Steve Weiner-Rennsport Systems

Hi Geoff:

The USA is highly unusual in that octane availabilities vary all over the country,...

Some states have 93, some have 92 and some only get 91. Its based on fuel distribution, local altitudes, and state-mandated emissions controls. Combine that with the variations in each engine from accumulated carbon, compression differences, and valve timing, you have cars with varying levels of octane appetites.

All software was developed and tuned on load-type chassis dynos at varying loads and no across-the-board (global) timing changes were made. Each & every load point at different RPMs were individually mapped for fuel and timing and I'm pretty sure you know how labor intensive this process is,......

JasonAndreas

The abscissa is the air temperature measured at the MAF and scaled in the chart to degrees of Fahrenheit.

Yes this is timing retard used as a trim value from whatever full advance happens to be.

Wouldn't a live remap allow you to set the timing for mean best torque without any knocking and the start and length of injection based on measured optimum values for each specific engine?

Steve Weiner-Rennsport Systems

Yessir, without question.

Two issues though:

1) Timing values during remap are valid for that day, fuel load, and atmospheric conditions. Mapped values must be "loose" enough to permit a margin so that the engine will not detonate when its hotter or when one gets an inferior batch of fuel (not uncommon). This was the initial problem with "The Program" aka Unichip. Its a fine line to plot noticable performance gains and enable the car to run on available octanes (including the seasonal variations).

2) Although a live re-map is ideal to be sure, its expensive and impractical to do as I'm sure you can appreciate. Given the time it takes to do that, IMHO, not many people would be willing to shoulder the costs.

pcar964

Did you develop your own mapping? Or do you choose from the different maps provided by GIAC?

Steve Weiner-Rennsport Systems

We work with GIAC to develop different software for custom solutions. In short; both.

pcar964

If I have an off-the-shelf GIAC chip (from AWE tuning), would I benefit from upgrading to a Rennsport chip? My car is basically stock except RSR mufflers. (If so, what would it cost to have you reflash my current chip?) Thanks!

Lorenfb

"Wouldn't a live remap allow you to set the timing for mean best torque without any knocking and the start and length of injection based on measured optimum values for each specific engine?"

Jason, you must be playing "devil's advocate", right?

"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 !"

It should be obvious from the before and after torque curve, i.e. that's what was basically done.

"Mapped values must be "loose" enough to permit a margin so that the engine will not detonate when its hotter or when one gets an inferior batch of fuel (not uncommon)."

Right! And this is what Porsche/Bosch did during product development.
The so-called tuners just narrow this margin which results in detonation.

"Each & every load point at different RPMs were individually mapped for fuel and timing and I'm pretty sure you know how labor intensive this process is,......"

Please!!!!!!!!!!!

1. Modifying the fuel maps has really no effect other that at WOT, i.e. because the ECM operates
closed loop the majority of the time, and at WOT the AFR is very close to ideal anyway.

2. The key result occurs from just tweaking the timing a few degrees, which can be done in
10 minutes (change ignition map) on a PC. Hardly a major effort requiring MAJOR dyno work.
Sounds like more marketing hype! And now that the chip source has beed mentioned,
it's Giac that usually results in the most problematic pinging issues, as those cars are
where the requests come from for replacement stock chips to solve detonation & poor running problems.

Bottom line: The extent of hyperbole never ends to promote a product!

Steve Weiner-Rennsport Systems

Loren:

I'm quite surprised that apparently, you know little about dyno mapping these cars since your comments about "10 minutes on a PC" and "marketing hype", just border the absurd,....

Personally, I think you're a LOT smarter than that, but your obsession about this subject totally clouds your judgement in this area. I cannot respond to your comments any longer on this since you have lost your objectivity, sir.

Red rooster

Steve,
Thanks for that . I began to think the USA had 100 fuel everywhere ! You are certainly right that some motors with a little carbon build up etc can easily become detonation prone .
Mine runs fine on 91 with no det confirmed by a Hammer knock log.
Maybe its a good thing that very few 993s have a real 11 CR. Maybe one day Porsche will get the history book out and go back to the 1970s 2.4 compression like 8:1 !!

Geoff

Steve Weiner-Rennsport Systems

Hi Geoff:

If 993's (and other Porsches) truly had the advertised compression, we would not be able to do much with engine management software, given the sad state of pump gasolines; at least here in the US.

IMHO, CR's will only go higher in the quest for improved fuel efficiencies. The new 997 motors have DFI which affords much better control of fuel atomization and even higher CR's. Thats how they are able to keep boosting HP while maintaining the same displacements,...