WhiteBlue wrote:Considering the different news and the figuring by members I would summarize the discussion so far:
- 1.6L four cylinder turbo charged engine with either V4 or L4 configuration limited to 3 bar intake pressure and 10,000 or 10,500 rpm
- fuel and/or fuel flow limit to reduce max engine power to 650 bhp, 115 kg race fuel likely target (- 25% compared to 2010)
Well the engine wont be at 650hp the whole race to achieve that 115kg. It reaches that value before 1 hr into the race!
I've struck a balance witht engine, i take it that 10% is loss to friction, so i put the boost at 2.5 bar gauge, so we get ~ 670hp.
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*ignore the power graph, i'm using my power and engine data* Obviously max power is not seen all the time, even at full throttle, and using the diagram above I'll try a little guesstimation.
19.8% is closed throttle, assume lean burning here so equivalence ratio 0.98, idle air coming in alone as if engine is at 1500rpm.
the fuel flow i get with this assuming the boost is about 0.1 bar??.
is 0.0017 kg/s
63.6% full throttle, assume equivalence ratio at bout 1.15 for maximum power
assuming the engine accelerates instantly to 10,000 rpm and stays there all the time for the duration:
0.0407 kg/s
16.6% part throttle, say stoichometry, since this is not steady running like on a highway, i wont expect the kinds of low lean burn ratios that the DI can give.
I'll use air flow for around 5500rpm assuming the drivers don't want the maximum torque then. Also boost drops to 2 bar from 2.5; don't know for sure, engineers decide that.
flow is 0.017 kg/s
so in total, for a 80minute race:
0.198 * 4800s * 0.0017kg/s = 1.615kg
0.636 * 4800s * 0.0407kg/s = 124.24kg
0.166 * 4800s * 0.017kg/s = 13.5kg total = 139.4kg higher than 115
This is if 650hp is the minimum. KERS would be additional power to get to 800.
If the KERS 150hp is used with the engine to bring up the power to 650 instead of adding to it,then it's an engine power of 500hp. this is only done at 19s a lap for an 80s lap 60 lap race, 23.75% of the race. ( 23.75% , this is why WB choses 19s, to drop consumption
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)
engine at 500hp : 0.2375 * 4800 * 0.0265 = 30.21kg
engine at 650hp: (0.636-0.2375) * 4800* 0.0407 = 77.85kg
total = 108kg + 1.615 + 13.5 = 123kg
very difficult to drop to 115kg, but it can be done, maybe on a track with less full throttle. For instance a track with 50% full, 30.2part the result is:
closed: 0.198 * 4800s * 0.0017kg/s = 1.615kg
kers + full: 0.2375 * 4800 * 0.0265 = 30.21kg
full: (0.500-0.2375) * 4800* 0.0407 = 51.282kg
part: 0.302 * 4800s * 0.017kg/s = 24.64kg total = 107kg
But the way i see it, it's too much torture to do all this to meet an arbitrary number of 115kg. Chances are a race using KERS like this ie not using it to increase power but save fuel, will increase race time from the 80minutes anyway.
It's an unnecessary statement to save a few kg of fuel. Might as well carry the extra 22kg of fuel and run full blast at 650hp+150hp of KERS and overtake the fuel savers.