Renault Power Unit Hardware & Software

[NL_Fer]

This engine is all about efficiency, the more energy you can extract from the fuel, the more power your engine has got. Increasing efficiency is ususlly done by increasing compression ratio or ignition timing advance. The limit introduces knocking, Renault is struggling with this problem.

Causes of knocking could be mixture temperature to high, caused by insufficient intercoolng or the air heating up during the transport trough the tubes. Maybe a air-water-air intercooler like Ferrari and Mercedes is just better.

Other causes would be the piston, head or valve shape. I believe they are working on it.

Still it is quite a shock, being the number two in 2014 and Ferrari copies the turbo layout and instant leap by, almost on pas with Mercedes.

If heat is the problem, i would be looking at Redbulls chassis and cooling capabilities. The have ran the Renault engine to hot in the past, with failing alternators as a result.

[godlameroso]

On the one hand, the Renault ICE is the weakest, on the other hand, their ERS is the class of the field, goes to show how important it is to have the total package. The Renault may be the least thirsty engine, if they can improve the ICE by 30-40bhp they would be a threat for victories. At least in the Red Bulls.

[Cold Fussion]

How can it be the least thirsty and least powerful engine? With a capped fuel flow then inorder to use less fuel it has to spend less time at WOT, which is beast achieved by spending less time on the straight and time on the straight is primarily a factor of drag and power. All through last year and parts of this year, the Renault cars were consistently showed as having used more fuel through the FOM graphics then the rest of the field.

[Tommy Cookers]

.......Increasing efficiency is ususlly done by increasing compression ratio or ignition timing advance .....

er, what ?

in principle there is only one optimal ignition timing (for any given compression ratio and boost condition)
(and only one optimal CR/boost condition for an engine designed under these rules)
the designer's job is to choose the CR/boost condition that with its optimal timing gives the optimal efficiency

if the CR/boost is too high, yes, the engine can be made to survive by retarding the ignition timing from the optimal
yes, this could be happening briefly, by programming and/or by knock sensing
if the CR/boost is too low, advancing the timing may be possible but is no benefit

'there is only one optimal ignition timing because combustion starts before tdc' - timing is a compromise
true there's an unavoidable inconsistency in cylinder filling and combustion rates (significant in N/A race engines anyway)
this inconsistency is what makes more advance look quite attractive
because some combustion strokes are lazy, they need more advance to be useful
but the most are normal, to these more advance causes distress (detonation or other)
in recent years timing might have become slightly conservative, because of the mandatory engine life

presumably the current engines are more consistent in this regard
though a lean (non-stratified) mixture would not help
their timing (for the typical boost condition) may well be fewer deg btdc than we expect in F1

[godlameroso]

How can it be the least thirsty and least powerful engine? With a capped fuel flow then inorder to use less fuel it has to spend less time at WOT, which is beast achieved by spending less time on the straight and time on the straight is primarily a factor of drag and power. All through last year and parts of this year, the Renault cars were consistently showed as having used more fuel through the FOM graphics then the rest of the field.

The engine isn't as powerful, so they're forced to run it more aggressively effectively nullifying their efficiency. More importantly, they rely on their ERS to achieve good economy, Renault never has a problem running out of fuel.

[Juzh]

How can it be the least thirsty and least powerful engine? With a capped fuel flow then inorder to use less fuel it has to spend less time at WOT, which is beast achieved by spending less time on the straight and time on the straight is primarily a factor of drag and power. All through last year and parts of this year, the Renault cars were consistently showed as having used more fuel through the FOM graphics then the rest of the field.

The engine isn't as powerful, so they're forced to run it more aggressively effectively nullifying their efficiency. More importantly, they rely on their ERS to achieve good economy, Renault never has a problem running out of fuel.

I don't think you really know what you're talking about. Their ERS is bollocks as has been proven a million times already.
And their ICE is not efficient at all. They're also not good on fuel economy and the reason why is very simple in this day and age.
More efficiency at 100 kg/h = more power at 100 kg/h (which we know renault does not have) = more speed = less time on full throttle = less fuel consumption. It's a spiralling effect. Button has talked about it a lot this year in the interviews.
They're better than honda, which is nothing to write home about.

[PlatinumZealot]

How can it be the least thirsty and least powerful engine? With a capped fuel flow then inorder to use less fuel it has to spend less time at WOT, which is beast achieved by spending less time on the straight and time on the straight is primarily a factor of drag and power. All through last year and parts of this year, the Renault cars were consistently showed as having used more fuel through the FOM graphics then the rest of the field.

The engine isn't as powerful, so they're forced to run it more aggressively effectively nullifying their efficiency. More importantly, they rely on their ERS to achieve good economy, Renault never has a problem running out of fuel.

On the other hand the engine is probably so compromised that it must be run in a weaker state, probably in resulting in a similar fuel efficiency but finishes the race a minute behind.

[NL_Fer]

ICE power is also depending on how efficient the turbine is harvasting power.mThenmore efficient, the longer the wastegate can be open, so backpressure is gone and ICE delicers more power.

[GoranF1]

0.15 sec per lap 11 tokens.....LOL!

http://www.autosport.com/news/report.php/id/121448

[toraabe]

As you said the mercedes engine don'thave to rev until 12k, so it means because of flame speed, internal friction and so on the merc is more to optimum rev range and is operating more at optimum revs

That if your engine can rev higher it can make more power is only if other factors stay the same.. but that is not so under this formula. Because of the fuel flow limit, the peak power you can extract from the fuel is basically capped, and as you rev the engine higher the friction losses still increase! So in the end the frictional losses are already dominant and it make no sense to rev higher than say 12k rpm. If the fuel flow limit was eradicated, then we would see engines using the full range 15,000 rpms.

Cool air is not Renaults problem that is an easy one to solve. Very basic one to solve in fact. At 100 miles per hour average speed around a circuit you will have plenty of cool air to cool the intercoolers. The air to the engine is also pressurised by the turbo charger so this cars will never be "gasping" for air. Under open throttle conditions they are almost always above 100% cylinder filling.

Another comment.. The Mercedes engine, actually makes all that power without needing to rev as high as the Ferrari or the Renault! This could either mean that the Ferrari and Ranault have slightly less friction and stand less to lose, or Mercedes makes that much more power there is no need for them to rev high and reduce engine life.

[NL_Fer]

Or maybe Mercedes' ERS is more efficient, so it can harvest enough at lower RPM. Think that at +10000 rpm, fuel is still burning when the opening the exhaust valves at bdc. The higher the rpm, the more fuel is burning inside the exhaust manifold, more can be harvest.

But if your ERS can harvest more energy, from less exhaust gasses, you don't to rev that high.

[trinidefender]

Or maybe Mercedes' ERS is more efficient, so it can harvest enough at lower RPM. Think that at +10000 rpm, fuel is still burning when the opening the exhaust valves at bdc. The higher the rpm, the more fuel is burning inside the exhaust manifold, more can be harvest.

But if your ERS can harvest more energy, from less exhaust gasses, you don't to rev that high.

For that to happen you will be running a spark timing that is to advanced (assuming of course the mixture hasn't already detonated on its own which seems to be Renault's limit this year) and reducing cylinder pressure. This just reduces the force on the crankshaft and reduces ICE power. Somehow I think that the net loss from reduced ice performance will be more than any gain from the increase in MGU-H recovery.

[gruntguru]

Or maybe Mercedes' ERS is more efficient, so it can harvest enough at lower RPM. Think that at +10000 rpm, fuel is still burning when the opening the exhaust valves at bdc. The higher the rpm, the more fuel is burning inside the exhaust manifold, more can be harvest.

But if your ERS can harvest more energy, from less exhaust gasses, you don't to rev that high.

The goal is to complete combustion as soon after TDC as possible. None of the current engines would have significant combustion still occurring after EVO - at any rpm.

[gandharva]

0.15 sec per lap 11 tokens.....LOL!

http://www.autosport.com/news/report.php/id/121448

0.15 speculated by autosport! But if this is true Renault totally screwed up. Beeing that far behind, and out of 12 tokens you only gain 0.15s would be miserable and more or less proof the speculations about Renault engineers beeing unable to find solutions at all.

The Renault ICE is now very strong... don't ask how I heard this... wait till Q3..

Seems Ricciardo didn't read your post, as he thinks "the new engine spec is probably not worth it".
http://www.autosport.com/news/report.php/id/121448

[jure]

He said: "wait till q3"
Seriously, why would Renault spend 11 tokens for 0.15s and the same time claim this is pure power upgrade? Wouldn't it be better to further develop the engine and maximize development time? If spent tokens are really worth just 0.15s then they are literally throwing the tokens away.