Close

    • Another slow 991 Turbo S magazine 1/4 mile test - Are magazine test cars different? MotorTrend gets a 10.9 @ 123.7 out of the 2014 911 Turbo S

      What is going on here? This is the second US magazine to get a slow trap speed but quick elapsed time with the 991 Turbo S. Road and Track matched the MotorTrend 10.9 second elapsed time but also got a 'slow' trap speed at 124.4 miles per hour. MotorTrend's 123.7 is the slowest recorded thus far by a major automotive publication. It makes one scratch their head when the car has run 10.68 @ 128 miles per hour on the drag strip.


      Additionally, the standard 991 Turbo that has less horsepower and torque than the 991 Turbo S has gone 10.9 @ 126 using launch control at the Palm Beach International Raceway drag strip. How is the less powerful car running the same elapsed time with a higher trap speed than two magazines testing the 991 Turbo S?

      This is puzzling considering the car is launching very well as indicated by the 2.6 second 0-60 times recorded by the magazines. Also, the 997.2 version of the Turbo with the PDK gearbox trapped 127.4 miles per hour as tested by MotorTrend. We know thanks to stock dyno numbers for the 991 Turbo that it makes more power and torque than the 997 Turbo. The 991 Turbo S should not just beat the 997.2's trap speed, it should crush it.

      Additionally, we have seen a tuned 997.2 Turbo go up against a stock 991 Turbo S in a roll on race and lose. So what in the world is going on with these magazine cars?

      MotorTrend's theory is this, "The trap speeds are even more telling, with the 997 version trapping at 127.4 mph compared to only 123.7 mph for the new car. What gives? Honestly, we don't know." MotorTrend's honesty is appreciated and it is nice to see them for once question trap speeds.

      PorscheBoost does not know either. Our only guess is that the software on the test cars is somehow different than production models. The cars launch as they should and pull well out of the hole but something is killing the top end. What other explanation is there when two different cars tested in different conditions come up with slow trap speeds? The main variable they have in common is that they are magazine test cars. Maybe it is pre-production software? Porsche would not want their top dog Turbo S to look slower than the previous generation Turbo. This will hopefully be investigated further.

      2014 Porsche 911 Turbo S
      BASE PRICE $182,050
      PRICE AS TESTED $199,065
      VEHICLE LAYOUT Rear-engine, AWD, 4-pass, 2-door coupe
      ENGINE 3.8L/560-hp/516-lb-ft twin-turbo DOHC 24-valve F-6
      TRANSMISSION 7-speed twin-clutch auto.
      CURB WEIGHT (F/R DIST) 3610 lb (39/61%)
      WHEELBASE 96.5 in
      LENGTH x WIDTH x HEIGHT 177.4 x 74.0 x 51.0 in
      0-60 MPH 2.6 sec
      QUARTER MILE 10.9 sec @ 123.7 mph
      BRAKING, 60-0 MPH 100 ft
      LATERAL ACCELERATION 1.04 g (avg)
      MT FIGURE EIGHT 23.0 sec @ 0.93 g (avg)
      EPA CITY/HWY/COMB FUEL ECON 17/24/20 mpg
      ENERGY CONS., CITY/HWY 198/140 kW-hrs/100 miles
      CO2 EMISSIONS 0.99 lb/mile







      This article was originally published in forum thread: Another slow 991 Turbo S magazine 1/4 mile test - Are magazine test cars different? MotorTrend gets a 10.9 @ 123.7 out of the 2014 911 Turbo S started by Sticky View original post
      Comments 13 Comments
      1. richpike's Avatar
        richpike -
        Did they change the inter cooler or gearing between the two generations? Perhaps it is heat soaking towards the end of the run? Or perhaps the 991 has shorter gearing so it is launching harder but running out of gear at the top end? Stickier tires with more rolling resistance slowing trap but allowing a faster ET? I'm throwing out all the ideas I've got. Click here to enlarge

        -Rich
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by richpike Click here to enlarge
        Did they change the inter cooler or gearing between the two generations? Perhaps it is heat soaking towards the end of the run? Or perhaps the 991 has shorter gearing so it is launching harder but running out of gear at the top end? Stickier tires with more rolling resistance slowing trap but allowing a faster ET? I'm throwing out all the ideas I've got. Click here to enlarge

        -Rich
        I think where you may be getting close to whatever is going on is *something* seems to be forcing the ECU to pull boost, timing, or maybe both once it gets up to and past 100 on these 1/4 mile runs.
      1. richpike's Avatar
        richpike -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I think where you may be getting close to whatever is going on is *something* seems to be forcing the ECU to pull boost, timing, or maybe both once it gets up to and past 100 on these 1/4 mile runs.
        Imagine what a tuner will be able to do if Porsche is artificially limiting it... Stage 0.5 just removes the Porsche restriction and you get mid 10s. Stage 1 (tune only) and you are low 10s. Pretty crazy to imagine what this thing can do given how robust the drivetrain is (50 straight launches? No problem).

        -Rich
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by richpike Click here to enlarge
        Imagine what a tuner will be able to do if Porsche is artificially limiting it... Stage 0.5 just removes the Porsche restriction and you get mid 10s. Stage 1 (tune only) and you are low 10s. Pretty crazy to imagine what this thing can do given how robust the drivetrain is (50 straight launches? No problem).

        -Rich
        Porsche isn't really artificially limiting it though as customer bought cars have gone faster and dynos show a bunch of power.

        I think it may be just these magazine/test cars.
      1. richpike's Avatar
        richpike -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Porsche isn't really artificially limited it though as customer bought cars have gone faster and dynos show a bunch of power.

        I think it may be just these magazine/test cars.
        Good point.

        -Rich
      1. Streetgear's Avatar
        Streetgear -
        As a tuner I am sure the problem is due to the hot tune in the ECU by Porsche. Unless conditions are 100% is it going to pull timing and probably limit boost. If one have access to 100 octane unleaded fuel try putting a third to half a tank in. In this way it will insure there is no knock retard taking place. I know some may consider this cheating because if one did the same on the previous 997.2 Turbo S it would likewise pickup some performance especially on warmer days.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Streetgear Click here to enlarge
        As a tuner I am sure the problem is due to the hot tune in the ECU by Porsche. Unless conditions are 100% is it going to pull timing and probably limit boost. If one have access to 100 octane unleaded fuel try putting a third to half a tank in. In this way it will insure there is no knock retard taking place. I know some may consider this cheating because if one did the same on the previous 997.2 Turbo S it would likewise pickup some performance especially on warmer days.
        Interesting. What is your experience as a tuner?
      1. Streetgear's Avatar
        Streetgear -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Interesting. What is your experience as a tuner?
        I have been tuning cars for over 30+ years all the way back to the carbureted days to the modern fuel injected cars of today. There have not been too many platforms that I have not tuned. Regardless of who makes the engine the principles are all the same for extracting power. The more power one extracts from a given engine the more safeties that have to be built in to prevent issues. Keep in mind Porsche did not up the size of the motor but simply extracted more power from a similar size engine.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Streetgear Click here to enlarge
        I have been tuning cars for over 30+ years all the way back to the carbureted days to the modern fuel injected cars of today. There have not been too many platforms that I have not tuned. Regardless of who makes the engine the principles are all the same for extracting power. The more power one extracts from a given engine the more safeties that have to be built in to prevent issues. Keep in mind Porsche did not up the size of the motor but simply extracted more power from a similar size engine.
        I'm not doubting your experience I just wanted to hear more about your background and who you tune for currently.
      1. leveraged sellout's Avatar
        leveraged sellout -
        Definitely strange - seems like it's definitely pulling boost/timing for some reason. Maybe the press fleet is simply just beat to hell and the thing is seeing the need to protect itself. The conditions will change the results of course but these are huge deltas.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        Definitely strange - seems like it's definitely pulling boost/timing for some reason. Maybe the press fleet is simply just beat to hell and the thing is seeing the need to protect itself. The conditions will change the results of course but these are huge deltas.
        If you look a the Fabspeed dyno results for the 991 Turbo the spread per pull is pretty large. Fabspeed didn't really explain it all that well when I asked them about it today and chalked it up to different gears but I'm saying it's the ECU.
      1. leveraged sellout's Avatar
        leveraged sellout -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        If you look a the Fabspeed dyno results for the 991 Turbo the spread per pull is pretty large. Fabspeed didn't really explain it all that well when I asked them about it today and chalked it up to different gears but I'm saying it's the ECU.
        It's gotta be. So the next question is why is it doing this. I'd love to see some IATs and even just some empirical observations of the heat exchangers/intercoolers after each pull. Just to see if things get really hot under there.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        It's gotta be. So the next question is why is it doing this. I'd love to see some IATs and even just some empirical observations of the heat exchangers/intercoolers after each pull. Just to see if things get really hot under there.
        Well the suggestion above by the tuner was that the stock tuning is aggressive meaning boost and timing gets pulled hard.