GMAN S2000

are S2000's faster from a dead stop or a rolling start..?

Shadow_S2K

Rolling start, in VTEC

ruexp67

What ISN"T faster from a rolling start?

Overcoming inertia is a major place that power is used in any thing. Remember Newton? "Things at rest tend to stay at rest." Physics 101.

Also 5-100 MPH is accel of 95MPH, 0-100 is accel of 100MPH. 95 is less than 100.

hoof

However, starting from a stop allows you to build up engine inertia (via revving the engine and dropping the clutch), which can act as a small momentum "battery" much like a flywheel. The act of slowing the engine down to wheel speed when the cluch is sidestepped gives the car a bit extra acceleration at the really slow speeds.

It's much much harder to use this trick when moving, since it requires disengaging the clutch (so you can rev the engine w/o accelerating), and the car tends to slow down. But in theory, you could get the car going to 10mph, push the cluch, rev to 7k, then at 5mph sidestep the clutch, and get a better 5-100mph than a "normal" start.

I wonder if anyone has ever tried adding a really heavy flywheel to a car engine to increase the inertia transfer at launch.

mjw182

It depends on the speed of the rollings start. 0-60 is usually faster than 5-60 according to magazines. The only exception I can think of is the SRT-4.

ruexp67

hoof, don't you think the extra speed you ALREADY have would make you faster than starting from a stop? No matter what kind of interia you have going. What would be the car's 0-60 time, then 5-60 time? It is going to be faster on any car 5-60. Or if you did distance, imagine running the quarter from a dead stop, or taking a rolling start. I have to believe the guy with the rolling start is going to win (all things being equal, I am not talking Yugo vs. Enzo here.)

I'll take having actual speed, over the potential to get it any day.

nodisguise

If you're rolling in 1st gear at 5mph, your revs are going to be low as hell. It makes sense to me that launching a car (spinning the wheels a bit and getting into the upper RPM range more quickly ) will yeild a faster 0-60 time than a 5-60 achieved by stomping on the gas at 5mph.

The only instance I can think of where a 5-60 is faster is when the particular car being tested has serious traction issues making it extremely difficult to get off the line efficiently. I suspect this is the case with the srt-4, though I would think even that car should probably 0-60 faster than it would 5-60.

My old turbo civic offers a good example. If I was rolling in gear at 5 mph and stomped on the gas, not much of anything would happen until I got into the higher revs which would take a while. However, If I launched, consequently spinning the tires to where I made more power (and keeping the engine loaded to make it easier to build boost, but I won't bring this into the equation as it will complicate things), I would reach 60 well before I would have from a rolling start.

On the other hand, if you launched from a 5mph roll (not typically how 5-60 tests are done, I believe), your 5-60 time would probably be faster.

hoof

What nodisguise said

Meeyatch1

wickerbill

5-60 MPH is almost always slower than 0-60. Here are some numbers from the latest Car & Driver roadster comparison test. Numbers are 0-60 and then 5-60 times.

Audi TT 6.9 8.3
BMW Z4 5.3 5.9
Honda S2000 5.4 7.0
Nissan 350Z 5.5 6.3
Porsche Boxster 6.0 6.7

I looked through the other road tests in that issue of C&D and none of the cars they tested had a faster 5-60 time than 0-60.