David S. Wallens
David S. Wallens Editorial Director
8/3/18 12:31 p.m.
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Does the 2019 Mazda MX-5 Miata ND2 really make more power than before? Time to find out.

While we had one in our hands, we visited Rob Fuller at Z Car Garage in San Jose, California. Did you notice the BRE Datsun 240Z on the cover of the latest issue of Classic Motorsports? He maintains it. And the 1971 Skyline that won the all-Nissan race at Speedfest at the Classic Motorsports Mitty? He preps that one, too.

Plus he has his own personal collection, including the turbo 510 that graced the May 1985 issue of Auto-X. That’s the magazine that became Grassroots Motorsports.

Rob also has a Dynojet chassis dynamometer.

We can’t yet share any driving impressions of the new MX-5 due to a media embargo, but we did gather some more facts and figures.

The first pull was made using sixth gear. The other two were made in fifth. Fifth gear delivered the best numbers: 168 horsepower at the wheels along with 149 lb.-ft. of torque. (And, yes, we rounded to the nearest number.)

Mazda's official numbers are 181 horsepower and 151 lb.-ft. of torque, which works out to about a 7% decrease in horsepower due to driveline loss. Calculating actual driveline loss is a notoriously inaccurate science, but for a rear-wheel-drive car, we're tempted to say that Mazda's rated power output might even be pessimistic.

What does this mean if you're planning your next autocross build, or ready to start unbolting those coil-overs from your ND1 MX-5 Miata? We'll cover that in our next ND2 update.

Read the rest of the story

NordicSaab
NordicSaab Dork
8/3/18 12:52 p.m.

Any chance of Dyno sheet overlays of the '19 vs a '17 or '18?  

Pete Gossett
Pete Gossett MegaDork
8/3/18 12:53 p.m.

How does this 168hp and 149lb-ft compare to ND1 dyno numbers?

Tom Suddard
Tom Suddard Digital Experience Director
8/3/18 1:17 p.m.

We're working on that story right now.

Vigo
Vigo UltimaDork
8/3/18 1:57 p.m.

Calculating actual driveline loss is a notoriously inaccurate science

My job here is.. totally precluded. cheekyyes

I've recently had Toyota 2zz's on my mind since acquiring a couple of real basketcases. Those were rated 180crank and dyno'd ~160whp through FWD drivelines that have a lot less spinning weight than RWD drivelines. I'd say your underrated comment is a fair guess! 

te72
te72 Reader
8/4/18 12:13 a.m.

That's a 50-60 whp increase over a fairly healthy NB in stock form. Not gonna lie, I'm a bit envious. Nevermind the torque...

David S. Wallens
David S. Wallens Editorial Director
8/4/18 1:41 a.m.
te72 said:

That's a 50-60 whp increase over a fairly healthy NB in stock form. Not gonna lie, I'm a bit envious. Nevermind the torque...

FWIW, I'll be driving an NB in STR at Solo Nats. :)

PeteD
PeteD New Reader
8/4/18 5:15 p.m.

The first pull was made using sixth gear. The other two were made in fifth.

Why did you make the dyno runs in both 5th and 6th gear?

Wouldn't the 6th-gear results be most accurate because of the 1:1 transmission ratio?

  -- Pete

Vigo
Vigo UltimaDork
8/5/18 12:45 p.m.

Technically as long as the dyno is directly measuring the engine speed (it always knows the drum speed) it is always going to calculate the gear ratio and you're still going to come up with basically the same power result. You can choose a gear either because you think it incurs the least 'loss' or because the gear isn't going to result in tire speeds on the roller where a tire failure would kill everyone close to the car. lol

codrus
codrus UltraDork
8/5/18 12:57 p.m.
Vigo said:

Technically as long as the dyno is directly measuring the engine speed (it always knows the drum speed) it is always going to calculate the gear ratio and you're still going to come up with basically the same power result. You can choose a gear either because you think it incurs the least 'loss' or because the gear isn't going to result in tire speeds on the roller where a tire failure would kill everyone close to the car. lol

 

Generally speaking, the 1:1 gear will have the least drivetrain loss because it's usually just directly coupling in the input and output shafts in the transmission, with no gears involved in changing speeds.  It's also usually the strongest gear, for the same reason.

Knurled.
Knurled. MegaDork
8/5/18 1:25 p.m.

In reply to codrus :

Hearty "it depends".  If it is an inertial dyno, testing in top gear may make the pull take so long that the engine heat soaks and loses power.  This is not as much a problem when you have a 100mph headwind.

 

I always tested my RX-7 in 3rd gear for this reason.

gearheadE30
gearheadE30 HalfDork
8/6/18 7:38 a.m.

The critical speed of the driveshaft in my Caprice is about halfway through 4th, which is my 1:1 gear. As a result, I have to run in 3rd to keep the driveline speed down.

David S. Wallens
David S. Wallens Editorial Director
8/6/18 10:04 a.m.
PeteD said:

The first pull was made using sixth gear. The other two were made in fifth.

Why did you make the dyno runs in both 5th and 6th gear?

Wouldn't the 6th-gear results be most accurate because of the 1:1 transmission ratio?

  -- Pete

Rob, the dyno operator, was concerned about running into a speed limiter. 

codrus
codrus UltraDork
8/6/18 10:38 a.m.
Knurled. said:

In reply to codrus :

Hearty "it depends".  If it is an inertial dyno, testing in top gear may make the pull take so long that the engine heat soaks and loses power.  

That just means you're not making enough power. :)

But yeah, it's worth doing a couple test runs to validate the testing methodology because it's going to vary by car.

 

te72
te72 Reader
8/7/18 4:35 p.m.
David S. Wallens said:
te72 said:

That's a 50-60 whp increase over a fairly healthy NB in stock form. Not gonna lie, I'm a bit envious. Nevermind the torque...

FWIW, I'll be driving an NB in STR at Solo Nats. :)

I still say value for the money is tough to beat when looking at the NB. Mom finally got to drive the one I bought my fiance in place of an engagement ring, and now totally understands why I did that.

 

***Disclaimer: Unless your lady is as much of a car geek as you, the car in lieu of a ring may not be the best idea.Fortunately, mine is a gearhead at heart. ***

Bunger78
Bunger78
8/8/18 3:22 p.m.

A slightly crude overlay for everyone:

Toebra
Toebra HalfDork
8/8/18 3:47 p.m.

Better they under estimate than over estimate like they have in the past.

Knurled.
Knurled. MegaDork
8/8/18 7:43 p.m.
Toebra said:

Better they under estimate than over estimate like they have in the past.

What, so an '04 RX-8 doesn't really make 255hp?

Vigo
Vigo UltimaDork
8/9/18 4:08 p.m.

What, so an '04 RX-8 doesn't really make 255hp?

Now that you mention it, it's slightly funny that when we finally get 1/4 mile numbers for the new ND they're going to be WAY better than the RX-8 ever did.  

Harvey
Harvey Dork
8/10/18 5:26 p.m.

To add to the fun, found this on Miata.net, guy says it's a 2016 ND and they did the pulls in 4th gear. 143hp / 138lb/ft of torque.

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