2014-2020 Formula One 1.6l V6 turbo engine formula

[xpensive]

...
Yes
and iirc Honda were actually using only 2.5 bar abs to burn 40 gm/sec to produce 675 bhp a quarter of a century ago

My mistake TC, the limit in 1988 was 2.5 absolute, which was all it took for Honda to burn 40 g/s with 1.5 liter at 12 kRpm,
which makes the claim of manufacturers using 3.5 Bar today in order to burn 27.8 g/sec all the more preposterous.

[gruntguru]

My mistake TC, the limit in 1988 was 2.5 absolute, which was all it took for Honda to burn 40 g/s with 1.5 liter at 12 kRpm, which makes the claim of manufacturers using 3.5 Bar today in order to burn 27.8 g/sec all the more preposterous.

1. Not sure where you got 40 g/s? My calculations based on the Honda Paper give 42.5 g/s in rich mode and 34.4 g/s in economy mode. Note that economy mode was at lambda = 0.98
2. Scaling down to 10,500 rpm in economy mode gives 34.4 x 10,500/12,500 = 28.9 g/s (getting closer)
3. I have made many posts in this thread showing why lambda needs to be a minimum of 1.2 under the current formula. The MAP required to do this with a 1.6 litre equivalent of the Honda RA168 would be 2.5 x (1.5/1.6) x (27.8/28.9) x (1.2/0.98) = 2.76 bar.

3.5 bar would give lambda = 1.52

Preposterous? Lets see. Renault says 3.5 bar. Facts only says 3.5 bar. I think 3.5 bar is possible.

[xpensive]

The 40 g/sec* was taken from this link, p 7, but the 1988 Quali-engine could according to this to be as much as 44.6 at 2.5 bar.

http://www.grandprixengines.co.uk/Egs_6 ... _Honda.pdf

Again, I'd be careful t believe what self-proclaimed insiders say, the 3.5 bar seems likely to be just a quote from Renault.

* Calculation error, should be 36.2 g/sec for the Racing engine. Mea Culpa.

[gruntguru]

I think the only valid comparison would be the economy mode. The effect of the current regulations is:

Max power = BSFC x 100 kg/hr

i.e. the only way to increase power is to increase BSFC.

The Honda Tech Paper says econo mode gave 456 kW @ 272 g/kW.hr i.e. 456 x 0.272 = 124 kg/hr = 34.45 g/s

[xpensive]

Close enough grunts, some 35 g/sec at 2.5 bar abs, now why would you need 3.5 to burn 27.8, can you plausibly xplain that?

[gruntguru]

Hmm I've been through all this before but here is the short version.

1. Max BSFC coincides with Max power because max-power-fuel-flow is regulated to 100 kg/hr
2. Max BSFC occurs at Lambda = 1.2 or thereabouts. Varies with engine design - sometimes much leaner.
3. If the DI system can produce stratified charge at 10,500 the burn zone would be at 1.2 lambda with air surrounding it. This air will reduce quenching and unburned fuel, reduce heat loss to the cylinder walls, increase mass flow through the compounding elements (compressor and turbine), reduce exhaust temperatures, reduce detonation . . .

Honda RA168 econo lambda 0.98. F1 2014 lambda 1.2 +++. The extra air means more boost required. Don't forget max power is 2000 rpm lower than the Honda too - more boost.

Think Diesel.

[Tommy Cookers]

P162 Fig4.10 shows that the efficiency benefits of lean mixture fall far short of (gg's ?) Fuel-Air cycle theoretical prediction
Fig 4.6 is more useful but unavailable from this link
chapter 4.7 says 'Thus the maximum efficiency is within the lean zone very near the stoichiometric ratio'

in another (4th) edition of this book the same figs are 3.6 and 3.10 and the sentence above is in chapter 3.7

http://books.google.co.uk/books?id=jcoZ ... &q&f=false

gg's extra air demands more compressor power (every kW costing about 2 kW of turbine recovery power) and more intercooling

[ringo]

I'll repeat again 3.5 bar abs, is not run at high revs. The only way i buy that figure is for low revs like 4000 rpm.
I've already posted a boost vs rpm chart. 3.5 bar is too high.
I don't know why we feel this number is of any significance, does it make the engines look more impressive? I don't know.

[GitanesBlondes]

3.5 BAR absolute?

The math shows that 3.5 BAR absolute isn't the case.

[xpensive]

As a relevant comparison, the 1987 Honda RA167E 1.5 V6 engine developed 900 Hp in Racing mode from 4.0 bar absolute.

There was a xtra 100 Hp available for Quali and overtaking, this is how Mansell was able to catch Piquet at Silverstone that year.

[gruntguru]

P162 Fig4.10 shows that the efficiency benefits of lean mixture fall far short of (gg's ?) Fuel-Air cycle theoretical prediction

Unfortunately Fig 4.10 is the only chart on the page with no scale on the AFR axis however it is clear that peak efficiency occurs a considerable distance to the lean side of stoichiometric. Supports my case nicely - thanks for posting.

[gruntguru]

gg's extra air demands more compressor power (every kW costing about 2 kW of turbine recovery power) and more intercooling

So according to you, a gas turbine should lose power and efficiency as pressure ratio is increased?

[gruntguru]

3.5 BAR absolute?

The math shows that 3.5 BAR absolute isn't the case.

I have done some math and 3.5 bar turns out to be probable. I have not seen any math that proves 3.5 bar to be impossible or even unlikely.

[gruntguru]

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.

[xpensive]

3.5 BAR absolute?

The math shows that 3.5 BAR absolute isn't the case.

I have done some math and 3.5 bar turns out to be probable. I have not seen any math that proves 3.5 bar to be impossible or even unlikely.

I think it mostly because it stands out so much from the xperiences of the turbo years in the 80s, which I referred to earlier.