Subaru Impreza GC8 & RS Forum & Community banner

Tune it?

  • Yep

    Votes: 40 93.0%
  • Nope

    Votes: 3 7.0%

  • Total voters
    43
1 - 20 of 23 Posts

·
LoBuk FTW
00 RS
Joined
·
680 Posts
Discussion Starter #1
Well, since I'm yet again on the verge of finishing the swap, I have a couple questions regarding tuning.

First off, I have a JDM WRX EJ20G/K being run by a v3 STi RA ecu. The motor is the same, its the turbo that's different. I have the TD04, while the ecu is programmed to run the vf23. Should I get the ecu reflashed for the TD04 or will it be okay as is?

Secondly, I know this has been talked in a circle countless times. But, being that the octane is supposedly higher in Japan, should I have the car tuned to run on 91 here? Or will it be close enough to not matter?

If any of you swap people have anything to say, please do. I'd like to know before I go and break another engine.
 

·
Registered
1999 Subaru Impreza 2.5rs BDP
Joined
·
2,079 Posts
should this even be a queston???? of course you should tune. tuning is the safest way to make more power. and yes, there is a difference between our 91 octane and japan's 94ish octane. You WILL blow your motor if you don't tune. it's not a matter of IF, it's a matter of WHEN. If you decide not to tune, then just don't run any boost and you should be fine.
 

·
Premium Member
95 L, 96 OUTBACK
Joined
·
2,883 Posts
Well the motor has a knock sensor. There are alot of people that are running JDM motors on 91 pump. It will just make alittle less power.

Is the motor currently running this way or do you have a motor and ecu waiting to go in the car. If you dont have a V3 sti ra motor it wont like that motor. More than the turbo is different. The injectors, cams, plus the ignition might be different. The V3 motor was changed half way through the year from G to K as you already know but your sure both are K or G what ever you have. You will have to rewire if they are differnt.

There arent many options asfar as reflashing. Your best bet is to get a Power FC. Or other stand-alone of your choice. Thats the problem with the older motors is other than a PFC your have to get a wire in Stand-alone or go inside the ecu and reflash the Eprom. There are some people that do this still. You can try and find someone. Yoshi rings a bell but I never looked into that option so maybe someone else will know more about it than me.
 

·
Registered
BRP ver5 RSTi, Beater Leggy
Joined
·
370 Posts
This thread potentially opens up a huge can of worms.

My swap doesn't go in 'til later this month, but once it does, I will be wrangling this same question as well. Until then, I can say this.

Relative of mine and I flew halfway across the country to buy a jdm SR20DET swapped 240sx, pretty much stock swap. Drove it almost 2 days and 2 nights back home at differing RPMs, couple WOT runs, on a mix of whatever grade premium gas we could get along the way, which usually turned out to be around 90-91ish octane... sometimes 89.

No problems at all with the engine during the trip (other things however...), and it still runs very smooth now. Of course, this is an SR20 vs an EJ20, so take it for what it's worth.

All of that said, I'd still get it tuned as soon as funds allow. Are you asking 'never get it tuned' or 'when funds allow'?
 

·
Registered
1999 Subaru Impreza 2.5rs BDP
Joined
·
2,079 Posts
Cubby said:
This thread potentially opens up a huge can of worms.

My swap doesn't go in 'til later this month, but once it does, I will be wrangling this same question as well. Until then, I can say this.

Relative of mine and I flew halfway across the country to buy a jdm SR20DET swapped 240sx, pretty much stock swap. Drove it almost 2 days and 2 nights back home at differing RPMs, couple WOT runs, on a mix of whatever grade premium gas we could get along the way, which usually turned out to be around 90-91ish octane... sometimes 89.

No problems at all with the engine during the trip (other things however...), and it still runs very smooth now. Of course, this is an SR20 vs an EJ20, so take it for what it's worth.

All of that said, I'd still get it tuned as soon as funds allow. Are you asking 'never get it tuned' or 'when funds allow'?


EJs are notorious for weak rod bearings..... :noes:


kay95 said:
Well the motor has a knock sensor.
Usually once the knock sensor goes off at 7500 RPM, your bearing's gone.

you don't HAVE to get a tune but it is EXTREMELY recommended. If you don't have a tune, the best bet to preserve your motor is to not drive it very hard for long periods of time.
 

·
LoBuk FTW
00 RS
Joined
·
680 Posts
Discussion Starter #9
I plan on running stock everything, it was just a matter of convinience when I ended up with that RA ecu. All my wiring is done, and correct. The first engine cranked, ran and idled perfectly. It was my mistake that led us to building a new block. Nothing the motor, ecu, or wiring did wrong.
 

·
Registered
'99 Black RS Coupe
Joined
·
691 Posts
You absolutely should tune that thing immediately. Especially because you have an RA ecu. I blew my type r a week after we got the car running.

The type R/RA tunes are just too advanced for the gas we have.
 

·
Registered
95 RHD WRX
Joined
·
1,799 Posts
I would have to agree. the RA ecu runs 1.4BAR stock. My friend just blew his EJ20g running 1.5bar of boost on 91 octane. Obviously retarded, but it's done with, he has a new one already. Although it's true that the ECU adjusts for octane, his wastegate was disconnected and a few other things....

I'm not sure what kind of setup you're running. I know you're running H's EJ20g shortblock that was sitting in my garage for like 2 months, but outside of that, I don't know the setup. Usually ECU will adjust for octane, my ej20g is running 91 octane very happily but if you're running some kind of hybrid setup with a v3 ej20k ecu, i'm not sure how it's going to react to all that. I don't understnad what you mean by ej20g/k setup.
 

·
Registered
95 RHD WRX
Joined
·
1,799 Posts
scoobaroo said:
should this even be a queston???? of course you should tune. tuning is the safest way to make more power. and yes, there is a difference between our 91 octane and japan's 94ish octane. You WILL blow your motor if you don't tune. it's not a matter of IF, it's a matter of WHEN. If you decide not to tune, then just don't run any boost and you should be fine.
I don't agree with that. My friend's ej20g ran 15 track days over the course of 2 years very happily on 91 octane. When we pulled it apart, the turbo had no shaft play, the short block was perfect, and the heads look immaculate.
 

·
Registered
1998 Forester on Orange 57F
Joined
·
4,129 Posts
Trusting a knock sensor to "tune" your car is a very bad idea. I have had many cars that ran on JDM ecus. I have seen many sr20det cars blow up. I have seen many cars go over 100k with no problems. Most run fine on 91+ octane but I would never put anything less in it. And for safety sake I would tune the car. Infact even a stock USDM WRX or STI can benefit from a tune. All cars and areas of the country are different so no one car is the same. This is only one of the reasons to tune your car.
 

·
Premium Member
95 L, 96 OUTBACK
Joined
·
2,883 Posts
The stock ECU doesnt tune with a Knock sensor. Only to choose which timing map to run. Its a stock setup with Subaru making it reliable as possible. Everything is still controlled by the ecu and it knows what to do.

Whether or not you agree with that theory there are alot of engine from Japan that are running and running hard on 91 octane.


What injectors do you have in that motor. You might have to upgrade them too if you put a VF23 on. Not a bad idea though.
 

·
Registered
95 RHD WRX
Joined
·
1,799 Posts
InsatiableAmos said:
^^^

Power FC though, right? ;)
If anything, its better to run on stock ecu than PowerFC. PowerFC has a pretty aggressive base map that does not adjust at all for what kind of gas you're putting in it. Yes it was running on PowerFC but if anything that just attributes to the motors reliability.
 

·
Registered
1998 BMW M3
Joined
·
2,657 Posts
powerfc is LESS reliable than stock ecu if not tuned. arguably less reliable if tuned :p

I ran 1.5 years on a Sti-RA ecu on garbage 91. did 8 trackdays.

then i went powerFC (but havnt had the chance to tune it). still untuned to the date- AND i run 91. 1 year now.

yes, it needs a tune. will happen sometime... :p

for those who are giving sex advice while being virgins....

brydon's point is the most thorough opinion in this thread.

Like i have said previously, smaller turbine will not be detrimental to things. bigger one may be.

the significant mechanical differance between K wrx and K sti is cams and turbine. Get it running and throw it on a dyno, and see what its doing from that.

i ran a td04 on my Td05 sti-ra ecu, and it was just happy.
 

·
Premium Member
RSTI
Joined
·
6,844 Posts
Whoa really? That would be like the best motor ever. I kind of doubt it came from the factory like that tho. EJ20G's came from the factory in open deck fashion like the EJ20K's did. If you have a closed deck shortblock and Version 3 STI heads you have a serious hum-dinger of an engine. But that didn't come frome SOJ like that. The EJ20G later models that are open deck are basically EJ20K shortblocks. At least thats what my research points to.

cheers

garrett


MeanBaby013 said:
Its a G bottom end, with a K top end. Apparently mid production.
 

·
Registered
1998 BMW M3
Joined
·
2,657 Posts
let me clear this up, since the engine came originated with me.

ej20G from 1992-1996 was normal WRX fare. wrx/sti sti-ra all the same. very minor differances.

Ej20G name was carried over from 1997-1998 as well. the G motor was put in wagons only, it was a ej20K wrx motor BUt had td04 turbine instead of VF22. in namesake it is a G, in all actuallity it is a Ej20K with full ej20K electronics, everything.

Steph, you had a 97/98 ej20G - so for all practical purposes, it is a Ej20K with a td04 instead of VF22. all ej20's from 1992-1998 have the same 440 cc injectors. OG legacy waterbox intercooler may have 370's, but those arnt real engines :p


Now you are running a hybrid EJ20H bottom end with ej20K wrx (or wagon 97-98 ej20g) heads. cams are Slightly differnt than ej20K sti/sti ra, but are interchangable.

if you really wanted cams to match the ecu profile, i do have a set of Sti-RA cams. I'd suggest you run it for now though, unless you really want factory spec everything to comply with the computer, i would argue that it would adapt to the slightly differnt cam profiles a-ok.

as far as valvetrain and valves are concerned, the differances between normal wrx and sti in ej20K are almost moot. the under cam shims of the K will still spin to 7500 happily, most turbos (besides brydon's) runs out of steam by 7K........

also. Open deck is better than closed. only person around that arguably needs a closed is again.... brydon.

hahah
 

·
Registered
1998 Forester on Orange 57F
Joined
·
4,129 Posts
supermoose said:
as far as valvetrain and valves are concerned, the differances between normal wrx and sti in ej20K are almost moot. the under cam shims of the K will still spin to 7500 happily, most turbos (besides brydon's) runs out of steam by 7K........

also. Open deck is better than closed. only person around that arguably needs a closed is again.... brydon.

hahah
:sunny: It's only funny because it's true. As far as motors go I think every ej motor is good for 400hp. I also think that tuning is very important for any modded setup. If you change turbos, your MAF is now reading in a different area then it once was. All turbos flow different and the factory spends more time then you can imagine tuning the factory ecu. The factory ecu is great for factory setups! Most of us are happily living close to sea level. The octane of Japan and here is really not that much different. JDM ecus much like USDM ecus are not tuned to run at there max timing and fuel. they have a little fudge factor do to bad gas or elevation changes or climate changes or general wear and tear on your engine.

If you run the stock motor over here on a stock setup you will probably not be hurting anything because you are still in the range of safety. I myself have ran many stock JDM ecus here with no problems. Levin, Silvia, Skyline, just to name a few. I have also seen many motors come from Japan with oil pump issues or general motor issues. Alot of people get motors that have been abused and no longer pass emissions in Japan. These motor might already be on there way out before they get here. This gives people an open door to blame octane or tuning or whatever.

That being said I perfer to tune every car because I like to know what is going on in that mystery box we call ecus. and I'm a nerd!
 
1 - 20 of 23 Posts
Top