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alfadriver GRM+ Memberand MegaDork
5/2/22 9:52 a.m.
Pete. (l33t FS) said:

In reply to Paul_VR6 (Forum Supporter) :

Not necessarily, if you can get the same precision with a carb.  Generally speaking a carb will always be able to get better fuel economy and make more peak power because the atomization is so much better.

If that were accurate, carbs would be the choice for almost every single racing out there.  Like the top two most important thing in auto racing is power and fuel economy.    Also, it's pretty interesting that CFI (which atomizes the fuel better than a controlled leak) is so bad compared to carbs.  In essense, they are the same thing- fuel a long way from the port that uses the intake heat to evaporate the fuel.  One is computer controlled, the other is a decent guess.

BTW, the whole "atomization" thing is very overstated.  Not sure why people are so convinced of that, but when injectors get to full operatring temp, they flash evaporate most of the fuel anyway.    Even DI injectors get to a point where they are injecting a vapor.  The biggest problems that arise from PFI is when they are aimed poorly- especially at gaps and gaskets.

One of my DI rants is about how open valve injection is so bad- since it has bore wash, but DI is ok spraying fuel directly on the walls.  Far more work could be put into OVI research to get most of DI's benefit without any of the drwabacks.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
5/2/22 10:37 a.m.

In reply to alfadriver :

The ability for a carb to make more power is well documented.  A lot of people have tried and failed to get a port injection scheme that can make more power.

This of course is on a dyno.  When you have the engine in a car, subject to all sorts of different acceleration loads and such, EFI is loads easier to be consistent.  Hell, that is why I switched.

I do note that F1 intakes for a while were running fuel pressure over 10 bar and pointing the injectors UP, not down the ports.

alfadriver GRM+ Memberand MegaDork
5/2/22 12:58 p.m.

In reply to Pete. (l33t FS) :

And they are really short ports. 

None the less, CFI and carbs are pretty much the same thing, other than computer controlled fuel flow, and CFI is constantly said as horrible, but carbs are somehow magic.  There's no real logic in both being absolutely true.

I still would contend with more power.  Even in the context of a dyno.  If you can track some SAE papers that show that, I would have a better time believing it.  Otherwise, I would suspect that people have an agenda.  

And I've come across more than one dyno focused engine program, and it drove me nuts that they got this magic BSFC, claiming best ever- and it could never live in a car.  To me, that's just a meaningless number.

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