RSS Plenum
#136
No way a RSS Plenum adds 28BHP at peak.
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.
Last edited by deputydog95; 04-20-2008 at 07:44 AM.
#137
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.
Last edited by florindi; 04-20-2008 at 08:10 AM.
#138
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?
Possible?
#139
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?
#141
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.
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
#143
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.
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.
#144
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.
Unfortunately the reverse is true too.
Incidently, that 32 hp is definately real and my butt dyno can't tell the difference.
Last edited by RickinColorado; 04-20-2008 at 02:03 PM.
#145
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.
Last edited by deputydog95; 04-20-2008 at 03:14 PM.
#146
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.
#148
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?
In short I agree with you .
#149
Having had some more time to digest the tests AWE have done, I have found one (very) minor inconsistency. It may be nothing and perhaps it's something Todd could explain in an instant. Anyway for what it's worth...
Day 1 - temp = 65F. Day 2 - temp = 78F. You would therefore expect that any results obtained on day 2 would be slightly lower than day 1.
This is borne out on dyno plot #2 where the car with plenum gives a 4BHP lower result on day 2 than day 1. No surprises here. However on dyno plot #5, the bone-stock car gives a 2BHP higher result on the hotter day 2. This is unusual.
Dyno plot #1 compares the bone-stock car to the plenum-equipped car on day 2 showing a zero HP increase at peak. If the day 1 numbers had been compared however, the bone-stock car would have given a lower result by 2BHP and the plenum-equipped car a higher result by 4BHP. This would have shown the plenum giving a 6BHP increase at peak. Almost as much as AWE's headers give on the plot on their site and a very different result indeed.
Food for thought? I don't know, but I'm interested in any comments anyone may have.
Day 1 - temp = 65F. Day 2 - temp = 78F. You would therefore expect that any results obtained on day 2 would be slightly lower than day 1.
This is borne out on dyno plot #2 where the car with plenum gives a 4BHP lower result on day 2 than day 1. No surprises here. However on dyno plot #5, the bone-stock car gives a 2BHP higher result on the hotter day 2. This is unusual.
Dyno plot #1 compares the bone-stock car to the plenum-equipped car on day 2 showing a zero HP increase at peak. If the day 1 numbers had been compared however, the bone-stock car would have given a lower result by 2BHP and the plenum-equipped car a higher result by 4BHP. This would have shown the plenum giving a 6BHP increase at peak. Almost as much as AWE's headers give on the plot on their site and a very different result indeed.
Food for thought? I don't know, but I'm interested in any comments anyone may have.
Here is the original sheet:
Here is the corrected one:
Sorry for the minor confusion.