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Mazda RX-7: Part 4

When Great Isn't Good Enough

Shiv S. Pathak
Oct 10, 2002
Photographer: Dave Coleman

Whoever coined the phrase "power corrupts" must have been driving an RX-7 twin-turbo. Months ago, we were praising this high-revving, rotary-powered rocket sled. While we are still mightily impressed, we can't help but wonder what some extra underhood potency would do to our beloved, yet maniacal, little Mazda. Still staying true to our initial goals of having a reliable, streetable, and durable track vehicle, we will not tolerate power at the expense of driveability or longevity. On the race track, we are still expecting a vehicle that can withstand hours and hours of gratuitous, flat-out, no-holds barred abuse--resting only to quench its unusually healthy thirst for gasoline.

Since the last installment, Project RX-7 has seen over 20 hours of track testing at Thunderhill and Laguna Seca Raceway. In fact, we have even logged a few days of tire-gnarling autocross to test its impeccably quick reflexes. When it's not running at full-steam on the race track or dodging big orange cones in a parking lot, Project RX-7 assumes the unglamorous role of a Northern Californian daily-driver. It makes nightly trips to Safeway and 7-Eleven, as well as all-too-frequent commutes between Los Angeles and San Francisco. To no one's surprise, since the car was acquired six months ago, it has accumulated 15,000 miles on its snazzy, amber-glowing digital odometer (52,000 miles total).

The RX-7's only downtime was at a local body shop caused by an embarrassing, fender-compromising excursion at Laguna Seca International Raceway. The bone-headed author/driver (that's me) accidentally planted two wheels off the track at turn nine. Trying to steer back on the pavement, I set the car into a high-speed, out-of-control, I-wish-I-could-wake-up-from-this-nightmare spin. Heading perilously toward the concrete wall at the inside of the turn, I stomped on the brakes, yanked the steering wheel ruthlessly, and chanted a quick prayer. Instead of smashing head-on into the unyielding barrier, the car pivoted and scraped backward along the wall. Fortunately, the damage was mainly cosmetic and failed to keep Project RX-7 from finishing the lap. (A roll bar will be installed in our next installment.) Fourteen days, several thousands of dollars, and a few cartons of Bondo later, Project RX-7 (and its humbled driver) were back on the track, as good as new, and ready to pick up where we left off.

And Where Exactly Did We Leave Off?
In the previous installments, Mostly Mazda carefully secured (with small tie wraps) the proverbial "rat's nest" of vacuum lines that hide under the RX-7's intake manifold. Left to their own adhesive strategies (Read: None.), these tiny hoses tend to harden with time--eventually blowing off and crippling the turbocharger's smooth, sequential operation. Mostly Mazda also replaced the well-used, semi-clogged fuel filter with a factory-fresh unit in an effort to minimize the chances of fuel starvation. To keep an watchful eye on underhood events, we also installed boost and fuel pressure gauges from Auto Meter on the A-pillar. Another helpful gizmo was a Blitz turbo timer which we mounted on top of the steering column. Later, Anthony Woodford of AWR installed a large-capacity radiator from Mazda Competition.

This exquisite, all-aluminum radiator offers nearly 50 percent more capacity than the ineffective stock unit. Woodford also installed a set of upgraded, heavy-duty front anti-roll bar mounts, replacing the stock units that have been known to bend and eventually break under heavy loads. Finally, a remarkably sophisticated front brake upgrade from Cooltech LLC., consisting of monstrous Porsche 993 turbo front "Big Red" calipers and 14x1.25-inch metal matrix composite rotors, were installed to improve the RX-7's already exceptional stopping performance. What we are left with is a reliable, cool-running, alarmingly short-stopping, race car begging for more muscle (and perhaps a better driver as well).

Horsepower, Engine Longevity, and You
According to Brian Richards of Mostly Mazda/M2 Performance, it is possible to substantially augment engine output without sacrificing long-term durability. Drawn from his experience in the race circuit, Richards' approach to increasing the RX-7's horsepower is time-tested, as well as track-proven. Due to the fact that these unique, high-output rotary engines are capable of self-destructing with just one serious knock, Richards goes to unusual lengths to maintain a significant margin of safety.

"There are only two things that you can't do a rotary engine," states Richards. "First of all, you can't run them lean. Second, you can't run them too hot. Rotaries naturally require gratuitous volumes of fuel to keep cool and happy. Running a relatively rich air/fuel mixture under boost allows the unburned gasoline to evaporate, which in turn, cools the combustion chamber. Without this chemical intercooling system, the engine can become extremely hot and can eventually detonate itself to death."

With these issues in mind, Richards has developed a series of power-enhancing upgrade "stages," available through his aftermarket product department, M2 Performance. Each of these stages has been thoroughly stress-tested on the road as well as on the track. Instead of offering an "a la carte" selection of bolt-on upgrades that could potentially lead to a poorly integrated and unsafe-running system, Richards has put together a concrete upgrade path that ensures appropriate fuel delivery and ignition management at every step.

To get baseline horsepower measurements we drove Project RX-7 to Fairfield, Calif. to pay a visit to Keith Paulsen of Superior Dyno Service. From his experience, a healthy, stock third-generation RX-7 typically generates somewhere between 215 and 225 hp at the rear wheels. Project RX-7 was no exception. Once strapped down on his portable Dynojet Model 248C dynamometer, Project RX-7 spun the heavy rollers with 218 rear-wheel hp in fourth gear--surely enough potency to squirt this sub-2800-lb lightweight around the street or track with impressive authority. With nearly 200 lb-ft of torque at only 3000 rpm, the dyno results prove the RX-7 doesn't need high engine speeds to provide alarming rates of acceleration. Interestingly, at around 4500 rpm, there is a small "hole" in the torque curve which indicates the brief dip in boost levels during the transition to the secondary turbo. Once both turbos are spinning at full clip (by approximately 5100rpm), a torque peak of 199.2 lb-ft is logged.

For a car that redlines at stratospheric 8000 rpm, there doesn't seem to be much need to spin much above 6500 rpm. According to the Dynojet results, the torque curve starts immediately tapering off once peak torque is produced. From the looks of it, the RX-7 suffers from the malady common to most OEM turbo cars--massive amounts of exhaust backpressure.

With nearly 200 lb-ft of torque at only 3000 rpm, the dyno results prove the RX-7 doesn't need high engine speeds to provide alarming rates of acceleration

More Power: M2 Performance Stage One
The first stage in Richards' series of power-enhancing upgrades consists of three components: A free-flow cat-back exhaust, a cold-air intake box, and a re-mapped ECU. After one test drive, it becomes audibly clear that Mazda designed the factory cat-back for unreasonably low noise levels and not for optimal performance. In bone-stock form, the RX-7 is a very quiet car. So silent and nondescript, in fact, that Mazda installed an audible redline "beep" to remind the driver to up-shift in case the radio or a helmet muffles the subtle sounds from the engine. In stock form, the RX-7 sounds like a finely-tuned Quisinart wrapped in a thick, woolen blanket. While the mini-wail is completely inoffensive, it is also depressingly uninspiring. With a power plant so wonderfully rev-happy and vibration-free, a more distinctive (and obvious) exhaust note would certainly be welcome.

Based on his experience with a variety of aftermarket exhaust systems, Richards chose to install a Racing Beat cat-back exhaust system in Project RX-7. Quiet at idle and drone-free under cruise conditions, this particular cat-back emits a sonorous bark under hard acceleration. It also touts polished 304 stainless steel construction, 3-inch mandrel-bent tubing, and a relatively inconspicuous (as far as aftermarket exhaust tips go) 4-inch tip (an optional 3-inch, dual-tip system is available for a more stock-like appearance). Besides its obvious visual and aural benefits, the cat-back offers a dramatic reduction in horsepower-robbing exhaust back-pressure as well as a 10 lb reduction in mass.

The second component in Richards' upgrade involves removal of the stock intake system in favor of a less restrictive design. The stock intake consists of a large panel filter which draws air, via a tuned, plastic cross tube, from a front-mounted duct. This duct, which also feeds the small air-to-air intercooler, is routed from the "mouth" of the car. While the stock intake system draws cool air, it also robs much-needed airflow from the underhood-mounted intercooler. Certainly not the best performance-minded approach.

Unsatisfied with the majority of aftermarket intake systems, few of which actually draw cold air, Richards designed his own system. Expertly crafted in lightweight aluminum, the M2 Performance cold-air box houses two generously sized K&N cone filters (one for each turbo) as well as all necessary orifices for the twin blow-off valves and air pump piping. Fully shielded from the super-heated underhood air, the intake box draws a fresh, ambient air charge through a 1.5x9.75-inch opening between the radiator and an adjacent frame rail. In our particular case, our Mazda Competition radiator had to be slightly trimmed to allow air to pass though. The straight-forward installation involved unbolting and removing the stock intake assembly, dropping in the form-fitting airbox, and sliding on all the rubber hoses. Like the stock intake, the M2 cold air box effectively silences the air pump nose which, when unmuffled, sounds like a dying goose.

As many RX-7 owners have experienced firsthand, increasing intake flow and reducing exhaust backpressure can adversely affect the carefully tuned, sequential operation of the twin turbocharger system. More precisely, the secondary turbo will tend to momentarily "spike" to abnormally high boost pressures during transitional operation. According to Richards, this brief over-boost can trigger a potentially dangerous lean-run condition, which, in turn, can lead to destructive detonation. To remedy this situation, Stage 1 also tackles the electronics side of the equations by re-mapping the stock boost curves. Not only does this ECU upgrade eliminate the unwelcome boost spike, it also raises maximum high-rpm boost levels from 10 psi to nearly 12 psi. The upgrade also takes advantage of the engine's enhanced breathing ability by carefully modifying fuel and ignition maps.

Back on the Dynojet (this time at The Dyno Room at Frey Racing in Mountain View, Calif.) the RX-7 spun the rollers to a staggering 269 hp, and 236 lb-ft of torque. Improvements below 4500 rpm (on one turbo) are healthy, but when the second turbo spools up, the intake, exhaust, and ECU really start working. Interestingly, power still drops off significantly past 6500 rpm.

M2 Performance Stage 2
The next step involves the elimination of the RX-7's troublesome "pre-cat" system. This highly-restrictive, kinked pipe connects the exhaust manifold to the main cat assembly. As its name implies, the pre-cat houses a small catalytic converter which is designed to reduce emissions during cold start. Not only does the pre-cat hinder turbo performance, it also traps heat within the engine compartment. To make matters worse, according to Richards, the pre-cat's innards tend to crumble and clog over time--the mechanical equivalent of sticking a proverbial banana in the tailpipe. This results in a dramatic loss of power and gobs of underhood heat. Replacing this hideous contraption with a 3-inch diameter, stainless-steel, mandrel-bent downpipe completely eliminates this possible point of failure while simultaneously improving engine performance and output.

Installing M2 Performance's downpipe proved to be another "plug 'n play" job. While the stock exhaust bolts can be stubborn and difficult to remove, once prepared, the downpipe literally snapped into place with minimal fuss. Using the stock exhaust manifold studs, the entire down-pipe installation procedure involved no tattered fingers, stress-induced headaches or gratuitous hair-pulling. As with the bolt-on modifications in Stage 1, the installation of the downpipe was met with appropriate ECU remapping. As Richards' predicted, the downpipe upgrade dramatically improved engine response and turbo spool up. The improvements were not only subjective. On the Dynojet the Stage 2 modifications yielded 284 hp and 252 lb-ft of torque at the wheels. At best, we gained over 68 hp vs. our stock run--not bad. Our featherweight RX-7 is fast. Very, very fast.

Knock Knock. Who's There? BOOM!
Detonation, as we all know by now, can be the end of a rotary engine. Those who are used to tuning their performance cars by listening for knock, will be a sorely disappointed if they ever try to do so with an RX-7. These engines are very strong and durable if operated within their parameters. Outside these parameters, they will blow apex seals (analogous to piston rings in a reciprocating engine) before you can yell "Crap!" Although we have taken many measures to reduce the chance of detonation, we are still aware that nothing is foolproof. We know our timing, fuel and ignition maps are safe and conservative.

However, there are always variables that are simply beyond our control. For example, there is always the remote chance of filling up the tank with poor quality gasoline. There is also a very real possibility of fuel starvation under hard cornering (especially with a low fuel tank). Not to mention the harmful effects of heat soak and prolonged periods of boost as often experienced on the track. Mazda addressed this need and designed the third-generation RX-7 with an electronic knock sensor that carefully listens for the early tell-tale signs of detonation and reacts by retarding ignition timing. However, for modified, high-output engines, the authority range of the knock sensor device can easily be exceeded. In other words, the knock sensor electronics are designed to provide an adequate margin of safety for a stock 255 hp, consumer-driven engine, not a 320-plus hp, race-driven engine. What is the solution?

According to Richards, the J&S Safeguard knock sensor is the best available alternative for our particular needs. Used in conjunction with the stock knock sensor, the J&S Safeguard carefully listens to the engine from a small pizeo-electric microphone which screws into the rear rotor housing. (The stock microphone screws into the front housing.) The control unit is mounted in the cabin (in our case, under the carpet in the passenger-side footwell). Offering adjustable threshold sensitivity, the Safeguard unit can be tuned to carefully listen for any preliminary signs of knock and react immediately by retarding up to 20 degrees of timing for each of the six individual rotor faces. Also available is a small, dual bar graph, LED monitor which displays amount of retard (1 light equals 2 degrees of retard), as well as a air/fuel ratio meter which reads voltage from the stock oxygen sensor.

Richards installed the Safeguard in Project RX-7 in preparation for the "Abuse-A-Thon" we have in store during our next track evaluation session. Tuning the unit takes but a few minutes. One simply adjusts the sensitivity (by turning a small knob on the control unit) until the Safeguard just barely begins to pull out ignition timing. This ensures that any atypical sound (Read: Knock.) will be met with an immediate reduction in ignition advance. For our dyno session, we ran our tests with and without the Safeguard. Since knock was not present during test, when activated, the Safeguard only retarded timing by 1-to-2 degrees. There was no appreciable reduction in wheel horsepower. While it wasn't necessary for our dyno testing, the J&S unit provided a very welcome peace of mind and perhaps the best insurance one can have against catastrophic, knock-induced, engine failure. Richards highly recommends this well-engineered system for a more modified rotary engine.

Horsepower Hype--Separating Fact from Fiction
Converting rear-wheel power figures to crank numbers is anything but straight-forward. When translating wheel figures to engine claims, some experts use fixed conversion factors. That is, if a stock 218 rear-wheel hp RX-7 is rated from the factory at 255 crank hp, it must have 17-percent driveline losses. A 284 rear-wheel hp RX-7, then, must be blessed with 332 crank hp. This popular, if somewhat optimistic, correction technique assumes driveline loss is proportionate with engine output. That is, as wheel horsepower increases, driveline loss must also increase commensurably. Some would even disregard stock quotes and apply a standard 20-percent drivetrain loss figure. Using this popular correction factor, we already have a 340-hp monster! Some would vehemently disagree. These folks would tend to use a fixed number to represent driveline loss. In this case, they would believe that all RX-7s are faced with a driveline loss of 37 hp. (255 minus 218). Using this correction method, Project RX-7 produces a more conservative 321 ponies at the crank. All three techniques, (as well as other far more [Ahem.] optimistic methods) have been used at one time or another.

Our friend at Superior Dyno Service, Keith Paulsen, looks at this issue from another perspective. "The first mistake people make is assuming that factory-quoted horsepower figures are accurate," Paulsen states. "Due to marketing hype and year-to-year tuning changes, it's not always accurate to derive drivetrain loss by comparing measured wheel horsepower and factory quotes."

Paulsen also believes that drivetrain losses are neither an absolute percentage nor a fixed number. Instead, he feels the crank-to-wheel relationship is far more beguiling. From his considerable experience, Paulsen suggests that low horsepower (100-200 hp) cars may suffer from as much as 15 to 20 percent of drivetrain loss at the rear wheels. For more powerful cars (200-400 hp), the figure is around 12 to 15 percent. And for mega-powered cars (above 400 hp), the drivetrain losses can reduce to 10 percent or less. What's going on? Getting into the physics behind this complex relationship is worthy of a project in itself. (Engineering editor, Dave Coleman says he's working on it.) For the scope of our project, let's take Paulsen's advice and only compare apples to apples. In our case, our apple is rear-wheel horsepower. So be it. Readers should also note that we made sure that at no time were race fuel, tweaked ignition maps, chilled intercooler, or wastegate trickery used during our dyno testing. We tested our daily driver, not a one-off test mule. Notable was the fact that the five consecutive runs, separated by five minute "cool down" periods, yielded variances of only 1 to 2 hp.

On the Road.....
With only 2,960 lbs to push around (including the driver), the additional power is a revelation. Even at low engine speeds, the difference in thrust is noticeable. Turbo lag has been reduced from "minimal" to "barely noticeable." It seems as if the car constantly tries to tempt you, the innocent driver, into participating in irrational displays of horsepower. If the RX-7 succeeds in persuading you to plant the throttle flush against the carpet, you'd better make sure that the road ahead is clear of traffic and law enforcement, for nothing will prepare you for the madness that takes over just above 4700 rpm. As soon as the secondary turbo gets online, the exhaust note deepens, the intake hisses ever so slightly, the car squats on its haunches and takes off like a twin-turbo-powered slingshot. It immediately becomes clear that the exhilarating rush a rotary provides cannot be matched by any conventional reciprocating engine. It spins to its 8000 rpm redline with absolutely no fuss or extraneous vibrations. The sequential operation of the turbo system, while now far more obvious to the driver, is still smooth and predicable. More impressively, the transition to the secondary turbo is accompanied by no perceptible "flat spot" or "spike" in boost pressures. During some impromptu displays of real-world horsepower, our Project RX-7 consistently showed its handsomely sculpted taillights to HKS's famed 180-mph Toyota Supra Turbo. While the modified Toyota is capable of extraordinarily high terminal velocities, its sheer heft hinders its ability to keep up with the nimble Mazda at more down-to-earth speeds.

Post-Modification Postulations
Since history has provided many instances where a "reprogrammed" ECU is actually nothing more than a stock unit with a fancy label (and a princely price), we felt it would only be fair to document the differences (if any) between a stock ECU and M2 Performance's remapped ECU. It only takes one brief sprint through third gear to feel (and see) the difference between the two ECUs. As Richards predicted, with the stock unit in place, the transition between single and twin turbo operation results in an un-Godly 15 psi spike in boost pressures. Not only does this sudden over-boost condition upset the car's nicely tuned driveability, this also becomes the most frequent cause of detonation.

"The stock ECU is mapped for stock boost and back pressure levels. Once these values are altered through modifications, the stock ECU can no longer compensate for safe operation," Richards explains. "Our remapped ECU solves this problem by compensating for the increased flow by retarding timing, altering boost controller values, and increasing fuel supply. The net result is a engine than can safely run higher power levels on premium pump gasoline, while still maintaining a margin of safety."

Fearing the very real possibility of detonation, Richards discouraged us from putting Project RX-7 through its paces on the Dynojet (let alone the track) while temporarily armed with a stock ECU. Although we were not able to log our own results, we did examine a dyno run of another modified RX-7 from the vast database at Superior Dyno Services. According to Keith Paulsen's notes, this particular car was equipped with an intercooler upgrade, an intake, a cat-back exhaust, and a stock ECU. The dyno results spoke for themselves. Below 4500rpm, it developed torque figures similar to our carefully tuned RX-7. However, as expected, a massive torque spike of 304 lb-ft occured at 5000 rpm. Just after this spike, the torque curve immediately falls to 225 lbft, reaching only 200 lb-ft by 6500 rpm. In contrast, when equipped with the remapped ECU, Project RX-7 exhibits a far more linear textbook approach to providing thrust. Although the RX-7 with the stock developed peak horsepower at the spike, it isn't what we would call usable horsepower. Its real peak of 255 wheel hp, which occurs at 6500 rpm, falls short of Project RX-7's lofty 284 wheel horsepower. More importantly, our car is far more driveable, faster, and resistant to detonation.

Just to make sure that we didn't turn Project RX-7 into an environmentally unfriendly smog monster, we drove Project RX-7 to a local California-state emissions referee. With the intake, downpipe, exhaust, remapped ECU, and the main catalytic converter in place, the vehicle passed California's stringent tailpipe sniff test with flying colors. An underhood visual inspection would be another story, of course. Well, at least everything is bolt-on (and more importantly, bolt-off).

Suspension Upgrades: Making Good even Better?
Sometimes it seems middle-aged, mainstream automotive journalists who spend much of their time behind the large-diameter steering wheels of sedate family sedans and dreary SUVs forget what it is like to drive a real sports car. Perhaps their backsides are overly sensitive to a firm, well-dampened suspension. Or perhaps they forget a car with low-profile tire and only a few inches of ground clearance cannot possibly tackle pot-holes and gravel-strewn roads without protesting. Frankly, this is the only reason I can think of as to why other journalists have accused the RX-7's suspension of being too stiff. Hogwash.

From the start, we've always felt that the stock suspension is a bit soft for our tastes. Apparently, Racing Beat Inc. of Anaheim, Calif. feels the same way. While we were at their headquarters a few months ago checking out their impressive facilities (which, by the way, still devote a lot of floor space to Mazda rotaries), Jim Langer showed us a glimpse of a brand new suspension system just made available for the third generation RX-7. Imported directly from RS*R in Japan, the coilover system offers stiffer spring rates (along with helper springs to keep the main springs seated under droop conditions), adjustable shock absorbers with enlarged oil reservoirs, and threaded spring perches for height adjustability. Also available through Racing Beat was a set of RS*R "Pillow Ball" upper mounts. The all-metal, disk-shaped devices employ a solid ball-and-socket joint (not a flex rubber interface) to provide a no-flex interface between the chassis and the shock absorber shaft. In effect, this upgrade removes every bit of rubber (with the exception of the bump stops) that existed in the stock suspension.

Installation was a breeze. Although the instructions were in Japanese, the easy-to-understand drawings speak for themselves. By the time of this writing, comprehensive directions in English should be included. The entire installation, from beginning to end, took only three hours. Since we were using the RS*R pillow ball mounts and not the stock upper mounts, there was no reason to disassemble the stock coilover assembly. The helper springs have a very light spring rate, and as a result, no spring compressors were necessary during the assembly and installation of the new coilover system. According to Jim Langer, the RS*R coilovers employ a 447 lb/inch spring up front and a 391 lb/inch in the back. For comparison, a stock '93 RX-7 sports 280 lb/inch and 198 lb/inch fore and aft, respectively. Up front, there is more height adjustability than anyone would need. It could be adjusted to ride low enough for the tires to scrape against fender lining or high enough to make a stock car look like an import low-rider. In the rear, however, the lowest perch setting could only lower our car approximately 1 inch. Significant drop, but not as low as some may desire. However, one can sucessfully lower the ride height by simply removing the small helper springs. Since our requirements didn't mandate a fashionably slammed, underbody-scraping low rider, we kept the rear helper springs in place, dropping Project RX-7 approximately 1 inch at each corner.

So how does it work on the street? From what we can tell so far, pretty darn well. With 16 steps of stiffness adjustment, the shock absorbers can vary from chatter-your-teeth stiff to exceptionally compliant and downright comfortable. Despite the significant increase in spring stiffness, the softest shock setting yielded a ride easily as compliant as the stock touring suspension and far less jarring than the over-dampened, "sport-tuned" factory R1 suspension. Road feel was also improved, no doubt due to the elimination of the rubber-laden upper mounts. While there would never be a reason to use the maximum shock stiffness under any conceivable circumstance, it's very easy to find intermediate settings that fit one's need. Once nicely dialed-in, the shock absorbers responded readily, swallowing violent bumps and pot-holes while resisting motion caused by steady state cornering and braking. What we're left with was the best of both worlds. A car that is undeniably comfortable under real-world conditions, yet still resists body roll and provides razor-sharp handling. From what could be garnered from an on-the-road evaluation, the car has become even more eager to change direction. In fact, it would be safe to say the car feels more tail-happy than a stock RX-7 which, by comparison, tends to push gently as cornering forces builds. The mild oversteer attitude provided by the new suspension does not come as a surprise considering the relatively stiff rear springs. It is possible, however, to tune for more understeer by increasing shock stiffness up front and reducing stiffness in the rear. Increasing air pressure a few pounds in the front tires would also help to keep the rear end in check.

However, for anything less than bonzai, no-holds barred driving, the cornering attitude at the limits of adhesion are never realized--especially in a vehicle that is capable of pulling 1.0 G on the skidpad. For autocross, which favors vehicles that sacrifice some stability for exceptional transient response, this suspension may be close to ideal. On a high-speed track, however, the uninitiated may find it a bit more than they bargained for. Either way, the RS*R system provides exceptional performance in a thoughtfully designed package.

Conclusions
In the next installment of Project RX-7, we will continue to increase power output through the installation of a upgraded intercooler, a high-flow fuel pump, and a J&S Safeguard knock sensor unit. With the help of Cooltech LLC., we will attempt to upgrade Project RX-7's rear brakes while installing some very trick brake cooling ducts from Mazda Competition. A second oil cooler is also in store for our trusty rotary-powered steed. And what race car would be complete without a real roll bar? That's next as well. Beyond that, we still have to investigate possible clutch and flywheel upgrade alternatives, further suspension work, a vented hood, a strengthened powerplant frame, race seats, as well a host of other functional modifications. We are also going back to Thunderhill Raceway for some serious evaluation. Stay tuned because things are just starting to heat up.

Sources
Cooltech
15216 Mansel Ave.
Lawndale, CA 90260
(310) 219-2888

The Dyno Room at Frey Racing
1911 Plymouth St.
Mountain View, CA 94043
(650) 964-2456

Mostly Mazda/M2 Performance
2111 Freemont Street
Concord, CA 94520
(925) 686-9047

Racing Beat
4789 E. Wesley Drive
Anaheim, CA 92807
(714) 779-8677

Superior Dyno Service
1740 Enterprise Dr. # 12
Fairfield, CA 94533
(707) 425-DYNO (Office)
(707) 425-6062 (Shop)

Thunderhill Park
5250 Hwy 162
Willows, CA 95988
(530) 934-5588

By Shiv S. Pathak
17 Articles

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