Performance Tuning - The Myth -

[LJ851]

Originally Posted by Lorenfb

Bottom line: For the typical stock factory engine which in all cases has AFRs
close to the ideal, no significant improvements result for AFR tweaks versus
'pushing' the ignition timing and that's the essence of what the so-called
performance chip really does. It's that simple!

This is true. However, when i put a wideband 02 sensor on my stock 3.2 i saw high 11's at full throttle at high RPM. It does not take a lot of dyno experience to understand that 11 AFRs are stealing real HP. The Aftermarket chip i tried next held the AFRs in the 13 flat range and the dyno loves that ***** !!! Been there too many times.

[dshepp806]

Good one bugermeister! It is kinda' funny, indeed,...there are many out there that will smoke the sheeit out of these 80's Carreras......although they might not "feel as good as the 911" while driving....it's a matter of tastes.....for the feel......

I'm up for adding a brand fuchin' new Carrera to the stable to fix that issue.a turbo to boot......Yeah,..I'll keep the "visceral" 911 in the stable...for the slower side.......but copping a good "feel", nonethe less...


Doyle

[Hydrocket]

Originally Posted by burgermeister

The main reason I don't have a chip in my car is that there isn't a knock sensor to tell me if things have gone awry... if Steve sold a reasonably priced one, I might change my mind about chips.

Link and TurboXS both sell one...and they aren't obscenely priced.

[Lorenfb]

"However, when i put a wideband 02 sensor on my stock 3.2 i saw high 11's at full throttle at high RPM. It does not take a lot of dyno experience to understand that 11 AFRs are stealing real HP."

Really, then let's see the data to corroborate that claim. My graph indicates that
there's little to no effect, i.e. Just look at the graph! If you don't have the supporting
data, then buy some dyno time to prove it. That's what I did.

[brads911sc]

Loren, Why do you care if a guy feels like his car is faster? then good for him. Whether it is or not.. its his money.
I can tell you that adding EFI and tuning AFR's to ideal made NO difference in my SC seat of the pants. Recurving the Dizzy was a night and day difference.
So Loren is more right than wrong...

[Rodsrsr]

Manipulate timing and you rob from one end to give to the other. I dont believe that this will truly add any significant hp, but your car will run nice with timing and air/fuel ratios in check.

[brads911sc]

you obviously dont drive an 81-83 SC...

Originally Posted by Rodsrsr

Manipulate timing and you rob from one end to give to the other. I dont believe that this will truly add any significant hp, but your car will run nice with timing and air/fuel ratios in check.

[Rodsrsr]

Originally Posted by brads911sc

you obviously dont drive an 81-83 SC...

No I don't, but in all my years working on all types of cars I have only noticed a significantly improvement from timing adjustment when the car is noticeably out of tune.

[pharlap71]

I don't really have a dog in this fight owning a stock 84 3.2, but 40 years of on and off P car ownership and 30+ years in the automotive repair business I don't share the belief that the "factory" does everything perfect. I don't mean they detune for emissions or octane, they just don't know what they are doing or are way behind in some areas. So in saying that, I have no problem that there is room for improvement in their chip mapping as in so many more areas of these cars.

[DanielDudley]

Originally Posted by Rodsrsr

Manipulate timing and you rob from one end to give to the other. I dont believe that this will truly add any significant hp, but your car will run nice with timing and air/fuel ratios in check.

That is often true for cam timing. However, if you optimize ignition timing, you may pick up power somewhere without losing it anywhere. Usually, optimum ignition timing gives the air fuel in the cylinder an earlier spark, and that means more pressure on the piston sooner. Your gas is doing more work, because it is burning longer on the power stroke. You are not robbing Peter to pay Paul. You are optimizing cylinder pressure.

Steve Wong has dyno sheets to verify his claims. There is no question that Porsche left power on the table. This is how they got more power from the later Carreras.

I wouldn't exactly say that the gearing on a later Carrera was optimal either, but hey, the factory is always right.

[Ofishbein]

Was the OP responding to someone's question? Or did he just get up one morning and decide to write an epistle?

[KFC911]

Originally Posted by pharlap71

I don't really have a dog in this fight owning a stock 84 3.2, but 40 years of on and off P car ownership and 30+ years in the automotive repair business I don't share the belief that the "factory" does everything perfect.... .

+1. Like exactly what they did in '87 with the chip maps to add 10 more stock hp. Custom chips with the calculated decisionb to run 93 octane can go a bit further.

Originally Posted by Ofishbein

Was the OP responding to someone's question? Or did he just get up one morning and decide to write an epistle?

Yep, but that morning was 8+ years ago . For you newcomers, go back and read Loren's earlier posts both on Rennlist and here on Pelican if you care for real entertainment. Then roll the calender forward to today and make your own educated opinions about SW's expertise. I've had mine a long time...cost less than my brake pads, and imo that was/is some REALLY cheap, yet "safe" hp gains.

ps: Of course, if I don't run a higher octane, I risk predetonation, but I don't.

[LJ851]

Loren,

1) Do you have a stock chip in your Ducati 996?


2) Is the 3.2 engine shown on your dyno charts stock? 7200 rpm seems really high for stock rod bolts!

[brads911sc]

I assure you that you can materially alter the timing on an 81-83 sc and not take performance from somewhere else.... has nothing to do with it being out of tune. It was SEVERELY detuned for emissions purposes. Dont believe me.. Call Barry Hershon at IEA and speak to him on this subject...He will forget more than you or I will ever know about Pre-89 porsche ingitions...

Originally Posted by Rodsrsr

No I don't, but in all my years working on all types of cars I have only noticed a significantly improvement from timing adjustment when the car is noticeably out of tune.

[brads911sc]

Ooops.

Busted! LOL

Originally Posted by LJ851

Loren,
2) Is the 3.2 engine shown on your dyno charts stock? 7200 rpm seems really high for stock rod bolts!

[Tippy]

Originally Posted by Lorenfb

once the AFRs are within 1-2 points of the ideal of 12.6 (that's 10.6 to 14.6) little to NO improvement in torque results

Loren, I listen to everything you say electronics wise (we all know you know a bunch), but this is wrong.

If that is the case, why did Mr. Bosch put a WOT switch on the Carrera 3.2's for example that ignores the oxygen sensor to provide AFR's in the 12's???

If there is no gains running a richer combustion at WOT over stoch, what is the point?

It was for power. High-12 to low-13 AFR's make more power than 14.7 AFR's.

[Rodsrsr]

I think the point is that yes you can get some marginal gains from performance tuning, but the cost can easily run into the thousands so not much bang for your buck if your car is running well to begin with.

[Tippy]

No, he said there is little to no gains. If that was the case, why would every EFI system in the world ignore the oxygen sensor for WOT?

It is for peak power.

[tobluforu]

I really don't see the point of starting a thread like this, is there something going on in the back ground that we don't know about? Lots of pm's pissing people off, etc...
There isn't one person mentioned in the first post, but it's obvious based on all the other threads that this is somewhat directed at Steve and the people that bought his chips??
I mean who really cares, except Loren I guess, I really don't think that there are more than a handful of people on this board that have complained about Steve's chips, so give it a rest already.
Also, one can't start talking about turbo's in regards to this thread, that is a whole other subject when it comes to boost pressure, a/f, egt's, etc.

[RarlyL8]

"Engine performance tuning is the act of optimizing the parameters of combustion as controlled by the OEM fuel, valve timing and ignition systems."

And that's called engine performance modification (engine mods). Performance
tuning is typically tweaking of the engine management system, i.e. the ECM
which controls the fuel and ignition or in the pre-ECM days re-'curving' the
distributor timing or re-jetting the carbs.

There is no engine management system on a CIS engine. In the days before EMS you had to mechanically adjust things instead of electrical adjustments. Lots left on the table with those engines. I see this thread is an attack on the chip industry though so no relevance on what I said anyway.