F1technical.net

The latest merc engine ( 7 tokens version - run by the merc team istelf ) has a different combustion chamber. They have developed a pre chamber where just a tiny amount of fuel is being ignited before the rest of the fuel is being feed into the main combustion chamber. That means longer flame time, and that the engine can be run in a leaner state. Longer flame time also means less general stress on the engine itself. And at lower rpm.

The Renault engine.. knocking knocking knocking.. In which can be traced back to not optimized combustion chamber, and too high temperature in the feed air. Then we are back to the general layout...

trinidefender wrote:

NL_Fer wrote: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.

I've read several times, especially this year, that Renault had and probably still have problems with knocking. They just cannot burn with the boost levels Mercedes is achieving and therefore cannot reach the same engine efficiency, directly leading to less power in this fuel-limited formula. There can be multiple reasons for this, from which higher air inlet temperature (possibly due to the layout) and a worse combustion chamber design are very well possible.

About the pre-chamber combustion which Mercedes is using, I found some interesting information from Mahle Powertrains (http://www.greencarcongress.com/2012/05 ... 20521.html). According to the article, 45% thermal efficiency is possible with this technology. But since Mahle is one of Ferrari's sponsors/technical partners, are they maybe also using this technology already?

jure wrote: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.

11 token, 6% , 50 bhp would be 0.15s ? Red bull is in PR mode still , making fool to renault still and they'll have Bernie to sue them soon!

end of the game ? Austin isn't strategic for them on points count, if they doesn't use the last upgrade, its rather they wanna quit f1 and they do'nt want to allow renault to show thier real potential for 2016

ReoPTy wrote:

jure wrote: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.

11 token, 6% , 50 bhp would be 0.15s ? Red bull is in PR mode still , making fool to renault still and they'll have Bernie to sue them soon!

end of the game ? Austin isn't strategic for them on points count, if they doesn't use the last upgrade, its rather they wanna quit f1 and they do'nt want to allow renault to show thier real potential for 2016

To be fair to RBR Renault used 21 tokens during the winter and ended up with ......................................

bergie88 wrote:I've read several times, especially this year, that Renault had and probably still have problems with knocking. They just cannot burn with the boost levels Mercedes is achieving and therefore cannot reach the same engine efficiency, directly leading to less power in this fuel-limited formula. There can be multiple reasons for this, from which higher air inlet temperature (possibly due to the layout) and a worse combustion chamber design are very well possible.
About the pre-chamber combustion which Mercedes is using, I found some interesting information from Mahle Powertrains (http://www.greencarcongress.com/2012/05 ... 20521.html). According to the article, 45% thermal efficiency is possible with this technology. But since Mahle is one of Ferrari's sponsors/technical partners, are they maybe also using this technology already?

did you mean 'Renault just cannot burn with the same CR Mercedes is achieving' ?

higher CR has a direct and substantial effect on efficiency (due to greater expansion)
higher boost does not

ok Renault (whose publicity long ago declared 3.5 bar 'boost') may be stuck with too much boost for their CR
HUCR being related to chosen boost condition

the source that you usefully linked has F1 value based on its allowing higher CR
its road value is based on using super-lean mixture to reduce or eleminate throttling at partial powers

and we still don't know actual CRs or actual boosts (or even actual Octane numbers)

Probably both Merc and Ferrari

bergie88 wrote:I've read several times, especially this year, that Renault had and probably still have problems with knocking. They just cannot burn with the boost levels Mercedes is achieving and therefore cannot reach the same engine efficiency, directly leading to less power in this fuel-limited formula. There can be multiple reasons for this, from which higher air inlet temperature (possibly due to the layout) and a worse combustion chamber design are very well possible.

About the pre-chamber combustion which Mercedes is using, I found some interesting information from Mahle Powertrains (http://www.greencarcongress.com/2012/05 ... 20521.html). According to the article, 45% thermal efficiency is possible with this technology. But since Mahle is one of Ferrari's sponsors/technical partners, are they maybe also using this technology already?

Tommy Cookers wrote:

bergie88 wrote:I've read several times, especially this year, that Renault had and probably still have problems with knocking. They just cannot burn with the boost levels Mercedes is achieving and therefore cannot reach the same engine efficiency, directly leading to less power in this fuel-limited formula. There can be multiple reasons for this, from which higher air inlet temperature (possibly due to the layout) and a worse combustion chamber design are very well possible.
About the pre-chamber combustion which Mercedes is using, I found some interesting information from Mahle Powertrains (http://www.greencarcongress.com/2012/05 ... 20521.html). According to the article, 45% thermal efficiency is possible with this technology. But since Mahle is one of Ferrari's sponsors/technical partners, are they maybe also using this technology already?

did you mean 'Renault just cannot burn with the same CR Mercedes is achieving' ?

higher CR has a direct and substantial effect on efficiency (due to greater expansion)
higher boost does not

ok Renault (whose publicity long ago declared 3.5 bar 'boost') may be stuck with too much boost for their CR
HUCR being related to chosen boost condition

the source that you usefully linked has F1 value based on its allowing higher CR
its road value is based on using super-lean mixture to reduce or eleminate throttling at partial powers

and we still don't know actual CRs or actual boosts (or even actual Octane numbers)

Since the bore,stroke and volume are fixed by the regulations, I think you mean with CR the overall compression of the air as a combination of the structural CR (fixed) and the boost pressure, am I correct? In that case you are right. However, with the fixed structural CR boost pressure and overall CR are essentially the same, but it is more clear to talk about CR.

In my opinion you want to burn as lean as possible in this engine formula, because higher efficiency = more power. This means that if you have a too small compressor (Renault? Honda?) you have a problem.

I mean nominal CR, also more usefully known as geometric CR, eg as in my road car the CR is 10.6:1
geometric CR is the ratio of swept volume to combustion chamber volume
it is not fixed by the rules

regarding lean mixture, there is homogeneous lean mixture and inhomogeneous lean mixture aka stratified charge
2 very different things
which is being advocated here ? (as something Renault hasn't but Mercedes has)

Tommy Cookers wrote:I mean nominal CR, also more usefully known as geometric CR, eg as in my road car the CR is 10.6:1
geometric CR is the ratio of swept volume to combustion chamber volume
it is not fixed by the rules

regarding lean mixture, there is homogeneous lean mixture and inhomogeneous lean mixture aka stratified charge
2 very different things
which is being advocated here ? (as something Renault hasn't but Mercedes has)

Sorry I was wrong, the swept volume is the same but the volume of the combustion chamber off course not. I am not really into these combustion modes, but I think they will use the one which results in the highest efficiency.

These racing engines and most the road engines, ar full load, are running pretty rich, like 1:10-12 to achieve max power and keep the temperature under control. I think for this fuel limited formula, the challenge is to achieve 1:14.7. Under a full load, that could be called lean.

Why is Renault keeping the air2air intercooler? Is their capacity sufficient, does the compressed air heat up, while running through all that tubing?

mass AFR 14.7 sounds like stoichiometric (assuming traditional non-bio gasoline and current F1 being similar to that value)
modern road cars are slightly rich (about 4% iirc) at all powers
because of the way they run the catalysts for simultaneous oxidation and reduction

the proponents of lean are talking maybe 20 (and more with inhomogeneous charge)

a big reason why a rich mixture maximises power in a high-boost fuel-unlimited engine is its chemical deterrence of dissociation
in an N/A engine eg the recent F1 V8s it reduced combustion variability affecting some cylinders

for the current engines we are surely talking some or other amount leaner than stoichiometric ?

NL_Fer wrote:These racing engines and most the road engines, ar full load, are running pretty rich, like 1:10-12 to achieve max power and keep the temperature under control. I think for this fuel limited formula, the challenge is to achieve 1:14.7. Under a full load, that could be called lean.

Why is Renault keeping the air2air intercooler? Is their capacity sufficient, does the compressed air heat up, while running through all that tubing?

Under full load that cannot be called lean. That can be called stoichiometric. It is road cars and race cars not limited by a maximum fuel flow that will be running rich. However yes I must admit it would be quite a challenge to get stable combustion at stoichiometric or leaner (homogenous mixture or not).

ReoPTy wrote:

jure wrote: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.

11 token, 6% , 50 bhp would be 0.15s ? Red bull is in PR mode still , making fool to renault still and they'll have Bernie to sue them soon!

end of the game ? Austin isn't strategic for them on points count, if they doesn't use the last upgrade, its rather they wanna quit f1 and they do'nt want to allow renault to show thier real potential for 2016

If there really was 50hp available RedBull would jump at it, especially at a track like this!

To achieve what, they cannot take Willams 3rd place in wcc or lose 4th to Force India.

djos wrote:

ReoPTy wrote:

jure wrote: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.

11 token, 6% , 50 bhp would be 0.15s ? Red bull is in PR mode still , making fool to renault still and they'll have Bernie to sue them soon!

end of the game ? Austin isn't strategic for them on points count, if they doesn't use the last upgrade, its rather they wanna quit f1 and they do'nt want to allow renault to show thier real potential for 2016

If there really was 50hp available RedBull would jump at it, especially at a track like this!

Renault brough 11 tokens and only a .2 s of austin lap upgrade? lot of politics in it , as taffin said this engine potential wasn't optimised polite move, my sources tells 50-60 hp output pick, but more than that, most of it at very smouth low rev steady powerfull torque ...