So 12.5:1 compression huh....

[nismo4life]

So forget about the 200hp, so the BRZ only runs 12:5.1 c/r? I don't think thats enough uphill passing power...




hah, but on a serious note I am curious about something and I'm sure the throng of very smart TCLr's can help me out.

Read the specs released not to long ago on the FA20 and was really surprised to find that its running a 12.5:1 c/r. Just off the top of my head I know the Honda J series runs 11:1, the F20C 11.7:1 and the K series varies between 9.5:1 to 11.5:1 so I was really surprised to find that Subaru put out a very high compression 4 banger, yet it seems to be lacking in power as opposed to other engines in that displacement range.

Now just take this with a grain of salt because I know its comparing apples to oranges, but lets just for a minute compare the K20a2 to the FA20. Both 2 liters, both 86x86 bore and stroke, both 4 cylinders, 16v's, dohc, and variable valve timing. The FA20 however has 12 years of technology advancements over the K, which includes direct injection, and im sure other small things.

When you take into consideration they make the same rated hp, and roughly the same rated tq at the crank, why does the 1.5 point higher c/r Subaru motor make the same as the K series? Does it really just come down to the intake/exhaust flow of the head design being less efficient? Much less aggresive cam lobe profiles? Another thing is the fuel economy. The RSX-S posted roughly the same numbers as the BRZ/FRS so does it just have to do with a boxer platform being less efficient in n/a trim versus an I configuration (though Porsche has clearly proven that not true with the GT3 engines) or is there other technical aspects that I'm missing?

[sicksappeal]

I think there are too many variables to accurately compare it to another 4 cylinder. Take gearing, for example..

[GRN6IX]

Isn't it direct injected?

<--- Doesn't actually know the answer

[nismo4life]

Isn't it direct injected?

<--- Doesn't actually know the answer

FA20 is, K series is not. From what I understand, Direct Injection increases fuel efficiency as well as power which is why I'm confused at its power figures.

[Omnilith]

It is direct injected, which alters the compression rules greatly.

Since you're only compressing air until the injection event occurs, pre-ignition is much less of an issue.

[nismo4life]

It is direct injected, which alters the compression rules greatly.

Since you're only compressing air until the injection event occurs, pre-ignition is much less of an issue.

So does that mean direct injected engines require a higher c/r to make the same power as opposed to a lower c/r with traditional fuel injection?

[Omnilith]

It doesn't mean a loss of efficiency, it just means that when you don't have to worry about your mixture detonating during compression that you can get away with high compression ratios, further improving efficiency.

As to why this particular 2.0L "only" makes 200hp, I can't comment, but I'd assume it is tuned with a bit more low end torque, which is probably limiting peak power but improving overall drivability.

Both the Mazda "Skyactiv" 2.0L and 2012 Focus DI 2.0 DI motor also run high compression... 12:1 in the states. They're obviously set up for fewer revs and a heavier torque bias than the Subrota motor.

[compy222]

gearing is a big factor.

the advances in technology primarily come in fuel maps, overall power for displacement/fuel used, better computer control of the ignition process, and more flexibility in determining timing advance.

[Toaster29]

Compression is only one piece of the puzzle, as is DI. This engine makes 200 hp from 2L, but doesn't need as much rpm to do it. I don't know the torque figures off the top of my head, but I would put money on the FA being more tractable...not that the K20 isn't either. They are making more torque out of 2L with the FA (particularly down low), no need to rev as high, and better low rpm performance. People like to talk about 8k screamers, but then everybody bitches about the revs on the hwy, etc...so they all are getting displacement (or torque) boosts and dropping the rpm/lengthening the gearing.

[someguy123]

It makes 100hp/L with no forced induction. All's good.

[nismo4life]

It makes 100hp/L with no forced induction. All's good.

Not arguing that, just surprised its not somewhere in the 220-235 range with all the tech advancements over the decade.

[compy222]

Compression is only one piece of the puzzle, as is DI. This engine makes 200 hp from 2L, but doesn't need as much rpm to do it. I don't know the torque figures off the top of my head, but I would put money on the FA being more tractable...not that the K20 isn't either. They are making more torque out of 2L with the FA (particularly down low), no need to rev as high, and better low rpm performance. People like to talk about 8k screamers, but then everybody bitches about the revs on the hwy, etc...so they all are getting displacement (or torque) boosts and dropping the rpm/lengthening the gearing.

and by having a high revver on the highway you will burn more gas. greater injector duty and less overall efficiency. to roll at 73mph is 4k in the s2000. i simply can't do better than 25-27mpg in that scenario without cutting my revs/speed back.

[boner]

CR isn't everything. it could very well be that they've got some realllly small cams in there so that not a heck of alot of air can get in there thus needing less fuel thus becoming more fuel efficient.

it's not that they couldn't make more power outta this package, it's that they chose not to.

[compy222]

CR isn't everything. it could very well be that they've got some realllly small cams in there so that not a heck of alot of air can get in there thus needing less fuel thus becoming more fuel efficient.

it's not that they couldn't make more power outta this package, it's that they chose not to.

this is probably also true. you'd probably really have to start looking into volumetric efficiency, flow rates, valve duration, etc. to really know what the motor is capable of.

[Spatzle]

Subaru's weigh more then cars they typically compare too. Plus AWD adds drag to the engine reving.

Like my 97 120hp GTI that weighs 2500 pounds will kill a 2010 Civic SI 200hp in a 3200 pound car up the block a bit till it actually gets revving hard. I was playing this one guy in a commercial parking lot for a bit, and off the line I could always get 3-4 cars on him quick. He had access to lock the park where he had a small shop, and it was on the weekend.

[DubNMiatafan]

Subaru's weigh more then cars they typically compare too. Plus AWD adds drag to the engine reving.

Like my 97 120hp GTI that weighs 2500 pounds will kill a 2010 Civic SI 200hp in a 3200 pound car up the block a bit till it actually gets revving hard. I was playing this one guy in a commercial parking lot for a bit, and off the line I could always get 3-4 cars on him quick. He had access to lock the park where he had a small shop, and it was on the weekend.

This is the 2nd person I've encountered on here that thinks the BRZ is AWD.

[SchnellFowVay]

Not arguing that, just surprised its not somewhere in the 220-235 range with all the tech advancements over the decade.

NOOOOOOOooo.

Don't suggest such a blasphemous thing.

I have been tarred and feathered in numerous threads for suggesting such a thing (I even brought up the K20 comparison).

Repeat after me:

"The BRZ/FR-S is perfect in every way . . . questioning its specifications or comparing it to other cars on the market is a sign of disloyalty to the BRZ/FR-S . . . it was made to handle, not to accelarate . . . 0-60 in 7.2 seconds is fast enough for me, no questions asked . . . [rinse, and repeat]."

[too_slow]

Subaru's weigh more then cars they typically compare too. Plus AWD adds drag to the engine reving.

Like my 97 120hp GTI that weighs 2500 pounds will kill a 2010 Civic SI 200hp in a 3200 pound car up the block a bit till it actually gets revving hard. I was playing this one guy in a commercial parking lot for a bit, and off the line I could always get 3-4 cars on him quick. He had access to lock the park where he had a small shop, and it was on the weekend.

Your GTI will not be able to beat a 1998 Civic DX, let alone a Civic Si. You VW fan boys are more delusional than the VTEC crew of the 2000s.

[SchnellFowVay]

In all seriousness, though, comparing HP to HP is kind of innappropriate here.

Since HP = (TQ x RPM) / 5252, making the same horsepower at lower RPM's means that the car is making more torque at lower RPMs than the K20.

So this begs the question, again, why can't the car make more torque at higher RPMs and put out a bit more peak horsepower? The the torch and pitchfork crew will be after me if I bring that up again.

[too_slow]

NOOOOOOOooo.

Don't suggest such a blasphemous thing.

I have been tarred and feathered in numerous threads for suggesting such a thing (I even brought up the K20 comparison).

Repeat after me:

"The BRZ/FR-S is perfect in every way . . . questioning its specifications or comparing it to other cars on the market is a sign of disloyalty to the BRZ/FR-S . . . it was made to handle, not to accelarate . . . 0-60 in 7.2 seconds is fast enough for me, no questions asked . . . [rinse, and repeat]."

Get back to us after you quote the hp/torque ratings for the K20 and the F20c (S2000). The Subaru has better power to weight ratio than a Lotus Elise for crying out loud.

Did you manage to fit a GPS in your car that knows wtf you live yet?

[Klim18]

Why are so many people commenting on the gear ratios, I am pretty sure when they were developing these motors they had them hooked up directly to the dynometer.

[SchnellFowVay]

Get back to us after you quote the hp/torque ratings for the K20 and the F20c (S2000). The Subaru has better power to weight ratio than a Lotus Elise for crying out loud.

Why so angry? I know all of this. That's my whole point.

The car is close to a Lotus Elise in power-weight, yet it goes 0-60 in 7.2 seconds, uses economy tires, and has nearly 15 years of technology on the S2000.

[SchnellFowVay]

Why are so many people commenting on the gear ratios, I am pretty sure when they were developing these motors they had them hooked up directly to the dynometer.

This, too. Gear Ratios are completely irrelevant to engine power .

They are relevant to accelaration numbers, but not to engine power.

[Biz]

I hate to beat the dead horse, but this car really is good despite a "slow" 0-60 and "only" 200hp. It's not perfect by any stretch, but nothing is. It could really use more oomph to please the boyracer/magazine cowboy set, but it's still a very fun car to drive. You can run the car hard without getting into trouble with the law. You can let your calm, responsible side rule by not getting involved in doing freeway pulls with the flat-billed, DC-shoed, dumped-and-chipped-GTI-driving brosephs because you'd lose anyways and you know it. You can fling it through corners pushing the car as hard as you want and get away from those brosephs where it really matters.

The car really is about balance. Things are as they should be in all areas. It's better than the numbers. I'll be interested to see what a turbo version drives like if it comes out. I don't think adding more than another 30hp and 40-50lb/ft to this car is going to enhance the driving experience. If anything I worry it'll detract from what the car is.

And yes, I've driven it - Probably more than most of the magazine editors, definitely more than most of those posting about it.

[Omnilith]

I can't wait to drive one.

On paper, a 7.2 second 0-60 sprint is disappointing, but everything I've owned is or was as slow as that yet a total blast to drive, so....

[Biz]

uses economy tires

This is going to sound like rampant fanboyism (it's not, I'm a VW guy), but it really didn't need more to stick to the road for anything shy of competitive driving. The tires which, to be fair, are off a "sport" version of an economy car don't need to be any better. They market the car as a track toy, going as far as to show you how to most efficiently pack up a set of track wheels and tires inside it. If I'm going to track the car and have dedicated rubber, I want my DD tires to be grippy enough, yet still fuel efficient, long lasting, and cheap to replace. If I'm not going to track it and I'm in the 39+ demographic they're aiming the car at, it's what I want as well. That's what they spec'd.

[hushypushy]

In all seriousness, though, comparing HP to HP is kind of innappropriate here.

Since HP = (TQ x RPM) / 5252, making the same horsepower at lower RPM's means that the car is making more torque at lower RPMs than the K20.

So this begs the question, again, why can't the car make more torque at higher RPMs and put out a bit more peak horsepower? The the torch and pitchfork crew will be after me if I bring that up again.

I think you answered your own question...

Subaru tuned the car that way. Because those are the characteristics they wanted to give the car. The K20 makes around 140tq (depending on which one it is) and the F20C makes 150tq. The FA20 makes 150tq, but at lower revs than the Honda mills, which would seem to indicate a lower placed torque curve.

Asking the question you asked is like asking of the S2000, since it makes so much horsepower already at such high RPM's, why don't they give it a bigger torque peak and just chop the top of the powerband off? Well, they did do that, but only for the 'moar torks' North Americans. I bet some people in Japan thought that was a pretty stupid concept

There will always be the "what if" crowd. I'm sure there are some people who would prefer that the S2000 would have gotten even more torque but with a 7000RPM cap; there are also some who want the BRZ to have a higher redline and more HP, low-end torque be damned.

I'm actually on your side, Schnell; on paper, I would trade some of the BRZ's low-end torks for an 8,000 RPM redline. But, I can still clearly understand why they tuned the car the way they did; it will probably prove to be supremely tractable in everyday driving, lacking as it may be in the 8000+ RPM department.

[Shomegrown]

It is direct injected, which alters the compression rules greatly.

Since you're only compressing air until the injection event occurs, pre-ignition is much less of an issue.

I don't think you understand how GDI works. Fuel is still injected during the intake stroke while the intake valves are open.

Only diesels inject after everything is compressed.

[nismo4life]

NOOOOOOOooo.

Don't suggest such a blasphemous thing.

I have been tarred and feathered in numerous threads for suggesting such a thing (I even brought up the K20 comparison).

Repeat after me:

"The BRZ/FR-S is perfect in every way . . . questioning its specifications or comparing it to other cars on the market is a sign of disloyalty to the BRZ/FR-S . . . it was made to handle, not to accelarate . . . 0-60 in 7.2 seconds is fast enough for me, no questions asked . . . [rinse, and repeat]."

Lol sorry to hear you got flamed for being opinionated. 0-60 time isn't very impressive, but pretty much everything else about the car is. Regardless of any of that, the car need a few things to be considered perfect in my eyes and I'm sure Toyobaru will handle that when they release their force inducted model...though I always did enjoy natural aspiration more.

Why so angry? I know all of this. That's my whole point.

The car is close to a Lotus Elise in power-weight, yet it goes 0-60 in 7.2 seconds, uses economy tires, and has nearly 15 years of technology on the S2000.

This, though it can be argued that the F20C is nearly tapped out from factory. The S2000 has factory components so well designed that there is little room for improvement in n/a horsepower without opening the valve cover. Honestly, I hope the fluid dynamics on the factory manifolds prove to be lackluster, the cams somewhat mild and the exhaust very restrictive. I can already tell theres going to be a nice amount of weight savings from switching to just a single, but how nice would it be if the FA20 responded as well as the K20a2 does to mild bolt ons and a tune. All in all you could see a possibility of 20-50whp gains in just those alone along with a nice increase of torque depending on the above said components.

[nismo4life]

I think you answered your own question...

Subaru tuned the car that way. Because those are the characteristics they wanted to give the car. The K20 makes around 140tq (depending on which one it is) and the F20C makes 150tq. The FA20 makes 150tq, but at lower revs than the Honda mills, which would seem to indicate a lower placed torque curve.

Asking the question you asked is like asking of the S2000, since it makes so much horsepower already at such high RPM's, why don't they give it a bigger torque peak and just chop the top of the powerband off? Well, they did do that, but only for the 'moar torks' North Americans. I bet some people in Japan thought that was a pretty stupid concept

There will always be the "what if" crowd. I'm sure there are some people who would prefer that the S2000 would have gotten even more torque but with a 7000RPM cap; there are also some who want the BRZ to have a higher redline and more HP, low-end torque be damned.

I'm actually on your side, Schnell; on paper, I would trade some of the BRZ's low-end torks for an 8,000 RPM redline. But, I can still clearly understand why they tuned the car the way they did; it will probably prove to be supremely tractable in everyday driving, lacking as it may be in the 8000+ RPM department.

We could only hope that the internals themselves are capable of reliably spinning that high, though I don't see it being completely out of the question.

[DrFrisker]

its toyota D4S fuel injection. Direct and port injection.
the FA20 does not have(correct me if in wrong) a high valve lift profile cam like vtec's switchable cam profile. If it had, it would have significantly upped its cost.

This is the 2nd person I've encountered on here that thinks the BRZ is AWD.

every single one of subaru's cars has been awd the past 10 years has it not? Easily assumed they would have had awd in this one too, but the curb weight does not back this claim.

[Omnilith]

I don't think you understand how GDI works. Fuel is still injected during the intake stroke while the intake valves are open.

Only diesels inject after everything is compressed.

Thanks for that. I was misinformed. I just found a couple good articles that better outline the process.

It sounds like the fuel timing event is about half the number of crank degrees from a port injected engine.

[nismo4life]

its toyota D4S fuel injection. Direct and port injection.
the FA20 does not have(correct me if in wrong) a high valve lift profile cam like vtec's switchable cam profile. If it had, it would have significantly upped its cost.




every single one of subaru's cars has been awd the past 10 years has it not? Easily assumed they would have had awd in this one too, but the curb weight does not back this claim.

More than that actually, I think they stopped making the fwd GC impreza in 95 and since then came standard with awd.

[hushypushy]

We could only hope that the internals themselves are capable of reliably spinning that high, though I don't see it being completely out of the question.

And, worst case scenario, even if they aren't....the aftermarket will surely deliver. Can't wait to see some beefy N/A builds

[SchnellFowVay]

its toyota D4S fuel injection. Direct and port injection.
the FA20 does not have(correct me if in wrong) a high valve lift profile cam like vtec's switchable cam profile. If it had, it would have significantly upped its cost.

I kind of doubt that vtec-style technology is THAT expensive any longer. Car companies regularly incorporate it on cars that cost well under $20k . . .