Max speed.
2nd Gear Member
Joined: Apr 2007
Posts: 246
From: Queens, NY
My car did 145mph with my stock 3.55 and intake and tune with 4th gear nearly red line (its set at 6750 in the tune). I switched to 5th gear and the car would not pull much over 150mph. It doesn't have enough torque in 5th as 5th is too tall. Theoretically the car with 3.55 and stock trans can do ~211mph if it had enough grunt @ 6250rpm. Now to only find that extra 300-400hp to get you near 200mph.
FYI, my hood did not shake at all at 150mph. I don't know what people here are talking about.
FYI, my hood did not shake at all at 150mph. I don't know what people here are talking about.
6th Gear Member
Joined: Feb 2007
Posts: 7,635
From: state of confusion
Mid-140's.
Understand that you cannot see the aerodynamic limit that's coming at you when you're only at 110, 120, or even 130. At 140 you're just beginning to "see" the wall.
Here are a few numbers to help the understanding, based on 300 hp/315 ft-lbs, 5M, 3.55's, 3500 lbs car + 175 lb driver. They (and a bunch of other factors) aren't exact for any particular car, but they are good enough to demonstrate what's happening here.
At 110 mph you might gain 1 mph every 55 feet traveled. About 1/3 second. (4th).
At 120 it takes 75 feet and not quite half a second to gain another 1 mph
At 130, 120 feet, 2/3 second
At 135, 160 feet, 3/4 second (4th) . . . . and over 400 feet and a little over 2.0 seconds in 5th
At 140 in 5th, you're looking at 680 feet/3.3 seconds (over 1/8 mile)
At 145, the next 1 mph takes over half a mile and 15 seconds to gain.
At 120 it takes 75 feet and not quite half a second to gain another 1 mph
At 130, 120 feet, 2/3 second
At 135, 160 feet, 3/4 second (4th) . . . . and over 400 feet and a little over 2.0 seconds in 5th
At 140 in 5th, you're looking at 680 feet/3.3 seconds (over 1/8 mile)
At 145, the next 1 mph takes over half a mile and 15 seconds to gain.
The last mph (147 in this particular simulation) takes 2.5 miles and at least a minute and a quarter.
Norm
Last edited by Norm Peterson; Nov 13, 2008 at 07:15 AM. Reason: edited out extra line breaks
5th Gear Member
Joined: Jun 2007
Posts: 2,276
From: Orlando, FL
I think I will end up getting hood pins just in case since I should trap around 118 at the track.
I have heard of some people whose have unlatched and hit the safety latch. That would scare me alot.
If you have never seen it then you are lucky.
5th Gear Member
Joined: Mar 2007
Posts: 2,031
From: Orlando, FL
Norm has a lot of great info. One thing I have not seen on here that hasn't been taken account of is your trap speed. If you trapped 122 mph, this is NOT your speed when you cross the finish line. Trap speed is the average speed you do for the last 66 ft (1/20) of the track. So you are actually crossing the finish line at a higher speed that what your trap speed indicates. I think 4.10s would be slightly too much gear.
edit: also you would be seeing full boost more quickly, which is also going to net you a little more mph.
Norm, How do we get the text to justify left?
edit: also you would be seeing full boost more quickly, which is also going to net you a little more mph.
Norm, How do we get the text to justify left?
Last edited by AmericanSpeed; Nov 13, 2008 at 10:23 AM.
6th Gear Member
Joined: Feb 2007
Posts: 7,635
From: state of confusion
I had thought about the speed trap measurement thing (it's about a 1 mph effect as far as the main thread discussion is concerned).
Anyway, question:
Do the traps time from 66 feet before the finish line to the finish line or from 66 feet before to 66 feet after? Or is it something else entirely? I seem to recall some NHRA discussion about this, but not the outcome. I found the following link that I can't look at it here at work (it's "Sports-related" and gets filtered out)
Norm
Last edited by Norm Peterson; Nov 13, 2008 at 10:37 AM. Reason: L J
5th Gear Member
Joined: Mar 2007
Posts: 2,031
From: Orlando, FL
It is 66 feet before the finish line. I'm pretty sure back in the day it use to be after, but they changed it for safety reasons
this is from the NHRA site:
Here is the glossery term for "speed trap" from the NHRA site:
Glad to see the site left justifying the text again.
this is from the NHRA site:
The start-to-finish clocking is the vehicle's elapsed time (e.t.), which serves to measure performance. Speed is measured in a 66-foot "speed trap" that ends at the finish line. Each lane is timed independently.
Speed trap: the final 66 feet to the finish line where speed is recorded.
6th Gear Member
Joined: Feb 2007
Posts: 7,635
From: state of confusion
Thanks, Speed.
I agree that with it being this close that it might be better overall to stick with the 3.73's and look to future developments elsewhere to be able to use them more fully. Really splitting hairs might be to try 3.90's for a little more "oomph" than 3.73's and a little more margin against the rev limit. Either way (4.10's or 3.90's), what's a marginally higher trap speed worth right now?
Norm
I agree that with it being this close that it might be better overall to stick with the 3.73's and look to future developments elsewhere to be able to use them more fully. Really splitting hairs might be to try 3.90's for a little more "oomph" than 3.73's and a little more margin against the rev limit. Either way (4.10's or 3.90's), what's a marginally higher trap speed worth right now?
Norm
Thread Starter
4th Gear Member
Joined: Apr 2007
Posts: 1,118
From: Virginia
Well I think the difference between my 3.73s now and the 4.10s would be low 11s (where I'm at now) and high 10s (where I want to be before I up the boost more.) In order for me to up the boost more its going to be a bit of work. I would have to convert to the 8 rib which isn't easy with the aftercooler and s/cer in the way. I think the rest of the car is ready, but the wallet isn't right now. Maybe I will add a 100 shot or something, thats not to crazy of a project.
4th Gear Member
Joined: Mar 2006
Posts: 1,470
From:
My car did 145mph with my stock 3.55 and intake and tune with 4th gear nearly red line (its set at 6750 in the tune). I switched to 5th gear and the car would not pull much over 150mph. It doesn't have enough torque in 5th as 5th is too tall. Theoretically the car with 3.55 and stock trans can do ~211mph if it had enough grunt @ 6250rpm. Now to only find that extra 300-400hp to get you near 200mph.
FYI, my hood did not shake at all at 150mph. I don't know what people here are talking about.
FYI, my hood did not shake at all at 150mph. I don't know what people here are talking about.
Approx. 200 mph is the top theoretical speed of an S197 GT in 5th at 6250 rpm with 3.55's and stock tires.
Picky, picky, picky!