Which WRX?

[Doc_FFR]

Does anyone know which generation WRX is going to be used for the donor car?

[spaceywilly]

I'm guessing it will be up to the builder. All EJ series engines are more or less interchangeable and have their advantages and disadvantages. It's pretty easy to go from, say, a WRX EJ205 to a USDM STi EJ257 or JDM EJ207. They all have the same dimensions, so it's just a matter of making sure you have the right ECU wiring and a good tune. For the suspension mount points, there are some differences. I think an 05-07 model would make the most sense since those are readily available, but they are also more expensive than an 02-04. What I'm more curious about is what they are planning for a transmission, since all WRX's, and all Subie's from the WRX era, have been Front-engine AWD.

[tkeyes]

I wish they would have had an AWD kit. That would have been cool.

[PhyrraM]

The '02+ sedans have a wider track than the wagons. In the front, this affects the CV shafts, lower arms, and the struts. In the rear it is the CV shafts, lateral suspension arms and the struts. If the kit uses any of those items, I hope accommodations are made for both donor types.

FYI, if they base it off the wagon, then virtually any '90-'99 Legacy/Outback, '93-'07 Impreza/WRX/STI and even '97-'08 Forester should make a reasonable donor.

[einy]

Must .... resist ..... the urge .... to start .... disassembling .... the Forester ..... in my garage !!!!

[BoxerFanatic]

Please, please, please...

Design enough room in the chassis to fit not only an EJ flat 4 engine, but also an EG33 flat 6. (The EG is longer than the EZ... so an EZ-series newer flat 6 would work, also)

The EG33 is particularly well suited for mid-engined duty, with a twin-rear-facing throttle-body and intake manifold, and very compact exhaust collectors under the engine, but it is longer than the EJ 4-cylinder on which it is based.

If rebuilt with turbocharging in mind, with EJ22 pistons, turbo specific cam profiles inside, the engine has 7 main bearings, and is quite robust... and could make a LOT of power. Significantly more than a standard STI EJ257.

I have an SVX that I am driving now, that could be a donor later, and would be great in front of a manual gearbox, instead of the SVX's stock automatic.

Just for a visual reference: (this isn't mine, but the same type of engine.)
http://www.attarco.com/images/IMG_7087.JPG
http://www.ecutune.com/posts/eg33_assembly/DSC_3013.jpg

[K Gesas]

I like the idea of being able to use other Subaru models. A larger pool to source from can lead to lower costs.

[BoxerFanatic]

Subarus are like legos, they pretty much all interchange in some ways... with a few variations to account for the specific differences in bodies and such.
Subaru has held pretty fast to the interchangeable parts premise.

[labmonkee]

I like the idea of a flexible range of Subaru engines. We have plenty of them over here, and i like the idea of it being a donor. shame that it won't be AWD, but with <1800lbs mid engine, and depending on the final shape, i can get over it :). It will be a good addition to the FFR line up.

[Joe Campbell]

My DD is an '08 STI, and it has plenty o' grunt. Just as quick as the '06 CTS-V I traded for it. I'll be watching this kit development very closely.

[Brad]

Please, please, please...

Design enough room in the chassis to fit not only an EJ flat 4 engine, but also an EG33 flat 6. (The EG is longer than the EZ... so an EZ-series newer flat 6 would work, also)

The EG33 is particularly well suited for mid-engined duty, with a twin-rear-facing throttle-body and intake manifold, and very compact exhaust collectors under the engine, but it is longer than the EJ 4-cylinder on which it is based.

If rebuilt with turbocharging in mind, with EJ22 pistons, turbo specific cam profiles inside, the engine has 7 main bearings, and is quite robust... and could make a LOT of power. Significantly more than a standard STI EJ257.

I have an SVX that I am driving now, that could be a donor later, and would be great in front of a manual gearbox, instead of the SVX's stock automatic.


Amen! Maybe I should stop beating the everloving hell out of my SVX. The 3.3 mated to a 5/6 speed would fun as hell!

[C.Tree]

The boxter (opposed four); what advantages does it have over V or in-line style motors. I.e. is the angle of the con rod better on the power stroke? or something else? I would think the stroke is longer so the motor is slower reving but maybe better torque? How about wear; doesn't the bottom of the bore wear more as the piston move horizontally vs an in-line moving vertically? Is the head flow better on the intake side; assisted by gravity? Physically the motor is more compact front to back but wider left to right. Correct me if I'm wrong. Thanks all!

[spaceywilly]

The main advantage of the boxer is that it can be packaged very low to the ground. This lowers the center of gravity which improves handling by reducing body roll. It also allows it to be mounted behind the driver without obstructing the view.

[Calamity J]

The boxter (opposed four); what advantages does it have over V or in-line style motors.As spaceywilly said, the low center of gravity.

Mainly, though, a horizontally opposed engine is perfectly balanced. Subaru makes 2.5L 4 cylinder engines that don't require balance shafts. An inline engine of the same size would require balance shafts. In other words, the engine isn't trying to tear itself apart when revving.

Also, it's a "boxer" engine.. because the pistons move in and out in opposite pairs like a boxer knocking his own gloves together.

http://i89.photobucket.com/albums/k239/Rexmcleod/th_engine-flat-4.gif

Porsche made the 'Boxster' roadster as a play on the engine's nickname.

I.e. is the angle of the con rod better on the power stroke? or something else? I would think the stroke is longer so the motor is slower reving but maybe better torque?Actually, the stroke is limited, the con rods are short and at worse angles than some inline 4 cylinders. The EJ25 is an oversquare engine because it's basically an overbored EJ20.

Because the crank shaft is competing for space with the cylinders the pistons have very short skirts and in some engines (particularly the N/A EJ22) are known for piston slap.. a clacking noise made by the piston wiggling within the bores in a cold engine.

Subaru's newest engines (the EZ36 and the FB25) use connecting rods that are split at an odd angle at the crank bearing to allow block assembly with a longer stroke than was possible previously.
http://www.caranddriver.com/news/car/11q1/examining_subaru_s_new_fb-series_flat-four-car_news

Horizontally opposed engines have an unfair reputation for being low-revving motors because the horizontally opposed engines most people are familiar with are in light aircraft and old Volkswagens. One was low revving so it didn't need a reduction gear to drive a propeller.. and the other was an inexpensive economy engine designed in the 1930s. Ferrari, Porsche, BMW, Subaru and many other manufactures have made high revving horizontally opposed engines. Subaru even made a H12 3.5L Formula 1 engine that made ~600hp at 12,500rpm.

How about wear; doesn't the bottom of the bore wear more as the piston move horizontally vs an in-line moving vertically?No. Just like any other properly lubricated engine, the pistons skim along on a thin film of oil and don't wear the cylinders any more than any other engine configuration.


Is the head flow better on the intake side; assisted by gravity?Not significantly enough to matter.


Physically the motor is more compact front to back but wider left to right.Correct. This packaging works well for Subaru and Porsche because their drivetrain designs place the engine completely outside the wheelbase. Have a shorter motor means a lower polar moment of inertia (than would be with an inline engine).

[Imp]

Well, uh.... what he said ^^^^

Calamity J... spot on with the knowledge. Nice to see someone else that knows their Subarus.

--kC
(Had 10 subarus in his lifetime from 80s to '05)

[Brad]

The main advantage of the boxer is that it can be packaged very low to the ground. This lowers the center of gravity which improves handling by reducing body roll. It also allows it to be mounted behind the driver without obstructing the view.

Also, it sounds really cool with an aftermarket exhaust.

Sorry. Someone was gonna say it. Might as well have been me.

/facepalm

[C.Tree]

Thanks Calamity J! You have been spot on in the two threads I posted in. Thank you.

Any subaru books or links you can recommend? Looks like I have to read up on subys and opposed motor theory. Thanks!

[Benji]

Also, it sounds really cool with an aftermarket exhaust.

Sorry. Someone was gonna say it. Might as well have been me.

/facepalm

As long as it's not equal length ;)

[Imp]

As long as it's not equal length ;)

Then it sounds better? :D

--kC
(Had an equal length header, and in the carefully selected combined system, everyone who heard it said it just sounded like the car was just plain p***ed off... which in my racing circle, was a complement. :D )

[Benji]

Then it sounds better? :D

--kC
(Had an equal length header, and in the carefully selected combined system, everyone who heard it said it just sounded like the car was just plain p***ed off... which in my racing circle, was a complement. :D )

In all honesty I've never heard an equal length exhaust in person so I may well be missing out!

[BrandonDrums]

I think it would be rather easy to have the kit accept all USDM GC chassis WRX's as donors. That's 02-07 including wagons.

Albiet that wagons have shorter lower front control arms, CV shafts and different spring heights up front, Spring, lateral link arm lenghts etc. on the back, all the mounting points in terms of the chassis are identical from the wagon to the sedan. The wheelbase difference in terms of hardware is only about 1/2'' (35mm to be specific) between the wagon and sedan.

Given the spaceframe chassis and the body allow the 35mm (about 1/4'' on each side) clearance to accept both wagon and sedan length suspension components, to make up the visual difference in wheelbase, one can get wheels with the appropriate offset or some spacers on the hubs to widen the track if you're using wagon components.

The MAIN difference will be the springs between the two. Spring-length varies by model year anyway, someone will just have to make a chart of how much to cut off depending on the year bodystyle you have. I imagine most people will end up getting coilovers or aftermarket springs anyway so that doesn't matter.

Handling differences would essentially be negated at that point.

[spaceywilly]

I agree 02-07 makes the most sense, but GC is 93-01. 02-07 is GD (sedan) and GG (wagon). They made plenty of them and they are just starting to bottom out in price, especially the 02. I think it makes the most sense to base it off the sedan, since it seems to be the more popular option, but if they could get it to work with either one, that would make sense. The wagons tend to have lower resale than sedans so it might be cheaper to pick up a wagon donor.

[PhyrraM]

My concern is that they use fabricated control arms on the factory hubs. IIRC, this is exactly what they do for the GTM.

If they indeed do that, we are essentially locked into whatever CV length FFR chooses. In that respect, wagons/Legacy/Forester width is much more common.

Realistically, there are likely enough sedan CVs to go around for a long time, it would just be 'one more thing'. And I'm sure keeping the 'one more thing' list very short is a goal of the kit.

[Big-Foot]

Also, it sounds really cool with an aftermarket exhaust.

Sorry. Someone was gonna say it. Might as well have been me.

/facepalm

Your kidding right?

To me - The Subs all sound like Civics with a missing plug-wire... Race exhaust or not..

[BrandonDrums]

LOL, "SUBARU'S are like Legos"

Pretty much true, I guess that's why it's such a good idea to use them for a donor-car based kit. You have 20 years worth of cars that have running gear that bolts together almost with complete interchangeability.

[Hondaslayer]

My concern is that they use fabricated control arms on the factory hubs. IIRC, this is exactly what they do for the GTM.

If they indeed do that, we are essentially locked into whatever CV length FFR chooses. In that respect, wagons/Legacy/Forester width is much more common.

Realistically, there are likely enough sedan CVs to go around for a long time, it would just be 'one more thing'. And I'm sure keeping the 'one more thing' list very short is a goal of the kit.

That's not a bad thing. AWD axles are fairly weak, I have seen stock 2.2 litre Legacy and Impreza snap AWD axles when installed in a FWD car (FWD axles are thicker). Either FWD, or preferably STI or driveshaft shop axles would be a good idea.

[PhyrraM]

That's not a bad thing. AWD axles are fairly weak, I have seen stock 2.2 litre Legacy and Impreza snap AWD axles when installed in a FWD car (FWD axles are thicker). Either FWD, or preferably STI or driveshaft shop axles would be a good idea.

Yep, and to my knowledge the FWD axles are not available in the wider '02 sedan length. Junkyards are full of 'narrow' FWD axles, just waiting to be reconditioned.

Either way, us Subaru guys will know how to mix and match for best effect. It's the non-Subaru folks that I'm thinking would be best served by designing around the more common base.

I guess it's all kinda moot anyways. The chassis is mostly done. Just gotta sit back and wait to see what they used.

[t d]

That's not a bad thing. AWD axles are fairly weak, I have seen stock 2.2 litre Legacy and Impreza snap AWD axles when installed in a FWD car (FWD axles are thicker). Either FWD, or preferably STI or driveshaft shop axles would be a good idea.

You do realize when an AWD axle is used in a FWD car the torque is double what it was designed for, right?

[Hondaslayer]

You do realize when an AWD axle is used in a FWD car the torque is double what it was designed for, right?

And what do you think will happen when it is used in this RWD car? ;)

[t d]

And what do you think will happen when it is used in this RWD car? ;)

Please know we seem to agree on the strength of the AWD axle in this application. My point is "used in the correct application both axles would be close to equal in strength."

[ddorrer]

I think they ought to look at the 2.0L Diesel as an option. Plenty of torque and good gas mileage. Diesels are also widely accept outside the US.

[UpstateCobraGuy]

https://www.iaai.com/VehicleImages/20110221/611/42/7826942/7826942_1_I.jpeg

https://www.iaai.com/Vehicles/VehicleDetails.aspx?auctionID=9960953&itemID=10661857&RowNumber=8

How about this car?

[BrandonDrums]

https://www.iaai.com/VehicleImages/20110221/611/42/7826942/7826942_1_I.jpeg

https://www.iaai.com/Vehicles/VehicleDetails.aspx?auctionID=9960953&itemID=10661857&RowNumber=8

How about this car?

Not too bad! Looks like an STI though, that's a big, heavy complicated gearbox you're going to have to crack open and weld some spider gears on to make it 2wd.

Get the car, sell the transmission....to me I want a 6MT in my wrx wagon.

Get a 5MT for the kit, it's lighter, simpler, easier to mod, cheaper to fix and has much better gear ratios for a lightweight car. The 6mt has ratios so short you'll never build enough engine load to spool the turbo until you're in 4th or 5th gear on a car weighting 18 or 1900 lbs....

Plus you can make 3500-4500 off a 6mt and buy a 5 speed for less than a grand ;) Use the extra cash for a good limited slip diff and new taller gears if you like...

Everything else on an STI is gravy and super strong for such a project albeit mostly identical to an 06+ wrx which just has floppier suspension, smaller turbo and smaller intercooler. Depending on IC configuration and suspension set-ups used on the kit car you might be throwing much of the upgraded parts out anyway (aside from the trubo) I imagine the kit will use koni coilovers in place of the giant wrx and sti spring/strut combo if it's at all like the rest of FFR kits.

Otherwise, the wheels brakes and higher ECU resolution are advantages as a donor over a regular WRX.

[subyrod]

^^ agreed, or buy it and sell all the parts off individually and have a big chunk towards your kit. :)