Video: HKS 86 drift car + first 86/FR-S/BRZ dyno = 170 rwhp!!!

[serialk11r]

WoW you need to go read the Drivetrain forum again :P Port injection cuts off at 2500rpm or so on the 2GR, I can't see it being too different on this engine. You shouldn't be able to tell on the dyno chart because the port injection is only there to stabilize low rpm combustion. I posted a link and arghx7 I think reposted the image for VVT-i control. There is not a "cutoff" for VVT-i, it probably gradually retards the cam from the mid-range rpm and up.

If you look at the Engine tech thread I wrote a bit about why I think the torque curve looks the way it does. In essence, the intake cam duration is a compromise to improve VE at lower speed, and what they do with the extra duration needed for high rpm power is they advance the cam to give excessive overlap, which creates a lot of EGR. This hurts low -mid rpm torque due to the decreased efficiency. D4-S helps things out by increasing the tolerance for EGR, I imagine because of the increased cooling effect.

At high rpm there is no scavenging effect because the cam duration isn't long enough to afford opening early but not reducing VE. Cams should improve high rpm torque on dual VVT-i type engines, at the expense of low end torque. On D4-S engines this may have a beneficial effect: direct injection improves combustion stability to the point where low rpm combustion efficiency is quite good, and the drop in VE comes with an increase in fuel economy.

That's the gist of what we were discussing in the thread.

[WingsofWar]

Originally Posted by serialk11r

WoW you need to go read the Drivetrain forum again :P Port injection cuts off at 2500rpm or so on the 2GR, I can't see it being too different on this engine. You shouldn't be able to tell on the dyno chart because the port injection is only there to stabilize low rpm combustion. I posted a link and arghx7 I think reposted the image for VVT-i control. There is not a "cutoff" for VVT-i, it probably gradually retards the cam from the mid-range rpm and up.

uurrggg do i haaffff tooo!!?

your probably right about those items..ill probably not see them on the graph. I was just curious about that IMO awkward spike in hp at ..what..5-6k rpms? around when powerband kicks in..then kinda gets short of breath to redline. Am I reading this right?

[serialk11r]

lol see my edits, I summarized it for you.
I don't know why the power drops so fast after 7000, I'll let someone else explain that. Only thing that I can think of that has an rpm "cutoff" like that would be exhaust pulse effects.

Something exciting (IMO) I was talking about in the Engine thread was that perhaps reducing EGR at low-mid rpm by retarding the cam a bit could maybe help torque (it would certainly help efficiency) by lowering charge temperature, at the expense of slightly higher emissions (I'm sure the cat can take care of it :P)

Okay graph aside, I think the HKS car has a great ride height and fender gap size, I wonder how they did it. The front and rear of the fenders seem closer, perhaps it's just the tires.

[Soravia]

Originally Posted by Guff

I got your Camry right here!!!

I'll take that Camry.

Seriously, people are making a big deal about power on this car. I mean WTF? 10 more or less HP won't mean jack. That's not what this car is about.
"MOA POWA!!" people should go start looking for turbo-kits from aftermarket. If you want power, they'll have full kits or STi swaps to satisfy your needs. I don't see a bunch of ppl asking for TRD super charger for MOA POWA from Camry LE. They didn't make this car for drag racing, same way Camry wasn't made for track racing.

All in all, this car will be as fast or faster than Miata, and that Mazda sells pretty good for something with only 2 seats.

If anything, I'd like to see the power curve with both HP and torque. It's very useful to know where to shift on a track.

[Spaceywilly]

Originally Posted by serialk11r

Um, Spacewilly thanks for the graphs, but your idea of torque is wrong.
Torque is not a force, torque is a change in rotational inertia. It is a force that acts on a pivot at a distance. Formally, it is the cross product of the radius upon which a force acts and the force itself. The unit Newton*meter is actually equal to 1 Joule. When we talk about rotational stuff we need to make sure there is the distinction that we are "multiplying" by the distance at which the force acts, but this distance has to be dealt with separately.

1 foot pound is the torque created by exerting 1 pound of force on a 1 foot lever. Since rotational stuff has pi's in it when you take derivatives, I won't say how much rotational inertia you can accelerate to whatever rotational speed with 1 pound of force.

Torque does work not over a distance, but over a dimensionless quantity we know as rotations. When you "multiply" torque (say in Newton-meters) by rpm, the "rpm" only makes sense when distributed to the "meters" part, as the meters is secretly talking about meters from the axis of rotation. If we pick a point at an arbitrary radius, the distance covered by that point is the number of revolutions times 2pi * the radius. The reason why torque is not dependent on the radius chosen is conservation of energy. Anyways, this is why we are allowed to say "newton-meters" instead of specifying the force and the distance. If a force acts for a certain distance, it does work. A torque effectively is a force acting over a certain distance in a circular path.

Yep, that is all true. I don't think it really contradicts what I said just a different way of thinking about it. Torque in general is a measure of force around an axis and doesn't require a specific distance, but I was taking about torque as measured in these dyno charts which is basically the force the engine applies to the Earth, which causes the car to move forward. The important takeaway is force=mass x acceleration. All else being equal, an engine with more torque will create more acceleration.

Okay now back to your chart. I don't seem to be seeing the same points as you are...but maybe I'm the blind one.

Using my eyeballometer, and drawing a line from peak power down to an extrapolated 0 hp point (this would be what would happen if torque were constant from 0 to 7000), I see that the torque is lower than it is at peak power all the way up to about 5500. Peak of about 6000 sounds about right, assuming we're not wrong with the scale. This car is short on torque up to about 4000 rpm me thinks.

The "flatness" of the torque curve can be determined by the slope of the hp line. A perfectly flat torque curve would give a constant slope on the hp line. If the hp line starts to slope up, we know there is more torque at that ppoint, and if it flattens out, we know there is less torque at that point. You are right that it looks like I am missing some holes in the torque since I just guessed hp values where the lines intersect the graph and used that to make my plot. Eyeballing it it does look like the torque probably drops off a bit in the middle before coming back again before peaking, which matches the reviews. Tomorrow I will try to make my hp plot look more like theirs and see what it does to the torque curve, but for now I think it's a good estimate.

[serialk11r]

So the problem was you were treating torque like a force, which wasn't exactly correct but anyways, small mistake.

A reliable way to eyeball the torque curve is to draw a line connecting (0,0) to the power peak. The power peak torque can be easily calculated. If the hp is above said line at a certain rpm, the torque is higher than torque at power peak. If hp is below said line, torque is lower. If the hp is increasing faster, the torque is going up at a pretty high rate. The derivative of the hp curve from 1500 to 4000 is bigger than the constant torque hp line, so torque is rapidly reaching that value.

The part I disagree with you on is that there is a marked drop in torque that your chart doesn't really show, but the rest looks more or less close.

At any rate, the torque curve is something like the 2GR-FSE, as we expected.

And I'm REALLY sorry about editing so much, I tend to click post, and then add a massive block of text after

[WingsofWar]

^urg..this is why i want to hard data..and not plots..even if its a good estimate.

[Jordo!]

Originally Posted by Itgb

Isn't the US version supposed to have +3hp(full 200hp, not 200PS) due to less restrictive exhaust? In that case, US dynos may end up even higher.

200 ps = ~197 hp

In terms of Octane, it's going to be tuned for 91 AKI/96 RON (approximately equivalent in terms of anti-knock) from the factory. The Japanese may have purer gas, but they use a different scale for rating octane than we do here -- in other words 96 octane there is NOT 96 octane here, it would be ~91.

Whichever nation has the most pissy emissions restrictions will have the least power in theory, but probably the factory ECU tune will be essentially identical there and here.

As to peak torque, going by lb/ft units, whatever the power reading is at 5252 is probably about right, give or take a few lb/ft. Looks like around 125 I think? That would be consistent with estimated drive train losses as well.

[bigbcraig]

Originally Posted by Jordo!

200 ps = ~197 hp

In terms of Octane, it's going to be tuned for 91 AKI/96 RON (approximately equivalent in terms of anti-knock) from the factory. The Japanese may have purer gas, but they use a different scale for rating octane than we do here -- in other words 96 octane there is NOT 96 octane here, it would be ~91.

Whichever nation has the most pissy emissions restrictions will have the least power in theory, but probably the factory ECU tune will be essentially identical there and here.

Being an entry-level car that's supposed to be about handling and driver feel over tires and numbers; and with D4-S, I'll bet it's tuned for 87 or maybe 89 but not 91.

They clearly aren't shooting for high numbers from the factory, but are paying attention to selling a composed chassis and good driving experience. See high ride height despite low CG efforts, Prius tires, etc...

[DSR2409]

Originally Posted by bigbcraig

Being an entry-level car that's supposed to be about handling and driver feel over tires and numbers; and with D4-S, I'll bet it's tuned for 87 or maybe 89 but not 91.

They clearly aren't shooting for high numbers from the factory, but are paying attention to selling a composed chassis and good driving experience. See high ride height despite low CG efforts, Prius tires, etc...

It has a 12.5:1 compression ratio...without direct injection, and a wide array of sensors, that is CR that far exceeds even 93 octane...It will almost certainly be recommended in the owner's manual to run minimum 91 octane...

[SCIONIZED]

I'll wait for the sports model that has been talked about at a later date. Either turbo charged or a different engine. This car has been over engineered for such a thing in the future. Secondly I don't like what they have done to the body. They basically took an exotic looking sports car,the FR-S concept and turned it into a Camry. Hopefully when the sports model comes out it will look like or at least more like the concept vehicle.

[SCIONIZED]

Originally Posted by bigbcraig

Being an entry-level car that's supposed to be about handling and driver feel over tires and numbers; and with D4-S, I'll bet it's tuned for 87 or maybe 89 but not 91.

They clearly aren't shooting for high numbers from the factory, but are paying attention to selling a composed chassis and good driving experience. See high ride height despite low CG efforts, Prius tires, etc...

It is supposed to run on premium. That's what I read in a few places.

[serialk11r]

So if you can get into the VVT-i controls, you can probably dial out the EGR and thereby lower volumetric efficiency, do not rev past 4500, and you can use 87. You could make it exactly like driving a Prius with DI and a tiny bit less compression ratio.

[Foonix]

Anyone else notice about 4 minutes in he checks if the parking break can chirp the tires.. and it does with no problem? I'm actually surprised. Many cars I've had you have to really yank hard to get anywhere near a lock.

There might be less drivetrain loss in 5th since the diff, wheels, and part of the transmission are moving more slowly.

Skip the rest of this post if you are tired of the old torque vs hp debate or hate math.

Torque for all intents and purposes is treated like a force and horsepower is a power. You can work back and forth from torque to horsepower at a specific RPM because RPM has both time and distance components needed to fill in the work=force*distance and power=work/time equations.

Wikipedia has a good explanation of where HP comes from both historically and mathematically, and where the hp=(tq*rpm)/5252 formula comes from. Anyone who really cares about what dyno graphs actually mean should probably read it carefully.

We can certainly work backwards by solving the equation for tq: (hp*5252)/rpm = tq

5252 = (33,000 ft·lbf/min)/(2π rad/rev)