Josh Able: puny fuel injectors

[mkii@nycap.rr.com (Josh Able)]

31 pound = 310cc
running at about 75% duty cycle

trust me Scott, other shops that sell full kits use these and produce 350ish
hp.


These are larger than stock.



Josh Able

----- Original Message -----
From: "Scott F. Williams" <sfwilliams@comcast.net>
To: "Josh Able" <mkii@nycap.rr.com>
Cc: "Scirocco List" <scirocco-l@scirocco.org>
Sent: Monday, June 10, 2002 11:48 PM
Subject: RE: Josh Able: puny fuel injectors


> > nope, even 20v turbos pushing closer to 375hp use 310 many times,
anything
> > they tend to run to rich.
>
> My man, this is 100% *impossible*. Way more gasoline is needed to make
that
> kind of power. This isn't even an engine capability discussion. We're
> talking about the amount of chemical energy stored in a given volume of
> gasoline. There's only but so much in there! Like I said before, there are
> three ways to flow more fuel:
>
> a) increase the fuel pressure
> In order to make 297hp at the wheels, you'd have to run a fuel pressure of
> 185psi. This is about 4x the stock amount. Not only would this burst the
> fuel lines, it would blow the fuel pressure regulator to bits, destroy the
> injectors immediately, and would completely overwhelm the engine
management
> system.
>
> b) leave the injectors on longer
> The injectors can only flow their maximum rated amount of fuel. In your
> stated case that is 310cc/minute at full duty cycle. However, the ECU
pulses
> them on/off at anything less than full load. That is how you get a
variable
> amount of fuel delivery. Figure at idle they might be running at 5% duty
> cycle. Running them at maximum flow (non-pulsed)is 100% duty cycle.
However,
> the maximum safe duty cycle is 80%. Pushing the injectors beyond this
point
> for a prolonged period of time will destroy them.
>
> To make the point clear, in order to deliver enough fuel at a *dangerous*
> 100% duty cycle (at 50.75psi fuel pressure) you'd need to run 480cc
> injectors! Those 310cc pee shooters would be overwhelmed at just 210hp! In
> fact, with that math considered, it sounds like the 310cc are the engine's
> *stock* injectors.
>
> c) install bigger injectors
> If you're following me so far, you'll understand why what you're claiming
> isn't feasible in the slightest.
>
> > hm..31 pound injectors do = 310cc right?
>
> Er... *no*. The conversion is actually 10.5:1. That is, 1lb/hour =
> 10.5cc/min. So, if you've really got .31 pound injectors, then the metric
> flow rating is really 3.25cc. Now *that* really is far fetched! :^)
>
> Seriously, man. You need to go back to your builder and demand accurate
> information. Little injectors like that are simply incapable of flowing
> enough gas to produce the horsepower that they've sold you on. I totally
> believe that your engine can make that level of power. However, the
> injectors aren't up to the task. You've either got erroneous flow capacity
> information or you're making a lot less power then you think.
>
> I'm not busting your balls, of course. These are the inflexible laws of
> physics and thermodynamics that we're playing with here!
>
> P.S. If you're injectors are grossly undersized, you will blow the thing
to
> smithereens in short order. You *must* do the research to ensure that
you've
> got a safe combination. Do it in the name of science, paranoia, or
whatever.
> Just do it and do it right away.
> --
> Scott F. Williams
> NJ Scirocco nut
> '99 Subaru Impreza 2.5 RS
> Mazda 323 GTX turbo "assaulted" vehicle
> Golf GTI 16v "rollycar"
> ClubVAC: "Roads found. Drivers wanted."
>
>
>
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