On Thu, 27 Aug 1998, Holloway,Frank T wrote:
> Bob,
> Thanks for providing the info to us. I have never played with the K&N open
> element before for two reasons. I don't like the sound at high throttle
> settings (personal
> preference, try listening to it for hours as you tug a boat across desert
> out here in Calif). And I am one that believes in ducting cold air to the
> engine (1% loss in
> horsepower for every 10 Deg. rise in inlet air temp). I prefer the drop-ins
> and I am pleased in them (definitely Not as nice looking). Again thanks for
> the info, no
> better way (for all of us), then a pull.
> Frank
>
Agreed. Its very nice to see some scientific before/after results;
usually we have to resort to conjecture. :-) One thing that comes to
mind though is that a dyno can be "wrong". Unless you can extrapolate
the numbers in the vehicle's "natural habitat" there's bound to be some
error. There are things in the "real world" which affect performance
that will not show up on a dyno. (Like aerodynamics, weight transfer, etc.)
One obvious example of this is ram-air. If done right, a ram-air system
can add some considerable power to a vehicle. However, this power won't
show up on a dyno. (Though if you had a dyno in a wind tunnel you could
probably do a very good simulation.) Anyway, there might be something
similar happening with the open element air filter. When its sitting on
the dyno, you don't get air flushing out the engine bay, so its bound
to be hotter than in an actual driving situation. So, if the K&N made
4hp on a dyno, it might actually be making 6hp. (or whatever...) On
a similar note, the dyno pull was probably done with the hood up, which
will probably change the airflow characteristics of the engine bay.
Another issue is that without the air flowing into the radiator, engine
temps will probably be higher than usual, resulting in reduced power numbers.
Just thought I'd bring that up; its probably a good thing to keep in
mind when considering dyno numbers. Seems like you can't take anything
for face value. :-)
On a related subject, I'm sort of working on a "do it yourself" dyno &
performance meter which will be microprocessor based. It'll use an
accelerometer to measure G forces which it can use with vehicle weight,
wheel size, rearend and tranny ratios, etc. to compute your power. It will
use something along the lines of an inductive pickup to read engine
RPM. Something like this wouldn't suffer from the problems inherit in a
chassis dyno; your numbers will be derived from (and applicable to) the
environment you are mainly concerned with. Something like this is bound
to have some slop in it, so in that sense, will probably be less accurate
than a chassis dyno as far as exact numbers go, but if you're looking for
net power changes, I think something along these lines would be ideal. I
say I'm "sort of" working on it because it is very much on the back burner.
I have a lot of the equipment I need to start working on it, but nowhere
near enough free time. (There is something that already does this which
is software based. (You record your run and use a computer to analize it.)
Its called home dyno or desktop dyno, something like that. I believe there
is some info about it on Sean Meldrum's web page.) Sean and I were working
on this thing together; it would be sort of a combination of a G-tech
and a dyno, but portable and realtime. Just need more hours in the day! :-)
-Jon-
.--- stei0302@cs.fredonia.edu ----------------------------------------.
| Jon Steiger * AOPA, DoD, EAA, MP Race Team, NMA, SPA, USUA * RP-SEL |
| '96 Dodge Dakota v8 SLT CC (14.85@90.72), '96 Kolb FireFly 447 |
`--------------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:09:27 EDT