What Performance Chips Really Do!
 

To many, there appears to be some mystical property associated with
performance chips. To some, Porsche/Bosch lacked the knowledge in
the early '80s to fully maximize the potential of the 911 Carrera engine.
Others believe that "savvy" computer programmers have "discovered"
special programming techniques for achieving additional performance.

To demystify these performance chips and determine what they actually
do, three performance chips as used by some on Pelican Parts were "opened"
and analyzed. This included analyzing all the fuel & ignition maps. As a
comparative base, a stock '88/'89 Porsche Carrera chip was also analyzed.

The results indicate that all the performance chips have kept the fuel
maps essentially unchanged from the stock '88/'89 911 Carrera.
The other similarity between all the performance chips, though, is the
"pushed" ignition timing map. The timing maps of these chips have
advanced the timing as much as 10 degrees over the stock maps to
a value of 50 degrees advance BTDC. This 50 degree advance value
exceeds by more than 10 degrees what Porsche techs consider the
maximum advance for a 911 engine irrespective of octane levels and
fuels available today.

In many cases, the "pushed" timing maps have advanced values which
may result in inaudible pinging/detonation under certain loads, even
though the timing has been advanced only a few degrees beyond stock.
Obviously, for those using the performance chip which "pushed" the
timing to 50 degrees, the pinging/detonation will be very noticeable.

Since the '84-'89 911 Porsche Carrera lacks the knock sensors of the
964/993, this can be very problematic for a 911 engine. Actually, the
964/993 may also be confronted with pinging/detonation when their
ignition maps are "pushed" beyond knock sensor control. The 964/993
can only retard the ignition by a maximum of 9 degrees. Check out
this web site ( www.andial.com ) on the FAQ page, Question #2,
for more info.

The data are presented in a tabular form here: www.systemsc.com/tests.htm
To minimize the data presented, selective ignition map values are shown
for the stock '88/'89 chip and three commonly used performance chips
as mentioned by Pelican Parts members for the '84-'89 911 Carreras,
where significant differences exist over the stock Porsche chip.

Based on the data, it now becomes obvious why performance
chips "feel" the way they do. The same results were achieved with the
911SC by just turning the distributor to advance the timing, although
without as much control over the advance curve. The same problematic
issues arose then as now with the later Carreras, i.e. pinging/detonation
as a result of engine loads, temperature, & fuels.

There was nothing new then as there's nothing new now, except some
become mystified and pay more for the same effect from a performance
chip versus using a socket wrench on the 911SC (see pg 73, "101 Projects
for Your Porsche 911")! Furthermore, the performance chips available now
are basically the same as those supplied 15+ years ago, i.e. "pushed"
timing maps.

Hopefully, the results of the analysis will provide an insight into what
a performance chip really does and the excessive timing values used
to achieve a noticeable effect, e.g. timing advances > 40 degrees.
As many have indicated, Porsche may have been conservative in the timing
values used, but exceeding 40 degrees can't be considered good tuning,
it's ridiculous & damaging to the engine, and that's the KEY point of the
analysis!

Bottomline: A timing advance NOT greater than 40 degrees and much
less under various loads, temperatures, and/or low grade fuels!

Good write-up.

But what's the sub-text, of what you're saying? . .. 'use high octane w/ the chip' (?)

. . . or; ' ya shoulda bought an SC' (?)

. . .or both?
:cool:

Thank you for introducing some objective data to this debate.

Loren....no real "new" news here.....

To go further..notice that even among aftermarket vendors...some are "aggressive" and some more "conservative"....

Isn't this what we have been saying to you too, Loren....that you can't paint all suppliers with the same brush.... ??

I just don't understand what service this provides, Loren. like all things there are good and bad suppliers...and in this case, not "all" chip suppliers are charletons who offer the same level of tuning aggressiveness....

Wil


EDIT:
Before I even ask "who" this is...let me ask candidly.... how would you characterize vendor "A" chip...relative to stock?

Well, it was a well written piece without any aggressive or attacking language, and that's a good thing, but hasn't this really all been said 100 times on this board before?

Phew, glad this is all cleared up!

Essentially unchanged isn't unchanged. Seems we are still only getting part of the picture. Like a statistician can make data say pretty much anything they want.

Wow, B really went all out didn't they.

ROFLMAO.

Thanks for that.

I learned something, Thx lorenfb
Charles

I don't understand a couple of things:

1) This thread was on Rennlist a few days ago, but it is gone, what happened?
2) In that thread, you stated that you had had enough with Pelican and you were posting exclusively in Rennlist, what happened to that?

This post?

http://forums.pelicanparts.com/uploa...1112984290.jpg

Jeremy,

That's FUNNY !!!

:)


-Chris

Exactly Jeremy! The thread seems to be gone. I guess you thought ahead and copied it, good job. So, the question still remains, what happened here?

The question also remains....."what's the verdict with the relatively mildly tweaked vendor "A" ... ???

- Wil

I'm more curious about your other log-on name.

ya know, the one you use for your "politically correct" posts.

edit: eh . .come to think of it, i'm not really all that interested in that either.

I've got the same answer here as the one I posted on Renn. The fact that I have a DME in my Carrera means I HAVE TO CHIP to get the "feel" you describe. Also, I run 93 Octane, so I think I can take advantage of some gain.

Secondly, as many here have posted, the "driveability" of the car is much better and smoother with my Steve W chip.

Again, what is causing you to post these statements? You are not responding to a thread, as you usually do, but rather seem to be fanning the flames of the arguement again. Maybe you need a hobby...

Back to the topic...

Do guys with chips pretty much simply run higher octanes . . .and get more HP?

That sound like what loren is saying.

:cool:

Of course history would tell us that he is saying more thatn just that . . . that it is unaceptable to change the minimum octane rating of a Carrera. (gasp, I know :rolleyes: ) But really, seems like a choice for the owner.

This is yet another post as to the superiority of the SC.....

SCWDP rides again!

David

Pretty much - not rocket science. I had a copy of a Loren quote here somewhere were he agreed that a chip could make a 5-10 HP difference (3-5%) alone it's somewhere on my computer...

I was once chatting with a guy at AX who said he has conclusive evidence that higher octane gas has more power. I know this to be false, but I listened. he said he dyno'd his engine, a late 3.6, using both types of gas and the Ethyl made more power. I didn't have the heart to tell him this was because his ignition system sensed that the Ethyl allowed a more advanced ignition timing, and it was this advanced ignition timing that resulted in increased power.