My ‘05 OBXT journal

[RumblyXT]

1 hour ago, Febreze Mee said:

Big ups! How long until first start-up?

Hopefully very soon if all goes according to plan.. I think the worst part is over.. 

[RumblyXT]

Of course I also need to get it tuned.

I have a few mods that makes it stage2 I think? CAI, Grimspeed boost controller and aftermarket DP. 

I recently received my Tactrix Openport 2.0. Hopefully the O2 sensor now being behind the turbo at the beginning of the DP won’t present a challenge for the tuner.. he seemed very experienced which made me feel better.

Edited June 6, 2023 by RumblyXT

[seanyb505]

Somewhere I posted a trick to install an intake manifold using really long bolts with heads cut off as guiding dowels. Will see if I can find it. 

 

Huzzah! 

 

Edited June 6, 2023 by seanyb505

[silverton]

I've done it both ways, the only thing you really have to watch out for is lipping the turbo inlet, and making sure you have everything plugged in.  the cam shaft sensors on the back of the heads can be a little...forgetful.

[RumblyXT]

1 hour ago, seanyb505 said:

Somewhere I posted a trick to install an intake manifold using really long bolts with heads cut off as guiding dowels. Will see if I can find it. 

 

Thanks! That’s a great idea, I’ll keep that in mind.

[RumblyXT]

7 minutes ago, silverton said:

I've done it both ways, the only thing you really have to watch out for is lipping the turbo inlet, and making sure you have everything plugged in.  the cam shaft sensors on the back of the heads can be a little...forgetful.

Most definitely.. plugging back all the wire harness connectors in all the tight spaces would be a breeze with the engine out.. 

I still needed to fix the turbo inlet silicone hose anyways, the big port came off. I posted it on the previous page.

[RumblyXT]

One thing I have to watch out for is rain.. it’s been pouring in South FL almost every day.. summer cycle.

Matter of fact, we’re about to get a big thunderstorm.

I was terrified last time I had the I/M off and found so much water laying on top of the motor, which could easily find its way into the heads. Thankfully I had the engine covered with tape and laid a big plastic bag on top of the engine.. I covered the hood scoop as well just in case..

Edited June 6, 2023 by RumblyXT

[RumblyXT]

Since I have no experience on the tuning subject, I have a question.

If I am keeping sort of the same aftermarket parts I had on the older 255 motor: (Cold Air Intake, GrimmSpeed Boost Controller and aftermarket Down Pipe), will I still need to tune the newer 20x engine being installed?

**(Actually it will now have a new catted DP vs the old Invidia catless DP)**

Obviously the 20x being it's a 2.0L has less displacement than the 255 2.5L, but I will be using the same yellow ej255 injectors. I was told they are the same as the blue JDM ones.

I will e-Tune the 20x engine regardless, but I was just wondering about this.. 

Edited June 7, 2023 by RumblyXT

[xt2005bonbon]

The turbo will be different. The tune controls the opening of the wastegate so as to achieve your boost targets. I am pretty sure the turbo that came with this engine has different characteristics, performance, and wastegate actuator. Therefore, the wastegate tables, boost targets and other related tables would have to be adjusted for this different turbo.

As for the CAI, are you reusing your MAF sensor?

Edited June 7, 2023 by xt2005bonbon

[RumblyXT]

I see..

You’re correct. I forgot I’m switching to the jdm VF38 twin scroll turbo and it is different from the VF52 I had in.

Yes, I will be reusing the MAF sensor from before.

The new 9.5:1 compression alone will require a tune of course..

[RumblyXT]

I’m so stoked about firing this motor up!

I just want to hurry up and get it done already, but I have to make sure everything is done right. I’ll be reusing the 255 engine harness and noticed there are a couple of broken connectors.. no biggie, but I’m not installing the harness with no zip ties this time.

[xt2005bonbon]

Don't rush too much though. Check and recheck, and re-recheck every single connector and stuff. At least that's what I do

[RumblyXT]

No doubt.. I feel comfortable following the diagram and hooking back all the wire harness connectors, all the wires pretty much fall on their designated location given their length.

It is actually all the 20+ vacuum lines these motors bring I have to make sure of not plugging them in the wrong place, particularly behind the I/M branching out and crossing under to the front and to the turbo Intake hose.

I will quadruple check everything. 

[RumblyXT]

Had a heck of a time today modifying the new DP brackets to make it fit. This aftermarket pipe bolts on perfectly to the jdm VF38 turbo exhaust flange as well as to the Catback exhaust, but both brackets it came with did not align at all with their respective mounting positions. I'm not sure if this DP was originally designed for another Subaru, maybe an STi.. but it does fit our LGTs with some modifications..

The lower/distal DP bracket was hitting the transmission, we ended up having to cut it off completely. My father in law helped out a lot.. Really glad I have the Riobi bench grinder, it came in really handy with all this work we had to do, would have taken forever with a file lol. We also had to modify the exhaust gasket OD and doughnut to fit the new DP's ID. I will eventually get new hardware, but for now, he DP is installed!

 

 

Edited June 9, 2023 by RumblyXT

[seanyb505]

On 6/7/2023 at 7:11 PM, RumblyXT said:

No doubt.. I feel comfortable following the diagram and hooking back all the wire harness connectors, all the wires pretty much fall on their designated location given their length.

It is actually all the 20+ vacuum lines these motors bring I have to make sure of not plugging them in the wrong place, particularly behind the I/M branching out and crossing under to the front and to the turbo Intake hose.

I will quadruple check everything. 

 

 

[RumblyXT]

Guys I have an important question, maybe one that I should have researched a bit more before jumping into this swap, but anyways. If others have 20x swaps working is because somehow they got it to work, tune it, etc

The topic is O2 sensors..

The ej255 has like three of them, please correct me if I'm wrong. The main O2 sensor comes off the up pipe which is the one I think the ECU uses to calculates the proper fuel Air/Fuel ratio for the injectors. The other ones located on the down pipe and towards the back of the exhaust system, one of them looks like a needle.

Anyways, I was looking at the 20x diagrams and the main O2 sensor seems to come off the beginning section of the down pipe, right after the twin scroll turbo..

Since the 20x dual chambers exhaust manifold doesn't have any O2 sensors, will it present an issue for my car now having the main O2 sensor on the DP section after the turbo?

 

[RumblyXT]

The ej20x seems to have only two O2 sensors vs the ej255 has three.. note how the exhaust manifold doesn't have one. 

Do you think the usdm ECU would calculate A/F ratios ok now with the O2 sensor on the beginning section of the down pipe?

ej20x exhaust diagrams:

 

Edited June 9, 2023 by RumblyXT

[KZJonny]

When you think about it, there really isn't any chance for the composition of the exaust gas to meaningfully change between the exhaust ports and the sensor, wherever it is. It will be cooler that far back, but chemically, the exhaust should be identicle. It is inside a closed system, under pressure. No chance for atmospheric oxygen to get into it and skew the results coming from the sensor. The sensor has a heater for a reason as well. If it is below optimal temps for the Nernst/reference cells to function properly it'll just run the heater longer. 

I hardly think that the exhaust will be "too cold" directly behind the turbo for the O2 to function properly. I suspect that the worst case situation is that you'll have the heaters run more often or longer and perhaps have slightly shorter sensor life? But even then, I really kind doubt it.

[xt2005bonbon]

Our cars has only two 02 sensors. The other sensor in the upipe is an EGT sensor.

I actually think that the o2 sensor placed right after the turbo will be more accurate for tuning.

[seanyb505]

My ej255 tune is based on the o2 sensor behind the turbo. 

Edited June 9, 2023 by seanyb505

[KZJonny]

It IS where you would put a wideband if you wanted to see that data/tune with it as well right?

Makes me think I should throw the wideband that was destined for the Datsun into the Subie for now, just to have a look at what's going on inside the tune. It's just collecting dust on a shelf ATM....

[xt2005bonbon]

That's right. I have a bung there and a wideband on my shelves. Still have not installed it

[RumblyXT]

Man, I’m glad you guys are on this thread.

Thank you!

[RumblyXT]

I also had asked FlatIronsTuning, they responded..

I feel better with you guys now confirming it will work ok for the tune.

Edited June 9, 2023 by RumblyXT

[RumblyXT]

1 hour ago, xt2005bonbon said:

Our cars has only two 02 sensors. The other sensor in the upipe is an EGT sensor.

I actually think that the o2 sensor placed right after the turbo will be more accurate for tuning.

I noticed that after taking a second look at the ej255 diagrams, not sure why I thought it had 3. Thank you fir clarifying.