DYNO this

 

The IPD plenum is a good design if used in conjunction with other mods will probably produce good results. It just doesn't seem to work well with stock 3.8 motor.

 

Gentlemen,

Let me just take a moment to clear the air and then I will leave everyone alone to battle it out amongst each other. When I spoke to Florindi earlier today he said that he didn't experience the gains that we advertise. He asked me what he thought he should do regarding the posting of his dyno graphs. I responded with, "They are your dyno graphs and you can do whatever you please with them. As a manufacturer and distributor of course I prefer only good news gets posted, but that is not for me to decide". That's just wishful thinking. I would never ever try to divert or prevent someone from posting their finding with any of the product we offer, whether it be IPD plenums, Cargraphic exhaust or Giro Disc Rotors.

The 997S is the ONLY Porsche to date that has come under such scrutiny and produced such varied results. Even after speaking with Florindi, he mentioned that he didn't "feel" the seat of your pants power gains which I found odd because that is what most customers claim after their first impressions of driving with the IPD plenum. We sell and install plenty of plenums and I'm being honest when I say we have a 99.9% customer satisfaction guarantee. Many of which were independently dyno verified.

We don't sell product that doesn't work and we stand behind each and every product and service we offer. We couldn't have made it this far and earned our solid reputation as a 6 Speed Sponsor without offering quality product and friendly knowledgeable service. We fully respect the fact there are members who didn't experience the "power of the plenum". One tuning truth is, every car is different and different mods affect different car differently. Without the car in question on our premises we cannot pin point any problems, shed any additional light on the subject or offer any kind of technical explanations as to why the plenum did not perform properly.

Thanks to everyone for all your time and consideration,
Greg

 

I made no comment on which intake was optimum, only that both would produce the same peak power. The optimum design would be the one that provides the best powerband for the individual driver. Any change in the path through which an engine sucks in air will change the power curve. It's all a matter of what produces the performance you are looking for.

 

Would it be possible for one plenum design to produce more hp at a partial throttle than a second but less at full throttle? This might make it feel "faster" in general driving but test poorer on the dyno. It of course would not in fact be "faster" but might be perceived as more responsive.

 

How long have you been waiting to post this? You must be fun at happy hour.

 

OMG give it up! Lets talk about Headers X-51 vs stock. Think we can get to 185 posts? Get your but dyno warmed up. OK go

 

Thanks Greg. For those that decide to return the piece, and I do not at all suggest this is the answer here, what procedure would you recommend? In some cases the purchase, as you know, was made through a secondary vendor. Gerry

 

Anytime you change the intake system, whether it's the size of the throttlebody, length or diameter of the runners or change in flow turbulance, the engines power band will change. You will not increase or decrease peak power by much, but just move the power to another area in the band.

Air moves into your engine at a peak speed of about 170 mph and the turbulance of this airflow effects where the power of your engine will fall within the rpm range. The RSS intake reduces air turbulance immediately after the throttlebody compared to the stock plenum so obviously there will be a change in the power band. The design of the intake system is a critical part of determining where your peak torque will fall.

Short or smaller intake path is great for low end power at the cost of high rpm power and long or larger intake path moves the powerband upwards and greatly enhances high rpm power.

 

I concur with what Greg said.

 

AWE Dyno...Note the Flat spot on the RSS Plenum at 5000-5500 Florindi dyno same flat spot at 4600-5200



FLORINDI

 

The stock engine also has a noticeable flat spot here too - note that the stock torque curve has a downturn around 5000rpm. There is also another even bigger torque 'hole' in this engine's delivery at 2500rpm. There it goes embarrasingly flat! Both these torque holes are clearly visible on the factory plots and are defining characteristics of this engine. If you look at various tuner's dyno plots, there are always these downturns in the torque curve, irrespective of what mods are applied. The plenum does seem to amplify them on a stock motor - in particular, the one at 5000rpm.

I'm of the opinion that the odd behaviour of this engine at these rpms is due to the basic design of the intake system, especially as the second 'hole' is at a multiple of 2 x the rpms of the 1st one. They may also be connected to the resonance valving Porsche uses to get an 'air ram' effect from the pressure waves in the intake at various rpms.

As one UK motoring journalist once said "Gas dynamics are really funny things...." He was right insofar as improving airflow in a complex system is at best very hit and miss unless you have the necessary computerised flow-modelling software or a very expensive flow rig. Even Porsche, with all the development equipment and budget at its disposal had to release the engine into production with one bloody-great-big hole in the delivery at 2500rpms and another smaller one at 5000rpm. And you would have to assume that this is the best they could get from this intake design (lifted straight from the 3.6 - economies of scale, anyone)!! It's also illuminating that the first thing Porsche does when looking for an improvement from the 3.8 is to scrap the lot! (X-51).

IMHO, getting more from the standard intake probably isn't possible!

 

Anyone done a dyno on the 996 or a non S 997 just to check if the results are the same?

Nikos

 

The resonance flap is the cause of the change in power you describe and is there purposely by design. As I explained above, changes in the size of the intake effect the velocity and turbulance of the air. Porsche slams the resonance flap shut at a lower rpm and then opens it when the rpm's increase.

This valve creates an inertia effect which directly effects engine response. This is a a good way to maximize both low speed and high speed engine performance. Think of this effect as similar to a water hammer. When you quickly shut off a water valve. The waterflow hammers against the shut valve and pressure before the valve is greatly increased momentarily. In the case of the intake runners, this sudden blockage of air flow causes the air to be momentarily forced along another path with higher velocity and extremely turbulant.

The use of a variable like the resonance flap has similar effects in all the Porsche NA engines, from the 996, 997 and GT3.

 

Are you speaking of the Helmholtz resonator?