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#4
22-06-2004, 07:42 AM
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Larry,
I could not really have asked for anymore. This was more than I had expected even given your somewhat god like mechanical and physics knowledge acompared with mine which leaves me stumbling around in the dark somewhat. Clearly the fact that not all of these systems have been implimented together in the past is relevant. The complexity issue is a clear example. Whilst obviously there is every possibilty that these supercooling systems have the potential to produce incredible power, it is of little use if the whole tuning map goes to *$@t across the board leaving flat spots all over the place and running rich at one place and lean in another. I am given to the thought that it might be better to utilize different methods at different rpm ranges leaving something like propane injection to cut in at near WOT when there is a clear demand for more fuel whilst using WI at lower rpms with the standard fuel supply. This however is no more easy to impliment and I am reminded somewhat of the old supercharger/turbocharger dual systems that allowed boost from tickover as low as 1000 rpms and ripped through the rev range up to massive boost levels that superchargers alone could not support. Acceleration was phenomenal. So was maintenance and only one vehicle (one of the old Lancia Deltas I believe) managed to use the system semi-reliably in battle. That said you have radically changed my thinking here and given humidity issues it is quite possible that some alcohol content in any water injection system I use may dramatically benefit my application. I also do not believe that 'carb-icing' or it's equivalent is likely in these climatic conditions and I think I'll be lucky to get charge temperatures below ambient. I want to throw a spanner in the works here though and act the Devil's Advocate. These opinions are not all my own but they are interesting. It seems clear that this is a 'genuine' DISCUSSION forum after all, and a good discussion yields a wealth of information. So Larry I want to challenge the propane injection 'cooling' issue. Users of propane injection report significant reduction of knock at high boost but almost no reduction in EGTs. Because it is injected as a vapour and not a liquid, the potential evaporation/heat reduction ability of the mixture has alraedy been lost at the tank. Some argue that the claims of raising octane content are also unfounded because when propane is injected it is a vapour significantly less dense and in lesser quantity than petrol and that it's ability to impart it's own octane rating on the compound fuel mixture virtually impossible. The fact that it burns is beyond doubt however and it burns well. The consensus of opinion I have seen so far therefore is that propane injection is nothing more than fuel dumping with the very possible side affect of rapid expansion of vapour through the combustion chamber leads to near 100% burn of the petrol and evening out of hot spots. So first Larry (or anyone else !!!) do you think the use of Propane injection removes the need for further 'cooling' whilst still offering the option of leaning out the petrol, or, is there an argument for water injection in conjunction with propane in the same way that alcohol and water injection have become integrated in 50/50 mix systems? Get your head round that one :shock: Paul 
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