BlackShadow

I usually race other cars just using D4. But I decided to try out the SS mode last night. I had a clear straightaway for like a mile or so. I put it in SS and took off. I got up to the rev limiter and past it a little for like a good 5-10 secs when the fuel cut off. Before it cut off, I got up to 120+ (~122 mph) in 3rd. I thought that was pretty good for 3rd gear. What do you guys think?

FYI, there were only a few cars around so I did not endangered anybody.

city001

u r going to destroy the tranny!!!

city

they should set the redline at 7.5 or 8 for us

FKNA

How is that going to destroy the tranny since the car has the fuel cutoff when rpms are too high.

FKNA

BlackShadow....there for a while I was only using drive mode when traveling past 100mph. But I had also noticed that once I reached 100mph, the acceleration wasn't all that great. Others turned me onto using SS mode and I sure do like it. Previously I was only using SS mode to zip in and out of traffic.

TypeSDragon

Binh, I just don't believe you that you drove your car that fast. How come you never speed when you are driving with us.

RAdams

Your top speed in a particular gear can be calculated fairly easily. Basically, if you calculate the circumference (outside diameter) of the tire and then calculate tire RPM (as a function of engine RPM, Gear Ratio and Final Drive Ratio) you can multiply the two and solve for MPH. There are 4 things you need to know:

Maximum RPM, gear ratio, final drive ratio and tire size. Obviously everyone with aftermarket wheels will have to plug their tire size information into the following equation. For the purposes of this discussion, let's use 7000RPM (the published fuel cutoff of a TL-S), 3rd gear and the stock tires/wheels on a TL-S. To find wheel speed in RPM, we do RPM/Gear Ratio/Final Drive Ratio

7000/1.021/4.428

We get 1548.334 wheel RPM. Let's go ahead and turn this into RPH (revolutions per hour) by multiplying by 60 since we ultimately want to solve for speed in miles per hour, not miles per minute. We get 92900.05 RPH, so we'll use 92900. Now we need to find out the circumference of the tire so we can see how far the car travels in one revolution of the tire.

A tire's size is expressed in the following format: 215/50/17. 215 is the tire's width in mm, 50 is the aspect ratio (the ratio of the tire's height to the tire's width) and 17 is the wheel diameter. First, let's convert mm to inches for simplicity's sake by multiplying the mm measurement by 0.039. The tire's width is 8.385 inches. Now, to calculate the tire's height (distance from the inner part of the tire that touches the wheel to the outer portion of the tire that touches the road) by taking the aspect ratio (in this case 50, as in 50%) and multiplying that by the tire's width.

8.385 inches * .50 = 4.1925 inches

Now we can calculate the diameter of the wheel/tire combo. Take 4.1925 inches, add the diameter of the wheel (17 inches) and add another 4.1925 inches for the "top" of the tire and we get

4.1925 + 17 + 4.1925 = 25.385 inches.

As we all remember from school, circumference = pi*diameter, so we have

3.14159 * 25.385 inches = 79.74926 inches. Let's round that to 79.75.

Almost done, I promise. Now let's convert that figure to miles. There are 63,360 inches in a mile, so we take inches/63360 to get the circumference in terms of miles (again, since we're looking for miles per hour)

79.75/63360 = 0.001259 (rounded, of course)

Now that we have wheel speed in terms of RPH and tire circumference in terms of miles, we simply multiply the two numbers

92900 RPH * 0.001259 Miles = 116.9611 MPH. Yay! Now you know that a TL-S with stock wheels/tires at 7000 RPM in 3rd gear is going 116.9611 MPH. You can use this newfound knowledge to impress the ladies.

As a disclaimer, I'll say that this formula is pretty accurate although it doesn't take into account the deformation that occurs on tires at high speeds that can ultimately affect the circumference -- it's assumes that the circumference is constant. Also, the more rounding you do with your figures, the further away from dead accurate you will be.

Sorry for the long post... I'm sitting at work nursing the printer (read: refilling the paper tray every half hour) waiting for an 11,000 page print job to complete and I figured writing this up would be more fun than just staring at the wall.

ChucksCL-S

RAdams that was the best, almost like horsepower comes from brainpower. Nice job.

Mstyle

LOL....Anyone gone higher than 60 in 1st.....Just wondering...SS is sooo much faster especially when you are in 2nd....

BlackShadow

Are you talking about the guys in the city? If you are then you're crazy. I have to speed to keep up with those crazy guys (they know who they are). And the times that I do hang out, you are never there.

RAdams, thanks for the detailed explanation.

ALFAV6

I hope your not talking about us .... since you went to 120 i assume you raised your car back up... if not i would love to see how low your car got when you hit 120:p

rominl

plus i heard that the speedometer is not as accurate when you change your rim and tire size?

FKNA

Radams....that calculator is too complicated. I have a much simplier calculator on how to determine top speed in each gear.

1) insert key into ignition

2) start car

3) put gear shift in SS mode

4) push gas

5) read rpm gage when fuel cut off engages

6) change gears and repeat steps 1-5

RAdams

It only seems complicated because I inserted a lot of commentary and explanation between each step. It's actually pretty simple. I tried to make it as easy as possible because some people are still under the idea that using SS or manually shifting will allow you to go much faster in any given gear when that is not true. My point was that every gear has a pretty finite speed that it will allow the car to go before you have to shift.

BlackShadow

Of course not, you guys always obey the speed limit.

BTW, I haven't raised up my car yet.

Acura3200

I can only hit about 104~ in 3rd gear

BTW: What can you get in 5th

( j/k )

BlackShadow

I can get up to 160+ mph in 6th. :p j/k

ALFAV6

i am glad you notice...we don't speed.. everyone just drive slow thats why it seem like we're speeding

FKNA

The TL's automatically shift from first to second in SS mode, right?

BlackShadow

How dare those people drive under 100 mph.

BlackShadow

Right on 00+ TL and TL-S. I can shift from 1st to 2nd in my 99 TL.:p But I read somewhere in the CL-S forum that somebody manually changed from 1st to 2nd (it was a while ago).

initialD

Is your TL 99?Why I asking you that because I just tried it lastnight it cut before 180kmh about 110mph in 3rd gear with my 00TL.Maybe because 4sp has taller gear ratio,that why they can reach 120mph in 3rd??Tell me what you think.

AzNTL

I held 3rd gear to somewhere around 115 and let go and upshift. At that speed my 3rd gear is gone i can tell. take 120 minus that from the error due to the rims and ill have around 115or so

BlackShadow

IMO, you are correct. Remember that the 00+ TL and TL-S's 4th and 5th gears are overdrive gears. Meaning it will have shorter gear ratios for improve gas mileage because it has 5 gears instead of4.

Yes my TL is a 99 and that's probably why I can hold 3rd gear a little longer than the 00+ TLs due to the fact that I only have 4 gears. I also held 3rd gear up to 7000 rpms for a good 5-10 secs before the fuel cut off.