2014-2020 Formula One 1.6l V6 turbo engine formula

[Vary]

If you browse the last 20 pages or so in this thread, you will find a lot of discussion of that issue.

1. 15:1 Otto cycle has Thermal Efficiency of 66% so I am not sure what cycle you have assumed.
2. F1 engines are Otto cyle plus exhaust turbocompounding.
3. MB have publicly claimed TE > 40%.
4. Top speeds for the cars are consistent with power well over 700 hp.
5. A number of researchers are claiming TE > 40% for SI engines in the lab.

I haven't already had the time to read last 20 pages, but i nave to correct some of your points.

1. Probably you've calculated TE with air, but work fluid is a mixture of air and gasoline (and the chemical species changes during combustion), so i assumed that gamma value drops to 1.27, like is stated here: courses.washington.edu/me341/oct22v2.htm
2. Turbocompounding doesn't increase TE of theoretical cycle (if the turbine is at the end of theoretical cycle with complete expansion, there isn't pressure drop on the turbine, so it doesn't spin and so no extra work) but it only reduce losses for incomplete expansion
3.(and .5) i can belive an optimal TE over 40% (usually the optimal efficiency isn't reached at max power), but here we're talking of overall efficiency, which includes ALL mechanical losses (bearing, gearbox, differential, etc)
4. (I'm not sure i nave understood correctly this sentence) i agree that real output power is well over 700 hp (in fact my calcs were done without the ERS power of 160hp) but i still find hard believe such high performance with the limited fuel flow...

[gruntguru]

Your position is a bit clearer now, thanks.
1. My position is that these engines are running very lean - similar ratios to typical diesels. At these AFR's gamma will be somewhere between your 1.27 and my 1.4
2. The Otto and Diesel theoretical cycles do NOT fully expand the working fluid down to the exhaust back pressure. This is the main reason that efficiency increases with increasing CR - it is actually the increase in expansion ratio (ER = CR for Otto and Diesel). The turbine captures some of this energy (normally lost as blowdown energy across the exhaust valve).
3. Everywhere I have mentioned TE figures, I mean BTE (after subtracting all losses) not ITE. BTE > 40% is possible. Current Toyota Prius has peak BTE around 37%. Toyota has test engines for next generation Prius running over 40% - without compounding! ITE is much higher - probably around 50%. Because of the fuel flow rules Maximum Power is in direct proportion to maximum efficiency - the two will coincide in the rev range above 10,500.
4. BTE would be calculated including some of the MGUK power. Max continuous rating is crankshaft power plus turbine (MGUH) power i.e. power available with no ES (or fully discharged ES).

[ringo]

The engines are not running lean.
There's no evidence to suggest that.

Also those magical prius engines you speak of are nothing like the typical otto cycle race engine. It's basically an Atkinson cycle, which is very efficient.

Let's have less dramatization and more objective thinking. There needs to be evidence or reasonable theory as to what the engines are doing and how they operate.

So far in the middle part of the season, i'm not really seeing a brutish power difference with the engines. I think it's more the ERS that is giving better average power over a lap than one power unit having a big peak power advantage.

What could tell you a lot about the energy recovery system is the EGT. if we can get some real data from the cars that would be good. Even if it's the thermal imaging of the exhaust plume.

[TinoBoost]

there is no evidence to suggest lean running.

how would you design a fuel flow limited engine?

the principles of the atkinson and miller cycle would be useful in getting high bsfc, by moving some of the compression power to the compressor of the turbo, removing it from the piston.

there is no way you can make more power by wasting fuel by not combusting it.

[Vary]

I totally agree about not running lean burn. Guys, we're talking about formula 1 engines, and if it's asked to you to design a F1 engines, what will be your main objective? Maximum power, not maximum efficiency! Look at the prius for example: their objective was efficiency, so they used an atkinson cycle and have l'essere than 100 hp; the engine we're talking about have over 750 hp, so a specific power output of (over) 468 hp/L, compared to circa 50 hp/L of a prius!

(I know that an prius and a F1 car don't have no think in common, but you've called out the prius )

[Pierce89]

I totally agree about not running lean burn. Guys, we're talking about formula 1 engines, and if it's asked to you to design a F1 engines, what will be your main objective? Maximum power, not maximum efficiency! Look at the prius for example: their objective was efficiency, so they used an atkinson cycle and have l'essere than 100 hp; the engine we're talking about have over 750 hp, so a specific power output of (over) 468 hp/L, compared to circa 50 hp/L of a prius!

(I know that an prius and a F1 car don't have no think in common, but you've called out the prius )

Well, in the case of 2014 f1, max power and max efficiency are one and the same. While I don't think they're running the super lean fully stratified charge like Guru believes , I do believe they are at least slightly lean on stoichiometry. Its no longer how much power can I get out of a limited amount of air but how much power can I get from a limited amount of fuel, that plus the turbo compounding just makes it a whole new ball game.

[trinidefender]

I totally agree about not running lean burn. Guys, we're talking about formula 1 engines, and if it's asked to you to design a F1 engines, what will be your main objective? Maximum power, not maximum efficiency! Look at the prius for example: their objective was efficiency, so they used an atkinson cycle and have l'essere than 100 hp; the engine we're talking about have over 750 hp, so a specific power output of (over) 468 hp/L, compared to circa 50 hp/L of a prius!

(I know that an prius and a F1 car don't have no think in common, but you've called out the prius )

Well, in the case of 2014 f1, max power and max efficiency are one and the same. While I don't think they're running the super lean fully stratified charge like Guru believes , I do believe they are at least slightly lean on stoichiometry. Its no longer how much power can I get out of a limited amount of air but how much power can I get from a limited amount of fuel, that plus the turbo compounding just makes it a whole new ball game.

Vary I'm sorry but I believe you have quite a bit of reading to do, try and go back a few pages and you will see that, as Pierce89 pointed out, maximum power and maximum thermal efficiency are the same.

Personally I do believe that these engines would run on the lean side, lambda 1.1 to 1.2 range and not run a fully stratified charge as Guru believes. At the same time I have to wonder if these engines do run a form stratified charge at lower rpm's and lower throttle loads, (read as fuel flows) (as fuel flow limits reduce below I think 10,500 rpm). I say this because the turbos can be artificially powered so a high airflow with a low fuel flow is possible at lower revs.

Another point I have to present to the general public here is. The viability of a an engine manufacturer running an Atkinson cycle engine of sorts. Do the regs allow this? With boost pressures being high enough then it should still be possible to achieve complete burning of the mixture with a the benefits of a longer expansion stroke that comes with the Atkinson cycle.

The thought also does present me with the problem that having a longer expansion stroke means less energy is released to the turbocharger turbine. I'm also not sure that an Atkinson cycle can work over the whole rpm range without variable valve timing.

Just a kind of thought experiment to put out there for anybody with enough time to listen to my rants.

[gruntguru]

The engines are not running lean. There's no evidence to suggest that. Also those magical prius engines you speak of are nothing like the typical otto cycle race engine. Let's have less dramatization and more objective thinking. There needs to be evidence or reasonable theory as to what the engines are doing and how they operate.

I have supplied both evidence and reasonable theory. Some members have the ability to understand - some don't. Try this.

BTE = Power/Fuel energy flow. therefore -

Power = BTE x Fuel energy flow. The rules limit the Fuel flow so the only way to increase power is to increase BTE. Imagine you have one of these engines on the dyno at 10,500 rpm. The fuel flow is set to the max - 100kg/hr. All you can adjust is the airflow (via boost) and parameters that affect knock and combustion rate e.g. timing, CR, Charge air temp etc.

As you increase airflow (boost) the power increases as BTE increases and continues until you are so lean the BTE is decreasing. This does not happen until somewhere between lambda 1.2 and 1.6 (depending on engine design.) 1.2 would be optimum AFR for older technology engines. Even with port injection some engines see peak BTE at up to 1.5 - I repost from the Bosch Automotive Handbook.

image from Bosch Automotive Handbook. 8th edition page 559. Quoting from the same page:

"Spark-ignition engines with intake manifold injection achieve the lowest fuel consumption at constant engine output dependant on the engine at 20-50% air surplus (lambda = 1.2 - 1.5)"

Clearly, direct injection engines will tolerate even leaner mixtures although some researchers are seeing peak efficiency at lambda 2.0 with port injection http://www.greencarcongress.com/2014/04 ... -hlsi.html.

The same link includes a Heat Balance chart for Lambda 2.0 vs stoichiometric showing dramatically reduced loss to cylinder walls and thermal efficiency at 39.9% vs 33.7% ie 18.4% more work from a given quantity of fuel.

Then again, perhaps F1 people are smarter than that and would rather run at stoichiometric than take the extra 18% power.

Trini - I am not certain that F1 engines are running with stratified charge at high power. I am certain that they run well lean of stoic - 1.2 or greater. The Honda research in the link above produced 40% BTE at Lambda 2.0 with a homogeneous, port injected charge. I am also convinced (for a number of reasons) that charge air temperatures are 70*C or higher - possibly much higher.

[trinidefender]

The engines are not running lean. There's no evidence to suggest that. Also those magical prius engines you speak of are nothing like the typical otto cycle race engine. Let's have less dramatization and more objective thinking. There needs to be evidence or reasonable theory as to what the engines are doing and how they operate.

I have supplied both evidence and reasonable theory. Some members have the ability to understand - some don't. Try this.

BTE = Power/Fuel energy flow. therefore -

Power = BTE x Fuel energy flow. The rules limit the Fuel flow so the only way to increase power is to increase BTE. Imagine you have one of these engines on the dyno at 10,500 rpm. The fuel flow is set to the max - 100kg/hr. All you can adjust is the airflow (via boost) and parameters that affect knock and combustion rate e.g. timing, CR, Charge air temp etc.

As you increase airflow (boost) the power increases as BTE increases and continues until you are so lean the BTE is decreasing. This does not happen until somewhere between lambda 1.2 and 1.6 (depending on engine design.) 1.2 would be optimum AFR for older technology engines. Even with port injection some engines see peak BTE at up to 1.5 - I repost from the Bosch Automotive Handbook.

http://i.imgur.com/Uom61JN.jpg
image from Bosch Automotive Handbook. 8th edition page 559. Quoting from the same page:

"Spark-ignition engines with intake manifold injection achieve the lowest fuel consumption at constant engine output dependant on the engine at 20-50% air surplus (lambda = 1.2 - 1.5)"

Clearly, direct injection engines will tolerate even leaner mixtures although some researchers are seeing peak efficiency at lambda 2.0 with port injection http://www.greencarcongress.com/2014/04 ... -hlsi.html.

The same link includes a Heat Balance chart for Lambda 2.0 vs stoichiometric showing dramatically reduced loss to cylinder walls and thermal efficiency at 39.9% vs 33.7% ie 18.4% more work from a given quantity of fuel.

Then again, perhaps F1 people are smarter than that and would rather run at stoichiometric than take the extra 18% power.

Trini - I am not certain that F1 engines are running with stratified charge at high power. I am certain that they run well lean of stoic - 1.2 or greater. The Honda research in the link above produced 40% BTE at Lambda 2.0 with a homogeneous, port injected charge. I am also convinced (for a number of reasons) that charge air temperatures are 70*C or higher - possibly much higher.

I don't disagree with your research per say. What makes me slightly skeptical about it is the fact that I didn't see mention of that running on a turbocharged/supercharged ICE. Aircraft which run turbo's (piston driven obviously) tend to not run as lean as their un-boosted counterparts for best range performance.

To add to that, in a turbocharged ICE with a fixed maximum fuel flow, the only thing you can do to increase A:F ratio is to obviously increase airflow. There for to get from lambda to lambda 2.0 you have to double the airflow. To double the airflow you have to double the power required by the turbocharger to pump that air (assuming the efficiency of turbocharger doesn't change) you also then have to double the size of the intercooler if you want the airflow to be at the same temp as lambda 1.

As you increase the airflow to raise the A:F ratio you increase power taken by the turbocharger. At some point the increased power usage by the turbocharger must overcome any BTE advantage by increasing the A:F ratio. Not to mention the enlarged intercooler that then needs to be packaged. Even with the intercooler only bringing the charge temp down to 70 degrees Celsius that you are using. Lastly any extra power used by the turbocharger compressor is power that is taken away from being harvested by the MGU-H.

Because of these reasons my estimate falls around Lambda 1.1 to 1.2 with a maximum of about 1.4.

[Pierce89]

I gave Guru the same reasons for not running quite so lean. If you double the compressors power requirement, I believe reduction in power at the ers-h will outweigh any increase of power in the ICE.

[gruntguru]

Trini and Pierce.
"Those who believe that high boost pressures rob unnecessary power from the turbine and reduce thermal efficiency should have a read. For example page 9 states "The best SFC and engine weight balance was found to exist at high compressor pressure ratios (over 10) This is even higher than the Napier Nomad turbo-compound which had a pressure ratio of 6.5 in 1952 and the highest thermal efficiency of any aircraft engine ever produced."

Best efficiency at pressure ratios over 10!!!. Yet you guys can't accept that F1 might be running at 3.5 as stated by Renault? Any additional compressor work is returned as extra mass flow and pressure drop through the turbine.

[gruntguru]

What makes me slightly skeptical about it is the fact that I didn't see mention of that running on a turbocharged/supercharged ICE. Aircraft which run turbo's (piston driven obviously) tend to not run as lean as their un-boosted counterparts for best range performance.

Perhaps you could give an example? Certainly as boost and BMEP increase it becomes more difficult to control knock and chamber temperature under lean conditions.

Wright turbo compound cruised at 1.2 and that was 72 years ago!

[Brian Coat]

http://www.fisita2012.com/programme/pro ... 01-041.pdf

I thought this looked somewhat relevant, especially pages 12, 13.

It is a research paper by Ricardo and Petronas.

[gruntguru]

http://www.fisita2012.com/programme/pro ... 01-041.pdf
I thought this looked somewhat relevant, especially pages 12, 13.
It is an research paper by Ricardo and Petronas.

Good find Brian. The results published in this paper are indicative of what could be happening in F1, especially when you remove the NOx emission constraint that does not apply to F1.

Also of interest is knock resistance - 36 Bar BMEP @ 10.7 CR. Current F1 engines are operating at about the same BMEP so we need to rethink what CR the engines might be running. (36 Bar @ 10, 500 rpm = 670 bhp crankshaft)

[J.A.W.]

Or - for a next step in the high power/efficiency mill, the controlled detonation combustion engine..
http://ftp.rta.nato.int/public//PubFull ... 150-08.pdf