Miata Mailing List: October 1997, Message #112
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From: 	David Okamoto <davo@lsil.com>

Subject: Re: 1.8l horsepower ratings

Date: 	Wed, 1 Oct 1997 12:23:41 +0000



Dan Scolnick wrote:

> 

> interesting question dave,

>         my '97 certainly 'feels' like it's putting out 5 more horsepower

> than my '94.  The only  difference I can find is the catalytic converter

> is bigger on the '97, but this shouldn't account for the HP.  Could be in

> the electronics since they  went to OBDII.  BUT the ignition curve still

> sucks, like the '94.  ie.  14 degrees is best for 7000rpm, but 18 is best

> for the bottom end.

> 

> fwiw

> /^\dans

> 

> On Mon, 29 Sep 1997, David Okamoto wrote:

> 

> > G'day folks...

> >

> > Was wondering about something that someone out there is sure to know.

> >

> > The 1.8 liter engine as introduced with the '94 Miata was rated at 128

> > crank horsepower.  Then, beginning in '96 (I think), the same engine

> > (same bore and stroke, I presume) was rated at 133 horsepower.  For the

> > '98 (or is it the '99?), I now hear from a number of sources that it

> > will be rated at 133 horsepower. (Mark Wold...thanks for the review of

> > the preview...sounds pretty much as has been described/pictured before,

> > in other words, pretty nice and worthy of the legacy!)

> >

> > How is this consistent power increase achieved?  Do you think it's all

> > ECU related?  Do you think it's a numbers game?  Has anyone dyno'd a

> > stock 128 hp vs. a stock 133 hp to see what the rear wheel results

> > were?  I'm wondering if there really was a 4 or 5 hp difference there.

> >

> > I have a '95 and while it's currently "Sebring'd" with a view to going

> > to an FM turbo someday (when Bill's got one and it's CARB'd), if I can

> > gain 5 to 10 horsepower in the meanwhile with a simple tweak or so, why

> > not?

> >

> > Any ideas?/facts?/opinions?/bullshit?

> >

> > Thanks folks,

> >

> > Dave

> > --

> > Dave Okamoto

> > LSI Logic Corporation

> > mailto:davo@lsil.com

> >

> >



Dan:



I received a number of responses (for which I thank all who responded).

I answered each of these directly, rather than to the list.



The most plausible response was, as you also surmised, that the OBDII

allowed finer tuning of timing curves, fuel mixture, etc., etc. to eke

out the additional 5 horsepower.



It would apear that no one yet know how the additional 7 or so

horsepower were discovered for the '98/'99, unless it's further

refinement of the ECU controls.



Regarding the ignition curve, I imagine the stock curve is fixed, mapped

relative to rpm.  A programmable ECU should allow you to modify it to

your personal tastes, as would Bill Cardell's, or the TECII that Shiv is

running...not cheap!



Dave

-- 

Dave Okamoto

LSI Logic Corporation

mailto:davo@lsil.com