Miata Mailing List: September 1993, Message #55
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   From: Herb Samuels 
Subject: Plug Wires, Fuil Filter, and other things
   Date: Tue, 7 Sep 1993 09:44:33 -0400

Hi Steve:  Sorry that I am just getting to respond to your e-mails but
I was away much of the time during the last several weeks.  First, I
didn't have any problem installing the A/C in my BBR conversion since
I had someone else do it.  From what I gather, the A/C installation is
almost as much work as the entire BBR installation.  My experience
with ALEX is that he frequently would make some mistakes so its
possible that he sent you the wrong belt thinking that your car had
power steering.  For example, Alex send me the ECU for a car without
A/C and this had to be swapped and now the A/C works.  The person at
BBR who is extremely informed is Keith Ramsey who seem to know a great
deal about the engineering of the BBR conversion for the MX-5.  As far
as charging my A/C, they charged mw about $100 when the conversion was
installed (big ripoff).

As far as rough running when the car is hot, does this mean normal
opperating temperature or is the temperature higher up on the
temperature dial?  I have always noted some mild vibration through the
clutch pedal when going up to 6,000 to 7,000 RPM.  However, below
5,000 the engine is reasonably smooth for a 4 cylinder.  If this is a
new finding, it may be related to advancing the timing  to 14 deg. 
The BBR ECU when the switch is set at the 92 octane position normally 
controls a timing advance at high RPMs.  Perhaps when you advanced the 
timing to 14 deg, the additional timing advance via the BBR computer is 
too much and the engine runs rough at high RPMs.

Did you advance the timing to get more power?  If so, there may be a
better way.  Keith Ramsey and Ken Brittain of BBR  told me that the
turbo is usually set for about 5 or 5.5 lbs of boost so they can sell
to the average person in the U.K. and have a Mazda warantee.  To
protect the engine from any possible damage, the ECU is set to cut off
fuel flow at more than 6.5 lbs.  However, if you set the peak boost to
about 6 lbs from 5 lbs, Keith said that you could get about another 5
to 10 horsepower without any possibility of engine damage.  To do so you
need to have a boost meter installed and determine the maximum boost
when in 5th gear going up a slight incline.  According to Keith, this
is the best way.  If the boost is less than 6 lbs, it is possible to
raise it by altering the turbo wastegate.  Keith can tell you how to
do this.  

I recently purchased a boost gauge from VDO which has a 270
degree sweep and goes from 0-15 lbs so it is easy to differentiate
between 5 and 6 lbs.  Did you install a boost gauge?  If so, where did
you put it.  I would like to place it where it is easy for me to see
but difficult for anyone else to see who might want to rip the car
off.  Mu car may already be set for about 6 lbs since it seems to have
higher 50-70 specs than indicated in the Performance CAR review of the
BBR turbo (I didn't want to try any 0-60 times because of possibly
damaging the engine).  My 50-70 times (air temperature about 75
degrees) were 3rd gear - 3.7 sec, 4th gear - 5.2 seconds, and 5th gear
- 6.75 seconds.  I don't know what the stock Miata times are in 3rd
gear but the reported values are 8.4 seconds for 4th gear and 12.5
seconds in 5th gear.  These values for the BBR conversion reflect the marked
increase in low end torque (about 150 lb-ft at 3,500 rpm and higher).

With regard to the fuel filter, if you never changed it and you have
over 35,000 miles it would be a good idea.

I did recently change my stock wires for NGK wires.  I have heard some
talk that some barches of stock wires developed problems over time.  I
had noticed some rough running between 2,000 and 4,000 RPM before and
after the BBR conversion even after the spark plugs were changed. 
When I changed the plug wires to new NGK wires everything below 5,000
RPM became quite smooth.

By the way, I am still looking for somwone with experience on Miata
suspensions in the lower New York, western Connecticut, eastern New
Jersey area if you or anyone on the list knows someone please let me
know.

Hope this helps,

Herb Samuels