I picked up 20 to the wheels max, and around 12 to the wheels peak. You are correct though, no 28


I for one believe the product works. RSS has been selling this product for some time now. Why risk your company's reputation on a product that doesn't work? With the considerable amount of R&D and production costs, I'm sure they would have scrapped this product a long time ago if there were no performance improvements.

Let's face it, although most don't dyno their mods like myself, some do and those results often go public. I for one wouldn't want to be the naked emperor and I don't believe Greg does either I don't have an explanation AWE's dyno runs in this thread. However, I've seen more positive results than negative so I would chalk this up to an anomaly.

There definitely needs to be a re-match Different car, different shop.

 

I am really starting to believe the IPD plenum only makes a difference when used in conjunction with a free flowing exhaust system, headers, cats, mufflers. AWE's dyno is not an anomaly. On a bone stock car it made no difference. Look at RSS's plot on their site and European Car Magazines spread. They both used a Cargraphic exhaust before adding the plenum. With all the testing AWE did, I wish they would of used a different protocol. I would have used only one plenum and dynoed a stock 997S first, then install the plenum as they did and dyno again. If no gains were to be seen, then I would have removed the plenum and installed AWE full exhaust system. Then dyno again to get a new baseline with their parts. I would then re-install the plenum and dyno again to see if a better breathing engine makes a difference. I have my results and will post tomorrow after speaking with Greg.

 

Yeah, I agree with the post above. I think the RSS Plenum needs to be mated to a more free-flowing exhaust to show the improvements. Note that the dyno on the RSS site was done on a car with a Cargraphic exhaust. And it makes sense: air in quickly needs air out more quickly. Impacting only one side of that equation yields nothing.

Possible?

 

The only way to know for sure would be to find someone else with a stock 996/997 and let them try it at a different shop. I have a hard time believing that a set of mufflers that generally yield no horsepower (generally only sound) would make that much of a difference. Who knows?

 

Well, my AWE exhasut, GIAC and EVO intake are done. they intend to dyno tomorrow i think. Not sure if they are inclined to put the plenum back on a dyno again...

 

Anthony,

As you know I am curious about your results. I am one of the original Butt dyno people. And I sit by my results.

One thing from AWE's test is the there is no decrease from Plenum in performance across the board, that is good. It is interesting how the results on the different runs on the plenum change slightly.

My first mod was the plenum and I felt a difference, NO REGRETS. Then I added the E-bay headers. Better top end and a difference in throttle response that I perceived to be better. As I have said before the best thing about getting rid of the stock headers was it got rid of a resonance at highway speeds in 6th gear that I simply found unbearable after an hour.

Then I added the complete AWE exhaust. Definite difference, much more noticeable and definitive in nature than the Plenum.

Also it is louder how much did the noise make it seem like it was better performance? Some I think.

I then went back to the Stock muffler. Still noisey but in a different way. This proves with out a doubt how much the stock cats are really part of the muffling system.

Finally I settled on the Remus muffler, AWE Headers, and Cats and I am happy with the quiet compromise.

Through out this process of working with the exhaust I added the X-51 Airbox, the RSS modified Throttle Body, and the APR ECU upgrade.

The results again, Butt Dyno, the car pulls much lower in the rev band than stock it feels like a V8 it just goes. No stumbles, except when cold, it just pulls so much better in every situation and the power band is much more linear than stock.

Bottom line I am thinking about switching back and forth between plenums to see if I can tell a difference on the old butt dyno.

One thing you have to give credit to RSS they believe in their research and results enough to support AWE in their efforts. I don't think either company for a minute is trying to be purposely deceptive.

David

 

I look forward to the dyno results for the full exhaust. Hopefully they turn out as expected, otherwise ebay will be flooded with mods

 

There is only one way to increase maximum horsepower in an NA engine with just an intake change, and that is to somehow increase the amount of air volume and corresponding fuel to the engine. The RSS plenum does not do this.

What the RSS does is reduce the friction of the air entering the intake and therefore, reduces the temperature of the air. Even taking into consideration that the RSS plenum transfers more heat to the air passing through it's metal body than does the plastic one, the net effect is still slightly cooler air.

This means that the amount of O2 entering the cylinders is greater than the computer had calculated and the engine runs slighlty leaner than normal, giving a very, very slight (alomst immeasurable) increase in peak hp.

The reason the butt dyno shows a change in power is because there IS a change in power. Not in peak power but where in the rpm range the power falls. The RSS plenum changes the turbulance of the air which directly effects the powerband. You would get a similar effect of you simply increased the size of one of the crossover tubes. You would not have anymore peak power but the power would shift dramatically to a different part of the rpm range.

Even with the stock intake system, you can achieve a 20 - 30 hp increase in power at a specific rpm by simply changing when the resonnance flap operates. And all for free.

Obviously. freeing up the exhaust will increase the amount of air the engine can suck in and, if the fuel can keep up, will increase peak power at a cost of lower end power. This is true whether you use the stock plenum of the more expensive and hyped RSS plenum.

If you're happy with the way your car performs with the RSS plenum, enjoy it, but don't try to convince anyone that it, in anyway, increases your peak power.....dyno chart or not. It can be neither practically proven or scientifically proven to be of any benefit to peak power.

 

I don't need a plenum to gain power. I live at 8,200', 30 minutes west of Denver. I can pick up 32 hp, by just driving down the hill to mile-high.

Unfortunately the reverse is true too.

Incidently, that 32 hp is definately real and my butt dyno can't tell the difference.

 

I'm not sure I understand your post. My dyno chart shows power increases over the entire rpm range. Clearly certain RPM's are much higher than others, but there are increases pretty much everywhere. Mine is a direct "back to back" comparison as well. My power increase with the plenum follows my base run curve almost perfectly. Can you explain further?

 

You don't drive a NA car.

 

Fair enough

 

I feel that independent testing is the way to go but one could equally say that about ALL the products --not just the plenum . I also feel that a one car sample is not enough to draw a conclusion.

In short I agree with you .

 

Good catch, Ian. I simply had the runs labeled backwards. Fixed now.

Here is the original sheet:




Here is the corrected one:




Sorry for the minor confusion.

 

Thanks Todd - I guessed it might be something simple.