12 GT4's for sale on PistonHeads and growing (Vol. 2)
Discussion
Thanks all for the feedback and T, thanks for the link ... I am very pleased for this experience to be shared, and at the expense of boring everybody, all because my OPC wouldn't sell me first a 718 GT4 and then a GT4RS ... go figure 
Passenger rides willingly offered, I need to get back up to speed
Passenger rides willingly offered, I need to get back up to speed
Edited by ChrisW. on Tuesday 22 November 14:21
ChrisW. said:
I had thought that the gearing-plus might do the job without the insurance company worrying too much ... but I have an open mind ... we can share details here or PM / email me ?
I’ve PM’d you. See what you think, but what you have at present is already a very cool and considered package… don’t really need more.
TDT said:
Only ST refinish their rotors and they are the only rotors that can be refinished.
The point is that by the time you get to need a refinish…. You’ve already outlasted more than 5 sets of steels… and used fewer pads. So per axle its break even at worst, at 5 sets and you’ve saved labour and fewer pads.
IF ST were fold, there is the option go back to the box fresh OEM PCCB or switch to steel. Brakes are consumables.
Also I can only say, if you buy right… for me it was nowhere near 12k or even 10k…ymmv.
A front / rear ST set wil do about €14k, need also the Pagid pads to it.The point is that by the time you get to need a refinish…. You’ve already outlasted more than 5 sets of steels… and used fewer pads. So per axle its break even at worst, at 5 sets and you’ve saved labour and fewer pads.
IF ST were fold, there is the option go back to the box fresh OEM PCCB or switch to steel. Brakes are consumables.
Also I can only say, if you buy right… for me it was nowhere near 12k or even 10k…ymmv.
The PCCP are prone to stone chip, are the ST stronger in that respect?
I do not track the car, is it overkill for road use to replace the PCCB for ST?
Thanks for reply and advise, much appreciated !
Regarding the 9A1 engine ... I found this rather interesting comparison with the M96/97 engines ... Porsche worked very hard on it !
This article is intended to provide a brief, technical description of the Porsche 9a1 engine. Its design is robust and advanced.
Main Differences from Predecessor M96 & M97 One of the main differences from the predecessors M96 & M97 is that the 9a1 engine has no IMS bearing or shaft. The timing chains on 9a1 engine are located on the front of engine for both banks as well as a small chain to drive the oil pump. Because of this configuration the chains are longer and the timing chain speed is faster. The engine block in the 9a1 engine is a monolithic-alusil (alloy material commonly used in sleeveless engine blocks, mostly used by German auto manufactures) with integral cylinders. Its weakness is that it is not very forgiving to overheating and cannot be welded; however, its design is robust and powerful. The 9a1 has 8 main bearings as opposed to 7 on the M96 & M97 engine. The crankshaft of the 9a1 is forged and nitro-carburized heat treated with a .015 depth (as opposed to the M96 & M97 has heat treating of .003). The crankshaft has 12 counterweights and 63mm main bearing journals. Number 2,4,6 main bearing journals are grooved to supply oil;
the rest are smooth. All timing chains and the oil pump drive run off the front of the crankshaft. There is no crankshaft carrier in the 9a1 engine. The main bearings are built into the block. The engine block has a closed deck design as opposed to the open deck of the M96 & M97. Just to note, the closed deck design is more robust; however, comes with higher coolant temperatures and higher oil temps under heavy load.
Pistons in the 9a1 are forged. The top ring land on the piston is hard anodized to handle the increased pressure due to the DFI (Direct Fuel Injection). On the bottom of the pistons are oil squirters for cooling. The compression ratio of the engine is 12.0:1. The oiling system on the 9a1 is an integral dry sump with 4 scavenger pumps. Oil pressure is controlled by the DME (Digital Motor Electronics) on demand. The DME recognizes combustion and responds with the correct oil pressure. The returning oil coming out of the scavenge pumps will be foamy and needs to de-aerate, which is done directly out of oil of the pump in anti-foam swirl pots.
HEADS/CAMSHAFT The 9a1 heads are die-cast (not sand cast), which is a good method of limiting and/or eliminating porosity issues and maintains more exact tolerances since the metal is forced into the die under high pressure; however, as a result they cannot be welded. There is no lifter carrier in the heads. The lifter bores are integral to the head. All 9a1s are variocam plus. The camshaft has hardly any duration but has huge lift and ramp speed. The camshafts are shorter on B2 because the fuel pump drives off bank 1. There are stronger cam caps, stronger gears (2014+ have module cam lobes like a 904 or a 4 cam Carrera). There is 5 mm more valve lift on 911 9a1 as opposed to the 9a1 Boxster and Cayman. Valves are bi-metallic with a 6mm stem and dual valve springs. Valve guides are short 31.75 mm or 1.25” long and made of manganese (Mn). The head gasket is a multilayer steel, coated with heat resistant plastic. Thermal heat transfer is good. There are coolant stabilizers to maintain and even coolant flow balance in the engine block. The water pump is a closed impeller, pretty much overkill but nice to have. DIRECT FUEL INJECTION
Fuel is injected directly into the combustion chamber under extremely high pressure (between 1400-1740 psi). Fuel pressure can only be checked using Porsche Scan Tool (PIWIS or equivalent tool). As previously noted, the fuel pump is driven off the front of the engine B1, exhaust cam. Advantages of DFI are that engines can have a higher compression ratio and run leaner mixtures. The stratified fuel charge does not require long idle periods to warm up the engine. CONCLUSION Best thing to do is go buy one, start the car and drive. Keep the RPMs under 3k until the engine warms up, which does not take long. Note: slow drives at low RPM are an unhealthy diet for this engine. Burn good fuel and drive hard. That is what this engine needs and loves.
This article is intended to provide a brief, technical description of the Porsche 9a1 engine. Its design is robust and advanced.
Main Differences from Predecessor M96 & M97 One of the main differences from the predecessors M96 & M97 is that the 9a1 engine has no IMS bearing or shaft. The timing chains on 9a1 engine are located on the front of engine for both banks as well as a small chain to drive the oil pump. Because of this configuration the chains are longer and the timing chain speed is faster. The engine block in the 9a1 engine is a monolithic-alusil (alloy material commonly used in sleeveless engine blocks, mostly used by German auto manufactures) with integral cylinders. Its weakness is that it is not very forgiving to overheating and cannot be welded; however, its design is robust and powerful. The 9a1 has 8 main bearings as opposed to 7 on the M96 & M97 engine. The crankshaft of the 9a1 is forged and nitro-carburized heat treated with a .015 depth (as opposed to the M96 & M97 has heat treating of .003). The crankshaft has 12 counterweights and 63mm main bearing journals. Number 2,4,6 main bearing journals are grooved to supply oil;
the rest are smooth. All timing chains and the oil pump drive run off the front of the crankshaft. There is no crankshaft carrier in the 9a1 engine. The main bearings are built into the block. The engine block has a closed deck design as opposed to the open deck of the M96 & M97. Just to note, the closed deck design is more robust; however, comes with higher coolant temperatures and higher oil temps under heavy load.
Pistons in the 9a1 are forged. The top ring land on the piston is hard anodized to handle the increased pressure due to the DFI (Direct Fuel Injection). On the bottom of the pistons are oil squirters for cooling. The compression ratio of the engine is 12.0:1. The oiling system on the 9a1 is an integral dry sump with 4 scavenger pumps. Oil pressure is controlled by the DME (Digital Motor Electronics) on demand. The DME recognizes combustion and responds with the correct oil pressure. The returning oil coming out of the scavenge pumps will be foamy and needs to de-aerate, which is done directly out of oil of the pump in anti-foam swirl pots.
HEADS/CAMSHAFT The 9a1 heads are die-cast (not sand cast), which is a good method of limiting and/or eliminating porosity issues and maintains more exact tolerances since the metal is forced into the die under high pressure; however, as a result they cannot be welded. There is no lifter carrier in the heads. The lifter bores are integral to the head. All 9a1s are variocam plus. The camshaft has hardly any duration but has huge lift and ramp speed. The camshafts are shorter on B2 because the fuel pump drives off bank 1. There are stronger cam caps, stronger gears (2014+ have module cam lobes like a 904 or a 4 cam Carrera). There is 5 mm more valve lift on 911 9a1 as opposed to the 9a1 Boxster and Cayman. Valves are bi-metallic with a 6mm stem and dual valve springs. Valve guides are short 31.75 mm or 1.25” long and made of manganese (Mn). The head gasket is a multilayer steel, coated with heat resistant plastic. Thermal heat transfer is good. There are coolant stabilizers to maintain and even coolant flow balance in the engine block. The water pump is a closed impeller, pretty much overkill but nice to have. DIRECT FUEL INJECTION
Fuel is injected directly into the combustion chamber under extremely high pressure (between 1400-1740 psi). Fuel pressure can only be checked using Porsche Scan Tool (PIWIS or equivalent tool). As previously noted, the fuel pump is driven off the front of the engine B1, exhaust cam. Advantages of DFI are that engines can have a higher compression ratio and run leaner mixtures. The stratified fuel charge does not require long idle periods to warm up the engine. CONCLUSION Best thing to do is go buy one, start the car and drive. Keep the RPMs under 3k until the engine warms up, which does not take long. Note: slow drives at low RPM are an unhealthy diet for this engine. Burn good fuel and drive hard. That is what this engine needs and loves.
Romo said:
A front / rear ST set wil do about €14k, need also the Pagid pads to it.
The PCCP are prone to stone chip, are the ST stronger in that respect?
I do not track the car, is it overkill for road use to replace the PCCB for ST?
Thanks for reply and advise, much appreciated !
I do have a very small chip on the rim of one of my discs, because they are solid it is quite stable and insufficient to create any dynamic effect, but it can be skimmed out when (eventually ?) this is done. Incidentally, I see that 9M suggest that ST's can only be skimmed 4 times ... just sayin'The PCCP are prone to stone chip, are the ST stronger in that respect?
I do not track the car, is it overkill for road use to replace the PCCB for ST?
Thanks for reply and advise, much appreciated !
A damaged edge on a laminated PCCB could be different, but to be fair when I wore out my Cayman R PCCB's the surface layer just wore down to the aggressively textured substrate which started to shred the pad ... and then little triangles of the laminate layer started to drop out, so there was no getting away from the need to re-surface them ... which at the time was done by SICOM. Do JZM now do this ?
P.S. PCCB's are more than up for road work ... if only to avoid corrosion issues and max the handling of the car, that's what I would choose them for. It took me 9000 miles and the need for a third (or fourth ??) set of pads to realise that for me and my trackday use, ST's were the way to go. I also figured that one day I might sell the PCCB's that I had removed ....
Edited by ChrisW. on Tuesday 22 November 15:33
Twinfan said:
You probably need to be a heavy track user, and most likely a fast driver/heavy braker for it to work out. Or a bad driver who wears out brakes easily! Alternatively, they've rusted heavily on the inside and have to be replaced because of that and not due to wear.
I believe Chris Harris has just converted his 991.2 GT3 Touring ("the banana") to PCCBs after getting 50k+(?) road miles out of the original steels. Don't know if he replaced pads in that time or not but clearly the discs can last a long time.
You pays yer money and takes yer choice, as with everything
Heavy duty track day goers are more likely to take the Factory Ceramics off and replace with Steel than vice versa I believe Chris Harris has just converted his 991.2 GT3 Touring ("the banana") to PCCBs after getting 50k+(?) road miles out of the original steels. Don't know if he replaced pads in that time or not but clearly the discs can last a long time.
You pays yer money and takes yer choice, as with everything
Romo said:
TDT said:
Only ST refinish their rotors and they are the only rotors that can be refinished.
The point is that by the time you get to need a refinish…. You’ve already outlasted more than 5 sets of steels… and used fewer pads. So per axle its break even at worst, at 5 sets and you’ve saved labour and fewer pads.
IF ST were fold, there is the option go back to the box fresh OEM PCCB or switch to steel. Brakes are consumables.
Also I can only say, if you buy right… for me it was nowhere near 12k or even 10k…ymmv.
A front / rear ST set wil do about €14k, need also the Pagid pads to it.The point is that by the time you get to need a refinish…. You’ve already outlasted more than 5 sets of steels… and used fewer pads. So per axle its break even at worst, at 5 sets and you’ve saved labour and fewer pads.
IF ST were fold, there is the option go back to the box fresh OEM PCCB or switch to steel. Brakes are consumables.
Also I can only say, if you buy right… for me it was nowhere near 12k or even 10k…ymmv.
The PCCP are prone to stone chip, are the ST stronger in that respect?
I do not track the car, is it overkill for road use to replace the PCCB for ST?
Thanks for reply and advise, much appreciated !
freedman said:
Heavy duty track day goers are more likely to take the Factory Ceramics off and replace with Steel than vice versa
Yep - the most hardcore also take off the factory calipers and go to something like an AP Racing or PFC full set up. The calipers are properly serviceable with metal pistons, instead of the ceramic ones we have in the 'road ' cars - which can crack with time and heat and none of the rubber dust covers that can split also.Thanks to everyone, especially ChrisW. TwinFan and TDT, for all the detail and experience on brakes, engines, gearboxes and everything else in this thread.
My very standard 2016 981 GT4 gets a mix of "better-weather" daily driving, the occasional longer outing, and 1-2 track days a year. I think it can stay on original steel brakes for now, and I'll evaluate options when it next needs a set of pads. It lives in a nice dry garage under an indoor cover when not being used, so the rust is kind of a "first world" problem. It doesn't get a lot worse if the car's idle for a while.
Liam
My very standard 2016 981 GT4 gets a mix of "better-weather" daily driving, the occasional longer outing, and 1-2 track days a year. I think it can stay on original steel brakes for now, and I'll evaluate options when it next needs a set of pads. It lives in a nice dry garage under an indoor cover when not being used, so the rust is kind of a "first world" problem. It doesn't get a lot worse if the car's idle for a while.
Liam
https://www.autotrader.co.uk/car-details/202211021...
2020 10k miles, Guards red, PCCB, buckets, nice options (reversing camera, some carbon and climate) and under £83k at an official Porsche network.
Starting to look very tempting.
2020 10k miles, Guards red, PCCB, buckets, nice options (reversing camera, some carbon and climate) and under £83k at an official Porsche network.
Starting to look very tempting.
Pflanzgarten said:
https://www.autotrader.co.uk/car-details/202211021...
2020 10k miles, Guards red, PCCB, buckets, nice options (reversing camera, some carbon and climate) and under £83k at an official Porsche network.
Starting to look very tempting.
Looks expensive to me! 2020 10k miles, Guards red, PCCB, buckets, nice options (reversing camera, some carbon and climate) and under £83k at an official Porsche network.
Starting to look very tempting.
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