SW chip issue put to rest...or not :)

[D Hanson]

Your running 350 ft lbs of torque or am I miss reading something. Looks like mass confussion at dyno day with those charts and the results on the 996. I agree with you that the lines do not appear to deviate much for the chip at all. Maybe I am not used to reading this type of dyno chart, but something looks amiss to me.

[KFC911]

Originally posted by D Hanson
Your running 350 ft lbs of torque or am I miss reading something. Looks like mass confussion at dyno day with those charts and the results on the 996. I agree with you that the lines do not appear to deviate much for the chip at all. Maybe I am not used to reading this type of dyno chart, but something looks amiss to me.

Yes, you are reading the graphs correctly (350+) on the torque curves. Paul mentioned that his torque numbers were impossibly high too (but I don't know what his actual values were). The hp numbers are very close to stock (if I remember correctly), and I would have 'thought' I'd be a bit higher than stock hp with my mods. You mentioned that 230 rwhp was too low for a new & healthy 996...how low? Also, the rpms depicted on the graphs don't represent what my tach was indicating, so now I've got a bunch of ??? regarding the 'actual' numbers depicted. Again, I didn't get too concerned with the numbers since I was looking for differences between the runs. I'm certainly a novice when it comes to dynos, so if anyone can offer some more insight, it would be greatly appreciated. The Mustang dyno owner/operator was raving about how the 'tuners' loved them due to their consistency between runs, but I don't know if he was bs'ing or not. Now this is REALLY starting to bug me, so I might just pay a visit to a local shop that has a Dynojet just to see how the numbers compare.

[D Hanson]

I am no expert either. If some of the data is off, it would seem to make you possibly question other data. I am not sure what a 3.6 996 should do at the rear wheels. 320 hp on a C2 would seemingly do 270.

[Steve W]

Looks like the hp line is still rising on both chips past 5958 rpm, unless it's a really a different rpm as you indicated. It's too bad the runs didn't extend past that point, as usually the stock chip starts declining in power after 5900 rpm, when the new chip should continue ascending out to 6200 rpm or so. There are typically wide differences after that point.

[KFC911]

Originally posted by D Hanson
I am no expert either. If some of the data is off, it would seem to make you possibly question other data...

Ain't that the truth! At this point, I don't know what to believe, because the the numbers just do NOT add up. Using the first run as an example, I've got another printout (which I didn't scan), that shows max hp of 184.3 @ 105 mph and max torque of 357.6 @ 96 mph. Well, I was watching my tach (along with the dyno's pc monitor) on all of the runs, and on each run, the rpms were climbing to the 6500+ range as I approached 105 mph. Granted, on the last few seconds of the run, I would concentrate on the dyno monitor (instead of the tach), but I was definitely past the rpm values (5900 stock/6200 SW) that Steve quotes (where the hp should begin to drop off). As the graphs clearly show, my max hp was always as I hit 105 mph (with my tach @ +/- 6500 rpms). At this point, all of these runs just don't seem to display believable numbers, so I think I will try again on a different dyno (after I've confirmed that the WOT switch is engaging). One other thing...although I was approaching redline, I never hit the rev limit (stock or SW chip) on any of my runs. Once again, thanks again for everyone's input!

[SRISER]

Mathematically it wouldn't matter what you divided with. You could divide by 100 if you are only trying to determine the DIFFERENCE between the SWC and your 358 chip. It DOES make a difference if you are trying to determine the ACTUAL HP ratings of the chips.

The 358 chip is pretty aggressive from what Steve has written on the BBS concerning OEM mapping. I would guess that most of the difference between the 358 and the custom burn would be mid-range HP and torque?

[KFC911]

Originally posted by SRISER
Mathematically it wouldn't matter what you divided with.

Well, it would if you divided by 0 ... I'm just kidding of course. Your're correct though, and as I stated, for comparison purposes, the math (and actual values) don't really matter at all. I was also just a "bit curious" as to what hp my car was actually putting out (with my mods), so that's why I asked about the 'fuzzy math'. On dyno day, I didn't put any significance into the dyno operator's math, and now, I'm questioning the actual dyno results... the results just don't jive with what I 'know' to be true. I'm soooo confused.....

[Halm]

Originally posted by KC911
On dyno day, I didn't put any significance into the dyno operator's math, and now, I'm questioning the actual dyno results... the results just don't jive with what I 'know' to be true. I'm soooo confused.....

One thing to keep in mind is the relatively correct order the cars fell. By that, I mean that the new 996 had the expected highest number, and Tom's '73 E was the lowest with you slotted properly between them. Paul's 3.5 and my 2.7 were clearly the exceptions and both of them were way down over expectation.

As someone totally disinterested in the "chip wars" I would say that the only possible variable for stock vs SW is a malfunctioning WOT switch. If you find that to be in good working order, then IMHO a chip is probably doesn't buy much new top end performance. Maybe a better butt-o-meter feel or mid-range feel, but not top end.

[SRISER]

But is zero REALLY a number?

[SRISER]

Further, I didn't feel a whole lotta difference between my 358 chip and a custom burned SWC.

Sounds like a dyno day with a competent operator is in your future.

[KFC911]

Thanks Hal! Yes, you are correct, and although the cars dyno'd as expected relative to each other (except that I would have thought Paul's 3.5 would have 'smoked' mine in terms of hp and Ken's hp should be much higher). I'm not having an issue with the 'chip comparison aspect' at all. The problem I've got is with the way the hp is graphed...did your (and everyone else's) max hp display at 105 mph, and what rpms were you turning at 105 mph? That's my issue...the rpms on the graph don't reflect what my car was turning, and I should have definitely seen the hp curve drop off as I approached 6500. Not to mention the torque values... You are spot on with your assessment that a chip would not change top end performance however. Saturday was a lot of fun though, and now I'm just more curious than ever...so now I think I will dyno mine on a local Dynajet just for grins. Good luck with your carb issues, and thanks again!

[KFC911]

Originally posted by SRISER
But is zero REALLY a number?

Depends on whether you have a NC public education or not ...
Counting to 0 is one of our graduation requirements!

[SRISER]

LOL...that's funny.

[Tim Walsh]

Keith, you forgot your ABC's.. A, B, C.. see I passed :-D

[KFC911]

Yes Tim, that's it...to graduate in NC, you need to be able to count to 0, and to know your ABC's...all three of them!

[Halm]

As best I remember, Ken's 996 was the only car to pull to 110 MPH for testing. I am out of town so I can't check the graphs but as I remember I was turning right at 5,800 RPM at 105 and I am absolutely sure that was all I could get!

[KFC911]

Originally posted by Halm
As best I remember, Ken's 996 was the only car to pull to 110 MPH for testing. I am out of town so I can't check the graphs but as I remember I was turning right at 5,800 RPM at 105 and I am absolutely sure that was all I could get!

Was that 5800 from the graph, or from the tach? Also, did any of y'alls (that's "you guys" for the rest of the country ) hp curves decline at the end of the run, or was everyone peaking on hp @ 105 (or 110 in Ken's case) mph? When you get home, check, and let me know...Thanks!

[Halm]

I'll check for more of the data when I get home this weekend, but the rpm was from the graph.

[Paul Thomas]

Keith,
I was passing 105mph pretty quick when i let off. The graph says about 5900rpm but i wasnt looking at my tach. If we use Taylor's 25% loss rule, that puts me at 246hp, which is about what i would expect. BA has a dyno graph of a twin-plug 3.5 in his book and it topped out at around 250, but it didnt post toque numbers.

My peak torque was at around 3900 and the 395 lb-ft it said i was making is way off. That is more than a 959 at 5500rpm (369).

I think we can agree that these runs will be good only for tuning purposes and future runs on the SAME dyno. I will go back in a month or so with different headers and an O2 bung for wide band analysis. If you want to have a go at Turbo Tune let me know.

Paul

[Lorenfb]

"As someone totally disinterested in the "chip wars" I would say that the only possible variable for stock vs SW is a malfunctioning WOT switch. If you find that to be in good working order, then IMHO a chip is probably doesn't buy much new top end performance. Maybe a better butt-o-meter feel or mid-range feel, but not top end.




__________________
Hal Michael
1970 911 E Targa w/ 2.7 RS spec"

Although the torque numbers numbers are in error, i.e. torque = HP @ 5252 RPM,
K = 5252 in HP = (torque x RPM)/K , the meaningful result is the difference determined
between the chips - insignificant. The results are consistent with other dyno tests
that have been done over the years, e.g. Bruce Anderson's test of six different
perfomance chips indicated no significant differences.

Most DMEs with non-358 chips will probably see a very small improvement with the
performance chips, because Porsche improved the torque output slightly (10 ft-lbs)
with the 082 DME (32K in '87 & 358 64K EPROM in '88/89). For most 3.2 Porsches,
though, as the data further indicate, performance chips are a waste of money even
if the WOT switch was not functioning. Unless you're one of those who drives at
at the redline in all gears all the time.

Many still fail to accept the facts even with this latest data. All the other B.S. that
gets posted won't change the reality about performance chips!