Finally: Dyno charts of de-snorked 986S!!!

[MNBoxster]

Originally Posted by RandallNeighbour

Now where are all the critical comments from forum members who have said emphatically that desnorkeling will not increase HP at all and it's all about making the intake a little louder?

Lurking now, aren't you?

Hi,

Just caught this thread - see: http://www.pca.org/tech/tech_qa_question.asp?id={5628EC8F-3626-40D2-8AE0-E9F524E0718F} . I'm still not totally convinced, I think there's an error in the methodology. That's an approx. 6 CHP gain, and I'm just not convinced this part robs 6 HP. I can hold a thermometer in my hand and watch the Mercury rise, that doesn't mean I've made the room any warmer, or conversely, that I have cooled the room when I release the thermometer. There's no reason for Porsche to do it...

Happy Motoring!... Jim'99

[Bavarian Motorist]

I'm not sure if the thermometer analogy conceptually applies here.

[pecivil]

Bisimoto!!

Welcome to the board! You are definitely the kind of Boxster guy we need on here.

I would love to drop by your place and test my engine. There are some great roads through the hills in Hacienda hts. I have transplanted a 3.4l 996 carrera engine in my car. I have revo software, the K&N intake and a somewhat screwed up set of headers, 200 cell cats and muffler from a shop in Maryland that was supposed to be designed for the swap. Alas, the exhaust system sounds really great, but there are fitment issues with suspension. I would love to see what you come up with for the 3.2 engine exhaust wise. The 3.4 and 3.2 are (almost) the same engine.

If you need/want a guinea pig for exhaust system work, I would be happy to volunteer!!

BTW nice work on the desnorkleing. I did this a long time ago, and decided it was worth it just for the sound. Glad to see it does add a bit of torque.

Monte

[Bisimoto]

Originally Posted by pecivil

Bisimoto!!

Welcome to the board! You are definitely the kind of Boxster guy we need on here.

I would love to drop by your place and test my engine. There are some great roads through the hills in Hacienda hts. I have transplanted a 3.4l 996 carrera engine in my car. I have revo software, the K&N intake and a somewhat screwed up set of headers, 200 cell cats and muffler from a shop in Maryland that was supposed to be designed for the swap. Alas, the exhaust system sounds really great, but there are fitment issues with suspension. I would love to see what you come up with for the 3.2 engine exhaust wise. The 3.4 and 3.2 are (almost) the same engine.

If you need/want a guinea pig for exhaust system work, I would be happy to volunteer!!

BTW nice work on the desnorkleing. I did this a long time ago, and decided it was worth it just for the sound. Glad to see it does add a bit of torque.

Monte

Greetings Monte,
Feel free to call my facility, and we can set up a good time to baseline your powerplant. I love the porsche 6-cyl, and look forward to applying some concepts to extract power. I may even take you up on the exhaust testing. I also appreciate your kind words.

Jim, I fail to understand why you feel this test is not factual. I duplicated both results, twice, as stated on page 1. As an engineer, who takes pride in being meticulous, I understand the value of repeating experiments to ensure validity. Such attention to detail has allowed me success in my present field of racing. In addition, I even invested in the most accurate and repeatable chassis dynamometer...no skimping there either.

I am here to share my experience, not to blow hot smoke. Feel free to perform the same tests...I am confident that you will perceive similar results.

In regard to the NACA ducts..at least we agree on that:



I use it to supply cool air to my induction throats!

[MNBoxster]

Originally Posted by Bisimoto

...Jim, I fail to understand why you feel this test is not factual. I duplicated both results, twice, as stated on page 1. As an engineer, who takes pride in being meticulous, I understand the value of repeating experiments to ensure validity. Such attention to detail has allowed me success in my present field of racing. In addition, I even invested in the most accurate and repeatable chassis dynamometer...no skimping there either.

I am here to share my experience, not to blow hot smoke. Feel free to perform the same tests...I am confident that you will perceive similar results.

In regard to the NACA ducts..at least we agree on that...

Hi,

Sorry, but we do not share the same confidence. In my years at the Naval Flight Test Center at Pax River MD, we spent about 5 times the effort on defining the methodology than we did in actual testing, to insure the results we got were valid, and even then, with virtually unlimited time and expenditures, we sometimes got it wrong. I was trained at MIT and Pax River to distrust all testing results until no other plausible explanation could be found to invalidate them.

Your results, IMHO, lie within the degree of error of the testing methodology as you describe it (or even within the HP variation between individual cars and engines), which automatically makes them suspect, if not altogether invalid.

You insinuate that this is the definitive test, but I remain skeptical for the reasons already stated. Did you even monitor Alternator Output? This variable alone could make your runs Doo-Doo.

I'm glad you shared your experience, but I'm concerned that many less-knowledgeable people will take it as Gospel, which I don't believe is the case. Judging from some of the Pied Piper responses already, of people believing what they want to hear without question, this seems to be the case.

A $61k Chassis Dyno, isn't any better than a $25k Inertial Dyno if the methodology is flawed. I'm not impressed by the cost of the gauges. An inertial Dyno can be just as good a tool, if used properly.

I spoke personally with a Porsche Engineer (an invited Guest Speaker at a Tech Session) in 2005 and asked him specifically about the Snorkel. His response was that it was solely a Noise Abatement device, aimed specifically at the Swiss Market (but with an eye toward increasing Noise Abatement regulations in other countries as well). He said that several prototypes were rejected for various reasons, including a power reduction, and Porsche, rather than mute the exhaust note - a Marketing Decision, chose to meet the overall madated Noise Levels, by reducing the Intake noise instead, so long as it didn't interfere with creating power. He said that this gen of Snorkel showed no change to the power/torque curves at all, which is why it was approved for production.

While I'm inclined to support his arguments, I am nonetheless prepared to change my mind in the face of definitive testing. I just don't think you have done any. You may in fact be on to something, but I don't believe you've proved it - yet. Improve your methodology, and you may just win me over.

It isn't a matter of Snorkel vs De-snorkel to me, I removed my snorkel well over a year ago - but for the sound enhancement, not to try and eek another 1-2% from the motor. Good Luck...

Happy Motoring!... Jim'99

[Bisimoto]

Greetings Jim,
I do not want to turn this into a debate, but honestly, feel free to perform the results yourself. Voltage will not skew results even within 8to 14.4volts since modern day EMS/ECU units have compensation values integrated into their programs. The $25K, or more, intertia dynos CANNOT replicate the sensitivity or repeatability of the hub chassis dyno simply because of the varibles introduced by the tyre, and the tyre interface...both of these in addition to how those dynos measure power. Even very slight changes in room temperation can affect the tyre growth and skew results. Straps introduce even more questionable readings the aformentioned units.

Bottom line, everyone is entitled to their opinion, but opinions can further become validated with data. Have a pleasant balance of the week.

[MNBoxster]

Hi,

As you say, "everyone is entitled to their opinion, but opinions can further become validated with data".

But, I think you're not fully understanding why I think your results are in jeopardy due to the Alternator Output.

I'm not referring to the Voltage variation and it's possible effect on the DME. I realize that it (DME) has compensatory circuitry designed to make it perform through the range of possible voltages it can see. I am referring to the mechanical power draw of the Alternator itself to produce that voltage.

An Alternator's parasitic draw from the crankshaft is variable. It can range to almost nothing (maybe as low as 0.05HP) to as high as 30HP depending upon how much electrical demand it's being asked to supply.

Alternator's are not very efficient so far as power generation in a car is concerned. First, they produce Alternating Current (AC) for a machine designed to use only Direct Current (DC).

In order to convert this AC to DC, the current is passed through a series of Diodes and Rectifiers which results in tremendous losses (mainly as Heat) due to inefficiencies. So much so, that Modern High-Amperage Alternators are now starting to become water-cooled, transferring their Heat to the Car's Cooling system to be carried away. GM has several of these in use today, and they will become standard in just a few years.

But, it's advantage (aside from the fact that it can produce larger amounts of current in roughly the same size pkg. than a Generator can) lay in the fact that, unlike a Generator, which has a constant parasitic loss of CHP (Crank Horse Power) regardless of the amount of demand placed upon it, the Alternator is variable - almost Freewheeling when not in demand, but can consume pretty high amounts of CHP when demand is high. Similar to the power consumption of the AC Compressor - Low when AC is OFF, but rather high when the AC is ON.

This is where it can skew the results of your testing. If the Alternator is really pulling on one run, but not the next, this will have a definite effect on the amount of WHP (Wheel Horse Power) you see on the graph, and well within the gains shown in your results.

Unless you're monitoring the Alternator Output (and extrapolating it's CHP draw from that data), you simply cannot be sure you've duplicated the Test Conditions from one run to the next. This is what I mean when I refer to your methodology, you simply haven't accounted for everything.

If the reported gains were in the 50HP range, then the Alternator draw would have no bearing on whether or not there was a definite increase (only the value of that increase).

But, when you report gains of only 5.78 (CHP) and 5(WHP), you are smack in the range where the Alternator draw can mask your results leading one to draw a possible incorrect conclusion. You could in fact actually have a decrease in WHP and not know it. The graph would lead you to assume otherwise, though incorrectly so. This is why I say that your results are within the degree of possible error which is at least the 0.05-30 CHP the Alternator can draw off before the Chassis Dyno can extract it's data.

Put simply, you're reporting a positive variation of 5 WHP within a test which has a ± variance (or degree of error) of at least 0.041 - 24.6 WHP (accounting for drivetrain losses of the Alternator draw). I say at least, because I believe there are other variables which could affect this as well, such as the fact the Sanden AC Compressor used in the Boxster is also variable, and never OFF (according to Porsche). It too draws a varying amount of CHP.

Also, while I agree with you that an Inertial Dyno introduces the variables of the Tire dynamics into the results. Except for finding absolute values easily, it too can be sufficient to determine whether or not a change in output is observed...

Happy Motoring!... Jim'99

[porsche986spyder]

Originally Posted by Bavarian Motorist

I'm not sure if the thermometer analogy conceptually applies here.

I agree. I look at the dyno results. I think it speaks for itself. By the way the link the other guy posted by PCA says he thinks by doing this we are removing the cooler air from the outside!?! Makes no sence, all we are doing is removing something that is restricting the air flow, not REMOVING the air flow all together, nor are we re-directing it from some place else, like from the inside of the engine. It will still pull the air from the outside! Look how close the opening is to the vents.

[MNBoxster]

Originally Posted by porsche986spyder

I agree. I look at the dyno results. I think it speaks for itself. By the way the link the other guy posted by PCA says he thinks by doing this we are removing the cooler air from the outside!?! Makes no sence, all we are doing is removing something that is restricting the air flow, not REMOVING the air flow all together, nor are we re-directing it from some place else, like from the inside of the engine. It will still pull the air from the outside! Look how close the opening is the the vents.

Hi,

Dyno results can be funny and not always verifiable or repeatable. The Lister must admit this if he's the kind of engineer, he seems to be.

So many variables must be exactly the same on each run for any results to be meaningful, especially since you're claiming a very small % gain of overall power (1.9%). Some, but not all include: Ambient Temp, Barometric pressure, Fuel flow, Octane, Alternator Output, each line of code in the DME operating w/o fault on each run, Engine Temp, Tranny Temp, Bearing Temp, and on and on.

For example, an Alternator (whose power draw is variable and not constant) alone can draw as much as 4-30 crank HP because of the inefficiencies in a Belt & Pulley system, so if it was filling demand on the 1st run, but not the 2nd, this alone could account for the variance seen.

The best method is to do multiple runs exactly duplicating the conditions of all previous runs and then averaging the results. Then, you reverse it, put the snorkel back on and see if you consistently achieve the previous Baseline numbers over an average of multiple runs. If these results aren't duplicated to within a pretty narrow degree, there is some variable not being accounted for.

Just because you get a graph from a single run which supports your theory, isn't in, and of, itself proof of anything...

Happy Motoring!... Jim'99

[pecivil]

I must admit that I too did not really "buy" what it suggests on the thread from the PCA website. I had seen that before, and it does not make sense how the snorkle would actually cool air as it flows inward. Why would the restriction cool airflow?

[Bavarian Motorist]

I can't figure out how to remove the blinds w/out breaking it. I see it has little snaps.


I have no clue what to do. Neither of the guides really explain how to do it.

[jwilson95]

Probably a dumb question, but just want to confirm that you only need to de-snorkel on driver's side???

Thanks in advance,

Jeff

Originally Posted by jwilson95

Probably a dumb question, but just want to confirm that you only need to de-snorkel on driver's side???

Thanks in advance,

Jeff

Jeff, correct, the passanger side vents are for cooling.

[Bavarian Motorist]

Anyone got an idea about how to remove the blinds?

[2000SoCalBoxsterS]

Originally Posted by porsche986spyder

I agree. I look at the dyno results. I think it speaks for itself. By the way the link the other guy posted by PCA says he thinks by doing this we are removing the cooler air from the outside!?! Makes no sence, all we are doing is removing something that is restricting the air flow, not REMOVING the air flow all together, nor are we re-directing it from some place else, like from the inside of the engine. It will still pull the air from the outside! Look how close the opening is to the vents.

I agree the air temp arguement doesn't really make sense. There is no heat source in that small vent cavity to warm up the air flowing in. How much difference could that snorkel tube really make in air temp? Besides, does the car not work perfectly fine in Florida or SoCal when the outside temps are very high, and in the Mid West and Northeast when the temps are very low? The enigine is computerized and designed to function and compensate at a wide temperature range.

I think that Snorkel has more to do with accelerating or focusing the air flow to the airbox. I'd like to know more about the aerodynamic design of that Snorkel.

[Adam]

@ Bisimoto, do you think any gain would be had on desnorkeling a 03 or 04 boxster that lacks the "shovel" at the end of the snorkel? If so, do you think it would be a less significant gain? Also, did you get the results in on the K&N filter?

If any 2003 or 2004 owners out there have desnorked I'd like to hear your opinions as well. Thanks!

[catmanluge]

Keep up the good work. Its amazing how many people replied without any dyno of their own to show different results... All theory!

I am having trouble with allowing enough air in a cold air box setup using a K&N filter. The car a 3.4 ltr Boxster can't produce any power above 4000 rpm with the air filter but its goes like a rocket with the air filter removed.

I have been asking K&N for assistance with no response from Tech department.

I have 3.5 inch tubing from the TB to the approximate former location of the stock air box that has been replaced with an aluminium shaped cold air intake drawing air from the side vent. The filter I have is cone shaped with a filter on the sides and at the end of the cone rather than having a typical end cap. RX something as I am on vacation and don't have the number with me.

I am looking for a filter that will allow enough air to the motor 3.4 ltr headers and free flow exhaust system.

Thanks

catmanluge

[boxster_s_boy_34]

Hey I know that they are kinda new in the Porsche world, but they are making a lot of waves and I'm sure the quality is just as good as K&N. There is a company called Evolution Motorsports and I'll almost bet my left nut that those guys could help you out on that whole intake problem that you have. Besides, my buddy owns EBS and he said that the best filters for the 986's are dry element because the MAF sensor is a little touchy.