Can someone explain the fundamental differences between the GT1 derived 3.6L block used in the GT2/GT3/TT and the 3.4/3.6/3.8 Carrera engines used in the 996/997 ?
There must be some kind of structural/design explanation why one is more reliable than the other, immune to RMS issues, etc ...
Would appreciate a lot if someone could point me to an article on this.

 

the one major diff i know about is that the GT1/tt/GT3 bock has a dry sump and our cars do not...

 

Hello ze shake,

it's nice to see you here

Vincent

 

The GT1 block is not immune to the RMS issue. Some GT3's and turbos have needed the RMS done.

 

I've heard that a lighter flywheel helps reduce the RMS leak frequency...

 

{From Wikipedia}

"

"996 GT3 RS




Most important of all was the re-tuned engine. Although it shared the same basic displacement as the 3.6 litre flat-six cylinder that powered the standard 911, it was based on the dry sump GT1 racing motor. Porsche made significant modifications to the heads, intake, exhaust and computer control systems. In addition, Porsche used a specialized manufacturing process on the GT3's engine; standard 911s use a two-piece engine block split down the center line of the crankcase. On the GT3 the split-crankcase parts are cast separately and bolted to the two blocks of three cylinders per bank, a design that was originally developed specifically for racing applications that makes the engine stiffer and capable of producing more power.
Porsche made significant updates to the GT3 for 2004, the first year the car was offered to US customers. Horsepower was raised to 381 horsepower and torque to 284lb.ft, 80% of which was available from a mere 2,000 RPM."

 

Basically, normal 996's received a glorified boxster engine to save money (More Profit!), while the Turbos and GTx's got a real Porsche mill.

 

the gt1 block is the original block used for the past 20 years because it has been so reliable. they wanted to try something new when they introduced the water cooled motors with the 996/986 but not the power haus cars ex. 996tt 996gt3, 996gt2 that old block has been so reliable over the years why change it. they just added water pockets to cool the motor. they made a mistake with this new block it is crap. glad they didn't do it with the turbo and gt3.

 

Purist crap... porsche is moving forward, the carreras is better than ever. There are alot of advances in these engines that are far to much to mention comparing them to the aircooled carreras. The lokasil process to make these blocks have made even higher tolerance in engine design and thus a more specialized design (throw away engines). The Nikasil process (GT1 based) is made for racing, but that is due to more for a modular design standpoint (for rebuilding and replacement). It is two different philosophy and application between these two motors.
Its just to bad that people hear of rms and then the motor is crap... I think they should really educate themselves... oh yeah and the engineers at porsche says its a great motor.

 

While blown Carrera engines are worrying hearsay, RMS failures are a reality that many owners have had more than their fair share of, in cars which are subjected to pretty mundane treatment compared to TTs and GT2/GT3.
The explanation about rigidity and separate cylinder blocks is interesting. Does anyone have a cut view of a 996 block ?

 

The turbo/GT2/GT3 block are I believe two halves put togather...I also believe that is the reason why you see that rib going right down the middle of the block. the turbo/GT2/GT3 block is also denser(I believe)...

 

Funny....A 996 engine with 100k miles was torn apart by a magazine to see what the internals looked like and they were surprised that the insides looked near new and they thought the M96 engines were good for 200k miles EASY. I have 120k on my car now....looking forward to 200k.....I would NOT put this kind of miles on an air cooled Porsche. Driving 25K+ miles a year, a 993 would be very expensive in upkeep...not to mention my 996 has more HP, torque, driveability, etc....its a better engine any way you look at it.

 

It may be reliable compared to the old aircooled engines, but the updated water cooled version in the 996 GT3, GT2, Turbo is certainly better than our boxster engine.

A Porsche 911 book (Brian Long, the definitive 911) I have seems to imply that our block is identical to the Boxsters.

"The 996 was powered by the M96/01 engine in all markets. The early 3.4 liter crankcase was very similar to that of the Boxster (it had the same bore centers to allow manufacture via the same machines, and actually, the centers were the same as those of the last air-cooled flat six.), being a two-piece aluminium alloy casting with a separate carrier with seven main bearings, and a silicon lining on the cylinder walls. With a bore and stroke of 96x 78mm, the cubic capacity of the M96/01 lump was 3387cc. As a matter of interest, the short stroke, oversquare characteristics were carried over from the Boxster engine (Type M96/20), although a bore and stroke measurement of 85.5 x 72mm gave a 2480cc displacement for the two-seater."

 

At 3 times the cost it better be better!!!!! But is it 3 times better? Will it run 3 times longer? NO.....Again....our M96 engine is pretty darn good. Inexpensive, reliable, fast, etc....

 

Yeah, what pisses me off is that Porsche (from some source on the net which I forget) apparently has the highest profit per car of any manufacturer. They put cheaper parts in the normal 996's (from the boxster...) and charge you more for "special" versions of the 911 with parts the old air-cooled cars had stock, such as the better block, dry sump, ect...