VNTGSPD

Disclaimer: This data was collected using means determined to be reasonably accurate and repeatable. However, the driver and timing devices are anything but perfect. I do feel strongly that this info is more useful than randomly quoted dyno numbers though.

For those that don't like to read: The Rennsport Chip works!

Now, the details...

I tested 0-60 and 1/4 mile using a G-Tech.
Acceleration runs were done from a stop at idle speed to help ensure consistency.
I used a stopwatch to measure the rpm specific acceleration.
I followed the Rennsport instructions exactly prior to testing with the exception of the "3 cold starts for full adaptability" (I hope to do another test under similar conditions in the future)
All tests were done using 91 octane fuel

Subjective evaluations:
The RS Chip felt better on the 1-2 shift by seeming to reduce the "dead spot" caused by the factory gearing.
The detonation heard under hard acceleration under 2,000rpm seemed to be the same if not slightly less than the factory software.
No detonation was heard by either chip during the rpm acceleration testing.
The RS Chip showed an initial propensity toward detonation under 1500rpm (like pulling out of a parking lot into traffic) but this seems to have gone away - I'll keep an ear out for this one.

Enjoy.

JasonAndreas

Are you using something (Bosch Hammer, PST2) other than your ear to detect knock? I'm a total believer in (and a witness to) the potential for a chip upgrade to provide a slight increase in performance but its beginning to look like the generic aftermarket chip solutions are pushing things too far for 91 octane at most load sites?

InTheAir

Simply from a data analysis standpoint, I'm not quite sure your times substantiate a performance increase. I say this between the calculated performance improvement appears to be about 1-2% in most cases (other than partial throttle). However, the variation in run data is also about 1-2%. Therefore, I would say that the alleged performance improvement is merely within the overal margin of error and thus not necessarily quantifiable.

I am a huge believer in chip improvements, however I don't think the data in this case actually substantiates it.

Steve Weiner-Rennsport Systems

Hi:

I think it bears mentioning that detonation thresholds vary with outside air temp, oil temp, cylinder temps and throttle position. Further, each engine's carbon buildups over time affect its sensitivity to fuel octane numbers as well as variations in every engine's cam timing. For these reasons, a live re-map is not practical since those values are only valid on that day & at that time.

Although we do improve the drivability of these cars with appropriate changes to the fuel & timing maps, 91 octane is not quite sufficient to get the maximum performance of any 993 (& 964) and I do recommend mixing some 100 unleaded for that purpose. For folks who have access to 93 octane gas, thats not an issue unless one does DE events.

JasonAndreas

The 993 uses cylinder head temperature readings only during warmup and the oil temperature during warmup and at the other end of the scale when things overheat which hasn't happened here. So that leaves intake air temperature which at 71-74F should be a non-factor (see graph below) at least according to Porsche and MAF/TPS which appears to have the timing set too advanced for this particular engine running 91 octane.



This is from a 964, the 993 is basically the same except that timing is reduced by 2.25 degrees at 95.9F/35.5C instead of 105.8/41C.


Can I make the suggestion that you offer a larger warning to future customers living in those areas where 91 octane is the maximum? I'd be curious to know how many from the GB that are stuck with 91 would have bought a chip if they were told they would have knocking?

tj90

Thanks for posting the results - I appreciate you taking the time and quantifying the differences with data. Go Rennlist!

VNTGSPD

In all fairness to Steve W., he was VERY upfront about the expectations for those of us with 91 octane. Perhaps that is why I am actually pleased with these numbers. I did not expect to get miracles from a chip for a normally asperated car running only 91 octane. Also, read my original post again and you will see that the audible knocking is no worse if not even better than the factory tuning.

As time permits I will run these tests again after full adaptation and will also see what happens with a mix of 91 and 100 octane (although the latter will be irrelevant as I don't intend to put the factory chip back in).

InTheAir - your comment on the statistical error and the measured change is valid. The small improvements were expected and the unsophisticated nature of the test doesn't help. That is one of the reasons for averaging the results. While the improvements COULD be a result of error, I believe the consistent improvement in all areas except one, despite the negative impact of slightly higher ambient temperature and the possible heat soak from the time to change chips and let the car idle, point to the chip being effective.

Keep the thoughts coming. This is the discussion I hoped to read before buying my chip. Maybe this will bear fruit for those considering the change in the future.

Lorenfb

"I tested 0-60 and 1/4 mile using a G-Tech."

Too highly subjective of a test with too many uncontrolled variables.
The "flipping-of-a-coin" will probably provide as scientific a conclusion.

"Can I make the suggestion that you offer a larger warning to future customers living in those areas where 91 octane is the maximum? I'd be curious to know how many from the GB that are stuck with 91 would have bought a chip if they were told they would have knocking?"

Right on!

This has been the case for over 15 years now, but some/most think there's really something
magical about performance chips other than their JUST having "pushed" the timing beyond
what's realistic for a normal (non-track) car. Porsche owners now pay $300-$500 for an effort
which took about a minute on the old 911SC with the use of a 13mm box wrench and a timing
light. And there's NO tweaking of the fuel maps as some hyperbole may indicate.

And for a "live programming" (custom) of a stock engine, that's a real ripoff, i.e. as if there's a real
difference between stock engines that'll benefit from a custom programming.

Steve Weiner-Rennsport Systems

Well Jason,......I DO offer the warning about 91 octane gas & full performance,..............

Further, I also remind people that 93 is Porsche's minimum recommended octane for full power and people living where the summers are hot should blend some 100 octane unleaded to see maximum performance, especially for DE events.

Thats a good suggestion and I'd invite you to call me anytime to discuss such subjects in detail.

Red rooster

Steve,
Maybe a revisit to the timing calibration will get round this 91 situation ?
That stuff is all we have here so some careful thought about rpm versus detonation limit will pay off.
It would be really interesting to know if any US states have our situation or are we alone with 91 only !

Certainly a crude attempt to raise timing by the same angle right across the rev band , just like a SC distributor swing , is not a good idea !
I am certain that that is not what you are doing.
It will be intruiging to see if ethonal added to fuel will make changes , maybe in the right direction .

All the best

Geoff

InTheAir

I won't tell anyone that we have 94 readily available around these here parts.

Red rooster

Jeff ,
Well lucky you !! That hasnt helped my morning !

Geoff

jdistefa

Loren,

I know that this is a plea for irrationality, but please accept that despite admittedly marginal 'best evidence' for the utility of chips, that many of us (myself included) will still indulge in this silly, wasteful purchase. Hey wait, I could be referring to the car itself. Or the diamond ring that I'm sure many of our wives wear. Oops, I digress. Anyway, please consider the following:

1. There may be a slight measureable performance improvement outside of statistical variance.
2. Placebo effect.
3. The sheer pleasure of belief in the butt dyno (see #2).
4. The sheer pleasure of installing the chip... not.

I'm sure that in many ways you are correct re. the content of your posts on this issue, however, I think you're missing the point of purchasing a chip: It is an exercise in belief, faith in Steve, and the ongoing fun of changing something on the car. I could have spent $$ on something equally vacuous, but this brings me more pleasure. Nonetheless, I will continue to marvel at your ongoing attempts to convert the heathens. You are to be commended for your persistence.

Yours in continued ignorance,
Matt

Jukelemon

I used to be able to get 100+ octane in Knoxville becasue of the HUGE population of Bass boats in the area. It was very nice ( :

I have never seen it here in KY although I suspect one could get it around the major lake cities.

In terms of this chip debate, I have a Rennsport AND I never expected HUGE results. It just does not happen with cars that are tuned, in general, pretty damn good from the factory.

What it did do is smooth out my throttle response. I had a notch-it was obvious. This chip smoothed it out and I ALWAYS ran/run 93 octane.

How or why I don't know. Could be that Steve spent one minute on it. Don't care. He knows how and I don't and knowledge is worth money in my opinion.

smddanny

Question on the chart proffered by Jason...

what is the abcissa? Degree of what? Woudl this be retard from full advance as a f(temp)?? If so.. .then only 4.5 degrees up to 134 degrees?

Here's to you where ever you may be.. in hopes that PV always equals NRT.....

Best!
Danny
96 993 T