UGOTNUFN wrote:Dzltec wrote:Interesting reading. Want to forward work out what 250 cc of fuel will give in a td42t from 2000-4000rpm for me.
Remember dyno's are measuring torque, power is a output from it.
Andy
How much boost do you plan on running for the given 250cc,50 will be a minimum i would suspect from what we already know.
So if we are seeing 220RwKw when loaded then why aren't we seeing the NM on the power run.
It has to be because of the lack of load on the rollers.???
If I stick to a almost stoichiometric AF ratio, but rich by diesel standards of 16:1, assuming an excellent intercooler and two different turbo arrangements for the two rpm zones and each compounded (so 4 in total...) with no worse than 1:1.5 IMP/EMP ratio, very approximately:
Assuming: 60 deg C inlet temps, 250cc/1000 strokes, 2 valve head, stock cams
2000rpm 56.5psi/84% VE
Flywheel: 310KW/1480nm
Wheels: 271KW
4000rpm 69psi/71% VE
Flywheel: 551KW/1316nm
Wheels: 428KW
bear in mind, many of the assumptions in this spreadsheet only work well as an approximation within a "normal" power range. Some of the fixed losses may not be adequately allowed for and reality will likely be a much lower loss. Also, the BSFC of the engine is anyones guess, I would expect it to improve slightly based on what is seen on the Merc diesels in Finland, but we are talking alot of fuel for a small displacement engine.
Also, my confusingly worded turbo assumptions were really trying to say "one tubo wont do all this". A compound would be required for the boost needed and they operate only over a very narrow range anyway, so two different setups would be needed for each rpm number listed.