Miata Mailing List: August 1993, Message #33
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   Date: Wed, 4 Aug 1993 18:28:23 -0400


>From jwa@yog-sothoth.dcrt.nih.gov Thu Aug  5 06:58:16 1993
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From: jwa@yog-sothoth.dcrt.nih.gov (James W. Adams)
Message-Id: <9308042057.AA19240@yog-sothoth.dcrt.nih.gov>
Subject: Re: Miata M2 1006
To: johnny@minnie.cs.su.oz.au
Date: Wed, 4 Aug 93 16:57:50 EDT
In-Reply-To: <93Aug2.212527edt.72870-4@jhunix.hcf.jhu.edu>; from "Sheik Chiang Fong" at Aug 2, 93 9:26 pm
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Sheik Chiang Fong epistolates:

> Has anyone thought of shoe-horning the 929 V6 into a Miata?
>
> What would this require?
>
> I know this would require a lot of money, :-)
>
> but would it require modification of the suspension and the guards.
>
> I've also heard of a monster miata, with a Ford 302.  Surely if someone
> can stuff a V8 in the miata, the 3 litre V6 would be easy.

>From what I understand the 929 V-6 swap was originally done as a one-off
prototype for one of the chief engineers at Mazda of Japan.  It then
found its way into the M2 in tamer tune.  (The prototype had over 300 HP).

The Ford is a much easier swap, oddly enough.  From what I read about
the V-6, they practically had to remanufacture the front of the car to
get it to fit.  It definitely didn't sound like something in the realm
of a do-it-yourself swap.

The Ford is a very compact engine, and fits the car with minimal
cutting.  The Ford 5-speed transmission is actually lighter than the
Miata unit, making up for some of the engine's added weight.  The
result, while handling surprisingly like the Miata, drives much more
like the Mustang in a straight line.

I'd recommend checking out the available turbos.  The mild BBR will still
give 0-100 KPH in the mid 7 second range with no loss of reliability or
driveability and no turbo lag.  Cartech, BBR and others make more potent
turbos as well that will easily match the V-6 at much lower cost and
effort to install.

I haven't done any mods to my Miata other than advancing the timing, but
I built a turbo RX-7 back in 1980 that made about 350 HP and would do
0-100 KPH in a shade under 5 seconds.  I didn't have access to the kind
of engineering facilities that the modern kitmakers have, so I used
water/alcohol injection and a 4-bbl carburetor instead of an intercooler
and fuel injection, and the car had a significant turbo lag since I
wanted the turbo to be large enough to deliver a full 12PSI of boost at
8,000 RPM.

The Miata turbo kits are more sophisticated, with less lag and better
thermodynamic and fuel efficiency.  The costs range from about $2,500
for the BBR to $5,000 to $7,500 for the more potent setups.  There is
now a kit for the Ford 5.0L V-8 swap (would be radical with the RHO
roller-cam engine you can get from Ford Parts), but I am unaware of the
cost.  I expect it would be in the $10,000+ range though since you have
to replace the engine, engine management, exhaust, transmission,
driveshaft, differential, rear brakes, suspension, etc.  The cost for
a 929 V-6 swap would probably be higher and would have to be done by
a shop.  The V-6 would have much less performance than the V-8 but
would sound, feel and rev more like the Miata four.

If you really wanted an A.C. Cobra-like car, the Ford RHO V-8 would give
you somewhere between 350-500 HP depending on whether you  use a
street/emissions legal fuel injection with catalyst exhaust or a
wide-open racing setup.

Jim

--
James W. Adams     --     Bioinformatics and Molecular Analysis Section
Building 12A, Room 1050              jwa@alw.nih.gov, uunet!nih-csl!jwa
National Institutes of Health              phone: (301) 402-4154
Bethesda, MD 20892                          "Spay the Children"