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    Getting ready to dyno, what did you get stock?

    This weekend I am installing headers and cats to my PSE and Fabspeed cold air kit. Unfortunatly I never dynoed when the car was completley stock, but I plan to before and after tuning.

    What numbers have people had on a CS?

    Thanls

    Re: Getting ready to dyno, what did you get stock?

    Anybody?

    Did you know that in the manual it says Porsche does not

    want you to dyno the car! We are all afraid since!

    Re: Getting ready to dyno, what did you get stock?

    Quote:
    Evil997 said:
    This weekend I am installing headers and cats to my PSE and Fabspeed cold air kit. Unfortunatly I never dynoed when the car was completley stock, but I plan to before and after tuning.

    What numbers have people had on a CS?

    Thanls



    Numbers from other people wouldn't help you much, I'm afraid. And if you want to make a "before-after" comparison after applying the tuning, make sure if happens within a certain time fram, same dyno, same air temperature and air pressure, etc. Otherwise, the results won't be accurate.
    And as long as you don't take out the engine to test it on an engine dyno, this whole dyno testing experience is fun and entertaining but of not very much value I'm afraid.

    Re: Getting ready to dyno, what did you get stock?

    It's of extremely good value, you just need to have the correct context. A chassis dyno will give you rear wheel horsepower, which is not what factories publish. However, it really IS the measurement that counts, after all, who cares about horsepower if a ton of it gets eaten up by driveline components before it gets to the pavement?? RC is correct, different dynos will be calibrated differently, causing potential apples to oranges comparisons. So always use the same dyno, and try your best to replicate the same operating temperatures and test procedures. As for air temperature, pressure, humidity, that's EASY for an experienced dyno operator to account for. Those measurements usually are part of your readout, so if any of those variables are different in later tests, you can use simple math to calculate the effect and correct the horsepower reading to match the conditions of your first test. It's actually very accurate. Removing the engine to run on an engine dyno doesn't improve accuracy necessarily, it just gives you a result that not driveline affected, netting you a larger horsepower figure. It's just different, not altogether more accurate.

    So, you're not wasting your time at all. Just keep tight records, and if your dyno guy doesn't have the formulas to correct for atmosphere variables, then get them and apply them yourself.

    If the factories would all convert to chassis dynos, then it would be far easier to understand why the 997S runs so close to the Corvette C6 in acceleration, considering they weigh about the same. You would also see how much power a Tiptronic robs you of...

    Re: Getting ready to dyno, what did you get stock?

    You may not gain anything. Amongst countless variables, you have to consider how efficient the oem products work. Many times you sacrifice low end h.p. and/or torque for less usable power. Additionally, your exhaust flow is directly connected to the car's intake. (If your using Fabspeed's cold air TUBE, I hope you don't expect much.)
    It can be very difficult to find addtional power in today's high performance n/a engines when you limit your mods to exhaust and/or intake. There's a reason that Porsche gains only 26 h.p from their X51 kit, and the kit has substantial mods.
    Regarding the dyno, aside from the fact that you didn't obtain a baseline, you may never know what gains or losses you achieved. A lower h.p. car with a spiked powerband will usually FEEL faster than a higher h.p. car with a linear powerband.
    Tire pressures, engine temp., ambient temp, different operators, etc.. can affect the results.

    Re: Getting ready to dyno, what did you get stock?

    I disagree. Although, costly and not probable, power measured at the "crankshaft" IS the most accurate, subject to far less error. Any driveline losses will exist regardless of what amount of power is being produced by the engine.

    Re: Getting ready to dyno, what did you get stock?

    I am very familiar with dynos and have experience with several cars on them. I would never use an engine dyno with out having removed the motor already for internal work. It's true that I don't expect the Fabspeed kit to get the best results.

    I plan on dynoing the car the same day, place and before and after tuning within a few hours of each other. How much drvetrain loss is common. I am used to 16-18% through alot of RWD American V8's.

    I will do a few runs comparing the stock intake tube to Fabspeeds with the headers and cats installed and if I can work a miracle and get some time off before Saturday I will definitly make an effort to get a baseline.

    Re: Getting ready to dyno, what did you get stock?

    Can't accurately say. I would guess 15-20%, similar to your experiences. If you're doing the before/after on the same day, that's great. Let me know what the cats and headers do. Good luck.

    Re: Getting ready to dyno, what did you get stock?

    Quote:
    devo said:
    You may not gain anything. Amongst countless variables, you have to consider how efficient the oem products work. Many times you sacrifice low end h.p. and/or torque for less usable power. Additionally, your exhaust flow is directly connected to the car's intake. (If your using Fabspeed's cold air TUBE, I hope you don't expect much.)
    It can be very difficult to find addtional power in today's high performance n/a engines when you limit your mods to exhaust and/or intake. There's a reason that Porsche gains only 26 h.p from their X51 kit, and the kit has substantial mods.
    Regarding the dyno, aside from the fact that you didn't obtain a baseline, you may never know what gains or losses you achieved. A lower h.p. car with a spiked powerband will usually FEEL faster than a higher h.p. car with a linear powerband.
    Tire pressures, engine temp., ambient temp, different operators, etc.. can affect the results.



    i have to disagree here.

    Porsche is only into making money. They hold their cars back so much simply to stave off the day they CANNOT go any further. They have themselves said that 4.0L is the max size for a F6 to work properly.

    Maybe a few years ago this was teh case re: porsche having the best engineering - but i will show you the cayman as my exhibit A.

    A 99 996 made 296HP from a non-egas 3.4L engine. A brand new cayman (using a newer 3.4 than the 996 3.4 had) makes (drum roll) 300HP while using variocam and other high tech features. Im pretty sure that they COULD have given s at least 325 from the new 3.4L.

    oh...but then that would mean that the 3.6997 would need more power...

    I see it like this, the last model will be the 999 (4.0L) - after that...we'll see some real innovation. Until then, porsche HAS to sell their quota of 500k 911s to the sheeop who (blindly) follow.

    Re: Getting ready to dyno, what did you get stock?

    Quote:
    tinbomber said:A 99 996 made 296HP from a non-egas 3.4L engine. A brand new cayman (using a newer 3.4 than the 996 3.4 had) makes (drum roll) 300HP while using variocam and other high tech features.


    Actually, the Cayman is rated at 295hp and I'm sure that's no coincidence compared to the 996's 296hp...

    Re: Getting ready to dyno, what did you get stock?

    Grant, You beat me to it.
    Tinbomber, I'm not quite sure what you disagree with. I quess all I'm saying is that I don't believe there is much power to be found in the many of today's n/a engines when you limit the upgrades to intake and exhaust.
    Agreed that Porsche holds back power in favor of the food chain; evidenced by the 997 GT3. But, I think it's safe to say that the 3.6l aforementioned GT3 has reached near it's potential for the masses; in street form that is.

    Re: Getting ready to dyno, what did you get stock?

    RC, Bossnine, and Grant - By far the guys i look up to on this board for a witty, intelligent, and collected answer.

    Re: Getting ready to dyno, what did you get stock?

    Dyno blah blah blah. TopherV, high res of your avatar please.

    First time you heard that, I know.

    Re: Getting ready to dyno, what did you get stock?

    hey tinbomber,

    i fully agree with you. 4.0 l is the maximum for the flat 6 engine. more bore and stroke would result in too thin cylinder walls and the engine would constantly overheat. unless by then they have developed a way to actively cool the cylinders, which again would hinder combustion.

    thats is exactly the reason why porsches power gains are so incremental. other car manufacturers have model increases of 100 hp and porsche does it in 30 hp steps.

    Re: Getting ready to dyno, what did you get stock?

    Quote:
    devo said:
    I disagree. Although, costly and not probable, power measured at the "crankshaft" IS the most accurate, subject to far less error. Any driveline losses will exist regardless of what amount of power is being produced by the engine.



    I'm a bit confused by your logic, and what you define as "accurate". An engine dyno will measure power from the crankshaft quite accurately, within whatever environmental context is present within the facility at the time of the test.

    Similarly, a chassis dyno will measure power from the rear wheels quite accurately, within whatever environmental context is present within the facility at the time of the test.

    Both are accurate measurements, just from two different points. "Accuracy" depends on what you're trying to find out. If all you care about is the power that a particular ENGINE is producing, regardless of what driveline it gets bolted to and what vehicle it gets dropped in, then your engine dyno is the answer. If what you care about is the car as a WHOLE, and the power that gets transferred to the ground and makes your car go, then the chassis dyno is the logical choice. After all (for the sake of illustration), if you've got an engine that makes 500 h.p. at the crank, but the car's driveline is horrifically inefficient and parasitic, you really don't have the slightest idea how the car is going to perform by virtue of the engine dyno result.

    All cars are different. The reason that everybody tosses around a broad range of 10-20% driveline loss, is because different cars with different configurations and different transmissions and differential types sap different amounts of power.

    But it is FALSE LOGIC to use that broad driveline-loss factor as a reason to consider a chassis dyno to be not accurate. The chassis dyno IS accurate. Where you become inaccurate is if you attempt to guesstimate the h.p. at the crank by multiplying the rear wheel horsepower by some sloppy and arbitrary factor that is based on "typical" driveline loss for any car on the planet.

    The driveline loss that exists in any SPECIFIC car is a CONSTANT. You cannot know what that constant factor is without performing tests on the driveline itself. Only the factory (and well-heeled race teams) have that type of equipment.

    But bottom line (so I can shut up), is that if you're wanting to baseline your car on a chassis dyno, then make some modifications and tuning tweeks, and then dyno again under the same conditions and methods, you'll garner VERY accurate results. The driveline loss is a CONSTANT on your car, not a variable, therefore it does not skew the results between one test and the next and the next, unless something changes/wears/breaks within your driveline. If you were to pull the engine, then measure power from the crank, then perform the same exact mods and tweeks, and measure again, you would find that the percentage of power increase you saw from the engine-dyno results would be virtually identical to the percentage gain you realized on the chassis dyno results. So why go to the trouble yanking the engine out of the car, especially when you're making street modifications. Race teams use engine dynos not necessarily because they are more accurate, but because they are constantly altering driveline variables to suit different venues (plus the fact that they pull the motors after each race anyhow), so the best way for them to get apples/apples testing is to measure from the crank.

    For your street car, you can get very accurate apples-to-apples results on a chassis dyno, unless you're constantly altering tires, or driveline equipment/gears/etc...

    How boring was that???

    Re: Getting ready to dyno, what did you get stock?

    I agree with what you've posted. I meant to say: consistent. I realize that the (RWHP) is the only number we care about. I assumed -from my experiences with motorcycle chassis dynos- that a chassis dyno was more finicky; yielding different numbers from different operators, tire pressures, set up, etc..., thereby, making consistent numbers less likely than those with a crankshaft measurement.
    I hope this makes some sense.

    Re: Getting ready to dyno, what did you get stock?

    Quote:
    devo said:
    I agree with what you've posted. I meant to say: consistent. I realize that the (RWHP) is the only number we care about. I assumed -from my experiences with motorcycle chassis dynos- that a chassis dyno was more finicky; yielding different numbers from different operators, tire pressures, set up, etc..., thereby, making consistent numbers less likely than those with a crankshaft measurement.
    I hope this makes some sense.



    What you said makes perfect sense, and yes, there can be disparity in numbers if the operator is not consistent with all those details you listed. After all, if somebody dyno's your car, then you do some mods and come back, and the bozo doesn't have your original dyno run archived, and doesn't replicate tire pressure, doesn't correct for weather, and doesn't replicate operating temperatures and all the other obvious variables that you can control, you'll get a whacky result when you compare the first run to the second. That's not the machine's fault, it's the operator's. Likewise, on an engine dyno, you've got plenty of variables that you need to either replicate, or adjust for, if you're going to compare one pull made on one day with another pull made on another...

    Re: Getting ready to dyno, what did you get stock?

    This is as big as it gets. Found it randomly - of course if one of the guys can increase its resolution without compromising the ... texture ... Dooooo it haha;j


    Re: Getting ready to dyno, what did you get stock?

    I have a different view on chassis dynos vs engine dynos - It is more valid for Porsche turbo engines due to the relatively higher heat generated.
    Porsche test the power of their engines on their engine dyno and sign them off with XXXhp
    Good chassis dynos are perfectly capable of measuring that same flywheel XXXhp number very accurately with correction software.
    Step in mr Tuner who starts tweaking the mapping to "match" the new components using the method of "10sec chassis dyno full power run" then tweak timing, fuelling etc followed by another "10sec chassis dyno full power run". The Tuner reapeats this process 'til his chassis dyno gives him a nice "bigger" torque/power curve.

    Does this mean that if the engine was returned to Porsche and bolted onto their engine dyno it would give the same chassis dyno power when held under specific load for the prescribed time (as per the original XXXhp number verification) - Certainly for a turbo motor I would say no.

    The chassis dyno, unless it is operated by someone who can use it and tune with it in loading mode cannot replicate the conditions of the engine dyno in terms of constant loading and environmental conditions (specifically cooling air flow).

    I am hoping to prove this (chassis dyno tuned hp vs engine dyno tuned hp) with some back to back on raod testing over the next couple of months.

    Re: Getting ready to dyno, what did you get stock?

    Back on the topic I got about 295rwhp from my 2005 997S. It is a six speed and had about 5000 miles when I dynoed. It was on a mustang dyno. I will be looking forward to see your results. I have since done headers, evo intake, and mufflers.

    Re: Getting ready to dyno, what did you get stock?

    I just got back from the shop where my buddy and I installed the Fabspeed 100 cell cats and headers to the PSE.

    The install went flawlessly and I was very impressed with the fit and finish of the parts. Between the two of us we were done in about 3 hours.

    I was surprised that the sound at idle wasn't changed much, but with my foot barely on it, the exhaust was music to my ears.

    Thumbs up to Fabspeed as I was not dissapointed and I would reccommend these mods to others.

    Hopefully some day this week I can get to the dyno for tuning.

     
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