Josh Able: puny fuel injectors

[jason@scirocco.org (16V Jason)]

I really have no right jumping in here as all of your arguments are over my 
level of knowledge.

But the one thing that I'd like to point out is that the software used to 
collect those dyno readings, DataMite 
(http://www.performancetrends.com/DTM-DYNO.htm) isn't part of a complete 
Dynamometer package.  It's a standalone product that can be used with any 
dyno -- and that means that the accuracy of the information gathered is 
dependent on the accuracy of the calibration numbers used for it.

Josh, I don't know where the dyno run was made, but if it was made by 
Eurospeed Ltd., and you're really curious to see what exactly the power 
output is, I'd recommend taking the car to an uninvolved, 3rd party Dyno 
Shop using a DynoJet or Mustang Dyno.  Those are both complete dyno systems 
that don't allow the operator to enter the variables; they're 
self-calibrating and the programs run specifically on that hardware.  Not 
that I know the slightest thing about Eurospeed Ltd., but it would be very, 
very easy for them to inflate the numbers just by changing the calibration 
measurements.  In the business of pulling out magical lost Horses, that's a 
very tempting proposition.

Of course, Josh this really comes down to you -- if you're happy with the 
car's output, don't worry about it!  Just enjoy the power you have and 
smile!  It doesn't matter if it's 300hp to the wheels or 200hp to the 
wheels, as long as you're happy with it.

Now I wasn't in your car this weekend, so I can't personally comment on 
what my estimate of your engine's output is.  But if indeed it's anywhere 
over 200hp to the wheels, you're walking on a tightrope in terms of your 
chassis.  The A1 was designed for a theoretical maximum of 130hp at the 
motor.  It simply can't reliably handle any more.  And we all know this -- 
even with stock 123hp 16V motors, guys are ripping front crossmembers apart 
like they're made of paper.  And we all know of one particular mad bastard 
that has destroyed 3 chassis with one normally-aspirated but psychotically 
strong 2.0 16V.  So my sincerest advice to you would be to dyno the car 
somewhere else (to put a quick end to this conversation) and forget about 
getting more power for the moment and concentrate all of your efforts on 
reinforcing that chassis.  The front of these cars will never be able to 
handle >300hp at the motor -- what will happen is that the whole front of 
the car will torque upwards against the force of the motor... and it 
probably won't take all that long.  So be careful! :)

Jason



At 12:22 PM 6/11/2002, Josh Able wrote:

>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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> >
>
>
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