Jeff,

They put me on here to keep you straight!
And someday you'll drive me car - just sign up to be my instructor at a DE or two.


Jon,

I actually don't know which gear was used for the dyno test, but 4th gear certainly makes sense. If I remember to do so I'll contact the gentleman who dyno'd the car for me and get back with the group.

 

Rich-

It would have to be a smart dyno to figure out your gearing...Most assume 1:1 transmission ratio. In a 964, if you went third gear lower you would have grossly overestimated torque/power value. Dyno'ing in 5th would understate your values (0.868 ratio). For a 964, 4th is best, but still not 1:1.

So unless these guys were so familiar with 964 they automatically accounted for the gearing when making the plots, adjustments will be needed for whatever gear was used.

 

Rich, Chuck did use fourth gear on all cars that day, seems that is the standard practice.

I would love to be your instructor at our next event...then maybe that car WILL go fast! I really should have took it for a spin that weekend, instead took that Twin Turbo out for five laps or so...now that was quite a thrill!

I really like this discussion on mods, some of the discussion is getting too technical in my book though. I truly believe that a wheel dyno is going to give slightly inaccurate readings. You can get a reading, a certain day, at a certain temp. and humidity index, on a certain dyno. If you come back to the same dyno the next day, I'm positive you'll get different numbers...not to mention if you go to a different dyno!!

What I can really appreciate about this topic is the idea that "Jon" wants to PROVE that some mods actually do make a significant difference. It is disappointing to find out that most are not.

As I finally got ahold of a certain East Coast exhaust fabricater today...my exhaust will soon be on my doorstep - then, only then will I plug in the "magic chip" I have on the workbench. This thing is supposed to add 23hp and compensate for my LWF, performance exhaust, airbox mod and extend the RPM range up to an even 7K, vice 6750.

My only goal is to achieve a noticeable difference from the "butt-dyno". If I do not, then I will be thoroughly disappointed!!

We'll see.

 

Jeff-
If the John you are referring to is me (Jon, actually), I set out not to PROVE anything. My study was not going to be a chip-shootout or to show any mods to be superior to any others. I simply choose three of the most talked-about, reversible, inexpensive (relatively) mods that are readily performed by the average DIY'er and proceeded to see what the effect would be. Yes it was disappointing, yet I think the value-add here is that 964 owners can use that information in making an informaed decision.

I wish the result were exactly as vendors claimed! It would be great to pull the supposed 8HP out of an air-box mod, 10HP out of a "cup" pipe, and 15HP out of a chip. I initially had quite a bit of problem with the legend of Porsche de-tuning the 964 by 25-30HP for reasons of noise abatement, 92 octane fuel and/or cost that could easily rectified by $500-700 worth of bolt-ons. I have much faith in the designers optimizing the 964 platform to wring out as much for the street user as possible in that day.

That is not to say it is not possible to do so. I just haven't seen the evidence. I really wish I had it as I would love to see that performance gain for that money spent. Someone (other than a vendor) please show me the before and after data! I would love to see it for simple research interest and to better understand why they don't work in my car.

After reading many posts in the various forums on this board and others, a question comes to mind. How many people bother to dyno their cars beforehand and then install mods? I see a lot of "data" that has the after-effects only. This is almost useless. Jeff, you point out the inaccuracy of dynos. I see them from a different angle- that of precision. If they are precise, and I believe a well-maintained instrument can be, then before and after dyno runs should reveal the real story.

In my case, my pre-mod dyno data was right on the money with what Porsche spec'd for the 964 (assuming 15% drivetrain loss). I am satisfied with that. My after-mod runs showed little improvement on the same dyno, under almost identical atmospheric conditions. Most dyno's, including the one I was on, can make the appropriate corrections for differing atmospheric conditions anyway. I don't know what else to say about it.

It embarrasing, but I wonder also how many people have assumed a tranmission ratio of 1:1 when the gear they test in actually overstates or understates their power/torque rating? It appears this was the case with Rich. I even overlooked it during my initial run and everyone was looking at my numbers with amazement because they were suggestive of very small drivetrain losses. When I made the correction, i was right on the money.

 

Jon, you actually got me all wrong...I am VERY supportive of what you are doing and agree with your goals. You want to see if there are significant changes with various mods.

I understand that this isn't a "chip shootout"...c'mon, I've been around this P-Car business for quite awhile, I know how us P-Car fanatics work, we're actually a pretty smart bunch of guys/gals!

I didn't say that chassis dynos were inaccurate in a definitive kind of way, but they could be instrumental in showing if certain mods are worthy of cost and labor. I like that you are using the same dyno each time, but environmentals are only controllable to a certain extent... although I'm sure those guys know what they're doing!!

It is too bad one can't do a "pull" on a dyno then just "pop in" a chip and do another pull...that would actually be a fairly accurate test. To put another chip in and drive around for a day or so would mean that you would have to come back the next day, where the humidity can easily change, 5,10...even 100%!!

I don't know about you guys...but from one night to the other, my car runs differently. Let's say that the ambient temp. last night on the way to work was 61deg, 25% humidity - the car was a little "shy" on HP...really. Tonight I went over to a friends house, it's about 46deg and about 51% humidity, the car feels a bit more stout, seriously. I notice these differences as I have little lead in my right foot at times...I am a spirited driver.

Don't get me wrong, you're doing this as right as one can possibly, and reasonably do it!

As far as Rich goes, we did ponder the various figures we could be using for drive train loss, I believe the figures the dyno owner/operator used were a 15% drive train loss. Assuming that this was a standard in the industry, we figured a 911 would be less loss due to the direct involvement of the transaxle. So, once again, while getting a little technical in my book...I do agree with what you two Mathematicians came up with!

Apologize for the name misspelling, I actually thought about it after typing it and couldn't quick review the previous threads because once your on the "reply" page, sometimes you can't review the previous threads if there are too many, as in this case.

Be good everyone, I'm off on vacation...again! Here's to eating too much Yard Bird!

Peace Love and Porsches!!

 

No sweat on the name Jeff- I only mentioned to be sure you were addressing me instead of someone named John.

BTW, what is your rod bolt situation since you are raising your limiter over stock?

 

Jeff,

Chuck was using 20%, and we were assuming a 1:1 final drive ratio, which gave the artificially high numbers.

And you are certainly correct that atmospheric conditions affect performance. However, those are variables which cannot be controlled by the mechanic or driver, so we spend our time searching for those elusive horsepower gains that still fit in our budget

 

I have the factory rod bolts right now...only raised the limiter from 6750 to 7k - I know, I know, there are several 964 buffs out there, including Steve W. that would freak at the thought of raising the rev limiter from stock w/stock hardware.

I figure I shift when the rev limiter causes the infamous "gurgle" at the track anyway, due to the fact that my car powers right up to the rev limiter, producing quite a bit of "umph" through the entire RPM spectrum. If I raised it a bit, and paid attention to the tach a little more, I could possibly gain a little bit of time by not waiting for the engine to "gurgle" at the limit and actually shift before the new 7k limit...also allowing a better HP curve at 6750, almost 21HP according to the new specs.

Since childhood, I have raced in almost every venue available, from carts/motorcycles to stock car and drag racing - I have always paid attention to the tachometer. I have found this to be reasonably unnecessary in my 964. So far it has survived 6 events and still running strong.

I can only imagine that the extra 250 RPM will allow me to actually shift at 6750 with no cut out, saving me a bit of time and allowing the extra HP to take effect??

Anyway, I plan in the future to build the crap out of this engine...up to and including Raceware hardware, just like my previous 911. I perform my own engine/trans. work and have been fairly successful with the 911 drivetrain over the last 7 years.

While I'm not expecting or hoping for any internal failure to necessitate this, I am patiently waiting for it.

 

Jon;

Thanks for your input and work. Now that you have you stock chip in, what are you feelings? Can you feel any difference? Steve has to be adjusting the advance and fuel curve in his chips, you would think that you'd notice it. What are your future plans?

 

Hello

I read only today this long and intersting post.

About the results shown and declared by jonfkaminsky at the beginning:

Are you sure that Porsche declares 247 hp SAE ? I think SAE is an american type of measurement, different from "DIN" hp,

where the "D" is for "Detusche"...

SAE hp are measured while disconnecting generator, fan, water pump (if present), etc.

(they are disconnect but moved by an other engine)

DIN hp, instead, are measured with all those subsystem installed on the engine.

An example: VW 1200 old beetle has 34 HP DIN and 40 HP SAE.

So, I guess that dyno results are correct but are expressed in SAE hp; the declared factory values are in DIN; after conversions all values have to match.

Just a supposition

 

Kevin- (and others interested)
I've had the stock chip in for about a month now, and didn't notice anything different when I put it back in. The biggest thing I noticed going from stock to the remapped chip was that a small bit of hunting at idle cleaned up. Other than that, you had to check the dyno curves to see any difference, which amounted to a some flattening, mostly outside usable areas.

My impressions? Here's how I look at it. I don't anyone can just stick a chip into an otherwise pretty much stock 964 and expect ANYTHING close to manufacturer's claims. In my case it was supposed to be 5-6% (15-17HP). Take a look at the RSA. Only 10HP over the regular 964. RSA gets it's gains from weight reduction. If it were just a simple case of remapping I'm sure Porsche would have performed that for the RSA to get the gains.

Now take someone who has ported and polished, changed out the induction system, and opened up the exhaust with some dual headers. They'd be fools not to remap with those changes. Right? If you are making a 993 out of a 964, then I'd say you'd have to remap to run like a 993.

But most people don't do before and after dyno runs and therefore just believe what these people are telling them. Or, they do a whole bunch of other stuff to their car (like what I mentioned above) and rechip, then dyno. They will see some gain, but they will never know how much was due to the chip.

I also see numerous posts here and there by people who have chipped and dyno for the first time, and never account for the transmission ratio advantage seen by running the 964 on the dyno in 4th gear...just like I initially did when I did my first pull. Everyone was amazed at my artificially high results. Luckily this was the stock run and the values were suspicious enough for me to think about it and figure it out. Once I accounted for the advantage, the stock results were right on the money according to Porsche specifications for the 964 (assuming 15% drivetrain loss). But had I not been conducting a study, and done a chip change and sat my car on a dyno and acquired those data without accounting for the 1.086 trans ratio advantage, I would be sitting here bragging about my 255 ft-lbs torque and 270 HP 964 and how great the chip is. I'm sure it happens.

Was it Bruce Anderson who said "The best chip for the 964 is an exhaust change"...? Maybe so.

I still offer an open invitation to all chip vendors. Send me your chip and well see what's what. Oh and another thing. Ever wonder why the Porsche magazines have never published a chip shoot-out? I mean what a great story- take a 964 pop in a series of remapped chips and test. I don't think its that easy, and the magazine I'm sure would really **** off their advertising clients.

Jon

 

Ok heres my information. I have had 2 runs, first run at AMD, second run at JZ Machtech.
Modifications are as follows:
cat bypass
primary bypass
sports tailpipe
AMD Chip (remap)

HP before chip was dead on the money @ 250hp and 227lb/ft.

Geoff had car on rollers for around 3hrs. Net result was 274hp/265lb ft.

So, feeling kinda happy (read, ) I went to JZ Machtech and asked Steve to put it on the rollers. They were more than interested to do this, because "apparently" they had heard similar results from other cars off of AMD's rollers, and wanted to see exactly how Geoff was making these claims.

Heres the info from JZ's rollers:
max pwr speed 6055rpm (119.5mph in gear used)
pwr @ flywheel (corrected) 265.8hp (din70020)
pwr @ flywheel (measured) 261.7hp
pwr @ wheels 237.1hp
pwr loss (transmission/tyres etc) 24.6hp

max torque spd 4914rpm (97mph in gear used)
max engine torque (corrected) 263.3lb ft

ambient temp: 23C
barometric pressure: 1002mb

so, the deduction was that the pwr loss figures being used by AMD were not necessarily correct, hence the increased readings. (Im not a mechanical engineer, so Im only regurgitating this).

Next thing is to test one of Steve's chips (JZ) in place of the AMD chip and see what we get.

will

 

Interesting take on the subject of chips from Andial, who I believe are people to be trusted with the truth:

<a href="http://www.andial.com/content/faqquest/quest2.htm" target="_blank">http://www.andial.com/content/faqquest/quest2.htm</a>

Jon

 

[quote]<strong>Interesting take on the subject of chips from Andial, who I believe are people to be trusted with the truth</strong><hr></blockquote>

As a related aside, I called Andial about buying a chip from them, and they said they only sell/install them for their customers.

 

Bill;

Did you talk to Pete. Did they imply that you are to drive your car to them? Send them your brain and have them install it in the DME unit.