raspberryroadster

when will we see backside of this posting? all leave in good humour hopefully, gerry.

92 964 turbo look (bonestock)
04 cobra (whipple blower@15p.s.i, pro tune,60lb injectors,some other stuff, on a dyno at 575rwHP)

N51

Paul,

Full agreement. Loren is an asset to the forum.

Have not done the search, but Loren was admonished by a moderator for telling
someone to 'get a life'.

Loren and I are mostly in agreement. I like the fact that I can go to him, whether we agree or not. If nothing else, we share thick skin.

raspberryroadster

.....is it really finished? did we get the bat?

N51

Just as me and everyone here, you're the sum of your post.

mongrelcat

*bump*

mongrelcat

The G/B is now closed, if you contacted me about it but I have not returned the msg please contact me asap. (I tried to keep the record straight by using a spreadsheet but doing the msg'ing via PM's is kludgy...) Thanks.

TR6

Here you go. Only thing missing I think is the AFR. I plan to dyno again in a month or so once our Texas heat gets consistently below 100 degrees. When this test was run, it was in the mid 90's, the dyno shop's big fan was broken, and my engine lid struts would not keep the lid up, so the test was run with the decklid closed. In other words, very warm and not much airflow in the engine bay. That's why I want to run the test again. Same scenario: 1) stock chip and 2) Steve Wong chip. The Autothority chip has long since been discarded. All three of the scenarios listed below were run within the same hour, so conditions were identical.

https://rennlist.com/forums/showthre...ferrerid=43271

Here's the summary:
1) Stock chip, open airbox, cat bypass, secondary bypass - 210.5 hp , 201.6 Torque
2) Autothority chip, open airbox, cat bypass, secondary bypass - 205.6 hp , 208.1 torque
3) Steve Wong chip, open airbox, cat bypass, secondary bypass - 229.4 hp , 219.1 torque.

Observations:
The Steve Wong chip gained 18.9 horsepower over the stock OEM chip which is a roughly 9% gain. Torque gain was 17.5 or roughly 8.5% over stock.
The Autothority chip actually had less horsepower than the stock OEM chip, but it did have a little more torque than the stock chip.

Feel free to rehash and argue these results endlessly....

mada1

Thanks. That's good info.
I installed a SW chip last week w/ cat bypass and cup pipe and can tell an increase in power for sure. Seems smoother too.

Lorenfb

"All three of the scenarios listed below were run within the same hour, so conditions were identical."

1. You indicated a 93 octane level used, i.e. spec. 964 octane is (R+M)/2 - 91.
Most acknowledge that the use of a higher octane will allow for a "pushed" timing which
the results indicate, i.e. the "jump" in torque. And we all know that HP = K X RPM X Torque.
Few areas of the U.S. have 91 octane readily available.

"The Autothority chip actually had less horsepower than the stock OEM chip, but it did have a little more torque than the stock chip."

Do what? A new relationship between HP & torque?

"Only thing missing I think is the AFR."

Kinda critical, you think?

2. You failed to monitor the knock count from the DME, which is an absolute in any engine tweak,
i.e. How much detonation resulted with the increased torque?

"cat bypass, secondary bypass"

So it's not really a stock engine configuration, right?
Few will challenge that exhaust mods can be tweaked for more torque.

"Well, technically, the open fabspeed air box added 1.7 hp but the stock airbox had slightly higher torque (1.5 torque difference)."

And what was the measurement error, e.g. < 1% (~ 2 HP) hardly, more like 3-4% (6-8 HP)?
A single sample of each variable change hardly represents a rigorous comparison,
e.g. the sequence of testing - warmer/cooler engine can account for some difference.

Bottom line: So! Given all the above, basically what's always been posted on Rennlist.

Duck

All our premium gas is 93 octane here.

I am definitely probably the least experienced on this board, but isn't the main objective of aftermarket chips is to adjust advance to gain more HP?

Also what does it matter if the engine is not stock if you look are only changing one thing at a time. How many of us do not at least have 1 exhaust bypass?

evoderby

You're a hard man to please!

To quote David Vizard: "I don't have an opinion, just a dyno"

Short of using state of the art climate controlled engine dyno facilities, TR6 has provided some very useful dyno insights....whereas you seem to gross on opinion;-)

<<Do what? A new relationship between HP & torque?>>

Come on you can do better than that! The autothority max torque registered is just a slight peak around 5000rpm (one column short of the 5250RPM HP -Torque intersection). Max HP occurs higher up in the rev range, so the peak torque registered there has no influence on max HP. If you bring out maths use it right.

springer3

Dynos in most performance shops are crude beasts, and useful mostly for putting engines under load for tuning. They are not particularly good research instruments.

I know a technician who operated a research dyno for several years. He is competent, and he thinks the total measurement variability is closer to 30% if you account for the range of atmospheric temperature/pressure/humidity, all temperatures in both the vehicle and the instrument, and the random factors (things that are not or cannot be measured).

The repeatability within a given hour might be <1% provided everything is warmed up, stable temperature, and there are no weather fronts moving through the area. Read tech topics in the current Pano. The writer reports that warming cold transmission oil raises roller dyno power by 24 HP. Warming the tires probably gets a few HP too.

See Wikipedia "Design of Experiments", and see how difficult it is to run a controlled experiment.

Run the test with high expectations for your HP gains, and you are lost already. The human element is critical. Transfer your expectations to the dyno operators, and they develop intentional or unintentional bias. They cannot help it. Neither can you. I am not a psychologist, but ask one and they will tell you it happens even if you are not aware of it. You should conceal the ID of the chip even to yourself. Make at least six runs (3 for each change), in a random order.

Compute the mean and standard deviation of each run (peak or average torque and power). If the mean of the data sets is different by more than 2 standard deviations, you are 95% confident that the difference is due to more than random variation. Most of the dyno charts show only one run, and some do not even report the inlet air temperature - a very strong factor in engine power.

Duck

Is the question whether there is more HP in aftermarket chips or the exact amount of HP difference between aftermarket and stock. I have done DOE's and know the difficulty. I wonder who is going to spend that kind of money to get exact numbers on this board.

So is there a question of whether there is a difference or exactly how much that difference is?

springer3

I agree. Just attempting to raise awareness that this is not nearly as simple as it gets portrayed. Your question is also too simple. I have no doubt that the Steve Wong chip will raise engine output a modest amount. Nobody disputes it solves the LWF and AC stall issues.

I hope nobody disputes that increasing power also increases heat loads and mechanical loads on the engine, transmission, and brakes. Heat and load accelerate aging of seals and mechanical wear, respectively. There are always tradeoffs. Choose wisely, you can increase your enjoyment. Make poor choices, and you may come to grief. Any 18-year-old engine is feeling its age, and now may be a poor time to raise its output.

Some reports of performance increases are hyped, and very few discuss risk. Steve Wong appears to avoid hype, as he is pretty modest with both the mod and his claims. Even he barely mentions risk.

The world of performance mods is not regulated. It is caveat emptor. Lack of independent data makes it difficult to understand what to do. Expert opinion matters. Kudos to Loren and a handfull of other experts who bring balance to this issue.

Lorenfb

All "performance" chips are basically the same, with many copies of others', essentially just
"pushing" the timing and requiring higher octane levels (which in most cases isn't available).
Finding the desired higher octane level is the most obvious issue with using a "performance"
chip.

Most are unaware of the problematic issue with using a "performance" chip in an air cooled engine,
i.e. the total cylinder head temperature is always increased by ambient plus the additional temperature
rise caused by the "pushed" timing. That's not the case for a water cooled engine, e.g. the 996. With water
cooled cylinder heads, the temperature is held fairly constant over a wide range of ambient temperatures
and engine loads. This is not the case for the air cooled 964/993 and as such is more prone to
detonation during hot days or during heavy engine loads, e.g. uphill grade and/or hard accelerations.

Additionally, the 964/993 head design has the inherent detonation problem which was reduced by
the additional spark plug. If one of the two fails or is weak in its effectiveness in igniting the charge,
detonation will occur because the normal timing is already "at the edge" initially without a
"performance" chip timing change. All later Porsche engines with their redesigned combustion
chambers (less prone to detonation) now use a single plug. Although the 964/993 DME ECMs have
cylinder head temperature as an input, once the engine reaches operating temperature that input has
basically no effect on either the fuel or ignition maps, i.e. the cylinder head temperature sensor is
essentially ignored once it reaches a maximum cylinder head temperature value and is not a "linear"
variable as in late water cooled engine management systems.

Users of "performance" chips in the earlier 911 3.2 Carrera ('84 - '89) are even at greater risk
than the 964/993 user as the 3.2 engine is single plugged and lacks the knock sensor control
of the 964/993 DME ECM. Those engines have no margin of safety once detonation occurs
and drivers most likely would not hear the sub-audible detonation, notwithstanding the typical
engine noise of the rear engine air cooled Porsche.

The result of the additional engine temperature rise results in potentially sooner detonation and the
knock sensors retarding the "pushed" timing for a net loss in torque. Some "tuners" use hyperbole
such as "the chip AFRs are tweaked to reduce head temperatures" which has essentially little to no
effect in reducing the increased combustion temperatures to avoid the new detonation point,
i.e. it can't really compensate for the basically uncontrolled ambient temperature effect.
That's the reason Porsche went to redesigned combustion chambers & water cooled heads,
e.g. 962/959 to allow greater compression ratios and timing advances in the '80s for race engines.
That's also why all subsequent, to the 993, Porsche engines were redesigned and use water cooling,
which additionally facilitates an emissions control system. Thus, the ambient temperature issue was
essentially eliminated and the cylinder head temperature became a controlled variable.

As with most automotive "performance" products, few if any of the marketing data relate to the
user's the trade-offs/risks involved in using those products. Furthermore, many promote the products
by indicating that the OEM vehicle producer was "overly conservative" (classic) in the performance
development resulting in "tuning" potentials for adding performance. And then there's always the
"evangelical" users that usually don't know the risks or fail to understand them and become
"sales advocates". When one "looks below the surface" of most easy to sell "performance" products,
one finds major issues.