Yes they do, but the whole set up is supposed to work together, my point was that you are taking a part of the control away from the ECU.

 

I've had mine on a couple of mustang dynos. The resolution was is rough they do not show the power losses you and TB are talking about. I based my power estimate on several things: That's what the original programming showed. I've spent a lot of money making sure my car is running as it should be. I have a lot of track time dicing with my brother's stock 996TT X50 (450 hp) and my car is no faster (but the hybrids definitely spool up faster).

Greg H.

 

Yes it does still pull timing. It just no longer has the ability to pull boost. IMHO the EBC does a MUCH better job of controlling boost because the factory approach does not use a MAP sensor so it really does not know what the pressure is. It can only guess based on the MAF. That is why many cars have boost spikes at times. Those can be the most damaging of all.

The upside of the EBC far outways any downsides.

 

I'm with ya...I run a Profec-BII and it is steady as a rock. No spikes and no taper..

 

lol I know Marin I was just giving him ****

 

Ahh another EBC vs Motronic debate...!

Maybe boost pressure really isn't that important, isn't it a surrogate for air/O2 molecules? Maybe MAF is a better surrogate? (or maybe MAP). Boost pressure (is it measured/referenced to atmospheric pressure) kept constant doesn't always mean the same number of molecules?

Just trying to stir some discussion, I accept your/our machines all work very well. Regardless of what's controlled or not.

 

No of course the colder air is more dense.

So you are suggesting that when the air is hotter and thinner the ECU packs more in via increased boost?

If that is the case then we are increasing boost when the air is hotter and more detonation prone. Does that make sense?

If the ECU was that smart and trying to increase air density via boost when hot why is it just a spike and not across the board ?

 

I'm just an enthusiast with limited knowledge so take everything I say with a grain of salt ...

Actually I'm not sure, in thin air/higher altitudes, the ecu probably makes the turbos work harder for the same air (might see higher boost number). In hot weather, boost/air is pulled since the ecu knows high temps are bad (knock overrides the ecu's wish for more air). In cool weather, some people have seen lower boost in certain conditions, probably since the ecu sees enough air at lower boost. I've also seen high/extra boost in certain ideal cool conditions. Just not sure the 'boost' number is all that important. Not sure keeping the 'boost' number the same is critical/seeing changes in boost is bad (it's the factory set-up - my mechanical boost gauge doesn't even correlate well with the factory gauge). Seems to make sense you'd be able to milk the best performance if you can control as many variables as possible. You don't seem to see many new cars come out with fixed boost setups.

 

As we all know the factory set up is based on air mass, cold air needs less boost than hot air to reach the same air mass target in the ECU. This is the main issue with fixed boost, if you are tuning for peak numbers, and you then drive the car in colder ambient temps than when you mapped the car, you will be running into trouble. If your car is always driven in the same conditions then there isn't a problem.
The stock set up is designed to give you roughly the same power whether you're driving in the hottest or coldest countries, it's basically set up with headroom. Hence why it's easy to tune the engine for more power, it's just more difficult to get more power safely in all environments.
In Europe we see hugely varying temps, i drive my car in anything from freezing temps to hot summer temps, my tune needs to allow for all, if it was set up for absolute max power in a 20degC day, then on a 0degC day the car would be spluttering as the ECU was cutting the spark to save the engine.

There's a good reason people like RS Tuning use K24/26 turbos for the 520ps kit, the turbos could probably run 650hp+ in the right environment, but to make sure the intake temps stay within check, and for it to produce 520ps in any place on earth, safely and consistently, even at top speed for mile after mile, whether freezing cold or baking hot.....

It all depends on what you do with your car, and the environment you use it in. Fixed boost set ups will work well for some. That's my understanding anyway, happy to be corrected

 

I'm not necessarily looking for the peak horsepower as much as I'm looking to smooth out the powerband. My car drops enough after 5000 rpm to where you can feel it when you drive.

Some good valid points for both ways though. Keep the input coming.

 

Could it be that your IAT (after the intercooler) is getting too high and the ECU is pulling timing? What's your boost level?

 

Why earth would new cars come with a fixed boost setup? Remember what your dealing with here, circa 1990's tech ME5 which is about as sophisticated as the calculator sitting next to your computer. If this was a car made past 2000 then I would agree but they are not

 

A larger mass air meter helps with the high RPM range. My car was on the edge of lean with the stock mass air, so we went with a larger unit. From 1,000 rpm to 6,000 rpm perfect EGT's. and very smooth.

 

For comparison the first Pentium chip was coming on line when the car was designed. Would you use that today?

Lets talk about about Torque and HP. Everyone focuses on peak yet its the area under the curve that gives us the best acceleration.

Peak torque=maximum cylinder fill

Modern technologies focus on getting the maximum cylinder fill across the broadest portion of the RPM band. In NA cars like the GT3 they use resonance intake tuning and variable cam timing to accomplish this. In the new turbo cars they use the variable vane turbo.

How can we apply modern technology to our beloved 993tt?

Variable cam timing is out. The VVT would work but there are no aftermarket boost controllers to manage it yet. The most logical application is the EBC to make improvements in boost response and broaden the torque curve.

Lets say the mechanical (and detonation) limits of the motor are 400tq. We would want to get to that level asap and extend that level as far as possible to get the broadest power curve.

The best EBC for doing such a thing is the AVCR.

If you ever played with an EBC you know that gain changes boost response. The more gain the faster the boost response. If you crank up the gain boost comes on FAST in the lower gears. In the higher gears you get boost spikes so you are forced to adjust gain to limit boost spikes.

The AVCR allows you to adjust gain by gear for best boost response and spike control.

Looking at the typical 993tt dyno you see very peaky torque curves. With the AVCR you can flatten it out by adjusting the gain by gear and boost by RPM. With the AVCR you can reach that 400tq sooner and stretch it out farther for better top end.

The attached dyno shows what can be accomplished using such techniques. This is a 993 VRAM motor running 6PSI of boost. This is before the motor was broken down to change the rods and flame ring the heads. After dyno will have torque coming in sooner and dropping off later but still staying very flat.

Think outside the box!!!

 

All the factory 993TT Porsche Motronics will pull timing AND boost prior to 5000 RPM and keep it at a lower threshold and restore the timing and boost AFTER 5300 RPM's.. Maximum combustion pressure is during this "range" Porsche wants to minimize "risk" to the engine.