Horses in the Cylinder, Half a Second in the Tunnel

Ahead of Zandvoort, two rather different pieces of news arrived from opposite ends of the field. Honda reported that it had finally managed to stuff back into its engine some of the horsepower the RA626H had misplaced over the winter, while Mercedes explained why the car that started the season at the front has suddenly begun receiving its major upgrades later than its rivals.

Honda: burn it faster

After Canada, the FIA activated its Additional Development and Upgrade Opportunities mechanism - ADUO - for the first time. The Red Bull Ford engine was taken as the benchmark, and Honda’s internal-combustion engine came out more than 4% down on the reference. That was enough to give the Japanese manufacturer two opportunities for substantial power-unit development.

They are not planning to use both in 2026, however. The entire present offensive has been concentrated into a single Spec 2, due to make its race debut at Zandvoort, while Sakura has already effectively split its workforce between the 2026 and 2027 programmes.

Project leader Shintaro Orihara says it quite plainly: the main bottleneck now is not the battery, nor even the management of electrical energy, but the internal-combustion engine itself. There is little point polishing the control of the 350 kW electric side if the other half of the power unit is throttling the total output.

That is why Spec 2 is almost entirely about the ICE. Honda has changed the pre-chamber, the piston shape and parts of the lubrication system. The official aim of the first two modifications can hardly be put more clearly: make the combustion faster.

Allow us, then, to dip you briefly into pure physics.

Cylinder pressure is useful only if it appears at the right moment. The smaller the fraction of the power stroke occupied by the main combustion phase, and the better the pressure peak is positioned relative to top dead centre, the greater the share of the fuel’s energy that can be turned into expansion work instead of continuing to burn after the piston has already disappeared down the bore.

The pre-chamber changes the speed and distribution of the flame fronts. The piston crown geometry changes charge motion and the shape of the combustion region itself. The result is more effective pressure for the same fuel allowance - and therefore more power at the crankshaft.

But cylinders do not hand out free horses. Raise the pressure faster and local thermal and mechanical loads rise with it, along with the demands on knock resistance and mixture control. This is precisely where Honda stumbled during the winter. It had already found individual power gains late last year, only to discover reliability problems attached to them and retreat again.

The full scale of the trouble became apparent only during the January running, when battery issues joined the party as well. So the present Spec 2 is not a miraculous discovery of thirty horsepower underneath a workbench. It is an attempt to make something survive in race conditions that had previously worked on the dyno without enough reliability margin.

And then tribology rides to the rescue. That is a slogan the engine department could quite reasonably hang on the wall in Sakura. According to cautious outside estimates, Honda has also made progress in the rather important business of reducing friction.

You did notice that the official description mentioned changes to the lubrication system, didn’t you?

Lubrication is not only about keeping things alive. It is also about reducing mechanical loss. Some of the power produced inside the cylinders never reaches the crankshaft at all; it disappears into the piston group, bearings, drives and assorted pieces of machinery rubbing against one another because reality insists on being inconvenient.

So an engine can become more powerful without touching the combustion process directly. It is enough to reduce the gap between indicated power - the horses already born inside the cylinders, before friction has robbed them - and brake power, the slightly thinner animals that actually make it as far as the crankshaft after encountering pistons, bearings and real life.

Orihara says Honda has met its internal Spec 2 target. The most optimistic outside estimates suggest a gain of roughly 30 bhp, although Honda itself has not confirmed the number.

And unfortunately we do not possess that mythical spy who can extract an exact ICE output figure from an audio recording. Our old acquaintance Driver X has become so deeply buried in writing that he appears not to have shaved for about two weeks, so directional microphones and spectral analysis are probably some way down his list of immediate concerns.

Things in Sakura are not entirely serene, either. There is one small nuisance capable of spoiling quite a lot of the good work done in lubrication and thermodynamics.

A new combustion character inevitably drags a new torque character along behind it. That means Honda must once again marry the ICE to the electrical side of the power unit and to the accelerator pedal. And after the Hungarian changes to the AMR26 increased its cornering speeds, the points at which the driver returns to the throttle and asks the power unit for torque have changed as well.

Orihara openly warns that the engine’s driveability calibration will have to be worked through again. That is why Spec 2 received its first run during a filming day after Hungary, before its official Dutch debut.

We shall also quietly push our little theme of self-learning power units back onto the table here. Compared with what the Japanese engineers now have to teach this thing, the old tales of tuning multi-barrel carburettors - assuming you even remember what those were, and people once terrified each other with such stories - begin to look like a child arranging coloured rings on a toy pyramid.

Zandvoort will reveal only part of the answer. This is not Spa, and certainly not Monza, where a power deficit gets stretched along a long straight and converts itself into lost time with absolutely no sense of embarrassment. Here, corner exits matter more.

So this will not be only about peak kilowatts. It will be about the shape of the torque curve, the smooth transition between combustion and electrical torque, and the ability to reproduce the same acceleration every time. And at that point the question has already moved away from the cylinders and into the control systems, which nowadays appear to have a private life of their own.

If Spec 2 has worked even half as well as Honda hopes, the first thing that should disappear at Zandvoort is the AMR26’s sense of heaviness on acceleration. How many horses Sakura has actually managed to squeeze back into the cylinders will be much easier to judge at Monza.

Mercedes: too early from the future

At the other end of the grid, the problem is of an entirely different species.

Mercedes is not suffering from any shortage of development. Quite the opposite. James Allison has produced a number capable of causing acute envy elsewhere in the paddock: at the beginning of this new technical cycle, the wind tunnel is bringing lap time to the W17 roughly six to seven times faster than it did a year ago - approximately half a second per lap every two months of development.

The opposition is hardly sitting around with its mane hanging sadly to the floor, of course. They are simply harvesting their next batch of performance at a different moment.

Mercedes created the timing problem itself. The freeze point for the original W17 specification was pushed several weeks later than usual - later than the team had previously dared. Manufacturing was left with almost no margin at all, but the reward was that several extra weeks of tunnel development could be stuffed into the very first version of the car.

In other words, part of what arrived as an upgrade on rival cars during the spring was already fitted to the Mercedes in Australia. The trouble was that the conveyor belt was then empty.

While Ferrari and McLaren were turning accumulated research into new parts, Brackley had gone back to filling the hopper for its next major step. Allison puts the phase shift at roughly one or two races. At the present development gradient, that is enough for half a second of advantage to appear and then almost disappear again after one rival upgrade cycle.

The W17 concept has not suddenly stopped working. The teams are simply harvesting performance from the same development field on different Sundays. Provided the rain does not ruin the harvest.

That is why, after the major Canadian package, most W17 changes were relatively small or circuit-specific - the low-downforce configuration used at Spa, for example. Simone Resta confirms that the next serious package is planned for after the summer break, but not necessarily for Zandvoort itself.

Mercedes also has another constraint: the cost cap.

Large early-season packages have already consumed a noticeable slice of the available budget, so every hundredth found in the tunnel now has to pass two tests. First, can it be turned into carbon fibre? And second, have enough hundredths accumulated to make manufacturing that carbon fibre worthwhile in the first place?

That is the whole trick behind Mercedes’ present situation. The team has not dropped out of the development race. It has dropped out of phase with the production cycle.

The W17 began the season carrying several “weeks of the future” already packed inside it. Mercedes paid for that with a quiet stretch in the middle of the year and is now waiting for the next large discharge of accumulated ideas. Its supporters can only hope that the discharge points in the right direction.

Honda, meanwhile, spent the first half of the season driving around with a power unit from its own past and is only now attempting to bring to the RA626H what ought to have been inside it during the winter.

At Zandvoort, these two peculiar development curves finally cross. And we shall discover just what those Japanese horses are worth against the benchmark Anglo-German “wagons”.