Engine Choices

[Xusia]

I'm new to Subaru's, so I don't really know what I should be looking for as a donor. Mine will be a daily driver, that may perhaps see the track from time to time. This means reliability and drive-ability trump all other goals. My HP goal - IF I can afford it - is ~340-350 whp. If I can't afford the parts/tuning to get there I'll probably just leave it stock (it's not like it'll be slow!). So what are the engine options? What are their relative advantages/disadvantages?

I had one person I spoke to privately recommend an EJ205 with an 18G-XT turbo. He also said the 2L is durable, so I assume an EJ205 is a 2L engine? Anyone have any thoughts on this recommendation or what kind of HP it would produce? Also, what cars have an EJ205?

Thanks in advance for educating my ignorant arse!

[PhyrraM]

To keep things simple, these are the stock motors/donor cars known to work at this time (FFR stated):

'02-'07 Impreza base 2.5 N/A, 165 HP, EJ251/EJ253
'02-'05 Impreza WRX, 2.0 liter turbo, 227 HP, EJ205
'06-'07 Impreza WRX, 2.5 liter turbo, 227 HP, EJ255 (official, concensus is the factory under rated it)

Engine-wise, the STIs will work, but not some of the suspension or transmission (FFR, officially)
'04-'07 Impreza WRX STI, 2.5 liter 300 HP, EJ257

The (basically stockish) trick would be to get the '06-'07 WRX 2.5 liter and add the STI turbo, intercooler, and engine tune for the 300HP rating.

I'm sure many others will walk you through the ENDLESS non-stock possibilities. It truely is "how fast can you afford to go?"

[PhilElement]

FF really needs to make the 6 speed fit and the only problem should be the length. The 5 speeds are really weak on the early 02-05 wrxs. They can break at 250 whp abused and babied 350 is borderline. They are also equipped with an open differential.

The 04 STIs has a viscous front differential and the hubs and axles are compatible with the wrx. The 05+ STIs have a torsen front differential but the axles and hubs are a little different. They have 5x114 hubs, bigger bearings, but also the strut mount is thicker. All can be swapped into a wrx however but not sure about the 818.

All the control arms can transfer but there are differences in sway bars.

Thanks,
Philip Grabow

[Street Rate Parts]

It would be nice but making the 6spd front drive only is a true *******. There is a ton of items in that tranny that cannot be removed (easy and cheap that is) and keeping them in makes the front drive option an issue.

I am actually working on this issue right now, I have two 6spds on the bench and I have been on the lathe and mill making parts to try to get this to work properly. I have a billion rally prep hours on Scoobies so the motor is already built for my first car..hahah The tranny....this is going to be a hard one.

[Xusia]

Thanks for the great info guys. This really helps!

[Etos]

Hey Phil, good to see more of the subaru community.

I kinda disagree with the 5 speed being an issue. They hold up well in AWD mode upto 350 so long as you don't dump the clutch. Not being able to spin the tires freely of excess power is what really killed the 5 speeds, along with bad driving. With a 2WD config it will allow excess power to bleed off as wheel spin.

What would be nice is if subaru were to supply an OEM solution by taking some of their earlier FWD transmissions, beefing up the gears and putting a nice diff in there. I'll be at SOA for the 48 hours charity drive and certainly bring up FFR and the possibility of making a crate kit much like GM and Ford are doing.

[Twinspool]

FF really needs to make the 6 speed fit and the only problem should be the length. The 5 speeds are really weak on the early 02-05 wrxs. They can break at 250 whp abused and babied 350 is borderline. They are also equipped with an open differential.

The transaxle strength has been discussed extensively, the 5 speed should take ample non-hamfisted performance driving in the 818.
5 gears or 6, who cares? I'd rather have good gear spacing and a 5 speed than bragging rights to a 6th gear. PPG 1-4 cluster anyone?

[Xusia]

So, is the reason to go with the 2.5L and not the 2.0L just because the STI has a 2.5L and that makes it easier to install the STI turbo onto the WRX 2.5L? Could the STI turbo be installed on the 2.0L? Not necessarily thinking that what I want, just looking at the options. I also don't know what I'll find in terms of a donor.

BTW, I REALLY appreciate everyone's help!

The (basically stockish) trick would be to get the '06-'07 WRX 2.5 liter and add the STI turbo, intercooler, and engine tune for the 300HP rating.

I'm sure many others will walk you through the ENDLESS non-stock possibilities. It truely is "how fast can you afford to go?"

[StatGSR]

^ no its just as easy to install an STI turbo on a 2.0, the benefit to the 2.5 is mostly just the better off boost torque and better spool time. Subaru engines/cars are like a bag of legos with only a few mega blocks mixed it, almost everything can be connected to something else with no modifications required.

[Street Rate Parts]

Ya but the 2.0l (n/a) is internally different than the 2.5 and can be a bear to deal with under high boost. Check the supports around the top of the sleeves at the water jacket. Totally different from 2.0 to 2.5 but is it really an issue? We are going to be stuck with 300hp tops through the 5spd. even with the reduced weight of the chassis I think that 300hp will be it. I have never had any luck with the 5spd at all...even treating it like it was made of eggs didnt help

So with that being said a 2.0 with the turbo will be fine if you keep the boost down...

If you want more its so easy to do with a Subi....but the 5spd becomes the fuse. Bring a broom basically

[BipDBo]

If you want more its so easy to do with a Subi....but the 5spd becomes the fuse. Bring a broom basically

A question for anyone who has more knowledge than me about these transmissions (which should be most of you): What parts of these 5sp gearboxes are first to fail? Depending on the answer to that question, the fact that the engine will be pushing an incredibly lighter car at only 2 of the wheels could make a very big difference in the life expectancy of the gearbox. How much of a difference would this make?

[Justen]

I'm no pro, but I think the consensus is that if you are going to push over 300 hp, you will want the PPG gear set, so my guess is that the gears themselves are the weak point.
Can anyone confirm this?
How hard/ time consuming is it to swap out the gears for the PPG ones?

[PhilElement]

The transaxle strength has been discussed extensively, the 5 speed should take ample non-hamfisted performance driving in the 818.
5 gears or 6, who cares? I'd rather have good gear spacing and a 5 speed than bragging rights to a 6th gear. PPG 1-4 cluster anyone?

Hey Phil, good to see more of the subaru community.

I kinda disagree with the 5 speed being an issue. They hold up well in AWD mode upto 350 so long as you don't dump the clutch. Not being able to spin the tires freely of excess power is what really killed the 5 speeds, along with bad driving. With a 2WD config it will allow excess power to bleed off as wheel spin.

What would be nice is if subaru were to supply an OEM solution by taking some of their earlier FWD transmissions, beefing up the gears and putting a nice diff in there. I'll be at SOA for the 48 hours charity drive and certainly bring up FFR and the possibility of making a crate kit much like GM and Ford are doing.

I disagree from experience. In all cases where I've broken 5 speeds or my customers have broken 5 speeds it's always from a roll and usually 3rd gear. Roll into it and break 3rd gear so it's a torque/HP issue more than a launch problem. This has been on 350+ whp cars. My 1st ever 5 speed must have been a gem because I ran in the high 11s at the drag strip but chipped first gear. My second OEM 5 speed broke 3rd gear from a roll again just over 350 whp. After building a number of 5 speeds with PPG gears they even have their limits and I've broken a helical 3rd gear in that transmission but at much higher power levels but again it was 3rd gear and about 600 whp. The straight cut gears are only about 20% stronger so really I think with a built 5 speed you shouldn't expect more than 600 HP out of them.

Now the Legacy GT 5 speed and the later 08+ WRX transmissions are much stronger. I ran my 08 WRX to 400 whp, never had an issue, and I raced that car. Even so I wouldn't push it that much farther and if you compare the gear size to the 6 speed you'll see why.

In terms of wheel spin helping, I don't disagree, but that's where two very different markets will have different needs. Your budget builders using OEM size wheels and street tires will be able to break loose but a racer on slicks or in my case someone who wants an 11-12 slick is going to have issues. To race this car in TTS or TTU you have to go against Corvette Z06s running 385 (TTS)-580 whp (TTU)!

Thanks,
Philip Grabow

[PhilElement]

I'm no pro, but I think the consensus is that if you are going to push over 300 hp, you will want the PPG gear set, so my guess is that the gears themselves are the weak point.
Can anyone confirm this?
How hard/ time consuming is it to swap out the gears for the PPG ones?

Yes basically. You could chance it at up to 350 whp but it's just a gamble unless you get the latest 5 speeds.

A PPG gearset is around $4k but with all the upgrades (speedo gear, interlocker, upgraded 5th gear syncro hub) you really need, it's $5k plus and don't forget you'll need to upgrade the differential at $800-1200. You could easily be hit $6k where 6 speeds are readily available for $3k to $3500 with shifter parts.

If 5 speed is going to be the only option given my history with the 5 speed vs. the 6 speed I would likely have to build a different car. I'm not going to be a typical builder however as we want to build a car on the GT1 scale. I think for the 02-04 5 speeds for those who would like 350+ go with the PPG synco, helical gear set and an upgraded differential. For 300 hp or less stock should be fine but the open differential is going to be an issue. If you can score a late model 5 speed from the Legacy GT or the 08+ WRX (it's possible the 06-07 are just as strong) you're good to 400 whp.

Thanks,
Philip Grabow

[Justen]

Are these prices serious?!?!
http://www.ppgearbox.com.au/page.asp?categoryid=14

$5,885.00 AUD (about the same USD) for the 1-4th straight cut gears? that's more than I plan on paying for a wrecked donor!

I guess you have to have deep pockets if you want to push high hp on this thing.
I think I'll stick to the 250 range and save my pennies for when i blow it up for the PPG's

[PhilElement]

It would be nice but making the 6spd front drive only is a true *******. There is a ton of items in that tranny that cannot be removed (easy and cheap that is) and keeping them in makes the front drive option an issue.

I am actually working on this issue right now, I have two 6spds on the bench and I have been on the lathe and mill making parts to try to get this to work properly. I have a billion rally prep hours on Scoobies so the motor is already built for my first car..hahah The tranny....this is going to be a hard one.

Good luck with this and I really hope you can figure a way to make it work for the high power guys. You would think it could be just as easy as installing a spool in place of the rear differential. This would lock the torque to both the front axles and the tail shaft. I'm guessing the back of the transmission would stick way out the back of the car though

[vozproto]

^ Yeah. I plan on starting with a base WRX, preferably 2.5L.

That way I have a good starting baseline and can upgrade as I go along.
I really don't see the purpose in upgrading everything before I know what I have.

That way I don't hemorrhage my budget before I ever start.
And the cool thing is that the subie community is pretty big out here. So I can always get a good chunk of my money back on any parts I swap out.

[PhilElement]

Are these prices serious?!?!
http://www.ppgearbox.com.au/page.asp?categoryid=14

$5,885.00 AUD (about the same USD) for the 1-4th straight cut gears? that's more than I plan on paying for a wrecked donor!

I guess you have to have deep pockets if you want to push high hp on this thing.
I think I'll stick to the 250 range and save my pennies for when i blow it up for the PPG's

An in-between solution would be hardened RA Subaru gears, cryo treating the gears, or using the newer 5 speeds I've mentioned. Let's not forget 300 whp on this thing is going to be really fast...similar power to weight ratio as a 500 hp STi!

[pressley311]

Will the legacy gt trans mount up to the EJ257 of the STi. I have the engine from my old 05 sti still with forged pistons stg2 cams and valve and spring kit (but still the crappy VF39 turbo), But could you go to like a 3076 turbo with out all ways heat soaking since it appears that you could not put a FMIC on the car?

[BipDBo]

I disagree from experience. In all cases where I've broken 5 speeds or my customers have broken 5 speeds it's always from a roll and usually 3rd gear.
Thanks,
Philip Grabow

That kind of answers my question. I would think a gearbox in a WRX would be more likely to fail at 2nd gear. The lower gear ratios are going to be more protected by the lower weight of the 818. When you get into the higher ratios, the tires are less willing to slip, so the driver can dump the clutch faster and the gears will absorb more "torque shock," to fabricate a term. Going into third gear, the lower weight of the car may give enough extra traction slip to prevent the too much torque from being applied to the gears. I'm no transmission expert, though. I'm just postulating.

[Xusia]

Does anyone know why the STI transmission won't work? The reason I ask is that I'm thinking the best route for me (definitely in the "budget builder" category) is hopefully buy the "Complete Kit" from FFR, and source an STI engine/transmission. That way I don't need a donor (the complete kits come with most of those parts new from FFR), and I get the most engine bang for my buck (and the better transmission - assuming it can work).

Engine-wise, the STIs will work, but not some of the suspension or transmission (FFR, officially)
'04-'07 Impreza WRX STI, 2.5 liter 300 HP, EJ257

[Etos]

I disagree from experience. In all cases where I've broken 5 speeds or my customers have broken 5 speeds it's always from a roll and usually 3rd gear. Roll into it and break 3rd gear so it's a torque/HP issue more than a launch problem. This has been on 350+ whp cars. My 1st ever 5 speed must have been a gem because I ran in the high 11s at the drag strip but chipped first gear. My second OEM 5 speed broke 3rd gear from a roll again just over 350 whp. After building a number of 5 speeds with PPG gears they even have their limits and I've broken a helical 3rd gear in that transmission but at much higher power levels but again it was 3rd gear and about 600 whp. The straight cut gears are only about 20% stronger so really I think with a built 5 speed you shouldn't expect more than 600 HP out of them.

Now the Legacy GT 5 speed and the later 08+ WRX transmissions are much stronger. I ran my 08 WRX to 400 whp, never had an issue, and I raced that car. Even so I wouldn't push it that much farther and if you compare the gear size to the 6 speed you'll see why.

In terms of wheel spin helping, I don't disagree, but that's where two very different markets will have different needs. Your budget builders using OEM size wheels and street tires will be able to break loose but a racer on slicks or in my case someone who wants an 11-12 slick is going to have issues. To race this car in TTS or TTU you have to go against Corvette Z06s running 385 (TTS)-580 whp (TTU)!

Thanks,
Philip Grabow

For every transmission that is grenaded at 300-350 there is another one holding up just fine. There's plenty of people who track and autox without a problem. Not to say you are a bad driver cause you obviously are not, but would you say you are good with finess or hammer on the anvil? Even abrupt on/off gas can cause quite some shock, it's not just shifting. There's people who were able to blow apart the all mighty STi transmission with relative ease just from bad driving/dumping the clutch.

I also doubt there's no way you can't fit a 6 speed. Will it look pretty? probably not but if it's a track rat like you're making I doubt you are going to care that much. Even then, do you really really believe you need more then an RA gear set for higher horsepower versions? You'd need to be running well over 400 to warrant it and 400hp should be downright scary in an 1800pound car.

[Xusia]

You say that like it's a BAD thing!

...and 400hp should be downright scary in an 1800pound car.

[Etos]

You say that like it's a BAD thing!

I believe in a balance. Sometimes there is such a thing as too much power. I learned that the hard way with a 560hp s2000.

[Xusia]

I agree. I was just being a smart arse...

[PhilElement]

Will the legacy gt trans mount up to the EJ257 of the STi. I have the engine from my old 05 sti still with forged pistons stg2 cams and valve and spring kit (but still the crappy VF39 turbo), But could you go to like a 3076 turbo with out all ways heat soaking since it appears that you could not put a FMIC on the car?

Yes but you will need a 5 speed clutch. It's basically the same case but it's somehow stronger internally. It's suggested that it has hardened gears as do the newer WRX transmission used with the 2.5 liter motors. The 2008+ WRX have some beefier components in them.

[PhilElement]

For every transmission that is grenaded at 300-350 there is another one holding up just fine. There's plenty of people who track and autox without a problem. Not to say you are a bad driver cause you obviously are not, but would you say you are good with finess or hammer on the anvil? Even abrupt on/off gas can cause quite some shock, it's not just shifting. There's people who were able to blow apart the all mighty STi transmission with relative ease just from bad driving/dumping the clutch.

I also doubt there's no way you can't fit a 6 speed. Will it look pretty? probably not but if it's a track rat like you're making I doubt you are going to care that much.

I would say early 5 speeds just about all break, it's the newer 06+ that are holding on well. Like I said my first one did really well.

Finesse matters and it's why some people have good luck and other don't but when it comes to 350+ it doesn't matter. Each one of my customers I tuned and sent home with 350+ was told not to dare go WOT in 1st or 2nd gear. I myself did the same thing and even on my 08 WRX I avoided it. This is why all of us broke 3rd gear and not 2nd because we all didn't temp fate. In most cases with higher power setups the reason why 3rd gear is more vulnerable is because you end up blasting through 1-2nd gear so peak torque isn't realized and once in third the engine has time to build full boost and therefore maximum power.

Take the personal experiences for what it's worth and if 50% handle the power fine and 50% don't well then you know your odds. My personal odds would be it's going to blow up don't waste your time with a 02-05 transmission since I'm not limiting myself to 300 HP.

Even then, do you really really believe you need more then an RA gear set for higher horsepower versions? You'd need to be running well over 400 to warrant it and 400hp should be downright scary in an 1800pound car.

We have broken many RA boxes, they are an improvement but no better than the 06+ OEM transmissions. I already race a scary car (love it!) and to match my current power to weight ratio (3180 lbs, 700 whp) I predict this car will need to make 485 whp if it weights 2200 fully prepped with driver. To be competitive against the 850-1000 whp cars I race against for overall fast time at the Ultimate Track Car Challenge (Glen Bunch Challenger, Ganassi built Car of Tomorrow Nascar) I will need this car to be putting out 675 whp at 2200 lbs. I just happen to have that engine and transmission ready to go

I think many, many, many people will be fine with the 5 speed but I don't want the design to exclude the 6 speed for those of us who need it. If the race body is a DP type then ugly won't matter since the body work would likely be open back there vs. a tail shaft sticking out a bumper

[PhilElement]

You say that like it's a BAD thing!

Car guys don't always get it! Absolutely ridiculous and scary is just right! What's so wrong with wanting a 9 second dragster that can turn. LOL!

[Street Rate Parts]

PhilElement the issues with the 6spd is two fold. First thing is they are fawking huge! about 240lbs if i remember correctly..ya monsters for sure. Second is the parts inside that do multiple things, the center diff is computer controlled (dccd) and also runs the internal oil pump. Its not as easy as pulling it out or welding it up.

Its a huge job but I am hoping to make it happen..it comes down to cost. If it will sell and it will fit....its going in.

Oh the 5spd fails because of a few reasons, the case is too weak to hold everything in place so it will flex under load. The 3rd gear failure is the outcome from torque passing from the lower to upper shaft and pushing the case halves apart throwing everything out of wack. The gears start to ride out, the tooth end snaps off, it gets jammed and boom!


Also the input shaft is teensy tiny and will snap like a twig, load up a 5spd and slide your foot off the side of the clutch....boom!!

It goes on and on.....

[Etos]

Phil, I think you are the only one crazy enough to want near 700hp in a 2100 pound car I don't even think an STi trans is going to hold up to that for long.

Let's take a step back for a minute and try to keep this discussion about what 99% of us are looking for. You as a shop who can some day be working on these for customers so it's probably more important to keep that perspective in check then your wild pony.

Considering no ones ever done anything like this(turning the trans to FWD config) it's hard to say what it will or will not hold. There's quite a few different variables(tires, year of trans, condition of used trans, power output) so that makes it even harder to guess.

Again it would be really nice if somehow we could get SOAs attention in them producing a FWD transmission that can handle most of the needs(06+ WRX trans quality) and the ability to swap out gears for bigger stronger ones for crazies like you who have a death wish :P This way you get a more compact, lighter(sti trans is OMG heavy), space friendly transmission.

[BrandonDrums]

Wow, this discussion again? There are tons of threads from April or March onwards about this stuff, we talked about it at great length.

First off, I and several friends with 300+ whp wrx's running 5 speeds have had no issues with the 5 speed, even after 200k miles. Remove 1500 lbs and make it 2wd and the 5 speed will probably have little issues because the fight is putting all the power to the ground.

Just don't drive like an a$$-hat, OEM transmissions on the mighty GT-R broke left and right too. Why? Nissan programmed the launch control to drop the hammer at 4500 rpm and had the foresight to void the warranty on the transmission if you used the launch control! How did Nissan fix their launch control problem? They changed the launch control rev-limit to 3000-3500 rpm, suddenly the transmissions stopped blowing up and somehow the 0-60 time got even faster.

I use a free ECU 'launch control' patch on my WRX and have the launching rev-limit set to 3500 rpm's. That's where the turbos just begin to spool and it's not so fast that my transmission destroys itself, I just flatfoot the throttle from a standstill and quickly engage the clutch (note, I didn't say "drop the clutch) and boom, everyone is behind me and my gears still have teeth to boot.

2nd, the STI's gearing is short, very short. On a 1800lb car, you'll be hurting your performance by having such short gear ratios, I mean 2 shifts to 60 when 60 will be coming in 4 seconds or less is just dumb. Also, achieving full boost is difficult in lower gears because the engine simply has too much mechanical advantage to build full boost easily, the engine will build revs faster than the turbo can build boost. Shed 1500 lbs, gearing as short as the 6 speed's will just make that even worse.

3rd, the STI transmission has a very complicated, very fancy and expensive center differential. It's a DCCD or Driver Controlled Center Differential. It's the bees knees for an AWD subie but in an 818 you'd have to weld it shut like a drift car or ditch it for a solid dummy piece in it's place which doesn't exist (while there are pre-made options available for the 5mt). That's like a $1k part that you have to destroy or remove.

If you buy an STI donor for an 818, you're literally going to be better off parting out the 6mt, it's a very popular upgrade for other Subies and buy a 5 speed to either drop right in or use the extra cash to upgrade it with PPG or RA gears and one of several viable and inexpensive front LSD upgrades.

If you're looking to put more than 400 whp in your 818, yeah, you might want a stronger box than a stock 5 speed but honestly the 6 speed isn't the answer to that in an 818. Fortunately, there are lots of strong aftermarket 5mt gear-sets available.

Save the 6 speeds for the AWD guys, they actually will benefit from them.

[SkiRideDrive]

While were on this topic, what modifications (and the relative cost of those modifications) would one need to get a 2.0 Liter WRX motor up to about 300 hp, which seems to be the consensus of where the stock tranny will no longer hold up reliably. I'm assuming this would include an up pipe, down pipe, bigger turbo, injectors, fuel pump, and tuning. Also, any discussion of much less expensive options and the power levels they can achieve would probably be helpful for many people here. Thanks for all the great info!

[BrandonDrums]

And to stay on topic...the STI engine is more or less the very same thing that comes in an 06+WRX or a Forester XT or a Legacy GT. The 04-07 STI long block has minor minor changes, mainly it has a slightly LOWER compression ratio vs. the other 2.5T subarus since the STI sees a higher effective compression ratio due to higher boost.

I have an 05 wrx with only a aftermarket turbo, upgraded injectors and a 04 STI intercooler on it, everything else is from my 05 which is the 2.0L engine. I just don't have anything to control the AVCS system so I just don't use it which is no big deal because AVCS is usually off by 3k rpm anyway, with a bigger turbo you never go below 3k rpm to begin with if you're trying to make power.

[crobin4]

Considering no ones ever done anything like this(turning the trans to FWD config) it's hard to say what it will or will not hold. There's quite a few different variables(tires, year of trans, condition of used trans, power output) so that makes it even harder to guess.

Again it would be really nice if somehow we could get SOAs attention in them producing a FWD transmission that can handle most of the needs(06+ WRX trans quality) and the ability to swap out gears for bigger stronger ones for crazies like you who have a death wish :P This way you get a more compact, lighter(sti trans is OMG heavy), space friendly transmission.

This is probably opening a can of worms on many levels, given the trouble Dave, FFR, and GTM builders have had. But, I think those of us that will pushing the limits of the 818 in any form of competition (other than a NASA Spec class), may need to look to Mendola for a suitable transaxle.
Now wait and think about it.
I'll help: They already have following in the sand rail community (Subie Power has become VERY popular there), They have stuff to handle as much power as we would throw at it (within reason), We would have some choice in gearing, ( Factory Subaru 6-spd ratios would not be my 1st 2nd or 3rd choice for an 818 with a "built" engine ), Would likely be lighter and slight more compact than the 6-spd requiring minimal fabrication to the chassis and transaxle for fitment.
As a matter of fact, I'm going to their sight right now to investigate. I've been there several times to have a look around, but not for this.
Anyone care to join me?

[SkiRideDrive]

This is probably opening a can of worms on many levels, given the trouble Dave, FFR, and GTM builders have had. But, I think those of us that will pushing the limits of the 818 in any form of competition (other than a NASA Spec class), may need to look to Mendola for a suitable transaxle.
Now wait and think about it.
I'll help: They already have following in the sand rail community (Subie Power has become VERY popular there), They have stuff to handle as much power as we would throw at it (within reason), We would have some choice in gearing, ( Factory Subaru 6-spd ratios would not be my 1st 2nd or 3rd choice for an 818 with a "built" engine ), Would likely be lighter and slight more compact than the 6-spd requiring minimal fabrication to the chassis and transaxle for fitment.
As a matter of fact, I'm going to their sight right now to investigate. I've been there several times to have a look around, but not for this.
Anyone care to join me?

http://mendeolamotors.com/trans-prot...d=47&Itemid=29

not cheap... but a sequential could be fun.

[PhyrraM]

So, is the reason to go with the 2.5L and not the 2.0L just because the STI has a 2.5L and that makes it easier to install the STI turbo onto the WRX 2.5L? Could the STI turbo be installed on the 2.0L? Not necessarily thinking that what I want, just looking at the options. I also don't know what I'll find in terms of a donor.

BTW, I REALLY appreciate everyone's help!

Yes, you can put all the STI stuff on a 2.0, but then it's not a stock USDM combination and wil always be debated to no end.

The only reason I posted what you quoted above is because I, personally, only wish to discuss stock options. Talking aftermarket ALWAYS opens the door to the type of never ending discussion that has ensued. It's simply too much for a non-Subaru guy to follow. It's too much for many Subaru guys to follow.

I only mentioned a '06-'07 2.5 liter WRX with an STI turbo and intercooler because if you put a *stock STI tune* from a '04-'06 STI into the WRX ECU, it is essentially a stock combination and should perform well and reliably.


A warning for non-Subaru folks.......
Transmission talk will never end, and will never have a difinitive answer either. In AWD form, there is still no common demominator - even after 10 years of WRXs in America. After a few years of 818's on the road we MAY see a common trends, but it's just as likely that we may not.

[Xusia]

So to answer my own question, it's because the STI comes with the 6-speed transmission which is too big to fit (according to FFR, but I'm sure there are those will probaby be able to make it work)?

Does anyone know why the STI transmission won't work? The reason I ask is that I'm thinking the best route for me (definitely in the "budget builder" category) is hopefully buy the "Complete Kit" from FFR, and source an STI engine/transmission. That way I don't need a donor (the complete kits come with most of those parts new from FFR), and I get the most engine bang for my buck (and the better transmission - assuming it can work).

[PhyrraM]

Yes, the STI 6 speed is big - however I don't include it (at this time) because FFR is only officially supporting the 5 speed. The AWD to 2WD parts are going to be included in the the kit. So, 6 speed AWD to 2WD parts would be "on the builder".

[Etos]

Wow, this discussion again? There are tons of threads from April or March onwards about this stuff, we talked about it at great length.

As I'm sure you can tell we weren't around for that. There is no need to act like we have all been around since day 1.

While were on this topic, what modifications (and the relative cost of those modifications) would one need to get a 2.0 Liter WRX motor up to about 300 hp

Not alot. Check NASIOCs Proven Power Bragging and you'll see plenty of WRXes go into 300WHP(with AWD loss) very easily.

And to stay on topic...the STI engine is more or less the very same thing that comes in an 06+WRX or a Forester XT or a Legacy GT. The 04-07 STI long block has minor minor changes, mainly it has a slightly LOWER compression ratio vs. the other 2.5T subarus since the STI sees a higher effective compression ratio due to higher boost.

This info is incorrect. There are drastic differences between the EJ255 and 257. The heads are much much different too. It's not the easy lego put together people associate subaru with. Subarus are like legos but they need to be fitted together correctly or else you have massive problems like the many before. Check hybrid builds and see how long and how much trouble people went through and still go through today with them. There's even 1 thread in built motor with a guy who ended up with over 10:1 CR cause the shop didn't know D25 heads have a smaller chamber then the B25. Subarus are finicky and must require ALOT of attention to detail.

A warning for non-Subaru folks.......
Transmission talk will never end, and will never have a difinitive answer either. In AWD form, there is still no common demominator - even after 10 years of WRXs in America. After a few years of 818's on the road we MAY see a common trends, but it's just as likely that we may not.

There are many common trends with trans issues. The first and foremost always will be people thinking their AWD split case trans can handle 300+hp clutch dumps like it was their old civic or mustang. Also just bad driving, shock is shock and the more the gears see the more fatigue they endure and eventually fail. The 2nd like others mentioned is the split case design and how it allows the gears to shift ever so slightly, enough to cause the teeth to take extra stress and boom.

[BrandonDrums]

.........

I only mentioned a '06-'07 2.5 liter WRX with an STI turbo and intercooler because if you put a *stock STI tune* from a '04-'06 STI into the WRX ECU, it is essentially a stock combination and should perform well and reliably.

........

To begin with, this is essentially what I did with my 05 wrx. I have a 16 bit ECU so the tune doesn't directly convert over, some of the columns we had to skip to copy the values for timing and fueling but it worked great...on an 06/07 wrx, converting over an STI tune aside from some of the gear-dependent boost control maps should nearly be a full on copy and paste maneuver in ECU flash or RomRaider.