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Source: Insight

Publication Date: 30^th May 2007

The FIA, which governs Formula One, has established that it will be 2011 when Grand Prix racing moves to a new engine formula. The provisional plan to admit systems that enable a proportion of waste energy from engine coolant and/or exhaust gases to be recovered and used to propel the car has now been postponed from 2010 until 2011, when new generation Formula One engines will be introduced (rather than in 2012, which date had also been mooted).

In the meantime the current 2.4 litre V8 Formula One engines will continue to be deployed. From 2009 engine performance will be supplemented by Kinetic Energy Recovery Systems (KERS), which recover energy from the powertrain under deceleration, store it and allow it to be reapplied it under acceleration. There will be a limit on the performance of such devices, which in 2009 will in effect be permitted to give approximately 10% power boost for just under seven seconds per lap.

KERS systems will continue to be deployed in 2011, when the current naturally aspirated Formula One engines are expected to be replaced by downsized turbo-supercharged engines, supplemented by the new energy recycling devices. The FIA has stated its intention to ensure that the new generation engines do not dilute the spectacle of Formula One. It talks of direct injection and is nevertheless looking to encourage engine speeds of the order of 15,000 rpm, presumably by limits on displacement and plenum pressure.

It spite of this the FIA plans an overall control of the level of horsepower by means of fuel flow metering. This will force engine development in the direction of efficiency and it will provide means to accommodate a variety of different fuel types, by setting an appropriate flow rate for each. The FIA seems keen to encourage the use of bio fuel. Of course, defining what is an appropriate rate for any given fuel is not a straightforward matter. The FIA threatens to complicate the matter further by equating different fuels on the basis of not only chemical potential but also overall environmental impact.

Short Term

Contrary to various reports in the specialist news media, the FIA has not significantly loosened the scope for homologated Formula One engine development in 2008. In fact, it has yet to offer the engine manufacturers potential for further development of the type that was permitted over the 2006/2007 off-season. Then there was scope to make significant modification to the specification raced in 2006 at the same time as re-tuning to the newly imposed 19,000 rpm rev limit.

The engines that are being raced this year are frozen to a specification established over the off-season and registered by the delivery of a 'control' engine to the FIA prior to the start of the season. The teams may not alter that specification as it applies to those components located within the seals fixed to the engine by the FIA, which puts them over the exhaust ports, the intake ports on the head and so forth.

Scope still exists to develop engine and engine-related components outside of the split lines as defined by the seals. In a modification to the 2008 Technical Regulations following a meeting of the FIA's World Motor Sport Council in Paris on March 28, the FIA has now specifically defined many of components that normally lie outside of the seals. It has done so to allow the specified components to be modified even in the event that for the engine in question alteration would not be possible without breaking a seal.

Thus, the new clause permits certain engine manufacturers to modify certain components that would normally lie outside of the seals but for extraordinary reason in their case do not. For example, a manufacturer might have a trumpet tray integral with the cylinder head casting, whereas normally this would be a separate carbonfibre component. The revised ruling declares that all trumpet trays are outside of the freeze. Overall, however, this is not a significant change to the scope for development, although some ill-informed observers interpreted it that way.

What is different next year is the imposition of a standard electronic control unit (the 'FIA ECU') for the entire powertrain. The hardware will be supplied by McLaren Electronic Systems and teams will continue to develop their own software, which the FIA will monitor. The FIA has taken advantage of the standardisation of electronic hardware and consequent improvement in scope for software monitoring to ban traction control. From 2008 the cars may not have a system or device "which is capable of preventing the driven wheels from spinning under power or of compensating for excess throttle demand by the driver".

In keeping with this, the FIA has also further restricted the scope for clutch control assist from 2008. In essence the operation of the clutch release bearing has to be by an electro-hydraulic system under the command of the powertrain ecu, which in turn must accurately interpret the driver's movement of the clutch control pedal or lever. The regulations now additionally state: "designs or systems which in addition to typical inherent or mechanical properties are designed to, or have the effect of, adjusting or otherwise influencing the amount, or rate, of engagement being demanded by the FIA ECU are not permitted".

At the time of writing, it was not clear if this new clause would outlaw the ZF Sachs 'helper spring' system or the AP Racing 'Phased Engagement' system, which are conceptually similar in using a second spring to influence the plate movement generated by the main diaphragm in response to release bearing travel.

In another change to the technical regulations governing the powertrain from 2008 gearboxes will be required to run four consecutive race meetings, as discussed in our GRID section. There remains a threat that at some stage in the not too distant future, Formula One engines will likewise have to run four rather than two Grands Prix.

Fuel Flow Metering

The FIA is expected to use fuel flow metering as the primary means of controlling the output of the next generation of Formula One engines. As an approach to race engine performance limitation fuel flow metering has much to commend it. The regulator prescribes a maximum permitted energy flow, a meter to measure that flow and the onus is on the competitor to keep their meter reading within the limit. The prescription allows the regulator to keep performance within acceptable bounds while allowing freedom of engine development. Moreover the fact that energy flow has been capped focuses that development upon efficiency.

On top of this, as discussed below, different prescriptions can be made for different fuel types so as to attempt to provide parity or to encourage the use of a particular type of fuel. Conceptually this is no different, for example, to prescribing different maximum engine displacements for naturally aspirated and turbocharged engines.

UK automotive engineering consultant Ricardo has identified as suitable a flow monitor supplied by Pi Research, one developed for use wherever accurate monitoring of fuel flow is required. At its core are an impellor driven by the flow and a Hall Effect sensor to measure its speed. In the racecar environment, all the fuel delivered to the engine passes through this device. Fuel temperature is also measured to allow the energy flow per unit time to be determined.

The meter and temperature sensor provide data signals to both the team and the regulator. For the team the data would be the primary input to its engine management system while for the regulator it would be its primary scrutineering tool. At Le Mans the current ACO boost pressure metering system could be modified by provider Stack to accommodate this change.

Of course, the first question many will ask is: how accurate is this meter?

Ricardo engineer Dave Morrison replies: "we believe that accuracy and repeatability will not be problems. Moreover, the culture of monitoring meter signals (ie boost pressure) is well established in some series and accepted. This can be seen as 'another signal'".

Morrison backs up his comment on accuracy with a statement referring to standards established by the USA's National Institute of Standards and Technology, as shown in the accompanying sidebar.

In issue 018 we suggested that the fuel metering approach is the best way forward for Le Mans type racing. Since then the FIA has indicated that it is seriously considering the approach for Formula One when new engines are introduced in 2011. At that time the FIA is keen to widen the scope of permitted fuels.

As we pointed out in the last issue, the fact that Pi Research founder Tony Purnell is now the FIA's Technical Consultant for future Formula One regulations can only make it more likely that the Pi Research meter will be at the core of 2011 Formula One regulations. With this in mind, we asked Morrison some pertinent questions that will concern teams and engine builders faced with working within this new context.

First though, it is worth emphasising that the use of the meter in itself has no effect on engine performance, even transients. "It is the value chosen for the fuel flow rate that will cap engine performance," remarks Morrison. "The meter is not a limiting device per se (eg physical throttle or valve), it is a measuring device. It is up to the teams to provide limitation, in the same way as is common for such parameters as engine speed or boost pressure in some series."

We asked Morrison: Where/how is the device to be fitted within the fuel system?

"It can be applied to both single and return systems. For a return system, two flow meters will be needed to obtain the net flow value.

"The siting of the meter(s) depends on the racing series. The preferred position would be somewhere away from engine heat, reasonably protected and fitted with anti-vibration mounting. For example, in a Touring Car the system has been fitted close to the fuel tank, behind the driver.

t is the cost of the device?

"The basic system comprises one or two fuel flow meters plus temperature sensor(s) and in-line filtering system and associated pipework. For indication, the price for the main element &ndash the fuel flow meter &ndash is approximately £1500 ($3000). Added to that will be the temperature sensor(s) and filter(s) plus some modifications to the pipework and general fitting. There is also the integration with the engine control system and data logger, which would exist already in many series."

What can go wrong?

"The system has been thoroughly tested in the British Touring Car Championship for more than a season without any problems occurring. The fuel filter needs to be serviced like any other filter and the pipework needs normal fitting standards applied but this is all motorsport commonsense.

"The worst that could happen to the meter is that it jams but without any restriction to the fuel flow or effect on engine performance (but the signal would cease). We have had no experience of any jamming whatsoever. The meters are pretty robust and the filter is sized to protect the meter anyway."

How quick/easy is it to change in the event of a suspected problem with it over a race distance, which might be as long as 24 hours? How would the replacement be validated by the scrutineers?

"Each meter would have its own calibration certificate and serial number. It would be easy to change, via quick-connect fuel line connections."

Legal and potential illegal ways of mitigating its effect?

"Creating a reservoir downstream of the meter would be one illegal method, so that additional fuel could be called on when needed, but this would be visible to scrutineers. Pipework to and from the system should always be clearly visible.

"Cooling the fuel to below ambient would increase the fuel density and increase the energy flow. However, this would not be productive because the meter measures volume flow and the combined temperature measurement would sense the lower temperature and compensate accordingly. (The system principle is based on energy flow/second, not volume)."

Recommended means of staying within prescribed limit?

"It is up to the team to integrate the signal from the flow meter with the ECU/data logger and provide feedback to the engine controller. This is just the same 'culture' as monitoring and limiting boost pressure and other parameters, common in many race series."

Fuel Type Efficiency

Ricardo has, via the UK's Energy Efficient Motor Sport (EEMS) body suggested that fuel flow metering is the best available means of equating the use of different fuels within a given racing category. It has suggested that each fuel's prescribed energy flow per unit time is based upon sophisticated performance modelling using software that it has developed.

Interestingly, as we reported in our last issue, we hear that for Formula One the FIA may well try to equate different fuels on the basis of the so-called 'well to wheels' energy use comparison rather than purely on chemical composition comparison. This may or may not take into account the theoretical modeling proposed by Ricardo.

We asked Morrison: Ricardo's proposed fuel flow rate modeling study: could and should this account, for example, in the Le Mans environment for the current LMP1 V12 turbo-diesels being significantly larger and heavier than the rival AER V8 gasoline indirect injection turbo engine?

Ditto respective fuel load weights over the course of a stint?

Ditto potential tyre degradation?

"The fuel flow system does not know anything about engine weight, fuel load, tyre degradation, or need to. It is simply monitoring an amount of energy to the engine for the team to use as best they can. However, if the regulating body wants to give some incentive to alternative fuel cars, then this is easily done by adjusting the fuel flow limit accordingly."

How to equate the performance of a petrol/electric hybrid to a conventional engine?

"Good question, which is currently under consideration. We are aware that hybrid systems store energy (like an energy reservoir) whereas we are monitoring an instantaneous fuel flow. The advantage gained is dependent on the storage capacity of the system. There are ways of measuring electrical energy flow that could be incorporated in this whole approach.

"It is up to the regulating body to decide how much advantage to give hybrid systems (or reduce the fuel flow to compensate for the energy reservoir effect)."

Added to the database on 8^th June 2007