Hoovey689

iTrader: (16)

A power increase was shown in a NHTSA filing

Source

situman

Hmm Toyota you got a bit of work to do. Your fancy new 2.0 is only making 169hp.

Johnhav430

I have only driven a Miata once, one of those $50 (I think?) test drive gift cards. It's obviously a car that can be loved, like the S2000, Z3, etc. We need these cars with sticks to stay around. Not everyone wants a self driving automatic iPad lol

rai

Hoovey689

iTrader: (16)

Sort of different though in their goals. The Mazda one is leaning more towards performance, whereas the Toyota one is one of the worlds most thermally efficient engines for it's displacement. You'll see it paired with many upcoming hybrids.

mmarshall

....and it's a blast to drive, just as it is, with only 148 ft-lbs. of torque, though the torque tends to be a little peaky for my tastes (you have to take it past 3500 RPM to get any significant response). I agree with rai, though, that more power wouldn't hurt it...or a re-tune of the engine for a lower-RPM torque peak.

rai

It's all personal, but I have no problem with lower TQ engines (or TQ occurring high in the rpm range) had a S2000 which I believe was 400 pounds heavier than the new MX5 with similar TQ (the effect that S2000 was able to carry the redline-HP way up made up for the lack of relative TQ to weight ratio). I don't have problem with accelerating from stop with said cars. Sure they are not any Hellcat or even GTi when it comes to TQ but they can get up and go. Just need to shift higher in the RPM range.

Also somewhat low TQ numbers can be misleading due to final drive ratios, whereas the Boxster S gets to 80 MPH in 2nd gear that speed would be closer to redline 3rd gear with the MX5 or BRZ or S2000

Just looking at the specs:
S2000 Torque: 153 lb-ft @ 7500 rpm
MX5 Torque: 148 lb-ft @ 4800 rpm
BRZ Torque: 156 lb-ft @ 6400 rpm

can be argued that the MX5 has good low end TQ (least compared to the S2000 and the BRZ) 2L naturally aspirated engines. I would say that the S2000 at least is misleading because it's VTEC seems to give it a higher peak.

situman

Wouldnt thermally efficient also mean they translate more of the energy into more power and efficiency? As in getting more out of each atom of fuel? I could be wrong though.

Hoovey689

iTrader: (16)

I'll leave that for someone who knows the topic better than I. What I meant was both engines while being of the same displacement, have different traits/biases. The Miata using an existing spark-ignition Skyactive-G (vs the new Skyactiv-X spark-controlled compression ignition) engine, updates the cylinder head, allowing it to rev higher and make more power for this upcoming model year. The new Toyota one is meant to be married to a hybrid system and includes a larger valve angle and a heat recovery system that reduces energy losses in the coolant and exhaust systems. There are laser-clad valve seats for improved air/fuel mix, mixing port and direct injection depending on load for better fuel efficiency and reducing friction loss. From what I understand the '169'horsepower it produces is capped so torque rises across the entire rev range. This all adds up to more economical hybrid units, and due to the better thermal performance, allows more power to be drawn from the battery under acceleration. I see what you're getting at though, and I'm sure future Toyota powertrains will implement new tech that improves the power density.

Sulu

Thermal efficiency of an vehicle's internal combustion engine is the ability to get the most mechanical energy out of the potential energy from burning the fuel. Toyota's world-leading 2.0-litre Dynamic Force engine has a thermal efficiency rating of 40% and a maximum output of 169 hp; 60% of the fuel's potential energy is lost as heat. In comparison, Mazda's SkyActiv-G (gasoline) engine has a thermal efficiency of 29% (71% lost as heat).

That does not mean that you can keep providing and burning more fuel in the 2.0-litre Dynamic Force and always get 40% of that power out. You may be able to burn more fuel in that engine (by forced induction perhaps) and get more than 169 hp, but efficiency starts to drop below 40%. For example, a supercharger places mechanical drag on the engine to spin the compressor, so some efficiency is lost to mechanical drag; increasing the redline would also increase mechanical friction due to the higher speed of the pistons. But spin the engine too fast or pump in too much air, and the operating temperature increases to the point when the engine reaches its maximum operating temperature. One way to reduce operating temperature is to burn richer (pump in more fuel than absolutely necessary); this reduces efficiency (increases fuel consumption).

Mazda has not yet said how it intends to increase the power output of the MX-5 but we can speculate on how Mazda could increase the breathing ability of the engine (pump in more air and you increase the amount of fuel that can be burned). But thermal efficiency of the engine very likely drops much below 29%: burning more fuel does not give you a straight line increase in power output.

Aron9000

I don't mean to hate on Mazda, but Honda had a 2.0 liter naturally aspirated 4 cylinder that came out in 1999 with 240hp. 20 years later and the best you can do is 181hp for your flagship car????

I know Miatas have never been about the hp, but IMO they should at least offer a "base" car and a "Mazdaspeed" car that will run a mid to low 13 second quarter mile time. That isn't even fast in this day and age, but I think they could reach that goal with a real naturally aspirated 4 cylinder screamer with 240-260hp, aka S2000 territory. The light weight chassis of the current Miata is superior to the S2000, if Mazda could come up with an engine like the S2000's, man it would be game over in the sports car market.

Main thing I think Mazda is afraid of doing is making the Miata too expensive. If it has the muscle/grip, I'd say price it above $40k. A special engine along the lines of that S2000 engine would be worth the price increase IMO.

mmarshall

That engine, though, if you remember, had one of the silliest torque-curves I ever saw. It was basically motorcycle-RPMs or nothing. In its first year, redline was 9000, peak HP at 8600, and peak torque at 7600.

F1Driver

Furthermore, to get any real motive force you'd have to drive it like you stole it. How fun is that in daily stop and go traffic??

Aron9000

I've driven the S2000 in traffic, its super easy. Light, easy to modulate clutch. You act like it has ZERO power under the curve, granted it isn't fast until you really rev it, it feels about like you're driving a garden variety 4 cylinder/5 speed Civic or Accord in traffic, it keeps up just fine, if you need to pass or cut somebody off, just shift down a gear(or two). Roadsters aren't like a big Suburban or large sedan, you don't really need torque, what you need IMO is revs. The more the engine is like a Formula 1 car, the better IMO.

Besides you are doing it wrong if you primarily drive your S2000 or Miata in stop/go traffic or commuting all the time. Its a fun 2nd car, they are IMO a bit to impractical, noisy and a bit unsafe(nothing like being at eye level with the lug nuts on a semi truck) driving the grind to work every day. These cars are a bit like a motorcycle, if you live in a gridlocked city/suburbs, spend all your time commuting and don't have any time/fun empty roads to drive on, what's the point????

mmarshall

Rev? With motorcycle-RPM peaks in that engine, that's an understatement.