Subaru tidbit of the day

[PhyrraM]

I have noticed a fair amount of interest in the 818 from possible FFR repeat customers. Folks who might be more knowledgeable on V8 American iron. While all the tech specs on these Subarus are easy to Google and find out, sometimes it's the little everyday stuff that makes just as much impact.

Motors, gearboxes and eventually brakes are going to have multiple threads dedicated to them. These things prolly won't.

Also, not knowing exactly what FFR is going to re-use and what is going to be in the kit, I'd figure we can use this thread to throw out those seemingly non-important factoids and details.

Tidbit #1:

'02-'03 WRX seats are very good, generally considered the most supportive of any Subaru factory seat. They however look like regular Ma-and-Pop Camry seats, with a squared off top and separate headrests.

'04-'07 WRX and STI seats look very sporty with tall, tapering seatbacks and integrated headrests. They would likely fit the style of the 818 very well and pretty much look like an aftermarket sports seat. They, however, are generally regarded as less supportive than the '02-'03 WRX seats.

[riptide motorsport]

good thread........Steven

[Horhay]

The STi seats are incredibly springy. They are my least favorite part of driving my STi.

[Sergio]

I don't think FFR is going to recommend to use the stock seats for the 818, saving weight would mean the stock seats would have to go.
lighter seats are available and also FFR has the connections (SubeSports) to make (or rename) a whole new seat for the 818.

[crackedcornish]

it will be interesting to see if FFR hits both the 1800lb and $9900 mark

if they use a lot of stock Subie parts I'd imagine weight will become an issue, if they use a lot of aftermarket/specialty parts then the price point may be in danger....we'll just have to wait and see what happens

[PhyrraM]

Tidbit #2

The Subaru front knuckle/hub is virtually universal. The only real exceptions are the rare SVX and the '05+ STI. Both of which are 5x114.5 vs. the 5x100 of every other Subaru.

This means that the same front spindle/hub assembly can accept tiny single piston 1.8 liter base Impreza brakes all the way up to 4 piston '04 (only) STI 13" Brembos. A sweet spot is the stock WRX 2 or 4 piston calipers.

The idea here is that if FFR uses the front assembly in the back, the smaller Impreza brakes can be swapped with zero issues. If FFR keeps them in front, the larger WRX and Brembo assemblies are appropriate. And if it uses custom hubs/knuckles? Well, then the info is still a tidbit.

[PhyrraM]

Tidbit #3

In the American market:

'02-'05 WRXs are 2.0 liters and use a traditional throttle cable.

All other turbos, including '06+ WRX, ALL STIs, Turbo Bajas, '05-'09 Legacy GTs, Forester XTs, and Outback XTs are 2.5 liters and have an electronic throttle.

Non-turbos phased in the electronic drive-by-wire at a slower pace.

[Evan78]

Regarding STi Brembos, I just want to point out that the 05 STi went to a 5x114.5 bolt pattern as PhyrraM mentioned, so the rotors changed to match, but the calipers are all the same as far as I know.

[Cooluser23]

I prefer Mitsubishi Evolution, or Dodge Viper seats over any Sti seats I sat in. (I worked as a valet. I drove A LOT of cars)

However I do like the idea of making the seats single donor to keep costs down.

As long as there is enough room to put Cobra Misano, Sparco Milano, or Recaro Sportster CS, Bride, etc. seats in for people who want to spring for extra dough, I'm happy.

[PhyrraM]

Tidbit 4

All the 5 speed transmissions bolted behind EJ motors are the same basic design. As they got newer they got upgrades. However, turbo models used a different clutch arraingement than non-turbo models.

All non-turbo models had a traditional push clutch. Early years had a cable mechanism, starting about '96ish hydraulic actuation was phased in depending on engine size.

Turbo models up to about '05 had a pull type clutch. All were hydraulic. All clutch parts, including flywheel are different. Bellhousing accomodations for the throw-out bearing make the trannys physically different, even if interenally similiar.

Starting about '05ish, the turbo 5-speeds started appearing with push clutches too.

The 6 speed on the STI is also a pull type of clutch, but again, all clutch parts are unique from other models.

[GTLee77]

Great info!! Keep it up...

[PhyrraM]

Tidbit #5

All of the Subarus that would make a good donor have headlights and parking lights that automatically go off with the ignition. While this is likely intended to protect the battery, the main switch can be left in the 'on' position for a basic autolamp feature. If you need parking lights while the ignition is off, there is a dedicated switch on top of the steering column.

The first time you accidentally flip it while cleaning the interior, it will take you 30 minutes (and a phone call to a 'Subaru friend') to figure out why your parking lights won't turn off, even though you turned the headlight switch off.

[MDRex]

The switch mentioned above is right on the top of the steering colum. That switch controls the corner marker lights/parking lights, not the headlights, just wanted to make sure people understood which lights PhyrraM is talking about. The marker lights will only stay on when the car is off if that switch is "On". The headlights will never stay on when the car is off, so you can leave your headlight switch to 'On' and have the headlights come on automatically when you start the car.

Also, the fog lights on the Impreza will only go on with the headlights on. The fogs turn off automatically when you turn the highbeams on. But there is a simple hack to get the fogs to go on and stay on whenever you'd like, more info can be found on any of the Subaru forums.

[PhyrraM]

Tidbit #6

The WRX and most other Subarus of the same era have a 16.5:1 steering rack ratio. The STI and '06-'07 WRX have a 15:1 rack.

The '91-'94 Subaru Legacy is unique with a 16.0:1.

[thebeerbaron]

Can you express the rack ratio in turns from lock to lock? I did some quick googling, but didn't come up with much. I know the 15:1 rack will be faster, but I'd like to know what that means in terms of steering wheel travel.

I'm guessing we'll have to de-power the rack for this car. Do you know of any guides to doing that? I know it can be as simple as just looping the lines, but there are better ways where you remove seals and weld up certain bits, depending on the car involved.

Great thread!

[PhyrraM]

Can you express the rack ratio in turns from lock to lock? I did some quick googling, but didn't come up with much. I know the 15:1 rack will be faster, but I'd like to know what that means in terms of steering wheel travel.

I'm guessing we'll have to de-power the rack for this car. Do you know of any guides to doing that? I know it can be as simple as just looping the lines, but there are better ways where you remove seals and weld up certain bits, depending on the car involved.

Great thread!

Without knowing what front knuckles FFR is planning on using, there can be no correlation between gear ratio and turns lock-to-lock. A lower ratio will be faster. Also, the length of the arm on the knuckles will effect how 'fast' the steering is.

I have never depowered a rack, but I'm sure that FFR will provide proper instuctions.

[thebeerbaron]

Without knowing what front knuckles FFR is planning on using, there can be no correlation between gear ratio and turns lock-to-lock.

I thought about that, but isn't lock-to-lock just a function of reaching the physical stops at the end of the rack? Even if you pull the rack off the car, you'd know how many input turns it takes to go from one end of the rack to the other.

The knuckle and arm length would affect steering angle per input degree, and thus a bunch of suspension geometries my pea-sized brain can't handle today, but unless the tires hit the chassis first, it will be the rack that stops the steering travel.

[PhyrraM]

Tidbit #7

Subarus use a 53mm offset wheel. Many aftermarket wheels used on Subarus are 45mm offset.

Folks start to talk about wheelbearings going bad with less than 45mm offset, but it is still debated.

[riptide motorsport]

great thread, i can feel my mind exspanding everyday!!!!!!!!!!!!!!!!!!!!!!!!

[MDRex]

The whole wheel bearing thing is very much up for debate. There are guys that complain theirs went bad fast and then those that race their cars a lot and never have an issue with the wheel bearings. So take any talk of wheel bearing issues with a grain of salt, just like the supposed glass tranny.

[crobin4]

The whole wheel bearing thing is very much up for debate. There are guys that complain theirs went bad fast and then those that race their cars a lot and never have an issue with the wheel bearings. So take any talk of wheel bearing issues with a grain of salt, just like the supposed glass tranny.

I agree I've run a very long time with 35mm offset, and had no issues.

[PhyrraM]

.....take any talk of wheel bearing issues with a grain of salt.....

Completely agree, that's why I made it point to mention it is still debated.

Considering the weight goal of the 818, I wouldn't worry about wheel bearings unless the go-cart/first builds have problems.

[PhyrraM]

Tidbit #8

The '02 and '03 WRXs had the speedometer centered in the middle of the cluster as the largest gauge. The tachometer was smaller and to the right. There were no USA STIs for these two years.

In '04 they got switched and put the tach as largest and in the middle, where it belongs. The speedo took up residence in the smaller spot to the right. This applied to WRXs and STIs, however STIs have a more 'stylish' electroluminescent cluster.

All speedometers are electronic. There are no speedo cables on the '02+ cars.


IMHO, I prefer the simpler, less distracting, WRX cluster.

[PhyrraM]

Tidbit #9

All modern EJ series turbo Subarus had DOHC heads. The only EJ series motor that had a turbo and SOHC heads was the USA market '91-'94 Legacy turbo.

2.0 turbos ('02-'05 WRX) were traditional DOHC with no variable valve timing.

2.5 turbos (Baja, Forester, Legacy, WRX '06-'07, and STI '04-'07) had variable valve timing on the intake.

'08+ STIs have variable valve timing on both intake and exhaust. Of course, the '08+ are outside the stated donor years and are not expected to be preferred donors.

[riptide motorsport]

how much diference can you exspect performancewise from the dohc verses the sohc? ....thanks Steven

[PhyrraM]

how much diference can you exspect performancewise from the dohc verses the sohc? ....thanks Steven

For the turbo, the SOHC is much older ('90-'94) and only rated at 160HP. It is however a 2.2 vs. a 2.0 in the WRXs ('02-'05). It is pre-OBDII electronics, pro or con? This SOHC is generally considered an inferior head design to newer ones.

For the non-turbos, the SOHC is considered better than the non-turbo DOHC used in mid-late 90s cars. Subaru has only recently ('10 models) switched back to DOHC for non turbo cars.


Subaru guys used to take the DOHC heads and swap them to the 2.2 block, however the advent of the factory 2.5 turbos has curtailed that.

[PhyrraM]

Tidbit #10
For cars Imprezas '93-'07, Legacies and Outbacks '90-'04, Foresters '97-'08, and all Bajas:

Turbo and non-turbo Subarus use different front crossmembers. The turbo crossmember has a notch to clear the exhaust pipe that routes gasses up to the turbo. Because of this slight shape change, the front anti-roll bar is also different between turbos and non-turbos.

Imprezas '08+, Legacies and Outbacks '05+, and Foresters '09+ no longer use the 'coporate' front crossmembers of earlier cars.

[Gollum]

The wheel bearing issue is definitely some muddy water to tread. From all that I've heard from quality subaru techs, the main consensus is that people are either using poor quality "direct replacement" off brand bearings, or they were changed at some point and weren't installed correctly, as the subaru wheel bearings aren't the simplest in the world to change.

On the other side, I've talked to people that have had wheel bearing issues, who seem to really know what they're talking about and say that once they switched to the larger 5x114 hubs the problem went away. One guy I'd talked to had gone through three sets of wheel bearings, all different brands. I can only assume he doesn't know how to install them very well, or there is indeed something else causing bearing failures.


This is all good info. Keep it coming.

[Brian Apple]

Also, wheel bearings are pressed in at a shop unless you use the 05-07 STI hub/carrier which bolt in the bearings and can be done by anyone. STI bearings are larger in diameter and the hub has to be the 5x114. Not interchangeable with the 5x100. This requires the STI axles as the number of splines are different. At the trans though, it requires the STI 6 speed also as the axles on the STI are female input and the WRX are male input to the trans.

[riptide motorsport]

wheres the tidbit??????

[PhyrraM]

wheres the tidbit??????

Travelling and work. Haven't had time to sit down and compose a good one. So, how about a quicky....

Tidbit #11

In addition to a slightly larger intercooler, STIs have a factory intercooler spray setup. It is a trunk mounted tank, nozzles and a dash mounted switch.

WRXs make do with just the hood scoop.

[PhyrraM]

And on a related note:

Tidbit #12

'02-'05 WRXs have a all aluminum intercooler. (2.0 liter)

'06-'07 WRXs switched to an intercooler with plastic endtanks. (2.5 liter)

All STIs had a slightly largr than WRX all aluminum intercooler.

'04+ Turbo Bajas and Foresters had a plastic endtank intercooler very similiar to the '06-'07 WRX.

'91-'94 Turbo Legacies did not have an intercooler.

Later cars ('05+ Legacy/Outback, '08+ WRX, '09+ Forester) use a slightly revised turbo/intercooler/throttlebody routing - making intercoolers non-interchangeable with earlier models. These models had the intercooler bolted to the turbo directly instead of a traditional hose. They also had a plastic intake manifold instead of the aluminum on earlier models. The later motors can be backdated to the earlier design with an intake manifold swap, if desired.

[crobin4]

'91-'94 legacys had a water to air intercooler

[PhyrraM]

'91-'94 legacys had a water to air intercooler

True. Overseas '89-'93 2.0 liter Legacy/Liberty models had an air-to-water intercooler.

North American Legacy 2.2 liter SOHC models had no intercooler.



For completeness:

Overseas '94-'03 turbo models were 2.0 liter twin turbos with normal air-to-air intercoolers

[bbjones121]

Tidbit of a Tidbit:

Plastic endtanks on the 06+ WRX, 05+LGT/OBT blow pretty easily with stage 2 upgrades. There are options available that are much larger and all aluminum.

And on a related note:

Tidbit #12

'02-'05 WRXs have a all aluminum intercooler. (2.0 liter)

'06-'07 WRXs switched to an intercooler with plastic endtanks. (2.5 liter)

All STIs had a slightly largr than WRX all aluminum intercooler.

'04+ Turbo Bajas and Foresters had a plastic endtank intercooler very similiar to the '06-'07 WRX.

'91-'94 Turbo Legacies did not have an intercooler.

Later cars ('05+ Legacy/Outback, '08+ WRX, '09+ Forester) use a slightly revised turbo/intercooler/throttlebody routing - making intercoolers non-interchangeable with earlier models. These models had the intercooler bolted to the turbo directly instead of a traditional hose. They also had a plastic intake manifold instead of the aluminum on earlier models. The later motors can be backdated to the earlier design with an intake manifold swap, if desired.

[Justen]

Twin turbos on a 2.0? 2 turbos or 1 twin scroll?

[PhyrraM]

Twin turbos on a 2.0? 2 turbos or 1 twin scroll?

Two sequential turbos. One small and one larger one. They made good power and had good low end, but Subaru struggled with the transition from primary to secondary. Subaru folks have called this the "Valley of Death" for years.

These motors are relatively cheap as imports here in the states because they don't fit left hand drive cars. The traditional Subaru single turbo system bolts up to the longblocks, so complete motors only have longblock value. The factory ECU wiring is fairrly complex, but doable. Of course a standalone will also work.

[PhyrraM]

Tidbit #13

Over the years, Subaru EJ series 4 cylinders have had many versions of heads and blocks. They however are generally catagorized into two groups, Phase 1 and Phase 2. The crossover year is about '98-'99 depending on model.

The main reason for the change seems to be to improve the 2.5 liter motors- which were "short-cutted" from the original 1.6-2.2 liter sizes. There were numerous upgrades, but the one that effects an engine build the most is the relocation of the thrust bearing from the center of the motor (#3 journal) to the flywheel end (#5 journal). There is also double the number of engine-to-transmission mounting bolts on the phase 2 (from 4 to 8), however early cars don't seem to have a problem in this regard.

Another of the improvements applies only to the 2.5 liter motors. Phase 1 had 48mm rod journals. This is smaller than the 52mm standard on all other EJ motors. The assumption is that Subaru used the smaller journal to cram the larger 79mm stroke into the early case. That was rectified on phase 2 when the journals on the 2.5 liter were now back to 52mm like all the rest.

[BrandonDrums]

Tidbit #14

PhyrraM is my current favorite FFR forum member. Awesome stuff man.

[PhyrraM]

Thanks. I intended for others to start throwing out their Tidbits(tm) too.

Tidbit #15

All EJ based Subarus have the engine ECU under the front passenger floorboard on a fairly long harness leg. This should allow a good amount of flexibility on mounting location and access when/if the harness is converted to 818 duty.

The exception is the '90-'94 Legacy which has the ECU stuffed under the dash on the drivers side and has almost no play in the harness.