BRZ vs. Prelude Si vs. S2000. . . Initial Thoughts

[CSG Mike]

Originally Posted by ZDan

All the above said, I don't really think the fr-s/brz are underpowered for the street. For the way I drive on the street, 200hp is more than enough. At the track I would want a lot more...

The throttle response is a lot more aggressive on the BRZ (at least, the perceived output) under street conditions (under 4k).

Going back and forth between various FRS/BRZ and s2ks, I REALLY get to compare them back to back.

The S2k does feel weaker down low, but as soon as we're comparing WOT vs WOT, the BRZ/FRS has no chance until you're talking triple digit speeds, at which point, the aero advantage kicks in for a short period.

[manonastick]

Im actually considering selling my s2000 now for an frs. i was about to purchase one back last year but the wait here 12months + really put me off. Though when i drive the s2k im just soo happy everyday but the noise and poor low end sucks for me. The frs is alot more useful for me since the s2000 is my only car. I just think the s2k is more fun but the 86s is the more true car in the aspect it does everything the s2000 can and cannot.

[Rampage]

Originally Posted by CSG Mike

I've always been the other way...

B and F engines are nowhere near as smooth as a K...

I cannot really argue the issue due to limited experience with K motors. My only experience was when I gave up the Integra I went and drove a RSX with the K motor. I did not like the sound of the engine or the look of the interior of the car. After a 20 minute test drive I walked away from Honda for good. Since then it has been 350Z then the Mr2 Spyder which I susequently swapped the 2ZZ-GE and the 6 speed into. I shopped the FR-S and BRZ but was disappointed in the price and the fact that I would have to start modding from scratch again to get back to the performance I currently have.

Now, I am helping to mod a FR-S anyway but my son is footing the bill. Win-win for me.

[ZDan]

Originally Posted by Jawnathin

There is a problem with your one dimensional approach to performance.

I develop vehicle performance models as part of my job. Currently doing all structural and drivetrain development for a vehicle for Daimler and am responsible for defining drivetrain performance characteristics and requirements for future projects.
I've also modeled the acceleration performance of my LS2 FD (including power curve, aero drag, rolling resistance, tire slip, tire growth, shift times, etc.) and predicted its standing 1-mile performance within 1mph (184 predicted, 184.8 actual).
I do not take a 1-d approach to vehicle performance modeling professionally or for my own personal vehicles.

I'm just pointing out in this thread that power/weight is not meaningless and does pretty well define basic vehicle performance, much better than misused/abused concepts like "power under the curve". For outright performance, the FA20 *is* inferior to the F20C (or F22C). Personally, for street usage, I don't find this to be a big deal, but for me the car *would* be cooler if its 2-liter engine revved to 9000rpm and made 240hp.

Peak power is just that, peak power. The amount of power the engine can make on its way to peak power is arguably more important than the peak number itself.

The way the f20c makes power is actually pretty similar to the way the FA20 does. They both have somewhat "peaky" powerbands, with peak power just short of redline. 7000/7400 for the FA, 8300/9000 for the f20c. What happens along the way is a little bit different, but not hugely so. The FA has the torque dip at 4000, the F20C has the VTEC discontinuity at 6000 (which would have been eliminated if they'd gotten the crossover rpm right, should have been set to the rpm where torque/power were the same on both sets of cam lobes, ~5000rpm).

There is a reason why people shit on peaky powerbands and prefer a flatter broader power curve. If you've ever driven a car with torque, maybe you'd understand that.

My daily FD makes more than 3x the torque of the FR-S/BRZ or the s2000. ~500 lb-ft/545hp. So yeah, I understand "moar torques".

And in my example, it wasn't about an FA20 or F20C, it was about the concept of power under the curve. So I'll ask again, do you prefer less power or more power at a given RPM?

What's with your fixation on "a given rpm"? You drive different engines differently. I don't shift my 2.0/9000rpm S2000 at the same points I shift in my 6.0/7000rpm RX-7, that would be absurd.

People act like there's something inherently difficult about revving out an engine that likes to rev. I don't get that.

A more appropriate question would be "do you prefer less power at a given *road speed*". To which I'd say "hell no!" And the S2000 will have more power on tap at any given road speed vs. the FR-S/BRZ.

If you can't see the benefit of having a stronger powerband earlier in the revs, you're only highlighting your inexperience.

I've been around a bunch of different tracks in dozens of different cars with very different drivetrains and won 6 time trial championships along the way. I'm not a professional race car driver or anything, but I do have more experience than most on road car forums. And probably ~half a million street miles? Something like that.

My current daily drivers are a totally stock S2000 and the aforementioned 6.0 liter 545hp FD RX-7. And you know what? On the street, I don't find the S2000's powerplant to be any less driveable.

There are plenty of situations where a downshift isn't going to be reasonable or the quickest way.

I don't usually put myself in positions where I have to go from low-rpm cruise to maximum acceleration in an instant.

Downshifts and upshifts take time. If you have a flexible powerband, you can stay in gear. If you can stay in gear, time can be saved. The fact of the matter is, more power is better than less power at a given RPM and that is why the power under the curve is very important.

Get over "at a given rpm". You drive different engines differently. If you can't drive a 9000rpm 240hp differently than you drive a 7400rpm 200hp engine, then you are doing it wrong.

It is irrelevant that the FA makes more torque "at a given rpm", because I'm generally going to be keeping the F20C spinning ~20% higher and hence have greater torque available *at the drive wheels* (you know, where it COUNTS) *at all times*.

This is ironic. You bash the dip (in which the FA20 still has greater output) yet justify the lack of low end on the F20C due to your driving style. Fair enough.
But hey, guess what? I could argue the very same exact point that the dip is avoided in regular driving and when driving competitively because you're either down low or revving it out.

It *is* "fair enough". The dip *is* an annoying feature, just like the VTEC bump is an annoying feature on the F20C. If I'm tooling around town, I'd honestly probably never encounter either on a regular basis, so really, for a street car, not a huge deal. At the track, I'm over 6000rpm in the S2000 100% of the time, so the VTEC crossover is nonexistent. In the FR-S/BRZ, I'm sure I'd be above 4500 (or whatever) most of the time as well, so no biggie there either.

The undesirable points of either powertrain are avoidable, but if I do need to speed up on the street, I can go all the way to 6000rpm with the S2000 without running into any weirdness, and above that it only pulls harder. whereas in the FR-S/BRZ I'm going to get a big lull right where I would like for it to start pulling.

But I'm not going to make excuses for the dip. Why? Because I understand the value of a broad powerband and the engine would be better with out it. Just like how an F20C would be much better if it had a flatter and broader powerband.

Neither the FA20 nor the f20C have broad/flat POWERbands. In fact, having a flat powerband just means your engine can't breathe at elevated rpm.
What you must be talking about is a flat TORQUE curve. Which *IS* very nice. The F20C has two of these, one from ~3k to 6k, another from 6k-9k (it does trail off a bit above 8k, but peak power is at 8300 and it's still making useful torque and more importantly POWER at 9000).

For the record, comparing an FA20 vs F20C is irrelevant to the point being made. My position is that a broader powerband is better and you seem to have a hard time understanding that.

I fully appreciate a broad TORQUE band. A broad POWERband just means torque is falling off as quickly as rpm is rising. A RISING powerband is what you get with a broad flat TORQUE curve.

And if we were to compare engines, I'm not trying to say one engine is better than the other. I see both sides of the coin for both engines, both have their strengths and weaknesses.

As do I...

I respect the F20C for its high revs, but in actuality it doesn't make much power up top and it is lethargic down low. By somehow suggesting a narrow powerband isn't an issue because only peak power matters reeks of typical S2000/JDM fanboyism.

It makes good power up top, and if you find it "lethargic" down low it's because you aren't driving it properly. It does make less torque below 6000rpm than the FR-S/BRZ, but all you have to do is keep the revs ~10-20% higher and this is MORE than compensated for.

FWIW, I like the S2000, a few close friends own one or have owned one. I've driven many on multiple occasions. I crossed shopped an S2000 before buying the BRZ (just last week). I decided that while an S2000 would be a better performance car stock, it wasn't fast enough to make up for the rest of its compromises.

Same here. I would prefer a 2+2 coupe and would have bought an RX-8 but for its abysmal fuel mileage.

Your statement doesn't make any sense here. One statement says it doesn't make more power under the curve (in which it does), then you say it makes more torque. Which is it? lol

Look at the power curves for both engines. Then tell me with a straight face which one has more area under the power curve. It's not even close.
Torque is not power. Torque is a means to make power, but power is more important than torque because torque by itself doesn't tell the whole story.
FA20 makes more torque down low, yes. But this is not the same as "more power under the curve".

The funny thing is that as much as you're touting the FA20 as some kind of low-end stump-puller, it actually is pretty peaky. The nice broad/flat torque curve above 4500 gives peak power at 7000rpm, just 400 short of redline/rev limit. Similarly, the F20C's broad/flat torque curve above 6000 gives it peak power at 8300rpm, 700rpm short of its redline.

The engines are pretty similar in terms of how they make power vs their rev limits, the MAJOR difference being the F20C's huge rpm advantage, which gives it a big power advantage.

A high 14 vs a low 14 isn't 'significantly' different. That kind of delta in a low ET would be great (10s, 11s), but with such high ETs, it is pretty minor. The fact that both cars trap in the mid-90s suggests that they aren't that far off.

S2000 traps in the 100/101 range, FR-S/BRZ ~94/95. That's a pretty big difference.

Both are slow but one is far better to live with.

I'm pretty jaded, but to me 14-flat/100mph is not what I'd call "slow" for a street car. But 14.5/95mph is :P (j/k)

[regal]

Originally Posted by Rampage

I now have a 2ZZ Mr2 Spyder which is smaller outside but roomier inside. The 2ZZ-GE is not as smooth as the 1.8 liter Honda engines but it sounds silky compared to my son's FR-S. s.

You have the ultimate Toyota sports car, the one Toyota should have built.

Remember this FR-S is a coupe, its definitely not an S2k, its performance is way way below an S2k. But it has a roof and it has huge trunk with the seats folded down. Its a car much like the 240sx, you can commute to work everyday even stop on the way home and get groceries. And also like the 240SX there is unlimited potential if these cars stay popular the aftermarket support should remain tremendous.

[DarkSunrise]

All this arguing over the F20c vs. FA20 reminds me of this dyno by Gardus at Supersprint:



I don't have time to do it, but someone should calculate torque to the wheels vs. RPM. I suspect the FR-S ends up being better for daily driving (under 3500 rpm, for example), but hard to say.

The S2000 obviously kills the FR-S at the top end, especially above 7000 rpm.

[ZDan]

Originally Posted by DarkSunrise

I don't have time to do it, but someone should calculate torque to the wheels vs. RPM. I suspect the FR-S ends up being better for daily driving (under 3500 rpm, for example), but hard to say.

It's not that hard, really.

3rd gear at 3500rpm in the FR-S is 39.5mph (given 1.541:1 3rd gear, 4.10 diff). The same 39.5mph in the AP1 S2000 3rd gear puts it at 3900rpm (4100 in the AP2, which gives it a big advantage here, but we'll keep it to 2.0 vs. 2.0 liter) with the AP1's 1.718:1 3rd gear.

At 3500rpm, FR-S is making 90hp. At 3900rpm, S2000 is making 100hp, 11% more. The S2000 is therefore putting 11% more torque to the wheels at 39.5mph in 3rd gear.

The S2000 obviously kills the FR-S at the top end, especially above 7000 rpm.

Yup.

[RIPTRD71]

Sound like you should of just bough another S2000.

[DarkSunrise]

Originally Posted by ZDan

It's not that hard, really.

3rd gear at 3500rpm in the FR-S is 39.5mph (given 1.541:1 3rd gear, 4.10 diff). The same 39.5mph in the AP1 S2000 3rd gear puts it at 3900rpm (4100 in the AP2, which gives it a big advantage here, but we'll keep it to 2.0 vs. 2.0 liter) with the AP1's 1.718:1 3rd gear.

At 3500rpm, FR-S is making 90hp. At 3900rpm, S2000 is making 100hp, 11% more. The S2000 is therefore putting 11% more torque to the wheels at 39.5mph in 3rd gear.


Yup.

Not exactly what I was looking for. I'll put together some torque to the wheels x rpm charts later when I have some time. Still suspect the FR-S will come out on top under 3500 rpm, even if the S2000 has shorter gearing.

[ZDan]

3500rpm vs. 3500rpm doesn't make any physical sense, as the cars are going at different speeds at that rpm.

But anyway, here it is:
At 3500rpm the FR-S/BRZ is making ~135 "rear-wheel" lb-ft.
At 3500rpm the AP1 S2000 is making ~125 "rear-wheel" lb-ft.

FR-S/BRZ actual torque at rear wheels at 3500rpm in 3rd gear = 135 lb-ft*1.541*4.1 = 853 lb-ft
S2000 actual torque at rear wheels at 3500rpm in 3rd gear = 125 lb-ft*1.718*4.1 = 880 lb-ft

880 > 853

[DarkSunrise]

Originally Posted by ZDan

3500rpm vs. 3500rpm doesn't make any physical sense, as the cars are going at different speeds at that rpm.

But anyway, here it is:
At 3500rpm the FR-S/BRZ is making ~135 "rear-wheel" lb-ft.
At 3500rpm the AP1 S2000 is making ~125 "rear-wheel" lb-ft.

FR-S/BRZ actual torque at rear wheels at 3500rpm in 3rd gear = 135 lb-ft*1.541*4.1 = 853 lb-ft
S2000 actual torque at rear wheels at 3500rpm in 3rd gear = 125 lb-ft*1.718*4.1 = 880 lb-ft

880 > 853

Thanks. How about 1st gear, 2000-3500 rpm, and 2nd gear, 2000-3500 rpm?

[ZDan]

At 2000rpm, both these cars are bogging *terribly*, both making ~40rwhp, ~102 rw-lb-ft.

2000rpm in 1st:
FR-S/BRZ torque at wheels = 102 lb-ft * 3.626 * 4.1 = 1516 lb-ft
AP1 torque at wheels = 102 lb-ft * 3.634 * 4.1 = 1519 lb-ft

2000rpm in 2nd:
FR-S/BRZ torque at wheels = 102 lb-ft * 2.188 * 4.1 = 915 lb-ft
AP1 torque at wheels = 102 lb-ft * 2.372 * 4.1 = 992 lb-ft

2000rpm in 3rd:
FR-S/BRZ torque at wheels = 102 lb-ft * 1.541 * 4.1 = 644 lb-ft
AP1 torque at wheels = 102 lb-ft * 1.718 * 4.1 = 718 lb-ft

That's going by these rear wheel power/torque curves:



3500rpm looks like 128 rw-lb-ft for the FR-S/BRZ, 119 for the F20C, easy enough to apply to the gear ratios given above.
3500rpm in 1st:
FR-S/BRZ torque at wheels = 128 rw lb-ft * 3.626 * 4.1 = 1769 lb-ft
AP1 torque at wheels = 119 rw lb-ft * 3.634 * 4.1 = 1773 lb-ft

3500rpm in 2nd:
FR-S/BRZ torque at wheels = 128 rw lb-ft * 2.188 * 4.1 = 1068 lb-ft
AP1 torque at wheels = 119 rw lb-ft * 2.372 * 4.1 = 1157 lb-ft

3500rpm in 3rd:
FR-S/BRZ torque at wheels = 128 rw lb-ft * 1.541 * 4.1 = 752 lb-ft
AP1 torque at wheels = 119 rw lb-ft * 1.718 * 4.1 = 838 lb-ft

FA20 does have a bigger torque advantage between 2000 and 3500, more so than at those specific rpms. Plug in values at 3000 and the FR-S/BRZ will look better there. But then worse from ~3500-4500

[DarkSunrise]

Actually this is more along the lines of what I meant (not just the endpoints, but the entire range):



The FR-S has a fairly sizeable torque advantage in all of 1st from 2000-3600 rpm. It's also got a torque advantage in much of 2nd for the same RPM range, although clearly the shorter gearing/2nd gear of the S2000 is already coming into play and closing the gap.

Some notes:

- I used the MAHA dyno from Gardus/Supersprint since the same dyno was used to test the output of both cars.

- I used your gear multiplier ratios, so I'm assuming those are accurate. Also saves me the trouble of looking up the gear ratios

- I would have gone from 1000-3600 rpm as I think that's fairly representative of how most people DD (at least in 1st), but the Supersprint dyno only started at 2000. I believe the FR-S would maintain a torque advantage under 2000 rpm though due to its higher compression ratio.

[ZDan]

More to come later, but I have to say I don't know where you're getting the idea that the F20C has a narrower powerband than the FA20.
If you define it as the range where an engine makes at least 80% of its peak power output, the FA20's powerband is from 5200-7400rpm (a 2200rpm wide band), whereas the F20C's powerband is from 6300 to 9000 (a 2700rpm wide band).

The FA20's powerband is actually narrower. And of course the F20C is making 160-200rwhp in its powerband vs. the FA20 making 138-173rwhp (a.k.a. "a lot less") in its powerband.

If you have a problem keeping the revs up (easiest thing in the world to do), then the S2000 is definitely not for you. But then again neither is the FR-S/BRZ, really.