Do you think EFI can’t do that and more?Orr89rocz wrote: ↑Thu Mar 11, 2021 8:51 amMost dyno tests of typical engine combos guys use, comparing a decent tuned carb to a decent tuned efi system, carbs have made more peak power and yes it is most likely due to cooling of intake charge. Its been pretty well displayed in many tests. Sometimes its very close. Port efi usually makes alittle more average power in other areas off peaks. Richard Holdener and even Steve Morris have done videos on the testsDavid Redszus wrote: ↑Wed Mar 10, 2021 10:37 amMaybe not. Throttle body injection is only better than a carb due to mixture ratio control over the entire range of operation (a function of the ECU). It is an obsolete (but cheap) system except for trucks.Get the AFR in the same ballpark the Inlet air temp due to evaporative cooling is better with the carb even compared to throttle body injection. Its enough to overcome the loss of airflow required to get a carb responsive
For a typical engine using isooctane, 100F deg air and fuel, 85% evaporation, the temperature drop
due to fuel evaporation will be 25.6F deg, resulting in an increase in charge density of 1.36%.
But the reduction in inlet air mass due to fuel vapor displacement would be 9%; a net loss in air mass.
One reason that port EFI could make more power is a result of more even fuel distribution to
reduce cycle to cycle and cylinder to cylinder variations.
But there is a dark side as well. NASCAR dumped carburetors a decade ago in order to reduce the number of engine failures, which it did. But it also allowed NASCAR to dial in the maximum speeds that can be driven because cars were getting too fast for the tracks.
No modern race engine would use carburetors unless the rules required them. And some do.
EFI tuners have understood this for decades, hence dual rows of injectors and also the raising of fuel rail pressure. Honda’s Formula 1 team measured wave speed in the intake tract to measure the cooling effect of the fuel evaporation and were able to tune that. You can’t do that with a carburetor... there is a ton of raw fuel floating around.
Dual rows give you the driveability of a Honda Civic while still being able to make the big power upstairs. A carburetor it’s an either or situation and you’re not as constrained with packaging EFI and having to worry about a skyscraper coming out of your hood. Carburetors to package also have chassis and aero implications, gravity matters a lot more with them.
Again, most everyone puts injectors in the runner of a carbureted manifold (be it a tunnel ram or whatever), moving the fuel source much closer to the valve, and wonders why there isn’t as much evaporative cooling.