• The Power of Crashes


29 April 2018

There is something special about street circuits.

In modern-day Formula 1, they are in stark contrast to some of the new venues with masses of run-off areas and smooth tarmac. A street circuit allows the driver to have an even greater influence compared to his machinery, taking risks by getting ever closer to unforgiving walls and barriers.

Get it right, and there are few better feelings for a driver than nailing a lap on a street circuit. Get it wrong and the penalty is usually a very big one.

Crashes may look spectacular, but after checking the driver is OK, an incident usually means it’s about to get very busy back in the garage in order to repair the car. While a lot of the damage may be obvious as shards of carbon fibre and car parts litter the circuit, under the bodywork there can also be plenty of work to do.

Masamitsu Motohashi is the deputy technical director of Honda’s F1 project, and knows just what can happen to the power unit when a car hits the wall.


“Data analysis is very important,” Motohashi explains. “So we will check the data in more detail when the car has stopped. We look at temperatures and whether there are any high pressures using the many sensors on the car.

“When the car has crashed we have to kill the engine so it means some electrical parts are shutting down. So we don’t have the data after that. Once the car gets back to the garage and we inspect it as a whole, then we can send power back to some sub units and if possible we will switch on the chassis power and then we will check some of the values from the sensors to see if it’s good or not.”

After a crash, sometimes power unit components need to be changed even if other parts of the car appeared to take the brunt of the impact. The incredible levels of energy that go through a car in the event of an accident test the mounting points between the power unit and chassis, which combine as load-bearing components.

“Basically the most likely parts to get damaged on the power unit are around the mounts between the chassis and the engine itself. Those can break and cause the most damage because of the stress that goes through the chassis. Some mountings including the cylinder heads or cylinder block are very critical for the power unit.

“We also have some connections to the chassis side, for example there are some gaps between the intercoolers and the radiators, so we have some pipes. When the car has been in a crash, we can get some stress through some of those pipes, the cylinder heads, the oil pump and some inlet chambers. So we have to do some visual inspections and sometimes ultrasonic inspections.


“So we have to clear some stress directions from the chassis side. First we inspect the whole chassis - including the power unit - when it gets back to the garage, looking at the impact and the direction, and then we will analyse some impact data about things like how big the stress was with the chassis team.

“Then we will share the information with the development side at Sakura in Japan. Basically after that we need to get the power unit back to the factory in Japan for inspections or some maintenance.

“We are restricted by regulations so we cannot run a power unit on the dyno once we have used it in the race. But we can still check for leakage and do some high pressure checks with a hand pump or similar. We have to see if there is any leakage or sometimes measure if anything twisted. We can also check some actuators which are part of the hydraulic system, so we will check every device to see if they are healthy.”

While a power unit is obviously not designed with crashing in mind, street circuits can also provide different physical challenges due to the severity of the bumps and kerbs, which can result in some unusual forces on the various components.

“Basically we design the power unit structure for performance,” Motohashi says. “So when we test it before the season with the chassis team, there are some tests for the whole vehicle - twist tests or vibration tests - but it’s main purpose is for chassis performance. Engines are already very big and heavy, so if we tried to include some countermeasures for accidents it would add even more weight, so basically it’s all for the performance.


“On the other hand we have the energy storage systems. It’s a very sensitive part, and we have installed it very close to the floor where it is easy to take some impacts. Sometimes that’s an impact from the kerbs at certain corners, so we have to check that in greater detail. We have some onboard checkers so when the driver finishes the run and we collect those we can see if it’s healthy.

“For example we sometimes hit the floor against a kerb and then the power unit is receiving some impacts and vibrations as a result. We have some accelerometers on the the power unit and also on the chassis side, so we can check if the vibrations cause some stress.”

With power units requiring a few hours to change, it is often imperative that a team knows as soon as possible if any damage has occurred from a crash that will require a replacement.

“If it needs a quick decision, firstly we can see the telemetry data so we will check the details. If it’s OK then we’ll wait for the car to come back to the garage and do some physical checks on some parts before deciding if we need to change it. But of course we are always preparing the spare power unit as a back-up just in case.

“If we don't need to change the power unit then the next time we head out on track we will do the normal procedure that we do at the start of every event. We always have an installation lap at the start of first practice, so it’s similar to that.

“The power unit would come back to the garage after a crash for some checks and if it appears to be OK so we would do an installation lap and check the power and some pressures. Then the car would return to the pits, we’ll take off the covers and do some more inspections and then if it’s OK we would use the PU.”

It’s common to hear of the gearbox needing changing after an accident - something that carries a grid penalty - and that is another component that can also have a knock-on effect to the power unit.

“Of course the gearbox is connected, so when the gearbox is damaged it can push the crankshaft and that can damage some thrust bearings. So we have a special window into some areas to have a look. It’s very fiddly work. It’s very difficult to find out some of those issues but we have to check it from a safety point of view.”


Motohashi has worked through various eras of Formula 1 and therefore been involved with a number of different types of engine. While the current V6s are extremely complex and technically advanced, the restrictions on the number of components that can be used in a season in turn makes them particularly robust.

“The big difference in the design between the V8 and the V6 depends on the limitations of how we can use the power units through the year. So before it wasn’t really restricted, and at the end of our last era we had to use an engine for two events so it was around 1000 miles.

“It was very low mileage and we could reduce the weight for performance. So every time we designed the engine for performance, but that meant the lighter one could get damaged quite easily in a crash.”

But the biggest damage to a power unit Motohashi has witnessed came courtesy of Fernando Alonso’s spectacular crash in the season-opening Australian Grand Prix two years ago, with the Spaniard having hit the rear of Esteban Gutierrez’s Haas at high speed.

“That was the biggest damage for the power unit I’ve seen. I checked the power unit myself in Sakura and some of the mountings include the cylinder heads were stripped out!

“In these regulations the cylinder heads are sealed by the FIA so we had to change the power unit. Of course on a case-by-case basis we negotiate with the FIA if we can change some parts or not. But the cylinder heads are not allowed so we had to change the PU.

“But even in such a big accident, it still came back as one block.”

The penalty for hitting the wall can be so much more than just a lost lap time. And that’s why it’s so special when a driver gets it just right.