Took my 550 GT to the Drag Strip

Because I have a history of owning performance-oriented cars and I was curious about my GT, I decided to take a trip to our local drag strip last night to see what my car could do. Here are the details:

Car: 2011 550 GT xDrive, bone stock, 7.9K miles
Weight: 5,025 lb per the scale at the strip, with me in the car
Strip: Bandimere Speedway, Morrison CO, 5,800 feet above seal level, 60 degrees F
Best 1/4 ET and trap: 13.24 @ 105.2 mph

Although I know that turbochargers can compensate for the lower air density we have in Colorado (about 20% less air mass per unit volume as compared to sea level), I was honestly surprised by how well the car ran. I know that some magazines have run GTs in the mid-13s at 105ish, but those tests are always conducted at much lower altitudes.

I made three passes in all, the first two were 13.30 at 104.x. I did manage a 1.894 second 60' time on the 13.2 second pass thanks to the AWD. I can post the time slip if anyone is interested.

Anyway, it was a fun and interesting night, and I thought that readers of this forum might appreciate some data on how the GT runs. Incidentally, a 13.2 second car is considered to be respectably quick at this altitude.

One more thing. There was an X6 M running last night. The owner wasn't launching/driving the car "properly" and was running mid-high 13s at 106 - 107.

Sounds like a good time. I may do a similar night once my car arrives. Thanks for the post.

Nice! Thanks for the info. Been looking for actual 1/4 times around the forums. Quick question, what tires are you running?

Originally Posted by WiseYoda

Quick question, what tires are you running?

My car is equipped with the Sports package and 20" wheels, and I'm running the OE tires. I've never actually looked at them, so I can't say what they are. If you'd really like to know, send me a message or reply to this thread and I'll get the details for you.

BTW, an AWD 550 GT at sea level, driven hard, might be able to manage a 12.9x in stock trim. With the updated 445 hp motor, I'd call it a foregone conclusion.

If the overpressure valve on the turbos is opening, not sure if the altitude really matters...it's stuffing as much air as the engine can handle once that happens. Now, I'm not sure the BMW engines actually have an overpressure valve in them, but most designs do. And, since the air is thinner, there's less wind resistance, and in a turbo engine, it might go faster at high altitudes! Probably not, as the turbos spool up, it would take longer to get to the overpressure situation so it won't be at max boost as long, but don't know.

Anybody know?

Originally Posted by jadnashuanh

If the overpressure valve on the turbos is opening, not sure if the altitude really matters...it's stuffing as much air as the engine can handle once that happens. Now, I'm not sure the BMW engines actually have an overpressure valve in them, but most designs do. And, since the air is thinner, there's less wind resistance, and in a turbo engine, it might go faster at high altitudes! Probably not, as the turbos spool up, it would take longer to get to the overpressure situation so it won't be at max boost as long, but don't know.

Anybody know?

While I'm not familiar with the details of the boost control on an N63, I'm fairly certain that it's done the traditional way, via the turbo wastegates. What I don't know is whether or not the ECU modulates the duty on the WG in an effort to achieve some pre-determined absolute manifold pressure, or if the duty on the WG is simply pre-programmed - or if some other method is used to determine WG duty cycle. At the end of the day, though, it's clear that my car is only slightly down on power compared to a similar car operating at sea level.

Incidentally, because I sit on the brake in the staging lane, and the stock stall on our transmission is about 3,100 RPM, I'm leaving the line at full boost. That's the reason the car comes out of the hole so well. Further, I manually shift the car, as I believe it's advantageous to shift before redline, because it seems that the stock program has a tendency to pull timing or otherwise reduce power slightly between shifts. By manually shifting at about 6300 rpm, I pick up the next gear instantly with no loss in boost pressure (the engine remains under load the entire time) and with no timing retardation.

I should note that I need to test this theory by doing a couple runs where I allow the ECU to shift automatically at redline to see if doing so positively or negatively affects my performance. I see another track day in my future...