How the 2018 IndyCar changes the game for engine manufacturers

“Honda’s problem winning [IndyCar] championships isn’t because of their engines,” a senior member of a Chevrolet-powered team told me a couple of months ago. “Honda has better torque than us, they fixed their reliability after Indy, and their aero package for big ovals is great.

“Their problem is they only have one consistent front runner – [Scott] Dixon – and a bunch of occasional ones. You ask anyone on our team and they’ll tell you that we never come to a track thinking Honda isn’t going to win – apart from short ovals because of these stupid aerokits. Honda’s top two or three guys are always on the pace, but apart from Dixon, who are the others? It changes weekend to weekend, and that’s why Dixon will be the only Honda guy in [championship contention] at Sonoma. Well if you only have one dog in the fight, and he’s up against four or five strong Chevys… it’s the law of averages, right?”

Right. Honda hasn’t won an IndyCar manufacturers’ title since Chevrolet’s return for the 2012 season, while there has been just one Honda-powered drivers’ champion [Dixon with Chip Ganassi Racing in 2013]. Yes, Honda has powered four Indy 500 winners over that same six-year period, but in the 101 races since the DW12 was introduced and the engine formula became twin-turbo 2.2-liter V6s, Chevy has beaten Honda 67-34.

Could that trend be about to change in favor of HPD? Many, including some apprehensive Chevy drivers, think so. Their reasoning is that without the limitations of a manufacturer aerokit that was deficient on short ovals and had a very small sweetspot on road/street courses, Honda’s supposed torque or power advantage will push them out of reach of the Bowtie drivers more often than not next year.

Maybe Chevy operators can find solace in the pre-manufacturer aerokit stats; the last time everyone ran the same bodywork, from 2012 through ’14, Honda scored only 19 wins to Chevy’s 33. But that’s history and fairly meaningless now if HPD’s units really do have an advantage over the Ilmor-built Chevys.

Assuming nothing

Allen Miller, HPD’s race team principal, who has headed trackside operations for the past three years and is a 24-year veteran of the Santa Clarita, CA-based company, is flattered by such a perception, but not convinced of its validity.

He tells Motorsport.com: “If we’re honest, the last three years with manufacturer aerokits, it’s been really difficult to assess relative engine performance. It’s so hard to eliminate the aero impact from the equation. But from the evaluations that we could make, then I’d say that if we were a small step ahead at the start of this year – or since Indy 500 in 2016 – I think there was a closing of that gap over the course of this year.”

Miller says the restrictions IndyCar has imposed on engine development this offseason will restrict both manufacturers’ progress to inches rather than yards.

“Yeah, the mechanical differences between this year and next year aren’t great. We have very small areas of development open for 2018 compared with two years ago. But pistons, connecting rods, valves – they’re open to us and are always being worked on.

“We both have the same restrictions, so if we do think we have an advantage – and that’s difficult to say – then it limits how far we can move ahead, but it should also make it difficult for Chevy to close the gap.

“If there is a gap, I don’t believe it’s big. And our attitude is to assume there’s no gap and it’s our job over winter to gain as much as we can. That’s the only approach to take in such a competitive situation. With aero discrepancies now gone, it’s the same for all. It comes down to engines – their power, torque and driveability – and the differences that teams can make with the limited amount of adjustments available to them.”

A rethink under the skin

If personnel who work on the Honda and Chevy engines have felt restricted by how few parts they can develop this offseason, they can throw a little sympathy in the direction of those who had to repackage the engine ancillaries under the sleek 2018 Dallara bodywork. They have had to contend with constraints in both regulation and physical space, as the removal of the overhead airbox has forced a major rethink regarding what goes where.

Says Miller: “We first discovered early this year – January-February time – about IndyCar deleting the airbox, so the 2018 car would need a side inlet feeding the engine. So we started CFD work early on, and at the first test of the new car in late July at Indianapolis, we ran prototype stuff. By the time we got to Sebring in September we had more of a production-intent layout.

“The inlet to the radiator duct is fixed, as is the radiator positioning. But there is a slot between the radiator duct and the monocoque designated as an inlet for engine air and cooling air – because we’re also responsible for cooling all the electronics and control systems.

“We have freedom regarding air duct design in front of the radiator and also behind, up to the turbos, which can’t be moved and are positioned based on last year’s installation. The transition pipe from the turbo to the engine is the same. It’s purely from the turbo inlet and compressor housing forward that we’re allowed to customize.

“So yeah, it’s tightly controlled where we can place things… but to be honest, there aren’t many options for IndyCar to give us. The much smaller sidepod/radiator duct layout means that space is pretty limited regarding where you can place the ECU and so on.”

Testing progress

Homologation rules imposed on HPD and Ilmor Engineering (Chevrolet’s engine builder) will dictate designs of air inlet ducts, filter assembly, engine, radiator inlet blanking and shuttering on the backs of the coolers for the 2018 season. Back-to-back runs of minutely-varied combinations have been a feature of Honda’s work so far and will continue up until the homologation deadline in mid-December. So too will windtunnel studies, expanding on Dallara’s baseline figures. Thus far, the only notable holdups have been occasional interruptions as data acquisition engineers try to synchronize the new Cosworth power distribution system and logging systems with Honda’s aero sensors.

Progress on such matters might have been faster had there been several cars testing, but Honda’s only representatives on track have been run by Chip Ganassi Racing and Schmidt Peterson Motorsports, while Chevrolet has been testing only with Team Penske and Ed Carpenter Racing.

Miller comments: “Even with the manufacturer aerokits being introduced for 2015, or the Dallara DW12 arriving in 2012, you’d have to say the teams in this era aren’t exactly used to having a lot of change in an offseason. So yeah, I do understand and sympathize with the teams that aren’t doing the testing at the moment.

“Certainly on our side, we had hoped to spread out testing among all the teams but the struggles we’ve been having either with Dallara delivering parts or the Cosworth items we’ve had to sort through, it’s made sense that we just leave everything on the two cars that we’ve got and march through the test items. That’s what’s best for the overall program.

“Now, we’re in full production mode, and so are Dallara. Their kits are supposed to start arriving with teams on the 27^th of this month, and we’re right behind that. Our installation kits should be arriving in the first week of December.”

Handling changes won’t affect engine priorities

In the absence of multi-car tests on ovals to check on the new machine’s handling traits in a high-speed draft, the main theme of driver feedback thus far has centered on road courses, its ‘loose’ nature on under braking and the care needed applying power on corner exits.

But despite the removal of vast amounts of downforce (I’ve heard everywhere between 1500 and 2400lbs) compared with the cars when adorned with 2015-’17 manufacturer aerokits, and the consequent lower cornering speeds, Miller says the engine characteristics haven’t required a radical adjustment.

“The lower apex speeds and the higher terminal speeds on straights have not changed how we approach our year-on-year improvements,” says Miller. “Things like accelerating from a lower speed out of a tight corner, or hitting a higher top speed because of the drag reduction – they’re dealt with through gearing and, to a lesser extent, car setup. And I think Xtrac have enough gear ratio options available to deal with these changes.

“So engine operation hasn’t changed drastically. The cars are rev limited to 12,000rpm so that obviously takes away a lot of potential choices for us as manufacturers. The gearshift points down the straight change, and you have to gear for the higher end-of-straight speed, but it’s the better aero that’s allowing the higher speed for the same rev, which is limited. So it’s situation normal as far as that’s concerned. We just want to make our engine better in all parts of the rev range.”

Road course power on short ovals

The best drivers in the series are already excited by the idea of having to change down gears and even brush the brakes on IndyCar’s short ovals next year. Gone are the days of excess downforce allowing everyone to carry so much speed through the turns that they barely accelerate on straights.

But what if IndyCar wanted to make the cars even more demanding than 2018 spec? At the moment, IndyCar’s BorgWarner turbochargers run at 1.3-bar (130kPa) on the superspeedways, 1.4-bar on short ovals (and for the Indy 500’s Fast Friday and qualifying) and 1.5-bar on road and street courses – with 1.65-bar as the push-to-pass ‘overboost’. The idea of the cars running road/streetcourse boost at short ovals such as Phoenix, Iowa and Gateway has been regularly batted around in the last two years, but one of the main drawbacks was assumed to be engine life. Currently IndyCar insists each engine reach 2500 miles before being changed; is that a realistic limit if the cars were to run at 1.5-bar boost?

“Yeah, I think we could sustain that boost at oval speeds and still make the 2500-mile limit on the engines,” said Miller. “We’ve talked about that internally, although obviously we’d want to test and confirm.

“But I don’t think it will be necessary. The test at Iowa suggested the cars do accelerate pretty well off the corners because they’re coming from a lower apex speed and there’s less drag. So already I think the opportunities for passing are going to be better than they were. And that’s true on all types of tracks.

“To answer your question, though, I don’t think it would be a stretch to run 150kPa on all tracks – and actually it would simplify the amount of calibration we have to do. Currently we have to work on three different levels of boost – or four including push to pass – and a lot of dyno work has to happen for each of those boost settings.”

Another popular theory when drivers (or journalists) are in blue-sky-thinking mode is that IndyCar could make a big horsepower gain in one hit with a radical fuel formula adjustment. And it’s true but…

“No, it’s not on the radar,” says Miller. “Changing the ethanol mix could make a difference but then we’d have to look at intercoolers, adding more complexity to the engine and adding weight to the car. So is it worth it? We don’t think so: our desire is to continue with the fuel as it is.”

For the same reasons – complexity, weight and inevitably cost – Miller doesn’t foresee hybrid power becoming part of IndyCar’s engine solutions longterm.

“That’s not what we’re in favor of,” he says. “The architecture of the engine as it is now – V6 twin turbo, small displacement – we like that, and want to keep a similar layout. We don’t have a desire or even a marketing reason to want to put a hybrid unit on it. It comes up in discussions but I don’t believe it will go that way.

“At the end of the day, I think the purpose of the series has to be to create great racing with super-fast cars but in a way whereby costs are kept under control.”