CIS HP

[QSHIPQ at aol.com]

Ok, I'm with you a bit on this Johnny.  IMS, Glen Powell stated that he was
adding extra fuel to a stock CIS system to get more HP.  WHICH MEANS,
Mockry's site (and altho good, is only calculated at 50% DC, IME there's a
whole bunch more at 75% DC, and even more at 90%DC, btdt) only applies to a
"given" stock CIS system.

When Glen is adding fuel tho Johnny, the CIS plate IS the restriction to HP.
If you look at the porsche units and the mercedes units, you are correct,
they all are interchangeable (in fact, the 6 cyl porsche turbo apps are 8 cyl
mercedes apps with 2 plugs on top, or specific to audis, 5 cyl apps are 6
cylinder apps with 1 plug on top).  However, what "tunes" a air/fuel CIS
system is the air cone and metering flap.  These are designed for each
individual motor to give optimum performance FOR that motor.

When Glen adds a aux fueler, he's supplementing the initial limit of urq fuel
system, which is the fuel part.  That said, what your books are going to show
you, is that for a given diameter oriface, you will have x cfm airflow at x
in/Hg.  What's a bit more difficult to calculate, is that obstruction to a
straight physics equation (like measuring a fan output with a piece of
cardboard blocking part of it).  I doubt it's really as much as some think,
since the design of the upper flap boot is pretty good.

In the context of this thread, I think it's very accurate to say that the CIS
plate/cone ARE the restrictions to HP with an aux fueler.  Without question
the speed density EFI systems have the lowest restriction wrt air flow.  If
you gander over to the S car list, you will see that the 2.75in
(unobstructed) MAF of the 20vt cars is good for a sustained 400hp, then IT
becomes the restriction to hp.

The easiest way to really measure this, is to test the airflow flap/cone
arrangement.  Right now, an even easier way to test this would be for Glen
Powell to disconnect his rear driveshaft and put his car on a dyno.  I'm
betting the HP is higher than many think, BUT the "potential gains" are
significantly hampered by the CIS cone/plate.

My .02 arbitraged thru the peso

Scott Justusson
QSHIPQ Performance Tuning
CIS and EFI cars aplenty
"Mostly I was making a point that all the Bosch systems (CIS,motronic, ect..=
.=2E) use the VERY SAME components, and I rather think that arguing sematic=
s on actual airflow through either a mass flow meter or air-meter plate is =
moot, as IT WILL FLOW MORE THAN ENOUGH AIR to make BIG HP. The original que=
ston was if the CIS airflow meter limits the HP, correct?
The answer is a qualified no.