F1technical.net

hurril wrote:What is the point of having a maximum compression ratio?

Probably to reduce pollution or something.

henry wrote:There is also a change to intake air temperature for 2018

I thought hot air was what was needed for these lean charge ICEs? This seems to indicate that cold air is being used and they want it stopped.

Only HCCI would need the hot air and massive EGR. But remember it was established that HCCI is not utilized.

Apparently teams must have been pumping ice cold coolant into the inter-coolers before their qualifying laps!

Possibly why Honda think they don't have the "qualifying mode" like Mercedes and Ferrari. I am going to see if the other teams move to a water cooled setup next year.

Not in the intercoolers. I think they stuff the airbox with dry ice before starts and quallies, for a few laps of cold intake.

NL_Fer wrote:Not in the intercoolers. I think they stuff the airbox with dry ice before starts and quallies, for a few laps of cold intake.

Dry ice is frozen CO2 so it won't be going in the air intake for the engine.

They can still lump it around the engine and under the engine covers. As the temperature increases it would just vaporize so it's a good idea to keep air temperatures down.

NL_Fer wrote:Not in the intercoolers. I think they stuff the airbox with dry ice before starts and quallies, for a few laps of cold intake.

Actually they could put it in the intercoolers. Could be why there are multiple intercooler setups.

Dry ice intercooler

I guess i misunderstood plenum for airbox. If i am correct now, the plenum is the shared part of inlet manifold. Then location where compressed and cooled air enters, coming from the intercooler.

Insane if they can get that below ambient.

In my opinion, best overall efficiency (and therefore best "self-sustaining" power output) would require a more elevated temperature - somewhere between 40 and 100 degrees C.

Qualy' mode is a different story. There is no exhaust back-pressure and little or no turbine recovery. Chilled inlet will reduce compressor power which is important because the MGUH is being used to drive the compressor.

Another possibility is the cold charge permits a higher boost without detonation. Higher boost has the advantage of doing more pumping work on the pistons allowing more ES energy to be used to drive the car.

NL_Fer wrote:Could it be a miller/adkinson cycle?

As far as I understand, in an Atkinson/Miller cycle you tune the engine such that the pressure when you open the exhaust valve is equal to the atmospheric pressure. so all the expansion of the combustion is used to move the piston.

In an Otto engine, instead, part of the combustion energy is lost as when the exhaust valve opens the gases are still expanding . If you have a turbocharger (or a turbo-compound) that energy is recovered.

So, by using the Atkinson cycle since you will need use engine power to move the turbo as the exhaust stroke will require more force, so you are technically in a Miller cycle. I don't think this is convenient since the engine is at the same time producing less power than an Otto, but perhaps it might be energetically favorable if you are limited in fuel.

NL_Fer wrote:I guess i misunderstood plenum for airbox. If i am correct now, the plenum is the shared part of inlet manifold. Then location where compressed and cooled air enters, coming from the intercooler.

Insane if they can get that below ambient.

I realize it is different but drag guys that run in turbo classes use those dry ice intercoolers and can get IAT below ambient . Not sure if F1 teams could utilize it to that extent in quali and it might be more trouble than it is worth.

1158 wrote:

NL_Fer wrote:I guess i misunderstood plenum for airbox. If i am correct now, the plenum is the shared part of inlet manifold. Then location where compressed and cooled air enters, coming from the intercooler.

Insane if they can get that below ambient.

I realize it is different but drag guys that run in turbo classes use those dry ice intercoolers and can get IAT below ambient . Not sure if F1 teams could utilize it to that extent in quali and it might be more trouble than it is worth.

Which allows them to use more fuel to get extra power. That is not an option in F1 at the moment.

Plus drag runs only last a few seconds, not an hour and a half.

dren wrote:Plus drag runs only last a few seconds, not an hour and a half.

Qualifying lap isn't an hour and a half either.

wuzak wrote:
Which allows them to use more fuel to get extra power. That is not an option in F1 at the moment.

Very valid point and since they can't make changes to any bodywork I guess there wouldn't even be any value to using it to cut down on flow through sidepods in qualifying.

However why would the FIA feel the need to limit IAT reduction if there wasn't some advantage to be gained?

I did not actually see that 2018 reg yet; but for one thing AIT reduction is a knock mitigant, which has performance value.

lower temp > less knock > more boost pressure > more compression