stilettoman’s 1984 Mazda RX-7

Rotary Powered Porsche 968  I had the opportunity to buy a Porsche 968 Cabriolet with nice body and interior, but with no engine or transmission.  The price was too good to pass up, even though I really didn't need another project. I had a very nice custom built 4 port 13b, street ported, and a very low mileage RX-7 trans, so I decided to do this conversion.   This conversion required some serious fabrication -  not for the average backyard mechanic.  I would not have attempted this without the help of Sean O'Brien, my fabricator/welder.

Bed can be lowered for easy loading, then raised to desired height for the load or the terrain. This 8 inch lift also allows a handy towing setup that does not require a winch. The money saved in tow bills in the past 20 years for my family and a few friends is enough to recover the entire cost of this project.

Page OneSee my other projects on the next six pages. My custom built three wheeler, the Stiletto, is described on pages 5 and 6.  The rotary powered Porsche 968, is shown on page 7.  My most recent project is the Skyline turbo motor conversion into the red and silver 84 RX-7 - see "Owners other rides" page.1984 RX-7 GSL with Ford V8, Ford AOD (automatic overdrive) transmission, Precision Industries (small diameter) 2800-3000 rpm torque converter, stock rear axle with limited slip, 1990 RX7 front and rear brakes, 15" BBS alloywheels from 1990 RX-7 convertible, Goodrich GForce tires are 205/50 front, 225/50 rear. Empty weight 2550 pounds. Driven only in nice weather, chassis had about 90,000 total miles, engine about  30,000 miles as of August 2011, when I sold the car.Engine - Ford 302/5.0, Edelbrock alum heads, Ford Mustang HO roller cam, Comp Cams roller rockers, KB 9.5 pistons, Edelbrock Performer RPM intake, Edelbrock 600 carb, Ford Racing aluminum water pump, MSD ignition. Custom airbox, K&N air filter, Ron Davis aluminum radiator provided by Grannys Speed Shop. Exhaust system by Sean O'Brien, 2 1/2 Y into 3 inch single exhaust, headers ceramic coated inside and out.The hood would not close over the air intake, so I welded on the hood bulge from a 280Z and did my "Bondo Magic".

Here are some of the past projects my sons and I did. The 1980 GLC had a stock 13B, RX4 trans, early RX7 struts and brakes, and a custom made rear axle to accept an RX7 Limited Slip. Built in 1987. I drove it over 100,000 miles in 4 years.  We built this 1984 red convertible in 1990. We grafted on an RX2 rear section, providing a trunk and a 60s Italian flavor to the car. Most people don't seem to know that the RX2 was designed by Bertone. We added GLC chrome door handles, polished the windshield trim, made the grille from the RX-2 rain gutter trim. This had the most extensive bodywork of any custom I have built.  I sold this car in 1992 to the current owner, who keeps in it pristine condition.

I have been thinking about building a 3 wheeler for many years, looked at some of the existing designs, and decided that I wanted something with better crashworthiness than the existing designs. The engine, rear suspension, instruments and various other parts are from a Kawasaki ZN 1300 Voyager. The engine is basically the same as the KZ 1300, but with electronic fuel injection, 130 HP. The complete vehicle weighs 1050 pounds without fuel, with almost equal distribution of 350 pounds on each wheel.The chassis is built by Sean O'Brien, TIG welded entirely of 4130 chrome moly tubing. The windshield frame is the primary rollover structure.  The chassis is built in two sections, joined at the firewall. Exhaust is stainless.

Fabricating tail and turn lights.  Housings made from PVC pipe fittings, lenses from some side marker lights.   Bar-end type mirrors incorporate the front turn signal lights.  Lights are fabbed using LEDs, 44 LEDs per light.    Hub caps & steering wheel cap are black anodized and laser engraved.

March 2010 - added wire spoke wheels, custom made by Pro Wheel Racing.June 2010  - Installed new custom billet oil pan designed and made by Tom Chamlee.  This is two inches shorter in height than the stock motorcycle pan.  We originally had modified a stock pan, but could never stop the leaks.  This billet pan is a real work of art.

Next photo shows the air filter, transmission cooler, radiator, custom modified oil pan, crossmember and engine mounts, and custom made fitting to allow use of RX7 oil pressure sensor. Notice the stock oil filter has good clearance. Of course after I did all this the hard way, Grannys Speed Shop started selling kits for this conversion! Second photo shows exhaust Y pipe and 3 inch Cat.

I built this 1984 GSL-SE convertible in 1992.  It used an Alfa Spyder top mechanism, and a section of a Corolla roof and sunroof for the trunk.  It is bright silver on top, shaded to charcoal silver on the rocker panels.  I sold it after a few years, and then in 2005 I was told it was in Japan, for sale on an internet auction.

The original Porsche transaxle was big and heavy, so there was plenty of room for a 2nd gen RX-7 LSD.  I did some grinding on the torsion bar tube to get more clearance for the diff, and Sean did some rebending of the sway bar.  The custom  mounting is hung from the original cast aluminum crossmember that supported the transaxle.

We put spacers on the front crossmember to move it down one inch.  Since the A-arms move down with it, this will have no  effect on bump steer.  We also moved the steering rack down one inch relative to the crossmember, so the top of the rack is flush with the top of the crossmember.  Modifying this aluminum crossmember requires some expert welding.  This theoretically could affect bump steer, but it seems to drive really well.

My first custom car was this 1972 240Z custom convertible, built in 1981. I used a Fiat Spyder top mechanism, made the trunk from the original hatchback. I sold it to the current owner in 1984. In the late 1990s, my son rebuilt it with a fresh engine and interior.  Just in case anyone here does not know, the early style RX-7 and the 240Z were never built by the factory as convertibles. All three of these custom convertibles required extensive structural reinforcement.

Front brake conversion parts custom fabricated by Tom Chamlee. Equivalent conversion parts are now available from commercial sources. These 4 pot aluminum calipers and 11 inch discs are common to any 5 bolt 2nd generation RX-7. The 5 by 4 1/2 bolt pattern is also common to many Ford, Toyota and other cars. A 1.25 inch spacer adapter was required to provide clearance with these wheels.  Stopping power is excellent.

The rotary engine is so small, we were able to move it forward, so only the narrowest part of the transmission is in the floor tunnel.  This required moving the shifter aft six inches on the transmission. We used a Twister race muffler as a presilencer, and then into the stock 968 muffler, which is stainless.  It has a pleasant exhaust note and is pretty quiet except at full throttle and high rpm.