How many 15-16 gt3's have engine replaced?
#1261
Rennlist Member
Originally Posted by sccchiii
I'm so sorry I have nothing new to say other than I have ADD and can't go back and read a lot of posts without losing my train of thought......I'm still driving the crap out of car. Only track use and taking it to redline about a million times and thing keeps ticking after 15k miles m.....I am weird and change oil every 3k miles because my grandfather always told me that was best?
For my daily driver as well as my wife's daily driver, I run my oil every 10k miles. For my toys, I never accumulate more than 2k a yr, so I change the oil yearly instead of mileage based.
#1262
Three Wheelin'
Yes, 3k was the golden rule back in the day when we only had mineral oil. With synthetic, multi-viscosity oils, the intervals can be much longer (depending on use).
For my daily driver as well as my wife's daily driver, I run my oil every 10k miles. For my toys, I never accumulate more than 2k a yr, so I change the oil yearly instead of mileage based.
For my daily driver as well as my wife's daily driver, I run my oil every 10k miles. For my toys, I never accumulate more than 2k a yr, so I change the oil yearly instead of mileage based.
#1263
Rennlist Member
I drive the snot out of car or at least my "best version" of snot.
#1264
Instructor
Higher revs are achieved at the bore/stroke level. Bigger bore, shorter stroke provide that on this engine.
#1265
Basic Sponsor
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Porsche just uses different Pistons, rods etc in the GT3 engine to reduce reciprocating mass.
Removing mass from valve train is also necessary, or the valves won't be controlled properly, or the lifetime of the valves/valve seats will be short.
From the horses mouth...
991 GT3 Valvetrain
I'll try to post up some pictures of the GT4 and GT3 valve train differences.
Bottom line is the issue with the GT3/RS is unique to the finger follower design.
__________________
Dundon Motorsports
Gig Harbor, WA
253-200-4454
jamie@dundonmotorsports.com
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Dundon Motorsports
Gig Harbor, WA
253-200-4454
jamie@dundonmotorsports.com
www.dundonmotorsports.com
Facebook.com/dundonmotorsports
Instagram @dundon_motorsports
Last edited by Jamie@dundonmotorsports; 08-14-2016 at 10:27 PM.
#1266
Instructor
The mass/geometry of the bottom end makes a difference yes. Removing mass from valve train is also necessary, or the valves won't be controlled properly, or the lifetime of the valves/valve seats will be short.
I'll try to post up some pictures of the GT4 and GT3 valve train differences.
Bottom line is the issue with the GT3/RS is unique to the finger follower design.
I'll try to post up some pictures of the GT4 and GT3 valve train differences.
Bottom line is the issue with the GT3/RS is unique to the finger follower design.
#1267
The CEL in this case (combustion issue) is activated when the engine has a misfire. A misfire is when the engine does not complete a full revolution without stopping. The crank sensor counts the trigger points and the ECU expects to see the number of trigger points. If it loses count, then it knows the engine has "stopped" for some reason and the engine must have misfired and the CEL is activated. The Camshaft sensor can also be included in this as the ECU may be looking for the same count of trigger points between the crank and Cam. If these change the engine must have stopped and the CEL is activated.
As much as we want these engines to be really trick and technical, they are basic ICE power units that require 3 components. Fuel, spark and air. If one is missing or wrong the engine will misfire. Reading the Porsche bulletin speaks directly to the issue. When the CEL is activated, unless there is a direct sensor problem the ECU cannot tell what is the cause. In this case, this is seen by how Porsche are going about the diagnosis. First change the Spark plugs, if no change, change the Coils, if no change, change the Injectors. That’s the Fuel and spark taken care of, so what’s left is air. At some point in time, they removed the valve covers and found the Cam lobes and fingers worn away. Now it’s a matter if sequence as they know there is a problem here.
It is thought that the actual misfire is “set off” by the Spark plugs fouling. If the Valves are not held open and lifted off their seats to the design parameters, then there will be less air pulled into the cylinder, the mixture will be rich and a “rich” mixture will always misfire. DI engines require exact amounts of fuel to be injected so the AFR is correct. Especially for emissions and fuel mileage reasons. Fuel injected directly into the combustion chamber never has the time to heat up and fully vaporize, so any extra fuel per unit of air will stay as droplets and not ignite as it should. Spark plugs foul and the misfire occurs. These engines have Inductive ignition and inductive ignition does not have the energy to fire dense mixtures or fouled plugs.
It is thought that the O2 sensors are not being used to detect and turn on the CEL light under these conditions. If there were individual sensors per exhaust primary them maybe, but it’s thought that the O2 sensors per bank are too non specific to monitor the AFR per cylinder per stroke. But the input value from these sensors is most probably and input in the algorithm fault code.
Getting back to my original thought, once the CEL is activated for reasons of combustion, damage has already happened to your Cam and fingers. The suggestion was not to wait but monitor the condition of these parts before wear starts.
^^^Perhaps if you had taken the time and read this thread a bit you would understand. It has been explained many times.
Yes sir, I did read the all of the posts. failed to read anywhere where is showed the CEL light is activated primarily by the wear on the cam lobes and fingers. If I misses it, I'm sorry.
As much as we want these engines to be really trick and technical, they are basic ICE power units that require 3 components. Fuel, spark and air. If one is missing or wrong the engine will misfire. Reading the Porsche bulletin speaks directly to the issue. When the CEL is activated, unless there is a direct sensor problem the ECU cannot tell what is the cause. In this case, this is seen by how Porsche are going about the diagnosis. First change the Spark plugs, if no change, change the Coils, if no change, change the Injectors. That’s the Fuel and spark taken care of, so what’s left is air. At some point in time, they removed the valve covers and found the Cam lobes and fingers worn away. Now it’s a matter if sequence as they know there is a problem here.
It is thought that the actual misfire is “set off” by the Spark plugs fouling. If the Valves are not held open and lifted off their seats to the design parameters, then there will be less air pulled into the cylinder, the mixture will be rich and a “rich” mixture will always misfire. DI engines require exact amounts of fuel to be injected so the AFR is correct. Especially for emissions and fuel mileage reasons. Fuel injected directly into the combustion chamber never has the time to heat up and fully vaporize, so any extra fuel per unit of air will stay as droplets and not ignite as it should. Spark plugs foul and the misfire occurs. These engines have Inductive ignition and inductive ignition does not have the energy to fire dense mixtures or fouled plugs.
It is thought that the O2 sensors are not being used to detect and turn on the CEL light under these conditions. If there were individual sensors per exhaust primary them maybe, but it’s thought that the O2 sensors per bank are too non specific to monitor the AFR per cylinder per stroke. But the input value from these sensors is most probably and input in the algorithm fault code.
Getting back to my original thought, once the CEL is activated for reasons of combustion, damage has already happened to your Cam and fingers. The suggestion was not to wait but monitor the condition of these parts before wear starts.
^^^Perhaps if you had taken the time and read this thread a bit you would understand. It has been explained many times.
Yes sir, I did read the all of the posts. failed to read anywhere where is showed the CEL light is activated primarily by the wear on the cam lobes and fingers. If I misses it, I'm sorry.
#1268
Rennlist Member
This is where I pause a little. Porsche has been recommending the same oil for a really long time. I'm not really sure, but think it is more than 15 years now. I really think this high revving GT3 engine may be slightly different from the early water cooled engines.
#1269
You are correct as well. But when it comes to physics, geometry and movement of parts, the shorter the stroke, the faster the cylinder can move and the more trips it can make up and down the bore. The heads with the valve design and the springs do place a significant role into maintaining that movement but not create the speed at which it happens. I can draw it for you and show with calculations why... I live math and physics. I do respect your opinion as a vendor and your company's effort into working on this issue and have been reading your posts, please do not take my approach as to discredit you in any way.
Also, I'm sure Porsche does not want the GT4 to out perform the GT3. The GT4 engine is limited to final upper RPM by its design, and the components included. Stroke has nothing to do with it.
#1270
You may be right, but I suggest this to keep your warranty in tact. I'm sure Porsche will find any wiggle room they can to get out of fixing an engine.
#1271
RL Community Team
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#1272
Nordschleife Master
Each manufacturer has a different name and approach for valve control. Porsche has been using Variocam for years. The Variocam controls the opening and closing of the valves. The electrical control is extremely accurate and detects the slightest anomalies. The DME gets info from the camshaft position sensors in relation to the crankshaft position sensor. The DME can order the Variocam high lift and high duration for maximum power at high RPM. If the Variocam can't sustain that opening because of abnormal wear,the engine will misfire on that particular cylinder or cylinders where the wear is most pronounced,so the DME will know there's a problem and put the engine in limp mode. Forget what you know about electronics of the past. An old system would've never detected this wear. The new one is incredibly accurate!
#1273
Each manufacturer has a different name and approach for valve control. Porsche has been using Variocam for years. The Variocam controls the opening and closing of the valves. The electrical control is extremely accurate and detects the slightest anomalies. The DME gets info from the camshaft position sensors in relation to the crankshaft position sensor. The DME can order the Variocam high lift and high duration for maximum power at high RPM. If the Variocam can't sustain that opening because of abnormal wear,the engine will misfire on that particular cylinder or cylinders where the wear is most pronounced,so the DME will know there's a problem and put the engine in limp mode. Forget what you know about electronics of the past. An old system would've never detected this wear. The new one is incredibly accurate!
#1274
Each manufacturer has a different name and approach for valve control. Porsche has been using Variocam for years. The Variocam controls the opening and closing of the valves. The electrical control is extremely accurate and detects the slightest anomalies. The DME gets info from the camshaft position sensors in relation to the crankshaft position sensor. The DME can order the Variocam high lift and high duration for maximum power at high RPM. If the Variocam can't sustain that opening because of abnormal wear,the engine will misfire on that particular cylinder or cylinders where the wear is most pronounced,so the DME will know there's a problem and put the engine in limp mode. Forget what you know about electronics of the past. An old system would've never detected this wear. The new one is incredibly accurate!
#1275
Technical Guru
Rennlist Member
Rennlist Member
Chris thanks for confirming the part number on your new heads. I will lose this question to Porsche. The part number is not the same as the latest GT3/RS heads (the same part) on the July onwards builds not is it the same as the 911R head. Also the last two digits "9R" are not consistent with the pet parts nomlature. The last two digits are usually decimal numbers and refer to the revision number or "83", "84" etc. at this stage I can only conclude they are a replacement part number for Retrofit kit as supplied to your dealer.