for the EJ22 stock heads with 135-140HP. I want build the EJ251 with Delta 220 mild street cams and bolt-on intake and exhaust. Would I see better performance using an EJ25D ECU or is that not worth the hassle? I know the EJ25D will throw the EGR CEL at least on this setup. I can't think of what else.

Edited October 25, 2016 by janas19

[86BRATMAN]

That iacv doesn't function the same electronically. It won't work with a phase 1 ecu, I had that thought several years ago. I actually think I suggested trying it in Chux's thread about the car he was talking about above. Either way, I tried it for myself on one of the cars I've done this type of swap in and no dice.

[janas19]

Thanks, that's good to know! That actually should be better for this project, in fact. The newer IACV is more expensive and harder to find. I guess the 1.8 TB should be easier to find, junkyard wise? Also it may be cheaper as well.

 

This is great info. I can use the 1.8 TB and block off the 2.5 mani, and I will have a functional cold idle!

Edited October 26, 2016 by janas19

[86BRATMAN]

You'll be looking for a 93-97 (maybe 98) impreza. These are the only cars in North America that came equipped with the ej18, 93 and 94 are strictly ej18 cars, 95-97/98 were a mix of ej18 and ej22 but it won't be hard to spot the difference.

[janas19]

OK, that's nailed down then, thanks.

 

Pretty sure there's no need to use the EJ25D ECU at all, especially since I'll be doing most of my driving under 4000 RPM. The Phase II SOHC heads are really good in the lower ranges.

 

You said you've done this swap before? Anything you'd do differently if you had to do it over again?

[86BRATMAN]

I just reread your first post, I missed a pertinent question. Is the car manual or auto?

[janas19]

It's manual. I'm going to find a 95-98 Legacy wagon 5MT and swap in the EJ251.

 

Won't need to port the head for EGR since the 2.2 manual doesn't have it.

[86BRATMAN]

So it's going into a 95-98 and not a 90, correct?

[janas19]

Yep, that's my plan. I am looking for 95-98 2.2 "L" trim or even the FWD models, because this will be a street/highway car.

 

The problem I am running into is that most of the cars selling cheap with bad engines are the 2.5 GTs. I am having no luck finding the 2.2 cars cheap for those model years

Edited October 26, 2016 by janas19

[Numbchux]

Weird. So you're looking to buy a 2.2 car, specifically to swap a 251 into? I think these cases are almost always someone that happens to have a 251 and a phase 1 car that needs an engine.

 

Up here, at least, a good 251 is worth more than a running-driving 2.2 car.

 

 

 

FYI, a '95 2.2 ECU is pinned differently, a 25D or '96-'99 22E ECU will plug in, but will not run.

[janas19]

Why is it weird? I want to buy a broken down 95-98 for cheap. They are lighter cars. The 95 FWD 5MT wagon weighs 2680. 00-04 wagons are 3200 lbs and up. I want to put a 2.5 165HP engine into a 2700-2800 lb vehicle. Bigger engines into lighter vehicles is a pretty classic formula for a good, cheap street car.

 

NASIOC Curb Weight thread

Edited October 26, 2016 by janas19

[Numbchux]

It's weird, as in, uncommon.

 

Don't think I'm not familiar with the "bigger engines into lighter vehicles" concept. I've been involved in probably a dozen EG33 swaps into '90s Imprezas and Legacies. Not to mention EJ22s into EA82s. And a handful of EJ22s into VWs, and a few WRX swaps. When I'm bored and want to wish I had stupid amounts of disposable income, I research 2GR (3.5l VVT All-aluminum 290-some-hp V6) swaps, and dream of putting one in my Celica. Or a 1UZ into an older Celica. Or a 1MZ engine with Rav4 5-speed transmission in an AWD Pontiac Vibe

 

 

Each to their own, and I'll certainly offer the knowledge I have that might help make it happen. But it just seems like a lot of work/money for a mediocre engine. The EJ25D is a much simpler option, for the same power. Typically people try to go for more power, or at least more reliability. EG33 or pre-VVT EZ30 would be a much better option. Or building a high-compression 4-cylinder (several recipes for that, some with a mix of OE parts, some with aftermarket).

Edited October 26, 2016 by Numbchux

[janas19]

Thanks, and don't think for a minute I don't appreciate the input you have offered. I certainly do.

 

I've looked at both the EJ25D and EJ251 and here's the conclusion I've come to.

 

EJ25D pros:

Basically plug N play except EGR matching

Cheap and easy to find motor

Higher horsepower

 

EJ25D cons:

More expensive timing belt

Twice as expensive to do cam regrind

Less reliable, higher likelihood of internal damage from lack of maintenance and overheating

 

For those reasons I'll pick the EJ51 if I have the choice.

[Numbchux]

Less reliable, higher likelihood of internal damage from lack of maintenance and overheating

 

I disagree with this. The EJ251s are not very robust. The DOHC heads are extremely tough, almost impossible to warp. As much as I do prefer the phase 2 bottom end, the DOHC heads are WAY better than the SOHC.

 

Timing belt cost difference is about $20 (we get Gates kits on Amazon, that's my source). Meh. That's a drop in the bucket when you're talking about an engine swap.

 

Yes, cams would be more expensive when there are 4 of them, but the DOHC heads flow much better than the SOHC, so you'd probably end up with more power.

 

 

 

 

At the end of the day, I go out of my way to avoid either engine. I have owned several examples of them, but my current Subarus are either H6's (XT6 and '04 OBK VDC), or EJ22e's ('97 Legacy and swap-in-progress Brat).

[86BRATMAN]

Knowing a little more about the reasoning behind this build let me offer up this.

 

Take a good ej251 shortblock, pair of 04-06 sti head gaskets, and 97-99 ej25d heads/intake manifold. This creates a 10.4:1 compression engine, that is both reliable and makes more power throughout the rpm band.

 

Take a good look at cam specs online, to get an ej251 cam that is equivalent to stock ej25d in terms of lift and duration you have to go with a stage 2 aftermarket cam which also usually requires an upgraded valvetrain and would be a negligible increase without tuning.

 

I've built a few of these type engines in the last few years too, it's the best bang for buck you can get without doing a turbo swap. I have seen one I assembled and installed in a 98 legacy outback wagon stay door to door with an 04 wrx wagon till roughly 100 mph, and it was capable of high 28-29 mpg on the highway with the 4.11 final drive outback 5mt. I could easily see this engine combo in a fwd 5mt legacy which has the 3.70 final drive 5mt and weighs roughly 500 lbs less getting 35-38 mpg with good driving habits.

 

The ej251 swaps into 2nd gen legacys that I've done have been to get a broken vehicle running with parts that were on hand at the moment. Given more time and providing that the cars were mine the dohc ej251 is what I would have put in them.

[janas19]

The DOHC heads might be tough and better at higher RPMs, but everything I've read says the SOHC heads are better overall. They have more low to mid torque and they're easier to maintain.

 

This is going to be a DD doing 80-90% of

driving under 4000 RPMs and for that reason I'm thinking of avoiding the DOHC altogether.

 

The other factor in play is budget. I'm looking for a EJ251 longblock and that comes with the heads for $300-500. Delta 220 regrind is $200. Valve job is $150 or so. So $600-800 for the engine and internal work. Plus the cost of head gaskets.

 

The 220 regrind should give a top end closer to the DOHC. That's HP for passing people on the highway, then I go back to the right lane and stay at 2500 RPM for higher MPG.

Edited October 26, 2016 by janas19

[janas19]

@86BRATMAN Yes but then we're running a frankenmotor with 10.4:1 compression and the goal is 87 octane pump gas with no knock. The ECU can retard the timing to compensate but that would also reduce MPG.

 

That hybrid is a great idea for making cheap power but if it doesn't run on 87 octane fuel I don't see it working for me.

Edited October 26, 2016 by janas19

[Numbchux]

I'm looking for a EJ251 longblock and that comes with the heads for $300-500

 

Good luck! Most junkyards, up here anyway, want more like $1500-2k for a good one. There are exceptions, of course, and other sources, but that would be a steal.

[janas19]

Ha, $1500 for a 15 year old 4 cylinder engine is a suckers price. I guess people without a clue would pay that much. Like the mom and pop junkyard here that wanted $100 for a Impreza TB. U-Pull had them for $50. Imdew is asking a six pack of IPA for his TB.

 

$300 is what the U-Pull charges for a complete engine. I think $400-500 is a good price for a private seller. Might go lower if it needs minor work done.

Edited October 26, 2016 by janas19

[86BRATMAN]

I have a couple local yards that want over 1k for ej25's of any kinda because they're hard to find in good condition. I've never paid that for one, I can buy complete cars for less. I'd rather drive a few hours to one of the chain yards that have standardized pricing like you're talking about

 

 

I see what you're getting at with the fuel situation, but also consider the ej251 is a 10:1 engine as well. It may not be happy running on an ecu that was tuned for a 9.5-9.7:1 compression engine, depending on year, to run on 87.

[janas19]

That might be a good idea, if it's the 97-99 EJ25D that run on 87 octane. Might be able to lower the compression ratio with a thicker head gasket, too.

[86BRATMAN]

You can to an extent, but too much you start messing with quench height which will mess with the flame propagation properties of the combustion chamber. Which will negatively effect fuel economy.