Around the turn of the century, several more recent generations of the Nissan Sentra had a strong cult following in North America. Plentiful, cheap, understated B13-generation cars offered the young enthusiast an option that would give them the sport compact experience without having to become “one of the Honda guys,” as MotoIQ’s Mike Kojima put it.
Then an engineer for Nissan, Kojima saw that the Sentra had some of the ingredients necessary for a thriving race category. By 2001, the B13/third-generation Sentras had been figured out. “We’d been working on those cars for a while by that point. Because they were cheap and easy to work on, we kept them around as beaters when we started making a little more money. Being the second or third car in some people’s collections, they didn’t seem to mind turning them into racecars.”
Pricing around that time made the conversion process easy. A ratty example of a car could go for as little as $500, and a decent motor could be bought for $350. For a lightweight coupe with a motor with a fairly significant aftermarket behind it, the uncommon SE-Rs weren’t an unwise choice for the aspiring club racer looking to be a little different.
At the request of NASA SoCal racer Tom Paule, Kojima was asked to help design a series that would support the then-current Sentras. The plan included a simple rules set revolving around a power-to-weight ratio that ensured parity across a reasonably wide range of models. These cars had to be front-drive and retain the standard subframe, floorpan, front clip, and unibody — the last item without any tube-frame additions.
For the more popular SR division of the series, the eligible models were as follows: any SR20DE-powered Nissan Sentra with chassis code B13, B14, B15, P10, or P11; or any QR25DE-powered Nissan Sentra with chassis code B15 by the United States Department of Transportation for street use at the time of manufacture.
Kojima knew the foundation was ripe for an enjoyable racing series, so he joined along as a racer. Rather than turn his street car into a racecar, he made the wise decision to skip a few superfluous steps and buy a body-in-white vehicle built by a racer.
Lou Reba built this B13 Sentra for IMSA Firehawk just years before he sadly succumbed to leukemia. After his death, his wife put this SE-R up for sale along with a second chassis, largely untouched, and a pile of spares. Kojima knew he’d found the perfect collection of parts to give this new series an honest stab.
Racing Reveals All
Dubbed “Dog I” from the livery celebrating the Petco sponsorship Reba had acquired, this car was already a real racing car without many shortcomings. Kojima attended the inaugural SE-R Cup weekend with this car in the same state he bought it from Reba’s widow, mainly as a favor to Paule. “I went mainly because [Paule] wanted me to help make up the numbers, but I left totally smitten with the series. I wanted to run the series and see what the car was capable of with a little fine-tuning.
Dog I’s SR20DE motor made healthy midrange torque and decent top end power — about 146 horsepower at 7,000 rpm — enough to run on par with the Honda Challenge H4 machines, provided the track suited them and their punchier motors. Therefore, the stronger SE-Rs worked well at Auto Club and Willow Springs, but the H4 cars had the technical advantage at Buttonwillow. Their respective strengths and the low running costs made the series fairly competitive and easily accessible.
Even better, that power could be achieved cheaply since the rulebook made it virtually impossible for the series to morph into an arms race. “The rules were such that even a junkyard motor would be competitive,” Kojima said.
And more than just powerful, the SR20DE was mostly solid. “From the factory, it would run hot and run high oil temps, but that was it. So I under-drove the water pump and added a big water pump and oil cooler and those two changes made it bomb-proof. If the powertrain had one weak link, it was the gearbox, which required a rebuild after a couple seasons of competition. It was definitely the most reliable inexpensive car I ever raced.”
The general problem with the B13 Sentra, and there weren’t many, was that the handling left a lot to be desired. “The suspension design was not the greatest,” Kojima began. “There was probably as much bump steer as there was suspension travel. The rear suspension design would bind pretty quickly, too.”
Additionally, its torsion beam rear was designed with a half-degree of static toe-in. In order to get the car rotating nicely, some tried using special shims, and employed a special jig to bend the rear axle to achieve a few degrees of toe-out.
Up front, things weren’t much better. “The front suspension geometry couldn’t be rectified under the SE-R rules,” he added. This handling made tire management a major performance factor.
“It was like Reba’s ghost was watching me,” Kojima said. “The more I complained about the way he’d built the car, the worse the failure(s) were at the next race. Then, after I stopped complaining, the car suddenly became more reliable.”
Sadly, several races after the car started taking all the abuse Kojima could throw at it, he had to take a lot — too much, actually — himself. The same year the series fizzled out almost overnight, Kojima suffered a career-ending accident.
His painful recovery gave him plenty of time to brainstorm, and when he was back on his feet and bending at the waist, he started to maximize the Sentra’s strengths, free from the shackles of the rulebook. Rather than use the flawed Dog I to build a better B13 Sentra; he chose to use the spare chassis which came with it — a car that, unlike Dog I, wasn’t hampered by Reba’s build practices. With the second in-white body and the box of parts it came with, he began building the Dog’s successor.
New Lease on Life
Rather than use the outdated SR20DE for a ground-up build, Kojima imported a SR20VE motor from a Nissan Bluebird, which featured a higher flowing cylinder head, higher compression, and variable valve timing system. Along with that, he sourced camshafts, an intake manifold, and a throttle body from a rare SR16VE N1 motor: a race homologation motor produced by Nissan to race in FIA N1 events. Kojima mated the cams to Jim Wolf Technology adjustable timing gears, then attached a 70mm N1 throttle body to the Technosquare aluminum intake, SN95 Mustang Cobra MAF, and JWT Pop Charger mounted just behind the ram-air vent.
Kojima built a custom exhaust manifold using lightweight thin wall 321 stainless using a Burns merged collector, stepped primaries and reverse cone megaphone by Charles Dundon of Advanced Street Performance.The headers exit into a 3″ thinwall 321 stainless Technosquare exhaust feeding into a Burns Ultralight muffler, exiting through a turndown right under the rear bumper.
Using G-Spec’s underdriven water pump pulley and Unorthodox Racing’s underdriven pulleys for the crank and alternator, he could address some of the cooling system’s flaws. Actually, the OEM water pump’s design can lead to cavitation so bad that, without the aforementioned modifications, water flow drops to zero at 6,500 rpm.
Using just stock SR20VE valve springs, the motor produces healthy power all the way to its rpm redline. The peak output is an impressive 200 horsepower and 153 pound-feet of torque at the driven wheels on a 50-50 blend of 91 and 100 octane fuel. With a newer aftermarket ECU, it might make another 20 horsepower nearer to the top. It’s a peaky motor, but it retains a surprising amount of midrange torque of the previous iteration. Straightline performance is still the Sentra’s strong suit.
When it came to solving the chassis problems, Kojima turned to Ritchie Watanabe, who fabricated a multipoint Touring Car/World Challenge inspired semi-tube frame cage using 1020 DOM tubing. This detailed cage connects the entire car together from shock tower to shock tower using aluminum triangulated brace bolts to the shock towers and an extension to the main roll cage for maximum stiffness. Several considerations were made to improve ergonomics; namely the contoured forward legs of the cage.
To reduce the chances of the fallible five-speed gearbox from ruining a weekend, Technosquare cryotreated and shotpeened the gears. Along with a set of hardened JWT transmission mounts, Kojima added a JWT clutch and aluminum flywheel to transfer power to the transmission, then onto a Nismo clutch-type one-way differential.
Kojima cut off the Scott-Russell lateral location link and replaced it with a panhard rod that would allow for roll center adjustment. Energy polyurethane bushings replace the soft stock rubber trailing arm pieces. Along with Advance Design two-way adjustable monotube shocks Eibach ERS springs, and Shigspeed monoball rear shock mounts, a Progress adjustable rear sway bar makes the Sentra significantly more amenable than it was in SE-R Cup trim.
Since the SE-R Cup rules mandated factory brakes, which were already marginal with a weaker motor, Kojima added 11.7″ two piece vane vented and slotted front rotors with Wilwood four-piston forged calipers and Performance Friction 01 brake pads. The rear brakes use slotted 11″ rotors with Maxima rear calipers and the same compound pad. Fastbrakes also supplied braided steel brake lines to harden the pedal feel.
A significant amount of composite material and lightweight options helped bring the total weight down to a respectable 2,240 pounds. These include an After Hours Automotive carbon dash, as well as Shields’ hardcoated lexan windshield, rear windows, and side windows. Along with those, a VIS carbon rear deck was fitted and reinforced to support an adjustable GTP carbon rear wing, and a carbon hood from the same company, complete with aftermarket venting, provided a hot air exit for an offset Koyo radiator, behind which they mounted a Setrab oil cooler to protect it from flying rocks and debris. These weight-saving measures saved roughly five-hundred pounds of heft in total.
Kojima’s back injury and growing family made it trickier to experience his vision of an idealized B13 SE-R outside of his garage. He and the new car fared decently over the few shakedowns he could squeeze into his schedule, but as his garage was the place it spent almost all its time, it was only fitting that another driver, one with a history in the series, was eventually handed the keys.
Full Circle
When Kojima was busy building the predecessor to this car, NASA NorCal’s Walter Catalan, a former SE-R Cup mechanic then crewing with Paule and John Almazon, wanted to be in the driver’s seat more than anything. However, daily life and a family took precedence, as is natural. The dreams would have to be shelved for the next 15 years, after which Catalan found himself in a position to take up racing for himself.
Catalan was the perfect recipient, a man with the wish to race this specific car, real sentimental attachment, and a strong technical understanding of the platform. Before he’d started crewing for the SE-R Cup teams, he’d been a knowledgeable voice in the greater California Sentra community and an in-demand mechanic.
This helped him work the last kinks out of the car, which had already been sitting for a while when he bought it. “The vehicle was in storage for a long time, so there were some minor gremlins from non-use that had to be sorted first. I replaced all the fluids, the old brittle rubber hoses, and other rubber components. I later updated all the safety items: the seats, steering wheel, and fire system,” Catalan added.
Catalan made the right decision when it came to buying a purpose-built car instead of taking one of his street machines at making the required changes. It’s just sorted with just about all the bugs worked out. In fact, the only thing he changed under his ownership was the final drive to improve upon the car’s greatest strength.
Robust, reliable, and raw, the car is now Catalan’s nostalgic splendor and his trustworthy HPDE car that should help him log laps until he’s winded without having to feel like the dedicated mechanic on site. It’s lively and analog, so it should help him develop his feel quickly, and as it’s essentially the thing he wished he’d been driving 20-some years ago, so it’s going to serve him well as a reliable source of nostalgic satisfaction.
Earning his spurs as a track driver had come 30 years after he would have liked it to, but he’s able to do it at his own pace, with the big race-oriented parts already in place. Getting to learn all the accessible tracks in Northern California in a race-prepped car built by an admirable name, all while being able to simultaneously revisit his tuning heyday and witness his racing future expand — well, it sounds like a fairy tale.
“I’ve got no plans other than to drive the hell out of it,” he said. It should take the beating happily, and if it protests, Catalan knows how to handle just about anything. If it happens to be one of the few issues outside of his purview, he’s got a renowned tuner on speed dial.
