Dear Unregistered, the permission changes should be complete, if you notice any issues with your access on the site please let us know and we will check into it.
Hey Unregistered it seems that you haven't posted a message in our forums yet. Please join in on the fun and post a message!
Dear Unregistered,
We've noticed that you are not yet a member of our Cayman Insiders group. This group provides a number of additional value-add services via this website for a very low annual fee. You can find out more about this group here:
Insider Announcement
You can join the Cayman Insiders Group here:
Insider Enrollment Form
We hope to see you "Inside" soon!
Your Donation Will Be Used To Pay For our ever increasing bandwidth costs, our hosting Service, domain registration, software licensing fees, maintenance costs and product evaluations Only!
Please enter your donation amount above, and then click on the donate button below.
First of all, let's review Bruce Anderson's quote about the problems of the manual transmission cars versus tiptronic transmission cars before going on to the subject of PDK:
Quote:
The rear main seal problem does seem more common with manual transmission cars, which makes sense when you take a closer look at the design of the engine. On all 986 and 987 engines, the tail of the crankshaft suffers from a lack of support - instead of resting on a bearing at the tail, the crankshaft is fitted with a chain drive for the intermediate shaft. On manual transmission cars, the crankshaft tail also bears the weight of the flywheel and clutch assembly. Over time, the motion of the unsupported cranskshaft tail can distort and fatigue the RMS. In certain cases, the entire crankshaft cradle can shift down-ward, putting more stress on the seal. If the flywheel and clutch are out of balance, the strain on the RMS can increase even more.
So, the concern question: is the PDK flywheel and 2 clutch assembly even heavier than the manual transmission one? The following picture is a cut-out of the DSG (same thing as PDK). You can see how thick the flywheel and 2-clutch assembly is (but diameter is smaller though):
No worries. The chain drive on the tail end of the crankshaft will be gone (DFI):
Weight down, stability up – the engine block
Despite their more sophisticated and complex technology, the new power units are approximately six kilos lighter than before. A two-piece crankcase with integrated crankshaft bearings is perhaps the most significant change in technology, replacing the former four-piece block with its separate crankshaft bearing housing. The advantage is not only a reduction of weight, but also a smaller number of individual components. At the same time Porsche’s engineers have enhanced the thermal and mechanical stability of the engine, making it even more robust by converting the design and configuration of the cylinders from open- to a closed-deck layout.
This means that the cylinder liners so far freely exposed around the cylinder gaskets are now connected with the housing by a top plate comprising the coolant sleeves. In particular, this helps to give the cylinders even greater stability in their shape and design, always remaining perfectly round. Two further advantages are the reduction of oil consumption and, thanks to less friction, even greater fuel economy.
Fewer moving parts – new timing chain drive
The new engines no longer require the former intermediate shaft serving to drive the timing chains. Originally this shaft had the task to reduce the loads acting on the camshaft drive.
Now, through the use of new, highly resistant timing chains, there is no longer a need for such an intermediate shaft, moving masses and the weight of the engine being reduced accordingly.
DFI
Direct Fuel Injection (DFI), is a new technology that Porsche states can cut fuel consumption by up to 15 percent, while increasing power by up to 13 percent. DFI cuts emissions by warming up the catalytic converter more quickly, and ensures a sharper throttle response. Better for your right foot - and the planet, then.
DFI allows much more precise measurement of fuel supply and injection at pressures up to 120 bar; it has numerous combustion modes, with different cycles for cold-starting, low-speed driving and performance driving.
As the name suggests, DFI injects fuel directly into the individual combustion chambers, instead of the intake manifold. The injector valves have an electromagnetic mechanism that controls each injection with astonishing precision, while a high-pressure pump provides the necessary pressure—up to 1,740 psi—to accompany the rapid fire of the fuel injection.
Precise geometry of the injector’s position and its spray pattern is a key factor in helping to improve power, torque and emissions of the engines. The specific placement of the fuel as it enters each chamber creates a swirl that improves the air/fuel mixture, and therefore the overall combustion process.
At engine speeds up to 3500 rpm, a double-injection process is used. In this mode, the required fuel volume is delivered in two successive injections per working stroke. The resulting benefits include faster catalyst warm-up and increased torque in the upper load range.
By forming the air/fuel mix directly in the combustion chamber, DFI contributes to engine cooling. As a result, it is possible to increase the compression ratio and with it the power and efficiency of the engine.
The direct injection process is continuously adjusted. The engine management system reads changes to throttle inputs and performance requirements and, as you drive, the air/fuel mix is monitored and adapted as required. Oxygen sensor circuits within the exhaust system provide accurate emissions control.
The Cayman/Boxster/911 have been using the same engine design since 1997. The exception being the Turbo, GT3, GT3 RS and GT2.
Porsche has re-designed the engine for MY09 on the 911. The new engine is not supposed to suffer from RMS, as they specifically handled this problem. I don't think Porsche will keep producing two different engine types for the 911/Cayman/Boxster, most likely these new engines will find their way into the Cayman/Boxster.
#1 QUOTE- No worries. The chain drive on the tail end of the crankshaft is now long gone:
#2 QUOTE
Quote:
Originally Posted by F430GT
Porsche has re-designed the engine for MY09 on the 911. The new engine is not supposed to suffer from RMS, as they specifically handled this problem. I don't think Porsche will keep producing two different engine types for the 911/Cayman/Boxster, most likely these new engines will find their way into the Cayman/Boxster.
Help please? Quote #1 says problem solved long ago? Looks like Quote #2 says problem will be solved. could someone explain this a bit more?
The new engine block and engine design "should" get rid of the old RMS problem.
Additionally I spoke to Porsche today at Parade in length about the PDK and it weighs between the weight of a manual and a tiptronic. Walter Rohl says he cannot shift a manual as fast at the PDK.
I was told that the newly redesigned engine block and the engine does in fact have a new name (like M96, M97, etc.) but the person I talked to from Porsche was going to look it up because he didn't want to get it wrong and send it to me. When I get the info I will post it.
I thought the new (987 vs the 986) engines had the extra bearing journal to keep the crankshaft supported. I remember reading this somewhere in a boxster buyers guide type article?
