1999Porsche911

Assuming you have a high efficiency intercooler downstream of the SC using two head gaskets each side might lower the CR enough to have a more positive effect. Otherwise an intake camshaft regrind to get an Atkinson cycle effect might help.

wwest, ive heard of doing to two head gaskets but hear more about changing out pistons. look at response for 1999Porsche991 below.

hello to all, finally had my car on the dyno and the mechanic was very informative. my supercharged 996 3.6 is pumping out a little less than 300 to the rear wheels in hp and torque. not too happy about that as i was hoping to have upwards of 400. understanding more and more of producing power, how would one go about lowering the compression to the motor? where can i buy better 996 pistons? anyone know of a shop in CA to do a complete engine rebuild?

best,

tecra

There is obviously something wrong with your SC setup or with the dyno/operator. You should be conservatively getting 350+ rwhp. Currently, my high boost 99 C2 is delivering in excess of 450 rwhp with stock compression. Check your boost behind the throttlebody, plugs and timing. A vacuum gauge may show a large vacuum leak. Many of these units were installed by people who did not know what there were doing.

It's relatively simple to produce 400 rwhp once your current system is running as designed.

1999Porsche911, the SC is installed correctly. what is wrong is the ECU is not mapped correctly. i should have the data soon to support that. my dyno guy explained where in the low-end there was not enough gas then also in the high-end it would drop off too. he mentioned that fuel pump maybe be bad or not pushing enough fuel but further testing he came to the conclusion that the ECU is not mapped correctly and not sending enough fuel out. who did your SC install 1999?

Who did your install? The ECU update is a standard part of the system, so your computer has either been updated or not. Lack of fuel would not allow you to even get close to redline so a proper dyno run would not be possible.

Basic readings should be known, such as fuel trim, MAF signal, timing and level of boost; at idle and near redline. Further tuning is not possible without these readings.

hello to all, finally had my car on the dyno and the mechanic was very informative. my supercharged 996 3.6 is pumping out a little less than 300 to the rear wheels in hp and torque. not too happy about that as i was hoping to have upwards of 400. understanding more and more of producing power, how would one go about lowering the compression to the motor? where can i buy better 996 pistons? anyone know of a shop in CA to do a complete engine rebuild?

best,

tecra

There is obviously something wrong with your SC setup or with the dyno/operator. You should be conservatively getting 350+ rwhp. Currently, my high boost 99 C2 is delivering in excess of 450 rwhp with stock compression. Check your boost behind the throttlebody, plugs and timing. A vacuum gauge may show a large vacuum leak. Many of these units were installed by people who did not know what there were doing.

It's relatively simple to produce 400 rwhp once your current system is running as designed.

Try pulling the cruise switches above brake and clutch pedals out all the way. One of them might have been bumped and is not not extended all the way.

A 997 GT3 will beat the Z06 and the BMW M3, M5 and M6 and the Audi R8 (V8 version.) They raced all these cars at an Airport (I think in Finland.) the races were not from a standing start. You can look for them on You Tube. "Top Gear" raced the first gen 997 GT3 against the V8 BMW M3 and the Audi R8 (v8) from a standing start. The GT3 won handily in a straight line (both cars) and ever more dramatically on the track. No he wasn't dreaming :rolleyes:

:cheers:

Of course if you take an older generation Z06 against the newer Porsche, the Vette has a harder time. Try comparing the same year and not the C5. All smoke and mirrors done to sway people.

Porsches are not drag cars. Many cars will beat Porsches off the line. However, top end speed, manueverability and cornering are their forte. I recall a TV show where they took a Corvette Z06 and at GT3 in a l mile drag race. The Z06 was much faster off the line, but the Porsche just blew by the ZO6 after the 1/4 mile and ended up beating the Corvette by at least 50 yards at the 1 mile marker. And that was in a straight line. Imagine what the Porsche would do on a mountain road. The problem is that around town you rarely go 120mph thru corners, however almost every stoplight you can jump on it until about 60mph and then slow down. At that time the Porsche is just warming up and would wipe out most cars in that 60+MPH zone. Would you want to go 120+mph in a Mitsubishi Lancer? Not me. Give me my Porsche at those speeds, anytime.

That would have to be a very mild corner to take it at 120 mph. Additionally, no GT3 will come close to beating a C6 Z06, even after a 1/4 mile. You must have been dreaming about that TV show, or watching The Twighlightezone. :P

Hi guys, this is my first post here. I've had my 1999 911 for 8 months now and I love it. I bought it knowing the clutch was on it's way out. Finally it started slipping, which the shop said if she's slipping most likely you'll have to replace the fly wheel too. So I bought the LUK OEM clutch kit and LUK dual mass flywheel from Gripforce Clutch, they have really great prices. It was installed suppossedly without a hitch and the shop went for a test drive - all was good.

When I got the car back, it was starting very awful and when I finally got a chance to step on the throttle, there seemed to be a phantom rev limiter kicking in around 6100 rpm on the nose. The check engine light would only come on for a half second then remain off. So today I dropped if off at the shop, they said a code was being stored ( I don't have the exact code as I haven't picked it up from the shop yet ) and it was coming from the crankshaft sensor. So they replaced the sensor but the code is still coming up. Now they're saying that the fly wheel must be defective! I provided the parts so they won't cover any labour, and I'll essentially be paying for the labour job twice!!!!

How can the fly wheel be defective? Until they pull the car apart they won't be able to confirm this, but they said this is the next step to solving this problem.

Is there any other thing that could be drawing that code? Like something pluggin up the suppossed "notch" that the sensor reads from? Any ideas would be great, I really won't want to have to drop the transmission again.

Thanks!

pat

I would not let them pull it apart again until I was there watching to make sure flywheel was installed correctly. It could be the flywheel or like they screwed up and might have hit the sensor or wiring. Sensor circuit can be tested without pulling the tranny. Code would be helpful.

Can anyone tell me the rough HP Output increase I can expect by putting a supercharger on my 996 C4S (2004).

That depends almost entirely on how much you are willing to derate the base engine performance via lowering the static compression ratio.

The more PRE-COMPRESSED and INTERCOOLED cylinder CHARGE you can make use of via the SC the more ON-BOOST HP/Torque you can get.

8:1 static would not be out-landish IMMHO.

Absent some level of CR derating I wouldn't bother.

You are absolute wrong in your statement. There is no speculation about this, although you always seem to have it. Low boost and high compression has been around for years and if the boost is managed properly, it produces as much power as a higher boosted, lower static compression engine does.

Whether you take a low static compression engine and boost it with 10 psi of boost or a high static compression engine and boost it with 5 psi, the boosted compression ratio of 18:1 creates the same stress on an engine and will deliver the same amount of power, all other things being equal. The engine with the higher staticc compression, however, will perform substantially better in off boost and low boost driving.

There are many good books available that you should read which will enlighten you about FI engines.

Sorry, simple matter of physics, the more, the higher %, of the cylinder charge that can be cooled AFTER compression the higher the effective BOOSTED compression ratio can be without resulting in detonation.

Due to the cooling effects of DFI the new NA engines can have a static compression ratio of ~12:1.

So, exactly what are you saying "sorry" for? You did not contradict a single thing I said.

Can anyone tell me the rough HP Output increase I can expect by putting a supercharger on my 996 C4S (2004).

That depends almost entirely on how much you are willing to derate the base engine performance via lowering the static compression ratio.

The more PRE-COMPRESSED and INTERCOOLED cylinder CHARGE you can make use of via the SC the more ON-BOOST HP/Torque you can get.

8:1 static would not be out-landish IMMHO.

Absent some level of CR derating I wouldn't bother.

You are absolute wrong in your statement. There is no speculation about this, although you always seem to have it. Low boost and high compression has been around for years and if the boost is managed properly, it produces as much power as a higher boosted, lower static compression engine does.

Whether you take a low static compression engine and boost it with 10 psi of boost or a high static compression engine and boost it with 5 psi, the boosted compression ratio of 18:1 creates the same stress on an engine and will deliver the same amount of power, all other things being equal. The engine with the higher staticc compression, however, will perform substantially better in off boost and low boost driving.

There are many good books available that you should read which will enlighten you about FI engines.

Around 100 rwhp with the VF system.

I suspect that they installed the incorrect clutch dis. I can't read the make or part number of the disc picture you posted. Possibly installed backwards if it was noisy.

2003 996 C4S

-----------------

Recently when i took my car to the dealer for minor service, they told me my battery is weak and needed changing. i changed it because i could feel that the battery was starting to give way.

Was driving in a traffic jam and the car stalled, so i hit the ignition and the car wouldn't start... after attempting a couple of more times the car finally started again...

The Car starts perfectly when cold, so i tested the stalling issue again when car is warm on the driveway and again, the car gave me such a tough time to start... I'm thinking it's the Alternator....

Anyone had similar issues???

Thanks

Is it cranking normally and just not starting or is the cranking slower than normal when hot?

ya so none of my questions were answered. what do you think about gt3 air filter w/o MAF sensor?

Your question was answered. Your MAF signal is not calibrated properly.

i also wasnt able to find "timing" and whats LTFT and STFT? dont think i saw those either??

is there anyway to alter durametric software to mph instead of kph and celcius to farenheit?

can i use a gt3 air filter and bypass the MAF sensor altogether?

LTFT = Long Term Fuel Trim

STFT = Short Term Fuel Trim

Durametric can show both metric and standard values

The MAF must be used.

Read the durametric manual for how to show the values mentioned.

I have an 02 C4S and it when it turns of, after the engine shuts off, you can hear this sort of winding down sound for a second or two, it's similar to the sound that happens in movies whenever someone shuts some big machine off, like a slow power down or something. It's not a bad sound (it actually sounds kinda cool) but I've never heard it in any of my other (non-porsche) cars so I was interested in what you guys think makes that sound.

Most likely one of the front fans.

ya so none of my questions were answered. what do you think about gt3 air filter w/o MAF sensor?

Your question was answered. Your MAF signal is not calibrated properly.

excel database format data from durametric

anyone have any idea what kind of readings im looking for or what safe operating ranges are?

The data you collected is meaningless. Capture the follwing information all the way to redline in 2nd or 3rd gear.

RPM

Coolant temp

MAF (in kg/h)

Timing

After Cat O2 sensor voltage

Throttle position

LTFT and STFT.

Also show MAF signal at idle with AC off. If you have the ability, measure vacuum at idle and boost at redline.

my interesting findings on run 2 of durametric deal

well i wish i had written down this list to check off when running the durametric deal. i had run some other values just off the hip and interesting findings. i will definately check those options next time im out with her. it just started raining and really couldnt push her or even come close to a redline. no fun...... keep you posted. i also wasnt able to find "timing" and whats LTFT and STFT? dont think i saw those either??

is there anyway to alter durametric software to mph instead of kph and celcius to farenheit? i have fault code P0103 - Heat Film MAF Sensor it displayed. i reviewed the DME 7.2 fault text and codes under that code and having a hard time determining how this chart works.

Your MAF signal is obviously way too high. Check to make sure that the installer made the necessary modifications to reduce the excess MAF signal generated by the increased air flow. Check with TPC to see how they reduce the signal. Because more air is flowing into the engine, the signal generated by the stock MAF must be reduced mechanically. It can either be controlled by reducing the signal with a resistor or modiication of the path of the airflow. Not sure how they do it but it is likely your problem. You need to reduce your idle MAF signal down to around 18 kg/hr.

MAF signal must be reduced..??

Huh..??

MAF signal MUST be proportional to the amount/volume of airflow intering the engine...

At engine idle or light engine load cruising the upstream oxygen sensors are used to control A/F mixture to stociometric standard.

With even moderately high engine loading the A/F mixture is enriched beyond stociometric, oxygen sensor out of range, and the MAF/IAT is used to control mixture.

If you reduce the MAF output signal (to prevent overscale..?) then ECU parametric air volume "multiplier" must be adjusted to compensate.

So what's your point? You answered your own question.

S

excel database format data from durametric

anyone have any idea what kind of readings im looking for or what safe operating ranges are?

The data you collected is meaningless. Capture the follwing information all the way to redline in 2nd or 3rd gear.

RPM

Coolant temp

MAF (in kg/h)

Timing

After Cat O2 sensor voltage

Throttle position

LTFT and STFT.

Also show MAF signal at idle with AC off. If you have the ability, measure vacuum at idle and boost at redline.

my interesting findings on run 2 of durametric deal

well i wish i had written down this list to check off when running the durametric deal. i had run some other values just off the hip and interesting findings. i will definately check those options next time im out with her. it just started raining and really couldnt push her or even come close to a redline. no fun...... keep you posted. i also wasnt able to find "timing" and whats LTFT and STFT? dont think i saw those either??

is there anyway to alter durametric software to mph instead of kph and celcius to farenheit? i have fault code P0103 - Heat Film MAF Sensor it displayed. i reviewed the DME 7.2 fault text and codes under that code and having a hard time determining how this chart works.

Your MAF signal is obviously way too high. Check to make sure that the installer made the necessary modifications to reduce the excess MAF signal generated by the increased air flow. Check with TPC to see how they reduce the signal. Because more air is flowing into the engine, the signal generated by the stock MAF must be reduced mechanically. It can either be controlled by reducing the signal with a resistor or modiication of the path of the airflow. Not sure how they do it but it is likely your problem. You need to reduce your idle MAF signal down to around 18 kg/hr.

excel database format data from durametric

anyone have any idea what kind of readings im looking for or what safe operating ranges are?

The data you collected is meaningless. Capture the follwing information all the way to redline in 2nd or 3rd gear.

RPM

Coolant temp

MAF (in kg/h)

Timing

After Cat O2 sensor voltage

Throttle position

LTFT and STFT.

Also show MAF signal at idle with AC off. If you have the ability, measure vacuum at idle and boost at redline.

wwest, hi there and thanks for your thoughts! first of all, im already running 103 octane. im sure the timing and air/gas ratio is off, i desperately need to get her on the dyno then i think this problem will be corrected.

btw when you refer to compression, are you suggesting a compression test? i asked for this test at a dealer prior to install of SC and they said it was not a good idea at that time. i have booked some time for a dyno this week and after that i guess im going to a dealer for a compression test. will a dyno produce these compression results?

where would one read more about knock/ping sensors on the 2nd gen 996?

"....suggesting a compression test?.."

No.

Your Porsche engine came from the factory with the MAXIMUM compression ratio assuming a FULL cylinder charge at WOT.

I simply do not see the object in adding an SC absent lowering the factory compression ratio in order to take full advantage of the external compression and intercooling.

Other than making the SC virtually or mostly non-functional I don't see how you could now "tune" your car for decent engine operation.

So, please explain the differnce in risk with running 1.2 BAR of boost on an engine running a 9.6 CR

Not just boost, but INTERCOOLED boost.

and 0.4 BAR of boost on the same engine running a 11.3 CR?

Intercooling of a larger MASS of precompressed air in the case of the lower CR engine.

How does boosting a high compression engine that adds more the 40% hp make it non functional?

4040% increase would take a 300HP engine up to 360HP, undoubtedly pushing the "edge".

First of all we should assume, MUST assume, that an engine with a CR of 10:1, 12:1 for DFI, could only run premium fuel with a factory standard mixture (HIGH engine loading mixture) without detonation, pre-ignition, ignition due to the heat of compression rather than "waiting" for the ignition spark. Assuming the forced induction air is intercooled the effective CR, WOT/Full boost, might be as high as 12:1(non-DFI).

When the cylinder is being fully charged then the greater portion of the charge that can be precompressed and then intercooled the less likely is the possibility of detonation due to the heat of compression. The same reason the new DFI engines can have a 12:1 static/native compression ratio. First, the fuel is NOT in the mixture, cylinder charge, until very late in the compression cycle, and then when it is injected it serves to partially cool the just pre-heated air "charge".

SFI results in the fuel being preheated as it passes through the intake, intake valve, and then is additionally preheated by compression. DFI fuel reaches the entry into the combustion chamber as a liquid, a comparitively COOL liquid.

An ideal system would have have a CR of 1:1, the air charge FULLY pre-compressed and then intercooled, allowing the effective CR to rise as high as maybe 18-20:1

Alright, so based on your statements, a lower CR engine needs a more efficient intercooler.

No.

A low CR allows an SC/intercooler combination to be more "efficient".

Assuming WOT and reaching a FULL cylinder charge, with a low static CR more of the "charge" will have been intercooled AFTER compressing. That would allow a higher effective CR with boost vs having a smaller portion of the charge intercooled with an already high static CR..

Using the same intercooler for 0.4 bar of boost on a high CR engine would be even more efficient.

No.

A 40% increase on a 300 hp engine is not 360 hp but 420 hp. There are a few otherwise stock 996 engines running far more hp than 420.

My bad.

I won’t even address your comments on a DFI engine since we are in the 996 forum.

So, I’ll ask again, why does supercharging a stock 996 make it non functional?

Why don't we just wait and see what turns out to be wrong with your SC modification..??

A low CR allows an SC/intercooler combination to be more "efficient".

Assuming WOT and reaching a FULL cylinder charge, with a low static CR more of the "charge" will have been intercooled AFTER compressing. That would allow a higher effective CR with boost vs having a smaller portion of the charge intercooled with an already high static CR..

[/b]

Isn't that exactly what I said? :o

Why don't we just wait and see what turns out to be wrong with your SC modification..??

How much longer should I wait before I see the negative effects of a supercharger on my otherwise stock 99 C2? 10,000, 20,000, 30,000, 40,000, 50,000 miles ? I've been running a centrifuge compressor with a boosted compression ratio of as much as 19 psi for more than 5 years and currently have 72,000 plus on the engine. I sure hope I don't have to wait much longer. :D

wwest, hi there and thanks for your thoughts! first of all, im already running 103 octane. im sure the timing and air/gas ratio is off, i desperately need to get her on the dyno then i think this problem will be corrected.

btw when you refer to compression, are you suggesting a compression test? i asked for this test at a dealer prior to install of SC and they said it was not a good idea at that time. i have booked some time for a dyno this week and after that i guess im going to a dealer for a compression test. will a dyno produce these compression results?

where would one read more about knock/ping sensors on the 2nd gen 996?

"....suggesting a compression test?.."

No.

Your Porsche engine came from the factory with the MAXIMUM compression ratio assuming a FULL cylinder charge at WOT.

I simply do not see the object in adding an SC absent lowering the factory compression ratio in order to take full advantage of the external compression and intercooling.

Other than making the SC virtually or mostly non-functional I don't see how you could now "tune" your car for decent engine operation.

So, please explain the differnce in risk with running 1.2 BAR of boost on an engine running a 9.6 CR

Not just boost, but INTERCOOLED boost.

and 0.4 BAR of boost on the same engine running a 11.3 CR?

Intercooling of a larger MASS of precompressed air in the case of the lower CR engine.

How does boosting a high compression engine that adds more the 40% hp make it non functional?

4040% increase would take a 300HP engine up to 360HP, undoubtedly pushing the "edge".

First of all we should assume, MUST assume, that an engine with a CR of 10:1, 12:1 for DFI, could only run premium fuel with a factory standard mixture (HIGH engine loading mixture) without detonation, pre-ignition, ignition due to the heat of compression rather than "waiting" for the ignition spark. Assuming the forced induction air is intercooled the effective CR, WOT/Full boost, might be as high as 12:1(non-DFI).

When the cylinder is being fully charged then the greater portion of the charge that can be precompressed and then intercooled the less likely is the possibility of detonation due to the heat of compression. The same reason the new DFI engines can have a 12:1 static/native compression ratio. First, the fuel is NOT in the mixture, cylinder charge, until very late in the compression cycle, and then when it is injected it serves to partially cool the just pre-heated air "charge".

SFI results in the fuel being preheated as it passes through the intake, intake valve, and then is additionally preheated by compression. DFI fuel reaches the entry into the combustion chamber as a liquid, a comparitively COOL liquid.

An ideal system would have have a CR of 1:1, the air charge FULLY pre-compressed and then intercooled, allowing the effective CR to rise as high as maybe 18-20:1

Alright, so based on your statements, a lower CR engine needs a more efficient intercooler. Using the same intercooler for 0.4 bar of boost on a high CR engine would be even more efficient.

A 40% increase on a 300 hp engine is not 360 hp but 420 hp. There are a few otherwise stock 996 engines running far more hp than 420.

I won’t even address your comments on a DFI engine since we are in the 996 forum.

So, I’ll ask again, why does supercharging a stock 996 make it non functional?

Did they install the new program control for the kit? I believe that generation TPC kit ran a piggy back system and if that is not installed, there is no sense in continuing until it is.

my ecu was sent out from my shop who installed the SC to TPC. TPC only remapped it and sent it back. last time i spoke with TPC they did not mention piggy back system.

Ok, as long as you are running TPC's program. The installer should easily be able to determine boost, if there are any leaks, fuel trim, timing, etc.

boost is 5 psi and she is not leaking, not sure what fuel trim is? what timing are you referring to? and what else might ask the shop about? i.e. etc

Your installer needs to check all sensors readings, Air/fuel ratio and timing along with boost levels and make sure they are within TPC specs. If not, he needs to make whatever corrections are neccesary. I assume that TPC support will provide a complete list of what these readings should be.

wwest, hi there and thanks for your thoughts! first of all, im already running 103 octane. im sure the timing and air/gas ratio is off, i desperately need to get her on the dyno then i think this problem will be corrected.

btw when you refer to compression, are you suggesting a compression test? i asked for this test at a dealer prior to install of SC and they said it was not a good idea at that time. i have booked some time for a dyno this week and after that i guess im going to a dealer for a compression test. will a dyno produce these compression results?

where would one read more about knock/ping sensors on the 2nd gen 996?

"....suggesting a compression test?.."

No.

Your Porsche engine came from the factory with the MAXIMUM compression ratio assuming a FULL cylinder charge at WOT.

I simply do not see the object in adding an SC absent lowering the factory compression ratio in order to take full advantage of the external compression and intercooling.

Other than making the SC virtually or mostly non-functional I don't see how you could now "tune" your car for decent engine operation.

So, please explain the differnce in risk with running 1.2 BAR of boost on an engine running a 9.6 CR and 0.4 BAR of boost on the same engine running a 11.3 CR? How does boosting a high compression engine that adds more the 40% hp make it non functional?

Did they install the new program control for the kit? I believe that generation TPC kit ran a piggy back system and if that is not installed, there is no sense in continuing until it is.

my ecu was sent out from my shop who installed the SC to TPC. TPC only remapped it and sent it back. last time i spoke with TPC they did not mention piggy back system.

Ok, as long as you are running TPC's program. The installer should easily be able to determine boost, if there are any leaks, fuel trim, timing, etc.

Did they install the new program control for the kit? I believe that generation TPC kit ran a piggy back system and if that is not installed, there is no sense in continuing until it is.

hi all thanx for the replies

i have the durametric and it didnt show any new codes so i cleaned the maf and throttle body and it now works perfectly although i have a new problem

i tried an old trick that i used to use when cleaning parts back in the day

find a smallish glass that the maf fits into

use the cleaner with straw and spray clean the maf allowing the cleaner to fall into the glass

when the glass is half full put the maf in sensor down

put the straw into the cleaner and continue to spray energising the fluid and createing bubbles etc

fill the glass to above the maf

then heres the genius part cable tie a vibrating item like a razor or ladies fun item and wait 10 mins and hey presto the cleanest maf you have ever seen and not a q tip in sight and no danger of damagimg your maf

towel dry on kitchen roll the refit and enjoy fresh new feeling engine

im quite happy to do the same to anybodies maf if you need it

regards dave

I soak mine in a jar of motor oil overnight and then just spray it with Gumout carb cleaner the next day. Oil is a good cleaner. Orginal MAF, 70,000+ miles.

Just so people do not continue to fall for gimick advertising of viscosity, the viscosity of oil is determined by the amount of flow caused by gravity. What you are not told, is that the flow of a 0W40 oil and a 15W50 oil under pressure such as in your engine, allows the oil to reach all engine components in the same amount of time, all the way down to around 0F. For hot oil visosity, you are also not told that the most important rating is the dynamic or absolute viscosity, which determines how much the oil will shear while under pressure. Look for higher HTHS Viscosity in an oil. Mobil 0W40 has a HTHS Viscosity of 3.7 and 15W50 has one of 4.5. The W (winter) rating of the oil effects the shear rating in many cases. For example, Mobil's 10W40 has a HTHS Viscosity of 4.06 which is 10% higher than their 0W40 oil, even tho they are both 40 weight oils.