Aerodynamic Drag with Targa Removed
07-15-2018, 12:01 PM
#1
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Aerodynamic Drag with Targa Removed
In doing some spirited driving yesterday on the way to Cars and Coffee with a friend who owns a stock S2000 we found the perfect stretch of road to go WOT from 60 to about 100. Much to my surprise I was not pulling away as I expected, and in fact the first thing I said upon arriving was "for the love of God, please tell me I was pulling away from you". He confirmed that I was not - he even had the top down and a passenger.
Three possibilities as to why this occurred as far as I am concerned:
1. I had the targa off and in the hatch.
2. I short shifted (using paddles) the 2-3 shift about 200 RPM early ( I don't think this should have any discernible effect but bring it up anyways)
3. My friend is a liar
Is the drag with the targa off THAT noticeable at those speeds? Do I need a supercharger and/or therapy??? Absolutely no offense at all to S2000s as I think they are extremely cool and fun, but everything I know tells me what happened shouldn't have.
And of course, if ever questioned I'll deny it happened 'til I die.
Three possibilities as to why this occurred as far as I am concerned:
1. I had the targa off and in the hatch.
2. I short shifted (using paddles) the 2-3 shift about 200 RPM early ( I don't think this should have any discernible effect but bring it up anyways)
3. My friend is a liar
Is the drag with the targa off THAT noticeable at those speeds? Do I need a supercharger and/or therapy??? Absolutely no offense at all to S2000s as I think they are extremely cool and fun, but everything I know tells me what happened shouldn't have.
And of course, if ever questioned I'll deny it happened 'til I die.
07-15-2018, 12:16 PM
#2
Dude, just the windows down at +60mph creates a nasty drag on the car. With the roof off, it gets much, much worse instead.
As for the S2000, what mods, since I have built a few with S/Cs, that are pushing plus 400hp, and with the shorter gearing and lighter weight, once you get to a speed that the rear end will stick so you can get all the power down, will pull like a monster up to it shorter top end speed of about 150 when it runs out of gearing.
As for if this is a stock S2000, then would dare to guess that your car in not tuned, still have TM holding back lot of instant power, and could be the reason that he was able to stick with you up to 100mph. Hence the S2000 is geared pretty low, so will pull hard up to about 120mph, then needs a bit of room to ring out the last of it top end speed of 149mph instead. Also to point out, the areo;s of the S200O even with the top down, are still pretty good. On the C6 with the roof off, it cause a nasty build up pressure at the back of the car from about the roof back, which translates back to the front of the car having a high pressure area as well.
As for the S2000, what mods, since I have built a few with S/Cs, that are pushing plus 400hp, and with the shorter gearing and lighter weight, once you get to a speed that the rear end will stick so you can get all the power down, will pull like a monster up to it shorter top end speed of about 150 when it runs out of gearing.
As for if this is a stock S2000, then would dare to guess that your car in not tuned, still have TM holding back lot of instant power, and could be the reason that he was able to stick with you up to 100mph. Hence the S2000 is geared pretty low, so will pull hard up to about 120mph, then needs a bit of room to ring out the last of it top end speed of 149mph instead. Also to point out, the areo;s of the S200O even with the top down, are still pretty good. On the C6 with the roof off, it cause a nasty build up pressure at the back of the car from about the roof back, which translates back to the front of the car having a high pressure area as well.
07-15-2018, 12:33 PM
#3
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Dude, just the windows down at +60mph creates a nasty drag on the car. With the roof off, it gets much, much worse instead.
As for the S2000, what mods, since I have built a few with S/Cs, that are pushing plus 400hp, and with the shorter gearing and lighter weight, once you get to a speed that the rear end will stick so you can get all the power down, will pull like a monster up to it shorter top end speed of about 150 when it runs out of gearing.
As for if this is a stock S2000, then would dare to guess that your car in not tuned, still have TM holding back lot of instant power, and could be the reason that he was able to stick with you up to 100mph. Hence the S2000 is geared pretty low, so will pull hard up to about 120mph, then needs a bit of room to ring out the last of it top end speed of 149mph instead. Also to point out, the areo;s of the S200O even with the top down, are still pretty good. On the C6 with the roof off, it cause a nasty build up pressure at the back of the car from about the roof back, which translates back to the front of the car having a high pressure area as well.
As for the S2000, what mods, since I have built a few with S/Cs, that are pushing plus 400hp, and with the shorter gearing and lighter weight, once you get to a speed that the rear end will stick so you can get all the power down, will pull like a monster up to it shorter top end speed of about 150 when it runs out of gearing.
As for if this is a stock S2000, then would dare to guess that your car in not tuned, still have TM holding back lot of instant power, and could be the reason that he was able to stick with you up to 100mph. Hence the S2000 is geared pretty low, so will pull hard up to about 120mph, then needs a bit of room to ring out the last of it top end speed of 149mph instead. Also to point out, the areo;s of the S200O even with the top down, are still pretty good. On the C6 with the roof off, it cause a nasty build up pressure at the back of the car from about the roof back, which translates back to the front of the car having a high pressure area as well.
Agree that the S2k will be more aerodynamic even top down. My thinking was that it might be akin to pulling a parachute if I have the top off in my coupe.
If anyone is familiar with ZentRose, he has a video comparison of his S/C S2k vs. his C5Z, 60-100. Both cars took the same amount of time to hit 100. Now this is not an apples to apples comparison, but my C6 should at least be comparable to the C5Z, and my friend's S2k is not supercharged, so like I said, everything I know tells me this shouldn't be.
Top will remain on next time we drive lol. At least in the beginning.
07-15-2018, 01:19 PM
#4
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I'm seeing it as a bit of all 3 items. The aero drag was certainly a contributor, but your gearing/shifting definitely didn't help your effort. Then of course, your friend yanking your chain was the kicker.
It's hard to put a number on the drag, especially at those low speeds, however gearing is easy. Starting at 60 in 2nd put you near the middle of the power band with a 2.56 rear gear, which is good. Unfortunately, short shifting put you below the bottom of the power band at about 75 mph which extends to 130. By only going to 100 mph, you only got to 5100 rpm.
If you play it again, put the top on and his top up, then in Sport mode let it shift itself and go to at least 110. Take a passenger to video the difference.
It's hard to put a number on the drag, especially at those low speeds, however gearing is easy. Starting at 60 in 2nd put you near the middle of the power band with a 2.56 rear gear, which is good. Unfortunately, short shifting put you below the bottom of the power band at about 75 mph which extends to 130. By only going to 100 mph, you only got to 5100 rpm.
If you play it again, put the top on and his top up, then in Sport mode let it shift itself and go to at least 110. Take a passenger to video the difference.
07-15-2018, 04:14 PM
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I'm seeing it as a bit of all 3 items. The aero drag was certainly a contributor, but your gearing/shifting definitely didn't help your effort. Then of course, your friend yanking your chain was the kicker.
It's hard to put a number on the drag, especially at those low speeds, however gearing is easy. Starting at 60 in 2nd put you near the middle of the power band with a 2.56 rear gear, which is good. Unfortunately, short shifting put you below the bottom of the power band at about 75 mph which extends to 130. By only going to 100 mph, you only got to 5100 rpm.
If you play it again, put the top on and his top up, then in Sport mode let it shift itself and go to at least 110. Take a passenger to video the difference.
It's hard to put a number on the drag, especially at those low speeds, however gearing is easy. Starting at 60 in 2nd put you near the middle of the power band with a 2.56 rear gear, which is good. Unfortunately, short shifting put you below the bottom of the power band at about 75 mph which extends to 130. By only going to 100 mph, you only got to 5100 rpm.
If you play it again, put the top on and his top up, then in Sport mode let it shift itself and go to at least 110. Take a passenger to video the difference.
I should add that this was not a formal pull or anything, just having fun with our respective machines. Now that this has happened though, I think one will be arranged for scientific purposes.
Either way, this has been very educational for me. Who said science and math couldn't be fun?
07-15-2018, 04:32 PM
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The more I think about this and do the math the more I feel I better understand the science behind it. My car might be making 2x-3x the torque as the S, but spinning at only 3500-4000 rpm in 3rd I'm likely putting out somewhere between 225-275hp at these speeds. This is based on a stock LS3 dyno chart I pulled - numbers may vary, but the point is that these hp figures are likely what the S was putting out despite our difference in torque. Add in my ~300lb weight difference and the aero drag, and maybe that makes for a balanced equation.
I should add that this was not a formal pull or anything, just having fun with our respective machines. Now that this has happened though, I think one will be arranged for scientific purposes.
Either way, this has been very educational for me. Who said science and math couldn't be fun?
I should add that this was not a formal pull or anything, just having fun with our respective machines. Now that this has happened though, I think one will be arranged for scientific purposes.
Either way, this has been very educational for me. Who said science and math couldn't be fun?
I wonder if anyone has done wind tunnel tests on an open coupe? It will certainly catch some of the wind, but how much difference does it make between 60-100?
07-15-2018, 04:42 PM
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07-15-2018, 04:43 PM
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