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Old 11-28-2004, 11:51 PM   #1
Diabolical1 CC
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Default H6 Twin Turbo

I was just wondering if a Twin Turbo H6 Porsche Engine would fit into a Subaru Legacy. Anybody know?

Maybe a Porsche Transmission as well.
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Old 11-28-2004, 11:58 PM   #2
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why not a svx flat 6...if i remember it is only 1 inch longer that 2.5 and 2.0 Litre blocks...same width.
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Old 11-29-2004, 12:05 AM   #3
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svx motor is def not the same width and an inch longer, it is a much larger motor and heavier which is why there arent too many swaps out there.

anything is possible in my opinion, you just have to either be very good at fabricating and creative, or have the money to pay someone who is

Ben
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Old 11-29-2004, 12:07 AM   #4
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The 911 Turbo S, is a H6 3.6L Twin Turbo 444 HP 457 ft-Lbs AWD.

The SVX had a huge H6 3.3L NA 230 HP 228 FT-Lbs AWD. The 3.3L engine was a 2.2L plus half of another making it too long compared to the much shorter 3.0L H6 Subaru now has.
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Old 11-29-2004, 12:11 AM   #5
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If Subaru were to bring out a Premium STi Legacy with a 3.6L H6 911 Turbo S Engine it would eliminate all the competition. It would cost lots and it would stick to the Subaru H6 philosophy, with a few tweaks. Plus it would give creadence to the Premium Subaru idea.
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Old 11-29-2004, 01:35 AM   #6
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Um yeah, I'm rather doubtful on seeing that Porsche engine, tranny and diff in the Subaru. Why does that mean Subaru can't put a bi-turbo H6 engine into the Legacy in the next year or two? For the market a Legacy STi would need to persue, 6-cylinders is a must. I wouldn't mind seeing a high-output NA H6 of maybe 3-3.3L (longer stroke) with slightly higher compression in a Legacy STi pushing 300hp and over 250lb-ft of torque, something 911-Carrera-ish. But an H6 bi-turbo is the best solution.

I'm pretty sure an EG33 from the SVX could be showhorned into a Legacy, but IIRC, it requires some interesting cooling system mods as I think the crank pulley would sit into the cooling fan area. I'm pretty sure people have turboed and I know at least someone fit a supercharger/intercooler on a 1st gen Leggy. It would be the torquest solution available, just find a drivetrain that will stay together.
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Old 11-29-2004, 01:54 PM   #7
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Is it possible to come up with a more expensive engine swap than that?
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Old 11-29-2004, 02:03 PM   #8
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ahh but think of the look on the STi drivers face should a car like mine blow past him on a nice straight road. Or a Legacy Wagon passing a 360 Ferrari. Atleast with the current STi he can see a big wing in front of him/her. But a Legacy wagon, that would be embarrasing.

Although I must admit that the current GT wagon probably does this to every older model Ferrari driver already.
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Old 11-29-2004, 02:35 PM   #9
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My wife has become obsessed with the possibility of the Leg. STi coming over. Latest rumor that I saw (and this was some time ago) was that it was a turboed H6 with 350 horse, and they kept blowing trannies. according to the rumor they outsourced the tranny to someone, but I can't remember who.

I do know that if they bring it over I'll be at the dealer getting on the short list for one as a wagon.


YOU HEAR THAT SUBARU!!! STI WAGONS IN THE US ARE A GOOD THING!!!!
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Old 11-29-2004, 03:05 PM   #10
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There is enough demand to warrant STi Legacy models, in fact, I think they'd possibly sell better than their Impreza brethren, being they won't be so flashy and are more spacious and comfortable, a true road/touring car. Heck, my GT Wagon can play well with a lot of other cars out there and I know it hasn't suprised too many people until it's passed them. If in about 2 years they have a Legacy STi Wagon (w/o leather & power seats) and making 300+hp & torque out of a forced induction H6 and in the current body style, they'd have me inline too!

Otherwise, for now, one of the best bets it to take a new GT Wagon and throw about $5k in mods into it and you've got one heck of a machine. Another 5k and it would really be over the top! But I really hope they do bring a Legacy STi Wagon. I'd be in seventh heaven.
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Old 11-29-2004, 03:13 PM   #11
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Why can't someone develop a twin-turbo Outback R H6 3.0? Stocj form it already develops 250 HP, I'm sure 350 - 380HP is easily achievable. Call it an Outback R STi.
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Old 11-29-2004, 06:13 PM   #12
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Every couple of weeks I think it would be super sweet to built a turbo kit for my wife's, but information on that block has been sorely lacking.

heck, I'd be happy (for now) just doing an exhaust, intake, and reflash with something like an accessport, but nobody is making the bits to do that. Something that would give me +25 AWHP and + 30 on the torque would be sweet.
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Old 11-29-2004, 06:30 PM   #13
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Subaru may be waiting for its market to grow and mature. A whole bunch of WRX drivers will be in their 30+'s in 5 or so years (I'm sure there are a bunch now but nothing compared to what there will be). When that time comes I'm sure Subaru will see the need for a twin turbo H6 sedan and man it will be sweet.
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Old 11-29-2004, 09:47 PM   #14
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Quote:
Originally Posted by powerslide23
Why can't someone develop a twin-turbo Outback R H6 3.0? Stocj form it already develops 250 HP, I'm sure 350 - 380HP is easily achievable. Call it an Outback R STi.
I don't think they'd warrant that outside of their performance models, no, I wouldn't consider an Outback XT or 3.0R a performance model, just a higher output utility version. A performance forced induction H6 should be reserved for a pure enthusiast machine or rather heavy model. And that big heavy model would likely have a different tune. The EJ25 is producing 250-300hp or up to 120hp/L, an EZ30 of similar output would be producing nearly 360hp, though it wouldn't be quite as easy as it is with the EJ25 because as displacement increases you have increased friction and other factors. It just means tuning needs to be at a slightly higher level to produce those desired numbers. And numbers are just that. Numbers, does it matter if it's 375 or 380 or 360, no not really, it's kind of symantecs.

I wouldn't mind seeing either a forced induction or N/A engine in the Legacy, but it would have to be making power figures around that of the 2.5L STi and that takes signficant amounts of engineering and money.

The EZ30R isn't all that bad considering we know it's state of tune isn't super high, and it uses many of the same features as Porsche's engines like variable valve timing and lift.

Subaru 3.0L Displacement (EZ30R Naturally Aspirated)
250hp (83.3hp/L)
219ft-lb (73.0ft-lb/L)
10.7:1 Compression


Porsche 2.7L Displacement (Naturally Aspirated)
225hp (83.3hp/L)
192ft-lb (71.1ft-lb/L)
11.0:1 Compression

Porsche 3.2L Displacement (Naturally Aspirated)
258hp (80.6hp/L)
229ft-lb (71.6ft-lb/L)
11.0:1 Compression

Porsche 3.6L Displacement (Naturally Aspirated)
325hp (90.3hp/L)
275ft-lb (76.4ft-lb/L)
11.3:1 Compression

Porsche 3.6L Displacement (Turbocharged & Intercooled) -Turbo S
444hp (123.3hp/L)
457ft-lb (126.9ft-lb/L)
9.4:1 Compression

Subaru 2.5L Displacement (EJ257 WRX STi - Turbcharged & Intercooled)
300hp (120hp/L)
300ft-lb (120ft-lb/L)
8.2:1 Compression


What does this show? Subaru engineering really isn't all that far off Porsche engineering and levels of tuning per liter (and in some configurations such as the 2.7 and 3.2L Boxster engines, beating them), both being the boxer configuration for comparison sake. But there is one significant difference. Cost. Subaru comes at a fraction of the cost. Give it another year or two and I think we'll be seeing a forced induction 3.0L H6 in an STi Legacy model (the target market requires those 6-cylinders if anything else), and I'd think it will probably make around 110-120hp/L with the same amount of torque. The biggest question will be how the drivetrain would be set up with that much power.
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Old 11-30-2004, 05:25 PM   #15
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too bad you cant just swap 6 of the wrx pistons and maybe rods into the H6 3.0 and then go from there !
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Old 11-30-2004, 06:11 PM   #16
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Yeah, wrong bore size (EJ20 is 92mm with the EZ30 being 89.2mm IIRC) and I'm sure other things would be needed special too like a lower CR as 10.7:1 would definitely lead to something catastrophic. But Subaru has the abilities to produce just as good of results as Porsche lest some people think so. It's all about the size of the engine they're working with.
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Old 11-30-2004, 11:04 PM   #17
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If you want to try a Porshe swap, you need a Boxster powertrain, otherwise the engine will be where your feet want to be - or you will have the fastest Wagon in reverse in the world!
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Old 12-01-2004, 06:15 PM   #18
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Honestly, I'd rather want a 3 liter H4 instead of a 3 liter H6. Then again, that would be a simply massive engine.

A 6 cylinder 2.5l engine should have about the same horsepower output of a 4 cylinder 2.5l engine, but the 4 cylinder should have more torque. This is assuming that the stroke is simlar. Then again, you would come upon some other problems, such as having a massive amount of mass due to a huge bore.

As for transmission, if you really want performance, best to go with RWD over AWD. If you are planning on racing in snow or low grip situations, AWD woudl be the way to go.
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Old 12-01-2004, 06:34 PM   #19
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Ok these last two comments are wierd. A 911 Turbo S engine could be installed in the front of a Subaru if you just flip the gearing.

(where your feet want to be???)

The Porsche 911 Turbo S is a performance car and it is Fulltime AWD. Albeit with a mainly RWD power split. Variable from 90r/10f to 60r/40f. 0-60 in 4.2 Seconds and tops out at 190MPH. I would rather see a lower top end and a faster accelleration time, but then mileage would suffer. Not that it would matter at the price you pay for such cars.
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Old 12-01-2004, 06:39 PM   #20
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Well, you can always have gears 1-5 as close ratio gears and have gear 6 as an overdrive gear. (This is assuming a 6 speed tranny, of course).
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Old 12-02-2004, 11:54 AM   #21
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Forester STi transmission

ding, ding, ding!!!!
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Old 12-02-2004, 03:36 PM   #22
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Quote:
Originally Posted by Chi_San
A 6 cylinder 2.5l engine should have about the same horsepower output of a 4 cylinder 2.5l engine, but the 4 cylinder should have more torque. This is assuming that the stroke is simlar. Then again, you would come upon some other problems, such as having a massive amount of mass due to a huge bore.
Not true. All other things being equal (ie displacement, format, induction etc.) more cylinders will ALWAYS mean more torque. Why? More pulses per rotation, plain and simple. And since horsepower is a function of torque, the horsepower will always be greater as well. I would MUCH rather have a 2.5L H6 than a 2.5L H4 if they were based on the exact same tuning. Unfortunately there are always packaging problems with the H6, and 2 extra cylinders inevitably costs more money, simply for the extra parts and assembly time.

Quote:
Originally Posted by Chi_San
As for transmission, if you really want performance, best to go with RWD over AWD. If you are planning on racing in snow or low grip situations, AWD would be the way to go.
Time, and time, and time again, this has been proven false. ANY racing series which has EVER experienced the onslaught of an AWD contender has either banned it or levied weight penalties. See the rules for F1, INDY, and the Touring Car Series(s) for examples.
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Old 12-02-2004, 07:09 PM   #23
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Quote:
Originally Posted by brandon
Not true. All other things being equal (ie displacement, format, induction etc.) more cylinders will ALWAYS mean more torque. Why? More pulses per rotation, plain and simple. And since horsepower is a function of torque, the horsepower will always be greater as well. I would MUCH rather have a 2.5L H6 than a 2.5L H4 if they were based on the exact same tuning. Unfortunately there are always packaging problems with the H6, and 2 extra cylinders inevitably costs more money, simply for the extra parts and assembly time.
Uh, Okay. Maybe on a turbo. If you have a 4 cylinder engine with 2.5 liters, NA, with the same stroke and displacement as a 6 cylinder engine that is 2.5 liters NA, the 4 cylinder will provide more power. Why? Because there is more surface area on each piston head. More sufrace area = more torque. Exhaust pulses only matter if you have headers with the proper scavange area.

Ever wonder why Crawford's 2.8 liter engine uses 880 CC injectors? Because there's a HUGE surface area, and the area where combustion happens is massive. There's a lot of air and fuel in there. More than in a 2.5l engine, obviously.
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Old 12-25-2004, 11:06 PM   #24
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I dont know if u know this but a 911tt engine will set u back about 20-30 grand. which im not sure that would be worth putting in a subaru
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Old 12-26-2004, 12:32 AM   #25
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imprezkid is right,

if you have the money to do something like that thenit might be better to just buy a 996 turbo.

porsches are rear engined vehicles, so the transmissions are situated 180 degrees different from front engine vehicles. If you could actually successfully use a 996 turbo engine and drive train in your car you would have 6 reverse gears and 1 forward gear.

however, if you were to have an adapter and custom flywheel made you could mount the porsche motor in the front of your car mated to your stock powertrain.
by the time you're done though, there would be a lot of nice cars you could buy with the money you spent.

If someone did this successfully though, it would almost be guaranteed a feature in a magazine.
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