Quote:
Originally Posted by Disturbed 01
It's a sad thing for me to think about he Viper never being the world beater it can be.
Now the ME-4-12.....that would be something to see.
TQ,
Can you go more into detail about hot fuel vs cold fuel???
|
sure - briefly - wet fuel does not burn well - proof is you can put out a match into a container of gasolene if you are quick enough. If you are too slow it is an excellent way to get rid of those arm hairs.
The point is that what burns is the vapor.
The extent that an engine can vaporize the fuel has a direct bearing on how efficient, economical, clean and even powerful it will be. The old carby's were actually quite good at this by firing a fine mist into the intake - which when at operating temperatures would vaporize the fuel pretty well. The trouble with carby's were that they were not precise over a broad range of rpms and loads etc and EFI is.
Injecting at 45psi does a reasonable job - not great - but the ECU is able to make the best of it by offering precise control under various conditions... but injecting it at 500psi would be even better for both economy and power - and you will find formula one engines use very high fuel pressures for this reason. Of course direct injection engines require several 1000 psi just to overcome combustion pressure.
In short - if you heat the fuel it vaporizes quickly and therefore less of it (by liquid volume) can do more work. It also burns more completely which translates to cleaner emissions. We found on just about every vehicle we tested with a prototype device that heated the fuel - that the common 4-5 gas analysers could detect zero emissions afterwards.... apart from some Nox in small amounts in some cars.. but less than before. In all cases emissions dropped dramatically.
What about for power? Well - here we have a conflict because cold fuel is more dense so therefore you can fit more into the same space than you can with hot fuel (which expands). Having more fuel in the same space is the same as having more energy in the same space... except for the other side of the coin is that vaporized fuel burns faster and cleaner and more completely - therefore makes more power per molecule than cold wet fuel.
In theory the ultimate may be to inject cold fuel at common rail diesel fuel pressures that instantly superheat it at the point of injection so it vaporizes almost completely as soon as the injector pulses... as direct injection gasolene engines develop we will likely see if this pans out.
I personally believe that hot fuel can make more power than cold fuel but it will require different calibrations to achieve it. I have not yet had the opportunity to test this however. With typical and factory settings - you can expect a drop in power with hot fuel, and this is why I suggested fuel temperature control to overcome that. I have seen incredible gas mileage with hot fuel - but the gains tend to diminish over time as though something in the fuel coats the engine and starts to undo the gains made over time. If the OEM's and Oil companies worked together this would be over come.
ECU mapped direct port water injection would also be very useful for super-performance engines wanting better economy and emissions. The argument that customers cannot be trusted to refill the water is mute... you do not forget to put gas in, why would you forget to add water if prompted?
Direct port water would enable 12 to 14:1+ on 93 pump gas depending on cam size... engines that high in c.r. can be quite efficient.