"performance" chips
04-29-2003, 10:44 AM
#1
Intermediate
Thread Starter
Join Date: Apr 2003
Location: Munich
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
"performance" chips
Hello!
Last night I spent some time going through some threads on the issue of chips. Some quite exhaustive and interesting posts such as those in:
<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=4;t=000397" target="_blank">http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=4;t=000397</a>
(Performace Enhancement Study - II )
it looks like quite different opinions on the matter are present . Some quote impressive improvements by the addition of chip, some really no sensible improvements at all (like the post above which seems to report practically no dyno extra measured HP's even with a cup bypass pipe on top of the chip). I trust dyno's more than "feelings" so I was quite surprised about it.
I could not find anywhere any clear explanation of this "problem".
What is the opinion of the experts? why? warum?
The only reason i could imagine is as follows:
-A performance chip in full throttle increases tipically the Fuel/Air mix by a few percent. Depending on the revs. For example about 3-4% at 4000rpms. In theory, if the "original" A/F ratio was near stechiometric (lambda~1), the gain in power should be measurable on dyno.
-Infact the gain in power IS a function of the "initial" lambda. it is larger starting with a lean mix and smaller as the mix is richer to begin with. At some point the gain in power may actually be a negative (a power loss) if the mix gets too rich.
-What I would then "guess" then is that installing a chip may give different gains in different cars as these cars may actually have slightly different mixture enrichment in open loop to begin with (consequent to different adjustement of the AF sensor, fuel pressure, leaks, etc..)
-Morale: before installing a chip, the injection system should be first tested to verify the enrichment at full throttle.
does it make sense? (probably not!)
cheers/ciao
Pietro
Last night I spent some time going through some threads on the issue of chips. Some quite exhaustive and interesting posts such as those in:
<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=4;t=000397" target="_blank">http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=4;t=000397</a>
(Performace Enhancement Study - II )
it looks like quite different opinions on the matter are present . Some quote impressive improvements by the addition of chip, some really no sensible improvements at all (like the post above which seems to report practically no dyno extra measured HP's even with a cup bypass pipe on top of the chip). I trust dyno's more than "feelings" so I was quite surprised about it.
I could not find anywhere any clear explanation of this "problem".
What is the opinion of the experts? why? warum?
The only reason i could imagine is as follows:
-A performance chip in full throttle increases tipically the Fuel/Air mix by a few percent. Depending on the revs. For example about 3-4% at 4000rpms. In theory, if the "original" A/F ratio was near stechiometric (lambda~1), the gain in power should be measurable on dyno.
-Infact the gain in power IS a function of the "initial" lambda. it is larger starting with a lean mix and smaller as the mix is richer to begin with. At some point the gain in power may actually be a negative (a power loss) if the mix gets too rich.
-What I would then "guess" then is that installing a chip may give different gains in different cars as these cars may actually have slightly different mixture enrichment in open loop to begin with (consequent to different adjustement of the AF sensor, fuel pressure, leaks, etc..)
-Morale: before installing a chip, the injection system should be first tested to verify the enrichment at full throttle.
does it make sense? (probably not!)
cheers/ciao
Pietro
04-30-2003, 04:15 AM
#2
Racer
Join Date: Jun 2001
Location: USA
Posts: 391
Likes: 0
Received 0 Likes
on
0 Posts
Pietro-
As the author of the "study" you refer to, I can only say definitively that without a double-blind study we will never know the answer to your question. Everyone's experience has been different. No two cars are the same, and no one's chip is the same. The chip I used for the study was a joke compared to the tuner's (Rennsport Systems) claims. On the other hand, another tuner's chip (Cyntex), while claiming more modest improvements, delivered.
I believe that the majority of the gains are tied to spark timing and air/fuel efficiencies that in the end, require higher quality fuel and/or higher octane rating to avoid detonation. The Cyntex chip in my car definitely changed things - most noticeably the breadth of the power band. The car now has more useable torque whereas power would come on late and hard with the stock chip. However, on a hot summer day, I experience slight detonation is 92 octane (RON+MON/2) if I do not add additional octane boosting agents to the fuel. Cool days I'm good with 92 octane.
It is also my belief that the trick airbox and cup pipe may move some things around, but there is no real signicant increase in power from these things alone. It appears that the 964 motor was pretty well optimized by Porsche for the claimed power.
The bottom line is that you must spend significant sums to get anything significant. In other words, you need to get that "air-pump" pumping more air/fuel through it - throttle bore increase, larger injectors, larger displacement, cylinder charging > atmospheric. Throwing on a cup pipe or popping holes in an air box just doesn't do it. It sounds cool though, and saving weight is a definite advantage. Myself, I'd like to learn how to drive better with what I got. Then perhaps invest in some nice light wheels, lose the air conditioning, add lightweight headers/exhaust, LWF, RS door panels, etc. and lose 10-15 lbs myself.
As the author of the "study" you refer to, I can only say definitively that without a double-blind study we will never know the answer to your question. Everyone's experience has been different. No two cars are the same, and no one's chip is the same. The chip I used for the study was a joke compared to the tuner's (Rennsport Systems) claims. On the other hand, another tuner's chip (Cyntex), while claiming more modest improvements, delivered.
I believe that the majority of the gains are tied to spark timing and air/fuel efficiencies that in the end, require higher quality fuel and/or higher octane rating to avoid detonation. The Cyntex chip in my car definitely changed things - most noticeably the breadth of the power band. The car now has more useable torque whereas power would come on late and hard with the stock chip. However, on a hot summer day, I experience slight detonation is 92 octane (RON+MON/2) if I do not add additional octane boosting agents to the fuel. Cool days I'm good with 92 octane.
It is also my belief that the trick airbox and cup pipe may move some things around, but there is no real signicant increase in power from these things alone. It appears that the 964 motor was pretty well optimized by Porsche for the claimed power.
The bottom line is that you must spend significant sums to get anything significant. In other words, you need to get that "air-pump" pumping more air/fuel through it - throttle bore increase, larger injectors, larger displacement, cylinder charging > atmospheric. Throwing on a cup pipe or popping holes in an air box just doesn't do it. It sounds cool though, and saving weight is a definite advantage. Myself, I'd like to learn how to drive better with what I got. Then perhaps invest in some nice light wheels, lose the air conditioning, add lightweight headers/exhaust, LWF, RS door panels, etc. and lose 10-15 lbs myself.
04-30-2003, 09:03 AM
#3
Race Car
A couple things here:
1) a chip is MUCH better burned when the car is on a dyno...so a few software experimenting tactics can find your best match.
2) we, as owners of such a finely tuned machine from the factory...should consider a chip as "precise" tuning, rather than a great way to increase HP, as it is NOT a great way to increase HP, but can pave the way and compliment other upgrades such as larger displacement (3.8pist./cyl.) and so on.
I, for one, am using a chip from Paul at Cyntex, it was burned for another Rennlister's car but should workout okay in mine...the chip is setup for a 10-12hp increase and is designed to eliminate the occasional stalling I get due to the lightweight flywheel/clutch assembly I installed upon purchasing said vehicle. <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />
One should NOT take the addition of a chip too seriously, consider it a "compliment" to the car and not this huge $400 "upgrade". Most chips will improve throttle response and show HP on the higher end.
Okay, so...that's my "two cents" anyway.
1) a chip is MUCH better burned when the car is on a dyno...so a few software experimenting tactics can find your best match.
2) we, as owners of such a finely tuned machine from the factory...should consider a chip as "precise" tuning, rather than a great way to increase HP, as it is NOT a great way to increase HP, but can pave the way and compliment other upgrades such as larger displacement (3.8pist./cyl.) and so on.
I, for one, am using a chip from Paul at Cyntex, it was burned for another Rennlister's car but should workout okay in mine...the chip is setup for a 10-12hp increase and is designed to eliminate the occasional stalling I get due to the lightweight flywheel/clutch assembly I installed upon purchasing said vehicle. <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />
One should NOT take the addition of a chip too seriously, consider it a "compliment" to the car and not this huge $400 "upgrade". Most chips will improve throttle response and show HP on the higher end.
Okay, so...that's my "two cents" anyway.
