Seems like we hit a nerve with you! Why do you take this personal? If I haven't done my homework and everyone is happy why are we waiting for results? I'm not here to stir things up I just want to know why there is so much doubt of performance gains with the plenum.

 

And by the way name calling isn't going to help.

 

I too am anxious (and hopeful) to see the dyno results. As to the "near universal praise", those have all been totally seat-of-the-pants and could be easily attributed to the Hawthorne effect. If you recall, a few months ago, the majority of folks were clamoring for more scientific (and independent) proof, but one by one they settled for the butt dyno. I too, agree that the design of the OEM plenum looks sub-optimal, however 27 bhp seems hard to believe. BTW, even if it's half of the claimed increase it will be a cost effective mod in comparison to other alternatives.

We'll soon see. I'm also curious to see florindi's results because his "dyno after a week" approach seems to allow time for the ECU to recalibrate. [AWE: are you putting the requisite 50 miles on in between?]

 

There is a lot of misinformation out there regarding modern Bosch fuel injection and adaptation routines.

Full throttle adaptation on the street can take a while to happen, simply because it is hard to do repeated full rpm WOT acceleration runs on the street.

However, it is very easy to do full throttle adaptation on the dyno, since you can do full throttle pulls all day long. Exposing the fuel injection ECU to full throttle operating conditions in such a condensed manner results in very quick setting of full throttle adaptation.

Usually we see power curves stabilize within 4-5 dyno runs on most cars after a part change. Proper care must be taken to ensure that the engine is not being overheated, as that will cause the ECU to take protection measures and pull back ignition timing or enrichen fueling, which will corrupt results.

What does take several miles of driving to ensure full adaptation is part throttle mapping. This is because of the multitude of loads that the car sees at part throttle. Driving on a level surface in 4th gear at a fixed rpm takes different mapping than the same rpm and gear going up a hill. All these variables are accounted for after many miles of driving, allowing the ECU to "tune in" on what your engine needs for all these different operating conditions.

Yet, the full throttle environment has far fewer variables to account for, which is why full throttle adaptation can be done so quickly on the dyno. Full throttle maps are much different and less numerous than part throttle maps.

 

Smart/good move on your part...please make sure peak #'s are provided. It would also be good to show the peak power gains per each individual item ie; plenum...exhaust...cats...etc.

 

Why does it seem that only peak numbers matter to everyone? If it only gains 2whp peak but 15whp across the midrange that would be significant imho.

 

If the car is rated @ 355 factory hp and the mods do not improve it, or only by a few hp, it's of no interest to me.

 

This was my post that referred to the results obtained over at Rennlist - no confusion whatsoever....

"..... I've not seen any independent dynos of the plenum on its own so I've no idea what to expect! Seems there are one or two cynics on here that are expecting a sensational zero however.....

One of the members on Rennlist had before and after dynos done on a full 997S AWE system last year and it produced a creditable 23BHP increase at the wheels - about 28BHP crank - not bad at all......"
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If a mod gives you a shed-load of extra mid-band torque but the same top end power (hence top speed too) then you have a vastly improved car. Under most give and take, day to day driving conditions it will easily out-accelerate the standard car.

Why is this of no interest?

 

So would it be fair to say the plenum on its own would be a heck of a lot less than 28 peak hp.

 

No idea - nobody has independently dyno'd it as far as I can tell. That's exactly the results we're all waiting for!

My example above wasn't supposed to refer to the plenum - just a thought experiment for you. If you hit the throttle at 3000rpm and your car pulls way harder than stock but by 7000rpm it only pulls the same, then you have a much faster car with nominally the same BHP. It's all about area under the curve.... but that's another discussion for when I've had some sleep. It's gettin' late over here!!

 

Because of there is no true gain in overall/max/.peak power it's of no interest to me. Peak power also affects much more than top speed. Plus there are plenty of mods out there especially for forced induction cars that greatly improve max power.

I also thinks it's very misleading when a companies state say a +30hp gain in power (without disclosing exactly where the gain is) when the engine itself still turns out the same or a fractionally better # over the factory max power.

 

Not to sound like an a$$ or anything, but you should do some research by running a few searches. I would be stunned if the results showed an increase of 5-10whp peak or for that matter across the rev range.

 

See my reply above... It also neatly explains why the 997S with 'only' 355BHP is a lot faster than many notionally more powerful cars. Obsession with peak power is a very common mistake to make when looking for real performance.

 

A car that makes more mid-range power and torque is going to be faster even if the peak hp is unchanged. That power under the curve, or increased midrange, is going to get you through the powerband faster and your car would be faster. A mod that would, for example, give you a 10hp peak increase but cause you to lose 10hp or torque through a lot of the powerband would be worthless because in the end your car would most likely be slower than what it was to begin with. Understand that peak is not everything.