Newey claims over-run necessary for engine reliability

[John S]

This is why the FIA cannot ban blown diffusers immediately.                       
Valve cooling he says is the main reason for over-run on the Renault engine and it's been part of the game for a few years. Has anyone heard anything about this prior to the blown diffuser row, or could this be another smokescreen to assist any prevarication on the part of the authorities in a crackdown?             

Ahead of last weekend's Spanish GP there was talk of the FIA banning the off-throttle blown diffusers, a device aided by hot air from exhaust gases that helps increase downforce and maintains stabilisation of the car. According to the FIA's Charlie Whiting, these devices infringe on Article 3.15 of the technical regulations.

However, motorsport's governing body held off on the ban, despite Hispania threatening to protest race results, with Newey explaining that it's because many teams will have unreliable engines on their hands unless they are given time to resolve the issue.

Adrian Newey has explained that the delay in banning off-throttle blown diffusers is possibly because it would hurt many of the teams' reliability.
 
"I think the key to 3.15 is that it talks about 'driver over-run then the throttle should be closed' then in brackets 'idle speed' so it seems to be implying that the throttle should be closed at idle, which it clearly is.
 
"What the throttle does on over-run at other times is not clear in the regulations, not as expected.
 
"Certainly, in the case of Renault, then they open the throttle to full open on the over-run for exhaust valve cooling, and that's part of the reliability of the engine.
 
"It has been signed off through the years for dyno testing and for them to change that would be quite a big issue, because the engine's not proven that it would be reliable if the throttle remained closed in that situation.
 
"Obviously if other people are going further and perhaps firing the engine on the over-run then clearly exhaust valve cooling is not part of that and that would be something that presumably they would need to explain to keep Charlie happy."

Planetf1.com, May 27.