Factory vs aftermarket (part1)

[Tomchou at aol.com]

Subj:	Factory vs aftermarket: was Valve train noise
Date:	01/21/97
To:	diy_efi at coulomb.eng.ohio-state.edu

Obviously my post was too long as it got kicked out the first time I sent it.
 Since list traffic is slow, I'll split it in 2 parts and get my .02 in!

>>From:  George M. Dailey[SMTP:gmd at tecinfo.com]
>>Don't feel bad. After market parts can confuse even the most seasoned hot
>>rodder. Some of the venders are liscened and bonded LIERS. Oh, it's not a
>>total loss though, I've heard that the Electromotive ECMs make excellent
and
>>attractive door stops or paper weights:}

>From: John Hess <JohnH at ixc-comm.net>
>This is what I mean by an instant expert.  First of all, the very fact 

Hey - I haven't been on this particular list very long, but I don't believe
George Dailey fits the term "instant expert" here!  Actually, and I know I'm
very biased here, but I consider _almost_ every aftermarket vendor I've met
with a few exceptions to be "instant experts".  Most have very little formal
education in anything remotely resembling Automotive Engineering, or
aerospace or electronics and have no technical experience working for any
major automotive related company.  Some of the better ones at least are
master mechanics of some sort and have considerable practical experience in
racing, etc. while others were probably shoe salesmen (no offense to them -
just thinking of Al Bundy) who picked up a Bosch Handbook and are now giving
all sorts of technical advice.  (I'm not even remotely refering to anybody on
this list as I haven't been on long enough!)  I'm not saying you must have a
degree or anything to know what you're talking about either, but most of
these guys  are really lacking in technical knowledge yet you'll think they
were PhD's in fluid dynamics or combustion analysis from their claims.

>that GM spent those millions dictated that they were obligated to 
>cover their costs.  The original TPI was designed for the 305 engine 
>and is woefully inadequate for even a mildly built 350.  The air 
>foils, ported plenums, opened up MAF do, in fact, increase horsepower 
>easily measurable on a dyno, 0-60 time, quarter mile, or even the seat 
>of ones pants.  I agree that the GM MAF system is the way to go for 

I have considerable insight into this, and we've looked at many of these
items.  I don't trust any dyno data I've seen in the popular magazines -
they're almost always performed at either the aftermarket manufacturers own
dyno or some biased shop.  There's just too many things you can do to get the
numbers you want.  In general, some of these products are based on a valid
idea or principle but taken out of context or only beneficial under very
specific conditions.  For example, maybe airspeed needs to be near airplane
velocities for some concept to work, or in the case of different ignition
schemes, their ideas may be good for alcohol or nitromethane only, or for
specific combustion chamber profiles/turbulances, etc.  We've run many of
these products on our extremely accurate/expensive dynos that no aftermarket
could come close to affording, and found none to offer exactly what they
claim or advertise.  At best, some products have a measureable effect -
usually detrimental, but if properly understood, given the proper conditions,
I can see them being beneficial.

When there are real measureable differences or benefits, it is not always due
to the product under evaluation!  What I mean is that the product has somehow
altered certain parameters to give better performance under that condition,
(i.e. made it richer/leaner or altered *delivered* spark timing (due to more
capacitance or inductance on the secondaries) and when you gather proper data
and determine exactly what change took place, you can remove that product,
change those parameters via other means, and achieve identical results.
 Well, one might say, that proves that product worked.  Well, ok - that's one
way of looking at it, and probably the way the vendor wants it to be viewed,
but the problem is this is usually only beneficial under that special
condition, and not due to the reasons the vendor claims.

Look at the aftermarket companies that are tightly connected to the Big 3,
such as McLaren, Roush, Shelby to name a few.  If you talk to their people,
and look at what they do, you'll see they use very few of the usual popular
aftermarket products out there.  Most of their creations use very factory
parts or custom ones they design for that specific application with
complementary changes in software/calibration or other components to
compensate any side effect.  No "black magic" gimmicks such as air foils are
used.  Look at the totally factory backed high tech race teams in endurance
racing, off road series, Indy Car/CART, Indy Lights - you don't see the same
stuff being used as the popular auto mags such as Hot Rod, Car Craft and such
advertise/evaluate.

(Continued in part 2)