Well, I don't know about the absolute number but I'm willing to
believe that (a) this Miata makes about 20% more power than the
preceeding 1.8L models and (b) this probably equates to about 130hp
on a rear-wheel dyno.

The Solstice claims 178 from a larger displacement, and is slower. 170
for the NC seems right in the ballpark for its 6.5 second 0-60 time.
It's just a number, anyway--all agree the car is significantly quicker
than the NB.

Only once, and that was due to changes made for exhaust requirements.

They do not claim it "belts out" at 170 hp.  They claim that the
engine produces 170 hp, which is a very different matter.

But I agree that it would be nice if manufacturers were required to
report actual, rear wheel horsepower instead of some technical,
immeasurable number.  Car & Driver and Road & Track ready to
stand tall for this for a change???

I guess it would cut down on advertisements $$$ for automatics.  :(

Leon

The new Miata will STILL have far less power than a Corvette and STILL get
worse gas mileage.  The original thought of making a modern Lotus Elan sure
was flushed down the toilet early in the history of this car.

KG

The current issue of Sport Compact Car (I know I know its not the kind of
rag a Miata guy should be reading, but I couldn't resist the cover promising
a "Miata Megatest.") includes a side by side comparison of the new 2006
Miata with the 2005 Mazdaspeed and of course a project car the editors have
done all sorts of stuff to.  Anyway, the tests include horsepower at the
wheels with the following results:  Project Miata = 187 HP, 2005 Mazdaspeed
= 152 HP, and 2006 Mazda MX-5 = 134 HP.  The editors wonder a lot about the
lower number for the 2006, but claim it had something to do with ambient
conditions at the time of the test and the engine control unit retarding
timing to protect the engine.

Gus (91 BRG)

Leon van Dommelen:

But I agree that it would be nice if manufacturers were required to
report actual, rear wheel horsepower instead of some technical,
immeasurable number.  

 By tradition and currently for comparisons on a fair basis, Shaft
 power from the engine is measured on an engine dyno to SAE J1349. My
 look at power from a lot of engine specs suggests that the values are
 pretty good. Losses from a train of gears and connections, inertias
 and tires really add up. The new spec can cause power quoted to go
 down or up depending on the interpretations of the spec.

 Now, the manufacturer can get a witness certified rating, but I can
 testify that this won't really improve the numbers. Just variations
 in build tolerances cause more than 3 % error in production.

 What organization would 'require' a change. The government does
 require the power consumption of the car at constant speed for their
 dyno loading. And, if you run air conditioning, are at high altitude
 (low atm. pressure) or it's a hot day, you could loose 10 % not to
 mention locking differentials, low tire pressure, winter tires and
 having the top down.

Car & Driver and Road & Track ready to stand tall for this for a change???

 They really don't want to be part of that argument. They just tell it
 like it appears to them as you do.

I guess it would cut down on advertisements $$$ for automatics.  :(

 Not a logical or relevant point. Automatics are a feature some folks
 need.

As Craig says yes.  The engine hp cited is supposedly measured with
some load, ("brake",) at the engine crankshaft.  Unless you plan to
take your engine out and use it to power your home generator, what
you really care about is what horsepower comes out at your rear
wheels, which is measured with a dyno.  

 A 'dyno' is used for the engine power measurement; a drive wheel
 dyno or a vehicle dyno measures drive wheel power.

 Again, the engine produces the power and there are several ways to
 burn it up before getting to the road.

(Dyno's might be optimistic.)

 Aside from cheating, yes, there are many ways the dyno can lie
 including bearing problems and ignorance of proper techniques.
 While you make every effort to get the correct absolute power,
 more important is consistent readings test to test.

Where does the other 25% go?  There you have me.  The few numbers I
have seen for gearbox loses (especially in high gear) and differential
are nowhere near to explaining the loss of a quarter of the power.

 Differential, Air Temperature, bearings, fluid coupling, tires,
 alignment, air cond., headlights, electric fuel pump, computers.......

I read somewhere (here or elsewhere) a vague explanation referencing
"accessories".  Some heavy accessories.  

 Many years ago, the test standard tightened up the 'accessories'
 issue, but the load on the generator and air cond. pump are variable
2
 as a function of battery 'soc', cabin temp. I don't begrudge anyone
 else their automatic trans. or air conditioning, but they are not
 performance options.

Horsepower is a big selling point, not?

 As testified earlier, power spec is a contractual value and the
 manufacturer really doesn't want to be caught too far out.

xs11eNO@spamyahoo.com wrote:

While sometimes I think the 6 speed would be nice I really have no
objection to the 5 speed, it does just fine out on the highway although
it does turn more RPM than I'd like at 75mph+, the tradeoff is being
able to pass w/o downshifting most of the time.

 This is removed from the 170 HP subject, but I agree; The newer var.
 valve timing improves the torque band, so why not use the 6th gear for
 a reasonable cruising. I've spent a few hours at 5000 rpm and days at
 4600 rpm (90 mph) crossing the country and that noise is hard to take.
 The car (an '00) doesn't seem to care.

OK, it might not say Miata on the front but it's still a Ford!

 I got 18 years out of my rusty '84 T-bird turbo with totally defective
 5 spd. transmission, failure prone electrics and leaking doors in
 Quebec winters. So, I won't make the Ford mistake again. If I thought
 for one minute the Miata had any input from Ford, I wouldn't own one.

Kevin Anderson wrote:

the advantage of the 6 speed is to be able to have more control of the
powerband .

 True, but I've never wanted more control over the power band than the
 5 spd. offers. Every shift is a bunch of time wasted. While I am in a
 low income bracket, the unoptioned '00 (with CD player/radio) is
 exactly what I wanted (given that my previous favorite car was a '62
 Sprite with reliable Smiths electrics.) They are right when they say
 it's an old guys car. Mine.

 My wife & I have been to San Jose, Glacier Nat. Park, NJ, Toronto and
 the Upper Peninsula of MI this year and our only complaint is the
 engine noise at 90 mph..........Martin in Vancouver, BC
 ______________________________________________________________________

MAJ:

44XS11E <xs11eNO@spamyahoo.com>                            

"But they do and you do...."

The original design of the Miata predated the involvement of Ford I
think. I doubt there is a single part designed by or manufactured by
Ford in the NA or NB Miata.

Leon van Dommelen <rammm@remove_this_tagdommelen.net>

Martin Jackson <mjackson@vcn.bc.ca> wrote:

"You seem to know something about those things.  In particular, thanks for
the reference.  That makes it easy to find:  
  http://www.sae.org/certifiedpower/details.htm

"Unfortunately, I am not going to spend $50 for a standard.  If you
have a summary somewhere available for free, I would like to see it."

While I joined SAE thinking I would have a career in cars, I ended up
working on aircraft gas turbine performance. My job was to determine the
cause of deficiencies in test method or engine build. I wouldn't buy the
spec either as a hobbiest. That's what the company/school library is for.

"Note that these standards are *voluntary*."

 That's true until you specify the spec. While individuals will
 circumvent the rules, the lawyers and associated government reps will
 attempt to conform.

 The following comments reflect your distrust of the manufacturers and
 the SAE which no one can debate. I am not now a committee member, but
 they are generally motivated by the reduced cost and competitive
 advantage specs provide. Without specs, your paranoia would be
 warranted. That's not to say that no one fudges.

"It appears then that there was a need felt for "fair, accurate ratings"
to formulate this standard, don't you think?"

 Yes, but this relates to honest errors as much as evil dooers

"J1349 was updated last year to eliminate
some ambiguities that allowed engine makers to cite power and torque
ratings higher than the engine's actual capabilities."  I do not need to
comment on this, except that somehow it does not say "lower".

 The NY Times article I read indicated the Corvette (for example) was
 able to increase its ratings. Again, it is interpretation of the spec
 that causes much trouble.

 I can assure you from personal experience that the SAE is a non profit
 organization. In fact, it is probably loosing money. The 'general
 public' isn't the SAE's customer except as it benefits from reflecting
 regulatory requirements.

                         
 O.K., 'pretty good' should read 'pretty comparable'

 On the road

"You must have numbers that I do not have, because I come
nowhere close. Please give us specific numbers from gearbox losses
in 1:1 gearing (3%), Torsen differential with equal wheel speeds L/R
(2%, sliding), rolling resistance of two tires on a dyno or four tires
on the street with two under load.

 Every bearing, universal joint or bevel gear contributes. If the car
 restraint increases the tire loading, that loss is increased.

Inertia is counted as production, *not* loss, on the road,

 This confuses me. Overcoming inertia while accelerating is a loss

"...and is small on normal dynos such as the ones my car was on."

 It is true I was thinking EPA schedule testing or on road loss.

"That is interesting.  How can you testify to that?"

 From reducing the test data from about 10,000 engines. Honest
 variability and poor equipment calibration & maintenance are two
 causes.

Was there a manufacturer challenged in court and retesting with a
witness produced the same numbers? What manufacturer(s)?  What car(s)?

 It doesn't get to court in my arena; the customer can get an engine
 from someone else. Wasn't the production Miata rating challenged ?

Don't dynos use a correction factor for that?

 The data reduction would correct if measured and calculated properly.

"From your knowledge of the SAE standards involved, it
appears that you may know something about those matters. If so, please
give us typical numbers........."

 I could spend hours in an engineering library looking up these
 numbers. Not needed for my current interests. If you do testing to
 maximize your performance, the important thing (ignoring bragging
 rights) is the change due to some modification. 'all else being equal'
 ______________________________________________________________________