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YOUR RESEARCHDisapointing Dyno Test
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Use valvoline durablend and not mobil 1
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Performed · outcome unconfirmed · Original poster
I use the Valvoline Durablend and not Mobil 1 because the Mobil 1 is more agressive to some of the sealing materials in the motor, plus the Valvoline has a stronger oil film than the Mobil 1.
Leading evidence: 'Use valvoline durablend and not mobil 1' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'plenum mod (and all plenum mods)' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check fuel filter and pressure regulator' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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I would highly suspect your plenum mod (and all plenum mods).
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Suggestion · Original poster
I will check fuel filter and pressure regulator, and inspect (+clean) the MAF sensor.
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Suggestion
(My last was about 20 runs, specifically different ECU and resonance tuning.) Take your plenum out, check the operation of the resonance tube, and if that doesn't show any improvement, than I wouldn't freak out too much as dynos can vary a lot.
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Suggestion
same conditions, tweak something then rerun and check results.
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Suggestion
(My last was about 20 runs, specifically different ECU and resonance tuning.) Take your plenum out, check the operation of the resonance tube, and if that doesn't show any improvement, than I wouldn't freak out too much as dynos can vary a lot.
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I did a dyno on my 2000 996 C2 yesterday, 243HP@6375rpm on the rear wheels. The factory figures are 300HP@6800 at the crank. The motor is a 2006brand new replacement motor with 15k miles, standard exhaust, standard air box with K&N filter cartridge, cold air intake and the plenum mod. According to the various advertisements, the modifications should give me an additional 25HP, which of course is BS. Assuming I still have 300HP at the crank, is it normal to lose 57HP on the way to the wheels? 57HP lost in the drive train! that's nearly 20% !!!
Could the replacement motor be a 3.4L Cayman S motor (less Variocam Plus)with 295HP@6250rpm? The peak HP occurs at 6375rpm rather than at 6800rpm, that is closer to the Cayman S figures.
There is also a spike in power at 5500rpm where it's up to 235HP, then to dramatically drop to 205HP at 5850, before it climbs up to the max 243HP at 6375. The HP curve seams very strange, I would expect some disturbance around 3500rpm, where the Variocam and Varioram are activated, but at that point the curve is smooth. Could the Variocam and Varioram switching points be wrong?
Please see the attached dyno curve. Are there any one out there who are experts on this, and could tell me if there is something wrong here?
Thanks!
20% is pretty normal for drivetrain loss. You think that's bad, try a awd car next time.
A 997 s put down about 298 last time we did runs, so you might be down a few. How new are your o2's, fuel and air filters are fresh?
Andrew
I would ignore all dyno's, whether they show improvement or not. Do you like the car's performance? Did your car's perfomance drop off on the way home from the dyno shop since it showed less power than you thought you had? Many shops will print a chart out for you showing whatever numbers you want if that will help you sleep better or you are into keyboard racing.
Remember, you drive the car, not the dyno chart.
That's about right power wise. 18% drivetrain loss is a pretty common figure.
As far as the mods giving you power. I think it's been well documented that they do very little for peak power, they help out with power under the curve however which you really wouldn't see without stock vs. modified graphs. Peak number isn't going to change much however.
If it helps you any my M3 dyno'd 278 stock and it has approx. 40 more hp than a 3.4 car does stock so your numbers aren't out of the ordinary.
Andy
Chassis dynos are only good for comparing before and after. I have little faith in the absolute readings of power. Mustang Dynos tend to produce lower results than Dynojet for example.
Best,
I'm no dyno expert. I get my 964 dyno'd every year as it's a requirement for my race group. I have a RSA 3.8L cup motor. The last dyno showed 266 RWHP and 252 ft lbs. torque(where's your torque number)? With no muffler and cooler, dryer conditions, I've gotten closer to 280 HP. Torque's always around 252.
My maximum HP is also around the 6,300-6,400 rpm range. Mine levels off, but does not dip around. That looks strange to me.
I like to use relative numbers on a dyno, i.e. same conditions, tweak something then rerun and check results. IMHO dyno's are like statistics, that can be massaged to show what you want to see.
Did he not give you any torque or lamda (air/fuel ratio) readings?
If the scale is the same, I'd estimate your torque at about 205 assuming the 2 numbers cross at 5200.
I race with folks in others car w/HP numbers in the 300++ range and beat them. HP ain't everything. Brakes and suspension go a long way.
May want to do a search on that K&N set up. Many folks have had MAF failures running K&N's on 996's. I like K&N's, but evidently they don't do so well w/the 996 MAF.
The dyno is not hand sketched, but the RPM's and other info is hand written.
Even if the top HP figure might be within the normal range, it occurs at a much lower RPM than normal, 6375rpm in stead of 6800rpm. Also the peak and dip don't make sense to me, at least not at that RPM.
I use the Valvoline Durablend and not Mobil 1 because the Mobil 1 is more agressive to some of the sealing materials in the motor, plus the Valvoline has a stronger oil film than the Mobil 1. Based on race engine tests, the engine wear is less with Valvoline Durablend than with Mobil 1. The viscous losses in the engine is slightly higher with the Valvoline, maybe 2-4Hp. The high temperature advantages with the Mobil 1 compared to the Valvoline Durablend, occur at temperatures way above "melt down" temperatures in the engine, and are of no use, even in racing. RMS leaks or failures, and other seal related failures do normally not occur with the Valvoline oils (according to Porsche race motor specialist, Sam Shalala, Pro Technik, Houston).
I will check fuel filter and pressure regulator, and inspect (+clean) the MAF sensor. But still, these things do not explain power drop off nearly 500rpm before the correct 6800rpm peak power.
Any other suggestions ot there?
In the 996 NA engine, it is normal to have a power drop at around 5500 rpm as that is when the ressonance valve is thrown open. However, any engine that dropped as much as your chart did would not need a dyno to show it. It would be like pulling your foot off the gas pedal and then slamming it down again. Something was wrong with the run. There is also no way a properly running 3.4 will drop off as much as chart shows above 6500 rpm.
If the chart is a true reflection of your engine's performance, you would feel it when you drove it.
I think you need to run another dyno. The results between 5500-6000 make no sense to me. When looking at mine, the curves are very similat except in that area. I don't think you'll get any more HP w/a new dyno, but I would be very surprised if the peak/valley reproduce themselves. looks like the driver's foot slipped off the pedal. Did he run 2 runs? Every time I've had a dyno done, it includes 2 runs.
Data, no, so flame away. But one of the things Porsche lovers have long bragged about is that the combination of rear engine and transaxle reduces drivetrain loss over systems that have transmissions and driveshafts. Bench racers used to say Porsches lose 15%, where 'normal' cars can lose up to 25% if the car has an old school automatic transmission.
It therefore stands to reason, I figure, that the addition of a longitudinal driveshaft and another differential would cause a pantload more power loss to the wheels.
I think (IIRC) that my S2000 and M3 had ~15% drivetrain loss. I mean the whole thing about dynoing is that it's not a perfect science especially the way us hobbyists are doing it on discounted dyno days at your local dyno shop watering hole.
I would've figured the Carrera 2s had less than 15% on avg. Curious to know what the approximations are between the 2s and the 4s.
I'm not trying to pour salt on the wound, but my '95 993 with a chip pulled the same numbers, and I thought at the time it was somewhat low. I would have expected the early 996's to be in the 260s.
When I had my intake off, if we are talking about the same thing, only had a vacuum hose going to it. I dont remember an electric plug.
The big butterfly valve inside the plenum right?
The one that the vacuum hose comes from the "T" off of the brake booster port?
My 964 dyno flattens our at 5500, but just for and instant, then gains again. It does not go down, however. I've never seen one that did that, not normally anyway.
If I knew how to compress the file, I'd show it to you
Was the rear engine cover open? I got similar results with mine open (although my curve was smoother). I read a few threads suggesting that it's necessary for the cover to be closed in order for the engine to reach full power. Apparently it's some kind of engine management "feature".
The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is no interface with the brake booster port.
The tuning flap is normally open and operates as follows:
Open from 700 to 3120 rpm and from 5120 rpm .
Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.
Maybe the '99 is different? I dont remember a vacuum pod on top of the motor connecting to the valve.
I remember snapping the plastic line that leads to the resonance valve coming from the rear port on the drivers side bank intake plenum where it was "T'ed" to.
Good point. Autos have more drivetrain loss, same as awd. You could also have an ailing tq converter perhaps. I'm not a fan of Dynojets. I would try to get it dyno'd on a proper dyno (Mustang) and do at least 3 pulls to have any real idea of your baseline. Where was this done? What were the conditions and how many pulls did you do?
Andrew
In order to ensure the car's very securely located and held in position on the dyno rollers the chassis dyno operator very likely really cinches the car down and in doing so causes the drive axle springs to compress to the point the drive axle half shafts are not parallel. (If an AWD the other drive axle's springs are also compressed.)
This out of parallel with the ground condition this deflection represents a parasitic load that can increase the amount of flywheel horsepower lost to drivetrain.
Best are those cars with the old fashioned solid rear axle. The car can be cinched down nice and tight and the axles being solid so to speak do not deflect and thus drive train losses are the least, though they can still be 15%.
And there are many factors that can affect dyno numbers. As I'm sure someone's already mentioned, dynos are better at doing a before/after reading.
Sincerely,
Macster
For a dynojet, it is about 10 hp low for a 3.4l 6-sp. If you look at the dynos of a 99'-01' Carrera and a Cayman S, they actually look the same. Both dyno consistantly in the 250-255 hp range stock. If you could get a low enough rpm reading, you might find a small improvement at low rpms with the Cayman S motor. A 3.6l dynos about 20 hp higher (low 270's) stock. This dyno is about right for a 3.4l tip. With tips, the torque converter loses a little extra HP. There is definitely a problem with the car. The high rpm dip of 30 hp is not normal. My guess is a varioram problem.
What is the "plenum" mod? Could be related...
Did they email you the run file? Standard (STD) mode gives a higher reading most times than SAE Mode(corrects for temp/Alt differences which makes it a bit better to compare against other 996 dynos).
In STD mode my 996 dyno numbers are 284hp/254tq, my SAE is 275hp/246tq.
I have alot more mods including the plenum and a 6spd, FYI.
That is a ****ty dyno read out.. I hope they did not charge you much for that. I do alot of tuning on my turbo rotary on a dyno dynamics unit and it is awesome.. The one you posted can not be reading right as there is no reason for power to go down then back up unless you are running some sort of sequential turbo and that was the transition...
Thanks folks for all the feed backs. My car is not a tip, it's a 6 speed. Also, the allignment of the wheels on the dyno rolls were good, so there is probably not a big loss due to miss allignment slippage. The motor lid was closed, so it might gotten hot under the lid, causing loss of HP. With the car running and the spoiler up, the motor compartment temperature is very low, and virtually not affected by exhaust and motor heat. This might be one explanation, but not all. The peak and the dip on 5500rpm and 5800rpm are caused by the VarioRam opening, but the drop of 30HP is too much. Also the drop of in HP above 6375rpm is strange. Could it be some kind of fuel starvation or air leak in the intake manifold?
The plenum mod is home made, but if the plenum modifications advertised for $8-900 are working, then my $5 mod is working too, the modification to air flow pattern is the same (Y-shaped plenum rather than T-shaped, with less turbulense and more laminar (and increased) air flow).
During the last week end's DE, the car perfomed just as well as other Carrera's, I can still kee up with 997S's on the main straight on TWS.
Some "experts" say it's the PSM that kicks in, because the front wheels are not turning, but I don't have PSM or any traction control (thank God...). But the ABS warning light came on during the dyno run, could that affect the ECU and upset the power output? Some "experts" I talked to last week end at the DE, said that the 996 is impossible to dyno correctly, due to ECU issues with only rear wheels turning. Any idea folks???
Haven't heard this before. Boxsters don't have this problem. I would highly suspect your plenum mod (and all plenum mods). The intakes tracts are tuned to resonate at certain RPMs, and you are likely messing up both the volume and the flow.
If you look at a 987, they have butterflies in both intake crossover tubes. If you split the throttle body side at high RPM, it kills the top end by about 15HP. Ironically, it's even worse when the TB side is split and the main resonance is opened. That dip looks a lot like a 987 motor with intake split and the main resonance not opening. I think a 3.4L 996 motor is closer to a Boxster motor.
Also, get more runs. One run is not statistically significant, and a single run can have a "burp" in it. You should get a minimum of 3. (My last was about 20 runs, specifically different ECU and resonance tuning.) Take your plenum out, check the operation of the resonance tube, and if that doesn't show any improvement, than I wouldn't freak out too much as dynos can vary a lot.
They are different, the 2000 I had doesnt have the configuration of vacuum lines like you said as you can see. I never hooked the butterfly (resonance) to any vacuum pods, it went to where the accordian hose goes into the drivers side intake. It was a straight shot to the nipple on the drivers side intake plenum. Here you go:
They are NOT different.. Your pictures show that. I can see the vacuum resevior in the second picture right next to the oil seperator along with the vacuum lines and electrical connection for the electric resonnance valve.. It resevior is not only necessary to operate the tuning flap but also the SAI.
I don't know what accordian hose you are talking about but if it is a vacuum connection, your intakes system will not work correctly. One vacuum line from electric resonnace valve to flap and the other to vacuum source, directly or indirectly.
I can chime in that when I'm at full throttle and cross 5120 rpm there is a noticably loud resonance as if something opens up, but then it goes away as I get to 6000 rpm and higher. I don't notice that at any other rpm but 5120...
Notice you have a valve that goes on the top of another gold part which I dont know what it is.
Notice mine, the same part in front of the vacuum pod is capped at the top, there is not a SAI valve going into it.
My resonance valve did not tie into any of the 3 parts you have in the pic, or the 2 parts I have in my pics, it went to a nipple on the front of the plenum .
Yours is there. Follow hose from the air pump to the front of the car. The valve is hidden in your picture behind hoses. If you did not have the valve or it was not connected, you would get a CEL.
Cory. Put your beer down and zoom in on the picture. Your hose does in fact go to the valve which you cannot see because of the other hoses on top of it. Yours is coming in more from the side. My picture is taken from beneath. Yours is not.
Trust me. If the SAI was not connected properly, the computer woud tell you. As to the tuner flap, if your resonnance system is not connected properly, the computer will not tell you about it.
Yes, I see the pod you are referring to. No, I did not connect the butterfly to that particular pod.
Second, clearly in your pic I see a hose with a vacuum operated valve using a spring clamp going over the top of a gold part (dont know the name) on the right side of the vacuum pod.
In my second pic, I do not have any hoses, especially that large traveling over the top of the part next to the vacuum pod as your pic shows.
That is my point. If there is a different configuration between the two, that would explain why my resonance valve was attached to a different vacuum source.
The tuning flap MUST be connected to the electric changeover valve (lower circle) There are 2 ports on the valve. The one that is closed when deactivated is connected to the vacuum source which MUST be the resevior, directly or indirectly. The other port, which is open when deactivated is connected to the tuning flap. Thee is no other possible way of connecting the tuning flap if you want it to work as designed. The flap needs vacuum at times when the engine is not supplying any.
You can test to see if things are hooked up properly by doing this:
Have someone sit in the driver's seat. Go to the engine compartment and look at the tuning flap pivot point on the back crossover tube. Have the person turn the key to the ON position. You should observe the flap moving to the closed position and then back again.
Tippy, you need to listen to 99. The secondary plenum flap is connected to the solenoid valve mounted on the intake manifold near the alternator. This solenoid is actuated between 3120 and 5120 rpm if the throttle is open more than 30%. The vacuum supply for the solenoid needs to be connected to the black vacuum reservoir as indicated by '99 since under the conditions when the flap is actuated, intake vacuum is low, thus if you connect it directly to the vacuum port on the intake manifold the flap will not close properly thus reducing performance. The only two vacuum sources to be directly connected to the intake manifold are the vacuum source for the fuel pres. reg. and the one way black/white check valve that supplies vacuum to the black reservoir allowing maintence of vacuum under all engine ranges for all other vacuum operated systems on the engine, such as the solenoid for the secondary plenum flap and the air injection system.
There are no differences in this in the different years, I have a '99 3.4, a 2004 3.6 and a 2005 3.6 X51 in the garage right now and all are identical. If your intake has dual plenums then it must be plumbed this way in order to operate correctly.
Todd
HOW MANY TIMES DID I SAY THAT IN MY POST!!!!!
IT DOES NOT TIE DIRECTLY INTO THE VACUUM POD IN THE BACK OF THE MOTOR LIKE '99 SIAD BUT ABOVE THE ALTERNATOR LIKE YOU SAID. I REMEMBER THIS VIVIDLY AND STATED THIS NUMEROUS TIMES.
OMG
Actually Cory, you never mentioned it and agrued with me about it. Your specifically stated that you did not remember "an electric plug". Nowhere in this thread did I state that he tuning flap connects directly to the vacuum pod. As a matter of fact, I stated directly that the flap is connected to the electronic crossover valve.
It was you who started with the wrong information by stating
"The resonance valve is vacuum operated, it should be fully open the second you drop the throttle"
. You also stated that the vacuum line was connected to the brake booster port which I told you was wrong.
Rather than trying to dispprove what I said, READ what I said and learn from it
I am losing my mind, I have to quote myself. Yes, I see the vacuum pod I didnt remember existed. No, the plenum butterfly did not tie into it directly, tied into the valve on the front of plenum above the alternator.
I'm not sure if the tuning valve is connected to the electric changeover valve.
Hell, I'm not even sure if the shin bone's connected to the knee bone.
I can, however, say with a high degree of certainty that your engine bay needs a thorough cleaning 1999Porsche911. I have seen Ford Pintos circa 1970 which have had shinier engines.
