Quote:
Originally Posted by Vekke
Ausias you havent seen all the tricks that the car will have.
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It's the wrong thing about living 3800 kms far away. I will enjoy to see and ask lots of things about your car, but also about your truck and the cordoba vario (because I found that Italdesign/Giugiaro prototype was very aerodynamic).
Quote:
Originally Posted by Vekke
Also the ECU is not optimised yet for efficiency so that first test I was not able to do any P/G as its planned on that 2 liter record run.
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I'm wondering what do you mean with optimizing for efficiency?
Optimized for f.e. is going Euro 2 or lower? I compared the timing maps of 1.9 TDI BXE 105 cv Euro IV with the 1.9 TDI AHF 110 Euro II and mainly the differences were the first one had different maps depending on coolant/(fuel above 60ºC) temperature and also there were differences in low load zone (wich almost you could manage to compensate advancing the static camshaft angle).
But the older one timings (when times calculated from angles) almost ever injected the fuel 0.6 ms before TDC (i'm talking also when timing fitted in the sweet spot of the injection pump, you can check with TDI Timing and Vag Com).
Does Optimized for f.e. mean to enrich the injection and getting lots of shoot and black smoke of death?
Quote:
Originally Posted by Vekke
And gearing is the biggest key to success I am afraid if I want to reach that two liters with steady throttle.
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I agree with you about the gearing but I think you need very tall gearing because your car is the best VW Lupo 1.2 TDI GTI ever. I'm happy you will drag race with those cars. Because your car will accelerate/ brake, havee a high top speed and even corner better than supposed sport cars wasting lots of gas moving air around and propelling fatty and non easy rolling alloys.
But I did several calculation before the previous post with this parameters and results:
standard gear, 155/80 r15 desired tires, rr = 6.4 kg/Tm, cd = 0.21, S=2; ro=1.2 kg/m3, mass =730 kg, cc = 1161; and power 61 cv (I use to relate the BSFC map and and load)
Top gear = 55.47 km/(h 1000 rpm)
f.c (100kph) = 2.18 L/100km
efficiency = 35.4%
engin rpm = 1804 ( slip ratio not taken into account)
needed torque = 43.8 Nm
6-speed tallest 02J gearbox FSM adapted, 155/80 r15 desired tires, rr = 6.4 kg/Tm, cd = 0.21, S=2; ro=1.2 kg/m3, mass =730 kg, cc = 1161; and power 61 cv (I use to relate the BSFC map and and load)
Top gear = 90.5 km/(h 1000 rpm)
f.c (100kph) = 1.89 L/100km
efficiency = 37.5%
engin rpm = 1105 ( slip ratio not taken into account)
needed torque = 65.7 Nm
P&G will save fuel if you are able to fill the turbo and reach fast the max pressure boost.
I think it will be tricky and very very difficult go under 1.9L/100km with your big block
engine. But I'm very sure (because I have done other perfomence and f.e. calculations, not explined in this post) that your car will go from 0 to 100 kmh in almost half the time (without the gear shifts times) than standard and your fuel consumption at standard top speed (178 km/h) will be about 4.5 L/100kms (52 mpg at 110 mph, wow). Also the top speed will raise up to 250 km/h. If you go to the autobahn or in the speedway maybe you will notice lift. Be careful, maybe your car should have wings.
I suppose (after doing calculations) that your engine's sweet spot is above 160 Nm (you went to 250 Nm), I'm sure with your mods you can get this torque at low rpms, but when full trhottle.
According to my assumptions I used to asses the calculations (maybe quite near to the reals, but i dont' know):
Your engine has 76.5 x 86.7 bore stroke, 3 cil, 1195 cc, C.ratio = 19.5, Boost pressure = 2 bar.
- so when it produces 160 Nm (max standard torque) wich means BMEP of 16.8 bar, but the ignition starting at 128 bar when pressure at top dead center PTDC (maybe getting a max pressure at full throttle between 144 to 160 bar).
- so 250 Nm mean 26.3 bar BMEP, assuming your boost pressure is 2.4 bar the ignition will found a PTDC around 154 bar (and max peak somewhere in a range 179 to 206 bar)
4.6 BMEP and 6.89 BMEP (respectively 43.8Nm and 65.7) with an air fuel ratio almost the same (it's an assumption) will mean about 1/4 of the air (so the pressure also being 1/4 of max PTDC when full throtle and full boost).
My numbers might be wrong because I ¿selflearned? to do them reading the Bosch diesel handbook and many other books, althought I'm physicist i don't have a lot of training on engine thermodynaics. Somewhere I read that 160 bar is a very good pressure in the cylinder to obtain a low BSFC.
i found some graphs in the Handbook of diesel but I remember to have seen one that not was a BSFC map -bsfc vs. BMEP vs. rpm- but a -bsfc vs. pressure of combustion vs. rpm-.
But the needed torque to maintain 100 kmh speed (43.8 to 65.7 Nm seem like being far from the sweet spot pressures in the cilynder) and volumetric efficiency not being improved with the turbo at steady throtle condition).
I'm sorry about the long post but I'm practicising because next july 26th I will take and english exam,
I'm not sure of having explained it in the best way. I'm sorry.
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