Forced Induction For Track Work: Supercharging Two Popular Platforms

Among E46 M3 and S2000 owners, power is almost considered a four-letter word. The majority of those who regularly lap these cars, for reasons of simplicity and cost, prefer to optimize their car’s handling and braking performance in pursuit of impressive lap times. Also, they typically pride themselves, though usually tacitly, on their ability to lap quickly without a big motor to lean on. However, the ratio of grip to power usually falls in favor of the former with most of these builds, which forces the builder to consider whether a significant bump in grunt is worth the time, expense, and possible hassle.

Two of our fastest drivers decided the relatively cost-effective path of forced induction to determine if more power makes a worthwhile difference with these two popular HPDE platforms.

Seigo Ma had been swooning over the videos of the Arvou S2000, a lightweight AP1 using an HKS supercharger to make a touch more than 400 horsepower. The already capable package could exploit that power bump well enough to lap the technical Tsukuba circuit in a remarkable 53.887 seconds.

Seigo wanted to double his engine’s output, but worried that the famously fragile platform wouldn’t be able to handle it. So, in an attempt to get some much-needed encouragement (and see F1 in person), Seigo took a trip to Tokyo. Three days in, he visited Arvou to consult with Mr. Shibata, who encouraged him to take the plunge.

Back in San Francisco, Seigo started speccing his own HKS kit. He did his homework and chose the option of the smaller pulley needed to make 400+ horsepower. After he installed the kit, he sent his car to Blacktrax for the first pass at tuning his Hondata Pro ECU. They were able to make a knock-limited 350 horsepower at the wheels available over a very narrow powerband. “It only revved to 7,000 safely. That lowered redline, the shorter AP2 gearing, and 4.3 final drive made it a challenge to drive; it required constant shifting.”

To make the most of his new kit, Seigo ordered a higher flow fuel pump, 1050cc injectors, colder spark plugs, and a surge tank with an integrated fuel pressure regulator — all the items needed to run E85 safely. A retune of the Hondata brought power up to a knock-free 420 horsepower available at 8,500 rpm. “Power delivery was like a stock F22, but with a lot more at the top end,” Seigo said.

Even with 285-section rear tires and an OS Giken differential to help meter out that power, the bump in grunt was challenging to manage. “Second gear was pretty much useless,” he added. It also proved too much for the factory gearbox; breaking fifth gear broke on his second track day at that power level. To get himself back on track, he picked up a used AP1 box and a larger supercharger pulley to drop boost and lower the power output.

Relocating the oil cooler made lowered temps enough to run full sessions on moderately warm days.

The AP1 box’s longer gearing combined with the lowered output — about 360 horsepower — helped Seigo get to grips with the car at his next outing. Usable power, strong traction, and drastically improved top speeds has helped him keep up with higher horsepower cars that previously left him in the dust. Before braking for Thunderhill East’s Turn 1, he was traveling at 133 miles per hour — roughly 15 miles an hour faster than he ever had before.

The only notable issue with the car were creeping supercharger oil temps, which he resolved by relocating the supercharger’s oil cooler under the right headlight. With that upgrade, the car has been mostly reliable.

On moderately warm days, the car can run full sessions without issue. Only on the hottest days does it begin to falter, but it still works well enough to run three consecutive laps before engine oil temperatures get too high.

A drawback of running E85 is that combined with the new powerplant, it gets quite thirsty. “I burn half a tank per session, so I’ve gotta bring a few jugs of e85 with me every day. It’s still cheaper than running 91 octane and is much safer for the engine though.”

For Christian Fernandez, power was the last box to be ticked after aero, weight reduction, and a solid suspension setup. He’d already set impressive times with his E85-fed E46 M3, but he wondered if there might be an easy solution to extract a little more from his S54.

Dan from RCrew, Christian’s dependable mechanic, made him an offer on an ESS supercharger kit which promised easy power and little-to-no hassle.

As Christian had already installed a larger pump and 550cc injectors in preparation for corn juice, there wouldn’t be much more he’d need for a successful install.

“Multiple YouTubers who’d used the same kit complained of overheating issues, though. The front-mounted intercooler wasn’t necessary with this entry-level kit, so I decided to take the band-aid solution and install a water injection kit to keep intake temps low.”

On a Dynojet, HTE Performance tuned the stock ECU to handle six pounds of boost from the the supercharged S54 put down 487 horsepower — 157 more than what the atmospheric, E85-fed motor had made on the same dyno.

The bump in power is felt largely at the top of the rev range; making the motor feel similarly linear in its delivery, but notably faster at the end of straights. “It’s pretty easy to put the power down, but the extra 3-4 miles an hour it nets at the end of the straights forces me to reconsider my braking points.”

This bump in straightline speed doesn’t overwhelm the current cooling system, which consists of a larger radiator, an oil cooler, and the water injector. “Even on 80° days, the needle never moves past the ¾ mark!

That said, I’m not sure I’m getting all that peak power over a whole session. It probably needs an intercooler.”

The blower hasn’t made maintenance a nightmare, but it has exposed a few leaks that weren’t an issue before. Running a leakdown test revealed a leak from the valve cover seal and around the aftermarket injectors, which never seat properly and require a washer for passable fitment.

Both drivers are content with their new engine setups, which have proven to be reliable after the little issues were addressed. Seigo bought a usable 150 horsepower and 2.5 seconds at his regular tracks. “So far, it’s been money well spent,” he said.

Christian is content with the improvement, though the M3 was never lacking power in the way the S2000 was. To be fair, the former has gone a step further in addressing all their supercharger’s shortcomings, while the latter has taken a more relaxed approach.

There’s still more to be done before the bare-basic ESS kit offers track-worthy performance, but once it’s sorted, there’s no reason it shouldn’t have that funny effect of shortening straightaways — so much so that Christian will have to start thinking of braking point right after he starts to accelerate.