Renault Power Unit Hardware & Software

[Blackout]

You should take into account the car and tire perf difference, but yes the Renault has obviously made a nice step forward and reduced its gap with 7 tokens. Viry and R seem very confident and that bodes well for the future.
I hear Ted Kravitz talked about pre-chamber for canada, but dont know his sources.

[gandharva]

So no more 35bhp but "the gap will be halved".

The ‘power unit’, however, is an entirely different matter, with Abiteboul saying Renault is “fighting like mad” to develop it.

“No matter what we do with the car, we must have a more competitive engine,” he said, amid reports a major upgrade is coming for Canada in June.

“I cannot put a precise figure on the extra horse power that comes from the new engine, but we think the gap that we currently have to Mercedes will be halved.”

[toraabe]

At least watching the RB12 it definitely seems that the Renault PU really begins to stretch it legs out. It also sounds more like the other engines and not so muted. Someone suggested that the engine would be up to 50 hp up on the current spec.

Nice

[godlameroso]

I think really the problem here is the technical level, Mercedes has everyone beat on that level. They have more experience and more facilities to draw talent and knowledge from than Renault and Nissan combined. Ferrari has Fiat and Chrysler and they're close, but Mercedes has the might of Daimler behind it. Renault has been spending massive amounts of money sponsoring Red Bull via Infinity, re-absorbing this into their own chassis plus the corporate interest in these engines means that now Renault can actually catch up. Honda is where it's at because they're a year behind, had they used this engine last year they'd be fighting it out with Mercedes, but the stakes have raised. Their manufacturing and engineering is top notch but they lack technical vision, at their current rate and the long turn over, Honda needs to be better than everyone just to catch up.

I think we'll start to see progress from Renault via Red Bull this year, the only place they really lack is at the start of the race, once the race starts winding down they're very strong. The factory squad has no chance, they'll be lucky if they score points this year.

[uniflow]

Why not HCCI at full throttle, no spark plug? It can be done, I have a test engine that clearly shows HCCI in operation. No throttle just fuel regulated, full gulp of air each cycle. It's pretty crude and a twostroke, but clearly shows HCCI working.
It uses a small piston (38 bore x 16mm stroke) in the combustion chamber (two to one crank speed), this small piston raises the compression ratio in the combustion chamber quickly to 21 to one at approx five to seven degrees after TDC on the working piston. There is no spark ignition and no exhaust gas recirculation (apart for normal twostroke operation). It runs well although a little hairy to control via my crude spray gun injection system

[Tommy Cookers]

presumably your (N/A 2 stroke) mep is very much lower than F1's ?
and congratulations on your doing this stuff

HCCI at full power ? - what do we know about anything ?

surely it has always been well known that (car etc) diesels do not manage burn rate as well as gg seems to suggest April 16th this page ?
combustion delay is independent of rpm, burn rate is managed well by injection rate only in (large) very slow engines such as Diesel made
car 'diesels' peak combustion pressures are non-ideally high because their burn rate (inherently fast and accelerative) is not ideally managed ?
so still they need heavier reciprocating etc parts and can only run much slower than comparable SI (eg as did Le Mans Audis)
if not for this, the SI engine would be found only in museums and maybe chainsaws

and .......
what AFR/equivalence ratio do current car diesels use at full power ?
less than they ever needed before I think - and so less than F1 ?

F1 seems able to use a higher AFR than modern car diesels do at full power, and so can 'dilute' the combustion heat relatively more
fundamentally this would give a lower peak temperature than otherwise
the turbocharging efficiency is adequate to support almost any AFR - beyond the range viable with SI ?

because of this high AFR 'dilution' - can F1 engine designs now physically tolerate CI or so-called HCCI at full power ?
we know that diesel-style part-steel or steel pistons are viable at the current F1 rpm regime
and HCCI literature seems to say HCCI works best at high boost/high AFR
F1 fuel is tailorable to the requirement, and significant hot residuals are readily available

fundamentally thermodynamics implies greater in-cylinder efficiency if the air mass is greater and peak temperature is lower
the engine rules fixed the design concept (they didn't tell us what it was, though)

[gruntguru]

A very common example of HCCI at full load is the "diesel" (not really a diesel) model two stroke engine. You know - the one with a screw on top to adjust CR.

[uniflow]

Yes and no, it's a HCCI engine yes, diesel, no. Head is adjusted to get combusion at a suitable time for that moment. As air pressure changes or fuel delivery changes or air temp changes, so does the compression requirment. Is designed for constant rev's constant load. Also can't be timed to ignite after TDC (working piston) as mine can.

[gruntguru]

Yes and no, it's a HCCI engine yes, diesel, no. Head is adjusted to get combusion at a suitable time for that moment. As air pressure changes or fuel delivery changes or air temp changes, so does the compression requirment. Is designed for constant rev's constant load. Also can't be timed to ignite after TDC (working piston) as mine can.

I don't recall saying it was a diesel.
Can be operated over a significant range of loads and speeds.
No need to ignite after TDC - ignition delay does that for you.
Not saying your engine does not have significant advantages - just correcting a few things.
http://papers.sae.org/2008-01-1662/

[gruntguru]

The curved limits are propeller characteristics not engine limits.

[PlatinumZealot]

OK, I have not the slightest understanding of that graph... but anyway. Guru, the rules stipulate fixed compression ratio right? I have been thinking about Mark Hugh's suggestion that Mercedes has a moving part on the piston or in the chamber but this regulation would definitely rule out any devices that alter the chamber volume at TDC.

[Frank_]

OK, I have not the slightest understanding of that graph... but anyway. Guru, the rules stipulate fixed compression ratio right? I have been thinking about Mark Hugh's suggestion that Mercedes has a moving part on the piston or in the chamber but this regulation would definitely rule out any devices that alter the chamber volume at TDC.

dynamic compression ratio,s constantly change on a throttled engine surely ? perhaps the rules apply to a fixed static c/r ?

[gruntguru]

OK, I have not the slightest understanding of that graph...

It shows the operating limits of the HCCI model aero engine tested in the paper linked in the previous post. The red boundary shows the overall limits and the yellow boundary applied when the CR was fixed at 15:1.

[uniflow]

I wonder why then this system is not used in general twostroke operation?

[Tommy Cookers]

re the model 'diesel' ......
this is all at uselessly low mep, of course
inherently, in large part because the (stoichiometric mass) calorific value of the fuel is so low
to get HCCI at the low-level thermodynamic conditions necessary for such simplicity
PAW product has changed little in 60 years ?