Miata Mailing List: January 1999, Message #1

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On 31 Dec 98 at 23:05, Tina B Csomo <tinabee3@juno.com> wrote:

> I know this does not apply to me since I own a '95, but is it next
> to impossible to install a turbo in '96 and'97's? Someone listed
> that the FM ECU is different in the later models. (Glad it's not
> me!)

Realizing my prior post could have been clearer :-)  I will clarify
a touch - the "FM ECU" is an aftermarket engine computer, sold by
our friend Bill over at dlralt.  It replaces the Mazda ECU (engine
control unit, I think ECU stands for).  "FM" standing for the
"Flyin' Miata" brand.  The Mazda ECU has three groups: 90-93, 
94-95 and 96-97.  The 96-97 has the OBDII schtuff (I am omitting the 
99 for purposes of this discussion)  Bill sells one model FM ECU to 
replace the 90-93's, and at the moment, another model to replace the 
94-97.  I think before too long, he will have a third version 
specifically to replace the 96-97.

So to the question: Is it impossible?  Kinda seems like "yes and no" 
- I think Sebring installs are going smoothly on the '96-97 models.  
IIRC they do add a resistor to one of the engine sensors, to change 
the readings that the stock ECU sees.  This helps to correct the A/F 
(Air to fuel) ratio and keeps the engine computer happy (so it does 
not "complain" by lighting the 'check engine' light).  The Sebring 
(and level 1 turbo kits) have low enough boost, that they do not go 
too far out of the stock operating range of the sensors, etc... and 
those setups seem to behave reasonably well, once the extra resistor 
is added.  Anything over about 6psi of boost, and things seem to go 
south.  Certain engine sensors start to get overloaded with all the 
boost, to which the engine computer does not take too kindly.  These 
sensors that get overloaded do not exist on the 90-95 cars - only the 
96-97 OBDII versions of the Mazda ECU have them.  Result - it 
suddenly becomes very hard to get the A/F ratio correct in the engine 
(very necessary to keep the engine in "one piece") and in general you 
get less than optimum performance.  Some folks like Beau (with an 
Autorotor - around 10-12psi IIRC) really had it bad, as the stock ECU 
really threw a fit, and made his '96 almost undrivable.  The FM ECU 
that Bill sells is especially designed to deal with such things as a 
high boost turbo/supercharger, and allows the engine to perform 
flawlessly (with the correct settings and user adjustments - it also 
"self tunes" or "learns" what it needs to do to keep the engine 
happy)

So the answer is "no, it's not impossible to install a turbo on a 
96-97 - for best results, add FM ECU and stir  :-)

> I just have to wonder if Mazda deliberately made it more difficult
> to put turbo-superchargers in by doing this. Let's face it...the
> mods most of us do to our beloved roadsters must certainly aggravate
> them, especialy since they spend big $$$ to make sure the car is
> ideal, to their standards.

I would say they have made it easier, if anything.  They really had
no say in going to the OBDII version of the engine computer.  The
government and environmentalists saw to that.  In general, OBDII is
a good thing, as it provides double checks as to the well being of
the engine, with regard to maintaining low exhaust emissions.  They
have made it easy for the aftermarket by providing a very strong
engine block and drivetrain (excepting the clutch) - both the 1.6
and 1.8 blocks have oil sprays under the pistons - an item that
Corky Bell lists in his book "Maximum Boost" as one of the last
things on the financial list to refit to an engine that has been
turbocharged.  That is to say, it costs a lot to add to an engine,
and most cars don't have it, turbocharged or no.  He indicated it's
somewhat of an "exotic" feature, that can be useful on high-boost
engines, and it comes stock on our Miatas - can't beat that!  Other
items, such as piston rods are much heavier than they need to be. 
Result, a stock Miata engine cannot make as much horsepower and
torque as say, a stock Honda engine of the same size.  Supposedly,
Honda "shaves to the bone" their engine internals.  Honda engines
(not picking on Honda here) are lighter, and can get more horsepower
out of the same sized engine - but turn up the boost, and things
start failing pretty quick, requiring major engine surgery (deep
internal upgrades) to make the engine survive.  From what I've read
and gathered in hearing others talk, if you took a high-boost turbo
kit (like from Bill), and managed to bolt it to a Honda engine, it
would pretty much destroy the Honda engine in short order (again not 
a flame bait, I've had no direct experience, could be proven wrong, 
but that appears to be the common wisdom among those I've talked to). 

The Miata engines have successfully performed quite well while 
maintaining power outputs almost 300% higher than stock.  250% higher 
than stock are commonplace numbers these days - and the only thing 
you gotta upgrade to get the power to the road is the clutch. Some of 
the 1.6l cars have problems with overheating - that may be somewhat 
due to age (IMO) and somewhat due to a marginal radiator setup, for 
high-boost applications.  Again, a few hundred bucks and an afternoon 
gets you a high-flow radiator and a cool running car.

a bit long winded - but that's my $0.02 on the forced induction bolt 
on scene for the Miata - hope I answered the original question?

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