• Here is a preview of what the Porsche 991 GT3 will sound like with an aftermarket exhaust

      Some Porsche purists are worried that the switch from the GT1 race inspired flat-6 block in the GT3 will take away from the sound quality of the GT3. Porsche is using the same facility to produce all the direct injected blocks and is sharing them among 911 models (the GT3 also sharing the timing chains, head bolts, AC compressor, and alternator from the 991 Carrera) to cut down on costs leading to speculation that the aural quality of the GT3 would be impacted. The video below shows that there is no need to fret as the GT3 sounds as great if not better than ever.

      Keep in mind this a cell phone recorded video so it is not the best quality. That said, the GT3 is going to sound even more amazing than it already does once uncorked with an aftermarket exhaust.



      This article was originally published in forum thread: Here is a preview of what the Porsche 991 GT3 will sound like with an aftermarket exhaust started by Sticky View original post
      Comments 24 Comments
      1. 5soko's Avatar
        5soko -
        I love this car..
      1. mjmarovi's Avatar
        mjmarovi -
        Sounds awesome, looks great too. Seems like everyone is going to the "slim" tail light and headlights, mustang, jaguar, Porsche, 15' Camaro, looks better on some than other and this 991 looks sick
      1. leveraged sellout's Avatar
        leveraged sellout -
        Beautiful. I love these cars so damn much. Anybody complaining about the new engine just doesn't know what they are talking about.
      1. benzy89's Avatar
        benzy89 -
        Sharkwerks makes great Porsche stuff, and who doesn't love a 9k Redline? Eargasm Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        Beautiful. I love these cars so damn much. Anybody complaining about the new engine just doesn't know what they are talking about.
        Well the complaints about the GT1 bock being ditched are valid I think. The change is for cost saving more than performance.
      1. leveraged sellout's Avatar
        leveraged sellout -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Well the complaints about the GT1 bock being ditched are valid I think. The change is for cost saving more than performance.
        I guess...I mean the rest of the engine is all-new anyway, I don't really see it being a problem however. It's just more modern all around. The 997 Turbo uses this engine as well, and so far it hasn't had any problems holding excess boost. To put it shortly, 475 hp with plenty of torque at accessible RPMs AND well over 8000 rpm straight from the factory at 3.8 liters was not going to happen with the Mezger engine.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        I guess...I mean the rest of the engine is all-new anyway, I don't really see it being a problem however. It's just more modern all around. The 997 Turbo uses this engine as well, and so far it hasn't had any problems holding excess boost. To put it shortly, 475 hp with plenty of torque at accessible RPMs AND well over 8000 rpm straight from the factory at 3.8 liters was not going to happen with the Mezger engine.
        I don't see it as a problem I just don't see it was being tested under Motorsport conditions to the same rigorous levels. That does not mean it is not good I just don't think it has seen nearly as much abuse.

        Considering what the 4.0 liter GT3 put out I'd have to disagree with you strongly.
      1. leveraged sellout's Avatar
        leveraged sellout -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I don't see it as a problem I just don't see it was being tested under Motorsport conditions to the same rigorous levels. That does not mean it is not good I just don't think it has seen nearly as much abuse.

        Considering what the 4.0 liter GT3 put out I'd have to disagree with you strongly.
        Yeah I mean it sucks that its no longer a "race" engine at heart, that was definitely cool. I did love that aspect of it.

        I didn't necessarily mean that it would have been impossible in absolute terms, but given the way emissions and fuel economy regulations are going...it would have been very difficult. Even Porsche has to give in to the politicians at some point, I guess.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        I didn't necessarily mean that it would have been impossible in absolute terms, but given the way emissions and fuel economy regulations are going...it would have been very difficult. Even Porsche has to give in to the politicians at some point, I guess.
        I thought you were speaking from a performance perspective. The 4.0 RS still is the most powerful GT3.

        Getting more out of it while improving emissions... well, tall order.
      1. leveraged sellout's Avatar
        leveraged sellout -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I thought you were speaking from a performance perspective. The 4.0 RS still is the most powerful GT3.

        Getting more out of it while improving emissions... well, tall order.
        Yeah that was more my point. The Mezger engine is undoubtedly an amazing performance machine...but its not politically correct anymore. Another interesting thing is that I read somewhere that while it is limited to 4 liters of displacement, the new engine is not...I wonder if we will be seeing many 4+ liter 911s in the future...that might be interesting...
      1. AlexQuattro's Avatar
        AlexQuattro -
        It sounds like the car is farting when it changes gears, I love it.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        Yeah that was more my point. The Mezger engine is undoubtedly an amazing performance machine...but its not politically correct anymore. Another interesting thing is that I read somewhere that while it is limited to 4 liters of displacement, the new engine is not...I wonder if we will be seeing many 4+ liter 911s in the future...that might be interesting...
        You can go over 4.0. It's really the bore where they get the displacement increase in these cars as the stroke (at least for the Carrera and Carrera S) is the same. So you could fairly easily turn a Cayman S into a Cayman S 3.8 just by borrowing the pistons and boring out block.

        The displacement limitations I think are pretty similar.
      1. leveraged sellout's Avatar
        leveraged sellout -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        You can go over 4.0. It's really the bore where they get the displacement increase in these cars as the stroke (at least for the Carrera and Carrera S) is the same. So you could fairly easily turn a Cayman S into a Cayman S 3.8 just by borrowing the pistons and boring out block.

        The displacement limitations I think are pretty similar.
        That's what I was thinking, I couldn't see how there would be any additional room in the new engine. I have seen some people go a bit over 4 liters on the Mezger but it was always met with apprehension, whether well-deserved or not. I really want to see a 9A1 torn down now to see what exactly it looks like in there.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        That's what I was thinking, I couldn't see how there would be any additional room in the new engine. I have seen some people go a bit over 4 liters on the Mezger but it was always met with apprehension, whether well-deserved or not. I really want to see a 9A1 torn down now to see what exactly it looks like in there.
        Here is a nice rundown Metzger GT1 displacement options:

        - Billet Stoker Crank

        - PAUTER Forged 4340 Con-rods (over 0.200" smaller rod journals to reduce weight and allow use of better rod bearings. This will also help with the oil pump clearance with added stroke!)

        - CLEVITE Highperformance Race Series rod bearings (modified to work with the billet crank, sized to give the proper clearance specific to each crank)

        - Porsche main bearings (modified grooved for oil delivery, oil holes enlarged, coating available for an additional $200)

        - JE FSR Pistons (light weight pistons, light weight but stronger wrist pins)
        (coating of the skirts and the piston top is available and advised for )

        - Total Seal Piston Ring Set. Slightly different combination for NA vs. Forced Induction.

        - Ductile Iron Sleeves (max bore 4.100")

        - Multi Layer Metal Head Gasket to suit each individual bore size you will pick and thickness. You will be able to pick thicker or thinner gaskets to further adjust your compression slightly.

        - Head stud kit. 205 tensile strength. Good for 1000+hp and 30 psi.

        Up to 5 kits (1-4) the price for the complete stroker kit including all of the above is $11,528.
        5 Kits and up the price drops another $500 to $11,028.

        10 Kits and up drops another $500 to $10,528. I will be very surprised if we can get this many but I would love the additional savings

        Available options:

        - Titanium Connecting Rods: +$4500 (I have been told 6 titanium rods weigh close to 4 steel ones) Big weigh difference for you GT3 guys. Not recommended for Turbo applications due to boost.

        - Piston Coating: +$250 (Skirt coating and Thermal Barrier Crown piston top coating) I highly recommend doing this! It will be worth every penny in my opinion to have the added benefit; especially when you are doing a build like this. I know I will go definitely go for it myself)

        - Main bearing coating: +$200

        - Rod bearing coating: +$100

        - Lightening of CrankShaft: $850
        There is also a super light weight Crankshaft option for the GT3s where the Cranks are gun\barrell drilled, and further knife edged but it costs $1500 more instead of $850 cost of lightening.

        Engine size choices:

        GT3:

        - 80 x 104.1 = 4085cc
        - 80.4 x 104.1 = 4106cc
        - 81 x 104.1 = 4136cc
        - 81.4 x 104.1 = 4157cc
        - 82 x 104.1 = 4186cc
        - 82.4 x 104.1 = 4208cc 4.2
        - 83 x 104.1 = 4238cc
        - 83.4 x 104.1 = 4259cc
        - 84 x 104.1 = 4289cc (MAX recommended)

        TURBO & GT2:

        - 80.4 x 102.6 = 3988cc
        - 81 x 102.6 = 4018cc 4.0
        - 81.4 x 102.6 = 4038cc
        - 82 x 102.6 = 4068cc
        - 82.4 x 102.6 = 4088cc
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        That's what I was thinking, I couldn't see how there would be any additional room in the new engine. I have seen some people go a bit over 4 liters on the Mezger but it was always met with apprehension, whether well-deserved or not. I really want to see a 9A1 torn down now to see what exactly it looks like in there.
        Also the question I have is if the 991 GT3 motor drops into the Boxster/Cayman. The different blocks made it a problem in the previous gen.

        This gen... it should be easy. At least on paper.
      1. Sticky's Avatar
        Sticky -
        The 991 GT3 shares the Carrera S bore and stroke. That says to me a lot of parts will be interchangeable.
      1. SpeedLimit?'s Avatar
        SpeedLimit? -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        The 991 GT3 shares the Carrera S bore and stroke. That says to me a lot of parts will be interchangeable.
        Doesn't the 991 GT3 still use the GT1 derived crank? Please correct me if I'm wrong. I still love the new motor however not only here but I hate it in general when a manufacturer sells a "motorsport" inspired street car that doesn't use the parts as the race car...
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by SpeedLimit? Click here to enlarge
        Doesn't the 991 GT3 still use the GT1 derived crank? Please correct me if I'm wrong.
        I don't believe so.

        Click here to enlarge Originally Posted by SpeedLimit? Click here to enlarge
        but I hate it in general when a manufacturer sells a "motorsport" inspired street car that doesn't use the parts as the race car...
        My pet peeve as well. Like with the 1M...
      1. leveraged sellout's Avatar
        leveraged sellout -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Here is a nice rundown Metzger GT1 displacement options:

        - Billet Stoker Crank

        - PAUTER Forged 4340 Con-rods (over 0.200" smaller rod journals to reduce weight and allow use of better rod bearings. This will also help with the oil pump clearance with added stroke!)

        - CLEVITE Highperformance Race Series rod bearings (modified to work with the billet crank, sized to give the proper clearance specific to each crank)

        - Porsche main bearings (modified grooved for oil delivery, oil holes enlarged, coating available for an additional $200)

        - JE FSR Pistons (light weight pistons, light weight but stronger wrist pins)
        (coating of the skirts and the piston top is available and advised for )

        - Total Seal Piston Ring Set. Slightly different combination for NA vs. Forced Induction.

        - Ductile Iron Sleeves (max bore 4.100")

        - Multi Layer Metal Head Gasket to suit each individual bore size you will pick and thickness. You will be able to pick thicker or thinner gaskets to further adjust your compression slightly.

        - Head stud kit. 205 tensile strength. Good for 1000+hp and 30 psi.

        Up to 5 kits (1-4) the price for the complete stroker kit including all of the above is $11,528.
        5 Kits and up the price drops another $500 to $11,028.

        10 Kits and up drops another $500 to $10,528. I will be very surprised if we can get this many but I would love the additional savings

        Available options:

        - Titanium Connecting Rods: +$4500 (I have been told 6 titanium rods weigh close to 4 steel ones) Big weigh difference for you GT3 guys. Not recommended for Turbo applications due to boost.

        - Piston Coating: +$250 (Skirt coating and Thermal Barrier Crown piston top coating) I highly recommend doing this! It will be worth every penny in my opinion to have the added benefit; especially when you are doing a build like this. I know I will go definitely go for it myself)

        - Main bearing coating: +$200

        - Rod bearing coating: +$100

        - Lightening of CrankShaft: $850
        There is also a super light weight Crankshaft option for the GT3s where the Cranks are gun\barrell drilled, and further knife edged but it costs $1500 more instead of $850 cost of lightening.

        Engine size choices:

        GT3:

        - 80 x 104.1 = 4085cc
        - 80.4 x 104.1 = 4106cc
        - 81 x 104.1 = 4136cc
        - 81.4 x 104.1 = 4157cc
        - 82 x 104.1 = 4186cc
        - 82.4 x 104.1 = 4208cc 4.2
        - 83 x 104.1 = 4238cc
        - 83.4 x 104.1 = 4259cc
        - 84 x 104.1 = 4289cc (MAX recommended)

        TURBO & GT2:

        - 80.4 x 102.6 = 3988cc
        - 81 x 102.6 = 4018cc 4.0
        - 81.4 x 102.6 = 4038cc
        - 82 x 102.6 = 4068cc
        - 82.4 x 102.6 = 4088cc
        Great, thanks for posting that.

        I think one of the main things that some people are saying is that either way, the new engine seems to be at least able to support pretty decent power on its internals, I know Switzer is doing a lot of work with them right now. However, not as much as the Mezger. However, on either engine, once you get past 750 whp, you're going to want to open things up and start making substitutions regardless. I mean, you don't really have to on the Mezger, we don't really know what the limits of the 9A1 are yet. Mechanically, the Mezger is definitely the superior engine in terms of strength. But, the strength of the 9A1 is likely more than adequate for any uses its likely to encounter. I must admit I haven't followed TT Mezger builds too much but I have a feeling (and have picked up over time) that most builds at or approaching 750 whp are using built internals anyway. So, maybe the end result is that you simply don't have as much headroom on boost. So far, I don't think anyone has popped a 9A1 though, so that's something to consider. Not sure how much boost has been run through one either, but it will be interesting to see what its ceiling is on stock internals.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        Great, thanks for posting that.

        I think one of the main things that some people are saying is that either way, the new engine seems to be at least able to support pretty decent power on its internals, I know Switzer is doing a lot of work with them right now. However, not as much as the Mezger. However, on either engine, once you get past 750 whp, you're going to want to open things up and start making substitutions regardless. I mean, you don't really have to on the Mezger, we don't really know what the limits of the 9A1 are yet. Mechanically, the Mezger is definitely the superior engine in terms of strength. But, the strength of the 9A1 is likely more than adequate for any uses its likely to encounter. I must admit I haven't followed TT Mezger builds too much but I have a feeling (and have picked up over time) that most builds at or approaching 750 whp are using built internals anyway. So, maybe the end result is that you simply don't have as much headroom on boost. So far, I don't think anyone has popped a 9A1 though, so that's something to consider. Not sure how much boost has been run through one either, but it will be interesting to see what its ceiling is on stock internals.
        We will know more with time but I'd be really interested in seeing the GT3's get some boost. I find that motor much preferable to the 991 turbo motor...