GT3 Cup engine
Discussion
following on from a few posts of late, i realised that quite a few folks havent had an opportunity to see in or around a GT3 mezger engine and that rather sadly, this also includes many who are lucky enough to have one in the back of their car.
theres a real beauty to the design of these engines and to many of the parts inside so with that in mind i have decided to post up a few pics while im refreshing and updating one of my GT3 Cup engines.
i dont want to do a step by step rebuild post, i dont have the photographic prowess for starters as this thread is about to show but i will try to make it interesting nonetheless.
i'll post photos of the wear items too where it can be captured properly on camera. i know many of you track and are either unsure or oblivious to the wear that occurs inside these so this might be of interest too. while the engines are very tough, this doesnt make them immune from wear. providing you get in nice and early a refresh is nice to do. wear is always in the same places and all the big ticket items can be reused.
hopefully this will be of interest to the aircooled fans too. theres so much similar about these engines its not real. many of the parts are interchangeable and wayne dempseys book, how to rebuild and modify porsche 911 engines 1965-1989 covers alot of the work that is still needed to be done today.
as a last point, i also have a bunch of extra and spare parts from my years of Cup ownership so where i think it might be interesting, ill post some side by side photos showing the changes.
the engine is already completely pulled apart and midway through preparation for rebuilding. as a result ill load up a few pics of the engine and bits of interest i have photos of while stripping but ill mostly just post bits of the insides.
all my water connections are welded up too so i will include pics of these at some point for those interested.
as an opener..... Porsche Motorsport engine seal. its always a mix of emotions popping one off to get into the engine.
theres a real beauty to the design of these engines and to many of the parts inside so with that in mind i have decided to post up a few pics while im refreshing and updating one of my GT3 Cup engines.
i dont want to do a step by step rebuild post, i dont have the photographic prowess for starters as this thread is about to show but i will try to make it interesting nonetheless.
i'll post photos of the wear items too where it can be captured properly on camera. i know many of you track and are either unsure or oblivious to the wear that occurs inside these so this might be of interest too. while the engines are very tough, this doesnt make them immune from wear. providing you get in nice and early a refresh is nice to do. wear is always in the same places and all the big ticket items can be reused.
hopefully this will be of interest to the aircooled fans too. theres so much similar about these engines its not real. many of the parts are interchangeable and wayne dempseys book, how to rebuild and modify porsche 911 engines 1965-1989 covers alot of the work that is still needed to be done today.
as a last point, i also have a bunch of extra and spare parts from my years of Cup ownership so where i think it might be interesting, ill post some side by side photos showing the changes.
the engine is already completely pulled apart and midway through preparation for rebuilding. as a result ill load up a few pics of the engine and bits of interest i have photos of while stripping but ill mostly just post bits of the insides.
all my water connections are welded up too so i will include pics of these at some point for those interested.
as an opener..... Porsche Motorsport engine seal. its always a mix of emotions popping one off to get into the engine.
Edited by fioran0 on Monday 22 October 17:55
heads off exposing the cylinder water jacket and pistons. water jacket slides off leaving the pistons and rods sticking out of the crankcase. liners are all replaceable using a simple press allowing you to fit new pistons and liners to get a brand new engine nice and easily. no4 piston at TDC.
... I think this is going to be good...thats all i have taken from disassembly.
heres a pic of the crank case half along side a later cup crankcase half from a 2008 car showing the new casting design (on the left). internal case design is unchanged. just some of the castings from the aircooled days were finally taken off.
heres a pic of the crank case half along side a later cup crankcase half from a 2008 car showing the new casting design (on the left). internal case design is unchanged. just some of the castings from the aircooled days were finally taken off.
rods:
the Cups changed from a 127.8mm length rod to a 130mm length rod in 2003. those of you with mk1 GT3s use the 127.8mm length while those from mk2 onwards use the 130mm length. the rods are titanium (including bolts) and made by pankl. photos show the two lengths side by side.
the shorter rod uses a bolt that passes straight through and secures with a brass washer and titanium nut, the longer rod uses a bolt threaded into the rod itself.
these are actually a 127.8mm rod for a GT3R and a 130mm rod for a GT3RSR that i used but the regular rods are very similar.
the Cups changed from a 127.8mm length rod to a 130mm length rod in 2003. those of you with mk1 GT3s use the 127.8mm length while those from mk2 onwards use the 130mm length. the rods are titanium (including bolts) and made by pankl. photos show the two lengths side by side.
the shorter rod uses a bolt that passes straight through and secures with a brass washer and titanium nut, the longer rod uses a bolt threaded into the rod itself.
these are actually a 127.8mm rod for a GT3R and a 130mm rod for a GT3RSR that i used but the regular rods are very similar.
GT Glee said:
Is that just timing then, or no lift or timing? I think was the difference between VarioCam and VarioCam Plus.
Must admit I always thought VarioCam Plus a little too intricate/clever for endurance.
Great post by the way.
neither. theres no "vario" on either the timing or the lift. its just old school cams Must admit I always thought VarioCam Plus a little too intricate/clever for endurance.
Great post by the way.
variable valve timing is actually prohibited under ACO regs from memory.
you are correct though on the differences between variocam and variocam plus. one is just variable timing, the plus added two stage lift on the intake side.
mic!
fioran0 said:
neither. theres no "vario" on either the timing or the lift. its just old school cams
variable valve timing is actually prohibited under ACO regs from memory.
you are correct though on the differences between variocam and variocam plus. one is just variable timing, the plus added two stage lift on the intake side.
I seem to have it my head that the 1999 Cup had VarioCam (don't know about the later Cups), so I must've had my wires crossed with the M96/76.variable valve timing is actually prohibited under ACO regs from memory.
you are correct though on the differences between variocam and variocam plus. one is just variable timing, the plus added two stage lift on the intake side.
GT Glee said:
I seem to have it my head that the 1999 Cup had VarioCam (don't know about the later Cups), so I must've had my wires crossed with the M96/76.
The 1999 and 2000 cups used solid lifters etc. this is the same design as used right through to the RSR and is really rather nice. I've got a set of 2000 heads complete with cams etc in my workshop. I'll drag them out and put up pics too.
The cups changed to hydraulic lifters in 2001.
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