Best of Both Worlds – v8rx7guy’s LS1 Swapped 1993 Mazda RX-7

V8rx7guy’s obsession with V8 engines started about 10 years ago while he was still in high school. At the time, Matt K. was driving a V6 Mazda MX-3 which he thought was one of the faster cars in his school. It wasn’t until the day he tested its acceleration against a 5.0L Foxbody Mustang that he realized that it was time for a different platform. Even though he knew that a large engine in a small car was the answer, he had a hard time finding the perfect car. “All of the cars I looked at that had V8’s that I could afford were always too heavy, not appealing on the outside, or really only performed well in a straight line,” Matt says. In his opinion, there were too many sacrifices when it came to domestic cars and he really wanted something that could handle well and still being fast in a straight line.

Matt’s roots began in the Japanese import world and he knew he wanted to keep it that way. He began researching which cars from Japan came with V8’s and as most of us know, there aren’t many options. While searching, he stumbled upon RX-7 owners who had swapped out the stock rotary engine in favor of an American V8. This piqued his interest and since he had always been a fan of Mazda, he wasted no time finding an FC RX-7 shell to build. While the shell wasn’t particularly clean, he was a poor high school student who was about to become a poor college student so it didn’t bother him too much. Matt ended up swapping an LT1 out of an early 90’s Camaro and drove the car all the way through college.

Upon finishing his degree in Mechanical Engineering and landing his first job, he bought this 1993 RX-7. An FD had been Matt’s dream car for many years and he wanted to take everything he learned from his previous RX-7 and apply it to a newer and nicer chassis. The first thing he did was source an engine and transmission from a 2002 Pontiac Firebird. The LS1 and T56 (6 speed transmission) was superior to his previous car’s LT1 in many ways but most importantly it was lighter. He knew that LS1 engines were aluminum which meant that there would be a minimal weight increase (if any at all) over the fully dressed turbo rotary.

Matt has owned his RX-7 for 5 years and it has gone through multiple iterations and upgrades. “My philosophy on building cars is to set achievable goals, modify to meet those goals, and to enjoy the car while taking feedback from how it behaves and determine a new set of goals,” he says. Every year Matt sets a new goal for the car which takes it to the next level. He feels that if he sets too lofty of goals at one time, the car will do nothing but sit on jack stands. By setting realistic goals and not trying to do too much all at once, he still gets to enjoy his car when summer rolls around. “Last year I met my goals of reaching 10’s in the quarter mile and competing in a handful of AutoX events. This year, I am shifting my focus to AutoX as I feel I have reached a level in drag racing where I will have to make comprimises to my car to go any faster,” Matt explains.

You may notice that Matt’s RX-7 is a slightly different yellow than other RX-7’s you’ve seen. When Matt was choosing a new yellow to paint his car (the car had already been painted yellow by a previous owner), he went through 10-12 different samples from various manufacturers before finally deciding on Mazda Bathurst Yellow. This yellow is the same color as Special Edition RX-7’s from the last year of production in Japan.

When I asked Matt what his favorite mod is, it was a difficult decision for him. He finally answered: “I think that my favorite mod, besides the LS1/T56 swap of course, is probably the roll bar. The roll bar was a requirement when I started running below 11.50 in the quarter mile. I actually designed and fabricated the whole bar myself which was a challenge for me. One of the nicest features about the roll bar is that even though it is welded in, I was able to design it to be moved in and out of the car throughout fabrication. This allowed me to do all the important welds outside the vehicle and even send it off for powder coating before welding it into place. A well-built roll bar that doesn’t interfere with daily driving is not an easy task, but I think it turned out really well and I get lots of compliments.”

One of the more sensitive questions that sometimes gets asked at car shows or drag racing events is: “Why would you replace the rotary with an American V8?”

His response: “I understand why people feel that the rotary engine is unique to the car, but that might just be the only valid argument. If people can get around that, they find that an LS1 does not add any weight or ruin the weight distribution. It is significantly more reliable, it has higher horsepower potential, and gets much better fuel economy. In my opinion, there really is a big difference in behavior between a high-sprung turbocharged car that makes it’s power up high (not just rotary, but in general) and a mildly built N/A LS1 that can easily produce 450 RWHP and over 380 ft-lb of torque through nearly the whole range of RPMs. It may not be a dyno queen of an engine at that level (though it is plenty capable if you chose to go down that path), but the low end torque and reliability allows the car to be competitive in any type of racing event you throw at it.”

Matt estimates that with his latest cam swap and other mods his car is making around 450 HP. He plans on having the car re-tuned in the near future and it should be making more power. His fastest quarter mile time is a 10.94 at 129 MPH with a 1.64 60′.

With all of the knowledge and experience from swapping V8’s into RX-7’s, Matt recently founded a company named Secondbolt Racing in Bellingham, WA. He currently designs parts for RX-7’s but would like to develop products for other import car owners that crave the power of a V8. Check out his Secondbolt Racing Facebook page.

Lastly, Matt (mattster03) would like to thank the community at norotors.com for being such an awesome group of guys. Most of them act differently than most car guys on online forums. They’re a no BS crew with a wealth of knowledge that he feels lucky to have learned from.

2011 Compilation Video – by v8rx7guy (Matt K.)

Modification List:

Engine/Transmission/Differential
2002 LS1/T56 Swap
EPS 230/238 112+2 LSA 0.600″/0.602″ Camshaft
PRC Stage 2.5 5.3L Ported Heads
LS6 Intake & Ported Throttle Body
Samberg Intake & Radiator System w/Spal Fans
JTR 1-3/4″ Long Tube Headers
Custom Mandrel Bent Exhaust & Magnaflow Muffler, Cutout Installed
Monster Stage III Clutch
Wilwood 7/8″ Clutch Master Cylinder
Katech rod bolts
ARP Head Bolts
PRC Dual Springs, Comp 7.425″ Hardened Push Rods
Denso “Supra” Fuel Pump
FMS 36lb/hr Injectors
-6AN Fuel Lines
MSD Spark Plug Wires
PC680 Battery
Custom-built Hybrid Mazda Differential 3.90:1 Gears & S4 TII Clutchpack
PCM Tuning by Ellis Groo @ Speedsecrets, Monroe WA

Exterior
R1 Wing & Front Lip
20% Tinted Windows
Replica ’99 Spec Tail Lights
Smoked Lenses
Shaved Antenna
V8 RX7 Badging

Interior
5-point Weld-in NHRA/SCCA Roll Bar, Removable Door Bar, Powdercoated Matte Black
RCI 5 Point Camlock Race Harness
Autometer Ultra Lite Oil Pressure & Water Temp Gauges
Kenwood/Infinity Sound System
Pro5.0, Steeda Triax Shifter & Cobra Shift Knob
Secondbolt Racing Shifter Thermal Plate
“V8-RX7” Floor Mats

Suspension/Wheels/Brakes
Enkei RPF1 17X9 +45mm wheels
Street/AutoX: 275/40/17 Nitto NT05 on 4 corners
Drag: Mickey Thomson ET STreet 26X10.5-16 Rear, Coker Excelsior 26X3.5-16 Front
Tockico Illumina 5-way Adjustable Struts
RSR Race Springs
Hawk HP Brake Pads
Improved Racing Front Strut Bar
Improved Racing Adjustable Front Sway Bar Endlinks
Corksport Stainless Brake Lines
Powerslot Brake Rotors
Tanabe Front Sway Bar
Speed Bleeder Fittings
Hinson Supercars Bumpsteer Correction Kit