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Honda tries an Indy comebackHonda tries an Indy comeback

DN Staff

May 22, 1995

10 Min Read
Honda tries an Indy comeback

Miami, FL--"We've come a long way since last year. It's taken a lot of time and hard work."

Those were the words of induction expert and race engineer David George of Honda Performance Development (HPD), Inc., Santa Clarita, CA, after the first day of qualifying by the Tasman Motorsports' LCI-sponsored Reynard-Honda at the Indy Car opener in Miami, FL. Driven by rookie Andre Ribeiro, the vehicle clocked a time second only to that of Michael Andretti's Newman-Haas' Lola-Ford/Cosworth XB. Ribeiro's best lap time and speed over the 1.843-mile course: 65.350 seconds and 101.528 mph. Andretti, Indy Car racing's most successful driver, ran a lap in 65.134 seconds and hit 101.864 mph.

An engine's development. How did Honda turn the 1995 Indy V-8 into a contender? The details are murky-Honda is famous for its secrecy.

Purpose-built turbocharged 4-cycle
780 bhp at
13.000 rpm (in Honda literature); 800+ bhp @ 13,000+ rpm (DN estimate)
315 lbs (with steel block); 283 lbs (with aluminum block) (Cosworth estimates)
Steel alloy (aluminum-alloy by Indy 500)
Dual-overhead cam with
4 valves/cylinder
Forged steel alloy
Machined steel alloy
Forged aluminum alloy
Honda/Motorola, electronic; driver can switch among multiple engine maps and control boost from cockpit
distributor-less CDI
Honda PGM-F1 electronically-controlled fuel injection
Khein Seikei
Dry sump
Single water pump
NOK (Nihon Oilseal Kogyo) and Arai
TEC (Toyo Electronics Co.) and NTK (Nihon Tokusyu Kogyo)
Nippon Denso
Limo connectors, Raychem cables

In fact, as imressive as Miami's results were, the company kept its latest aluminum-block engine under wraps. It won't make an appearance until Indy qualifying this month, though racing people have known about it for a long time.

Honda's entry last year into Indy Car's more regulated and relatively lower-tech world from Formula One's more wide-open guidelines challenged its engine designers more than you might think. Why? Indy Car mandates methanol fuel, up to eight cylinders, steel connecting rods, and conventional valve springs. These requirements make it impossible to employ the high-revving, power-producing titanium connecting rods and pneumatic valves used in Honda's Formula One engines.

George says Indy Car's rules limit rpms-exactly where power gains are sought, given the rules limiting turbo boost and engine displacement. So stifling are these requirements that Indy Car engines reputedly only reach 14,000 rpm, far shy of the screaming 16,000 rpm of Formula One engines.

But, before Honda could push their engine's rpm performance, they needed a strong base: a durable block. It had to last on big oval tracks like Indy and Michigan, where crankshafts must spin at 13,000+ rpm for 500 miles. Compare that situation to road races. In such races, drivers constantly shift through their gears, and alternately brake and accelerate into and out of corners and straights. Engines used in road races turn at substantially lower average rpm than those in Indy Cars, and therefore experience less wear and tear.

Robert Clarke, general manager of HPD and part-time club racer, says Honda began developing the 1994 Indy V-8 with an aluminum block that offered a significant weight reduction. When they use a lighter engine, engineers can distribute lead weights within channels in the vehicle's chassis to improve handling, yet still keep the car above the mandated minimum weight. So reducing block weight is worth some effort.

Unfortunately, tests revealed stress cracks in the aluminum block. Durability concerns arose immediately. Not wanting to place the program at risk, Honda engineers borrowed from the company's Formula One experience and switched to a stronger iron block. What was lost in weight they gained in greater reliability. As the 1994 season progressed, team members gathered data that helped them tame the vibration, wear, and heat problems caused by Indy Car's higher-weight, lower-strength materials and V-8 configuration. These efforts yielded refinements in drivability and increased power output.

Engineering tools. During this development process, Honda engineers used IBM RS6000 workstations running MICROCADAM(R) and mainframes running MICROCADAM and CADAM (2D studies). They also used CATIA (structural and volumetric studies), and custom in-house software to predict power, fuel usage, and volumetric efficiency, and to analyze friction. Zeiss and Mitutoyo matrix coordinate-measuring machines ensured that engine components met tolerances before they were assembled. Some of these engineering tools were at the Miami race, hidden inside Honda's traveling technical motorhome.

But engineering theories and models sometimes fall short. Such proved the case with the Indy V-8. Honda was particularly challenged by the mysteries of its turbocharged air-and-methanol-carrying induction system. Honda's George says that race engines are so advanced that "when you're working at the 95th or 96th percentile of maximum performance, simulation techniques break down and gains are made by a designer's feel." Dynamometer testing isn't even enough. Engines must run in cars and be driven under race-like conditions.

Take connecting rods, for example. To optimize the strength-to-weight ratio of these components, and thus maximize their rpm capacity, Honda started big and tested lighter and lighter prototypes until they finally broke. At that point, engineers knew they had trimmed too much mass. To improve strength further, Honda developed a proprietary ferrous alloy for those same connecting rods. They created a higher purity material that minimizes the number of failures caused by structural irregularities.

Engine magic. But the most serious limitation on the Indy V-8's performance last season involved the black magic of complex internal aerodynamic flows (induction). Clarke and George attribute these troubles to working with the methanol fuel, "pop-off" or 22 manifold pressure relief valves, and rpm limitations that demand a perfectly tuned induction system.

Methanol has an extremely high latent heat of vaporization. Under standard conditions in an Indy Car engine, this property can account for a temperature drop of well over 100 degrees F, increasing charge density dramatically. This evaporation process takes time, however, so injection location and quantity are crucial to performance.

Teams seem to have different ideas about how to optimally inject fuel. According to Honda's engineers, achieving proper balance between injection location and quantity under different loads, engine speeds, and atmospheric conditions challenged them.

Pop-up valves are intended to limit an Indy Car engine's boost pressure to 45 inches of mercury, and thereby limit power output. Track officials give teams pre-tested valves each day and watch mechanics take them on and off the top of the intake manifold. These valves create another technical challenge.

"Everyone tries to keep the valves from popping, within the rules," says Clarke. The idea is this: make the valve "see" 45 inches of mercury when in fact the engine experiences more than 45 inches. Doing so becomes especially important during engine transients such as those caused by abrupt full-throttle to closed-throttle changes going into corners. The pressure spike that develops in a corner can pop the valve and spill boost, causing a power lag when the driver reopens the throttle.

Surprises for '95. With that problem behind them, Honda engineers focused on raising the 1995 engine's power 7% into the 800+ hp league. They won't say exactly how they did it, but improvements in the induction, heads, exhausts, and injection all contributed. No doubt slightly reduced reciprocating mass and higher rpm accompanies better breathing.

On the track, the Indy V-8 has a distinctly smooth, turbine-like sound and is quieter than the competition. Tasman's driver Ribeiro said the fastest cars could not pull away from him during the race. His lap times and trap speeds confirmed that the car was as quick as the leaders. Unfortunately, a minor crash took Ribeiro out of the Miami race at its midpoint.

"They had a pretty good show in Miami," agrees Ian Bisco, vice president and general manager of competitor Cosworth Engineering N.A. He tempers his impression by noting that Miami is a traction track, where power takes a back seat to handling. The acid tests, he says, are courses with longer straights, and especially the superspeedways at Michigan and Indianapolis.

Bisco did not appear worried by Honda's progress, but he expects them to make "large incremental steps this season, especially if they are in it for the long term." He knows Honda faces a tough challenge, lacking the many years experience of Cosworth and Ilmor. And he remembers how companies like Porsche and Alfa underestimated Indy-Car's competition level in the past.

American Honda, which sponsors the Indy V-8 program, expects improvements with the Indy V-8 to follow a gradual developmental path-aided and tempered by race experience, says HPD's Clarke. That approach put the highest priority on durability last year, and led to the iron-block choice, a decision that cost Honda 50 lbs, Bisco estimates.

750 to 800 bhp, depending
on boost, etc.
0.452 to 0.516 bhp/lb (DN estimate)
(note: Acura Integra GS-R coupe Power/Weight ratio is 0.064 Bhp/lb)
0-60 MPH
2.2 seconds
0-100 MPH
4.2 seconds
240 mph (depending on gearing)
230 mph (Indy 500 and Michigan)
2,800 to 3,500+ lbs (depending on wings, angles, and mph)

Honda's all-new aluminum Indy V-8 debuts this weekend in the venerable Indy 500, and the company transferred every lesson learned on the iron-block engines to it. Clarke says it could be 10% lighter than the iron-block version. Using Bisco's estimate, the new engine may weigh in at 283 lbs, just 18 lbs heavier than Cosworth's. Whatever the engine's weight, Tasman's team engineer and chassis-design innovator Don Halliday (see DN 5/17/93) expects Tasman to run in the top 10 at the Indy 500 with Honda power.

Outer limits? How far can engineers take Indy Car engines under the current rules? Bisco claims Cosworth operates at 13,500 rpm and should push to 14,000 by the end of this season. To be competitive, he says, more than 800 hp is essential. Clarke believes Cosworth already runs at 14,000 rpm and is aiming higher. So, even with material shortcomings, 15,000 rpm and 900 hp represent reasonable next plateaus, he speculates. But, he cautions, will that power be useable? Will the engine be drivable? Or will the power occupy too narrow an rpm band, making it practically useless in competitive racing? Those are key issues.

Honda currently designs the Indy V-8s in Japan. Over the long term, however, they plan to develop a strong U.S. R&D presence to complement their consumer vehicle design and manufacturing capability. In 1995, HPD will also begin procuring components from U.S. companies.

Will Honda's Indy Technology find its way into the company's street-legal consumer cars? For sure. The engineers who design Formula One and Indy engines also design the engines in Honda's Accord and Civic and Acura's Integra, Legend, and renowned NSX.


An Indy Car chassis must be aerodynamic and allow for numerous weight distribution, suspension, wheel loading and wing adjustments. But above all, it must protect the driver. According to Indy Car rules, a chassis must not deform past the driver's feet when it undergoes a double impact test. That test calls for a 22 mph head-on crash into a brick wall, with a 15-mph, head-on rebound collision into the same wall. What chassis design features protect drivers during a wreck? Three deformable safety zones-a front pod and two side pods-surround the tub (monocoque) that holds the driver. In a crash, the carbon-fiber pods absorb energy by failing locally. This failure prevents impacts from progressing further into the monocoque's rigid aluminum-honeycomb construction, where they might cause buckling. To impede buckling and further control impact energy dissipation, the monocoque is designed to undergo progressive local deformation down its length. Carbon-fiber and aluminum bulkheads and carbon-fiber side beams also bolster the tub. The resulting monocoque feels dense as concrete when tapped.

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