What rpm to shift?

[Kevdog]

I've got 2 tibbies and I like making em go fast.

Any tips on launching/shifting spots? I know sometimes "as high an rpm as possible" isn't always the best option. Is that true with the tibby?

I usually launch at between 3-4k rpm (depending on the competition and how much I love my tires that day <img src=icon_smile_big.gif border=0 align=middle>). I think I shift most gears around 6k rpm (too busy driving to fully look at the tach <img src=icon_smile_cool.gif border=0 align=middle>).

I'm learning the double-clutching/rev matching from another thread (which will really help when I need to drop gears quick and disappear).

Basically just looking for any tips to go faster (other than modding the car.. not an option atm <img src=icon_smile_dissapprove.gif border=0 align=middle>).

Thanks guys

2000 Red Tiburon
1999 Blue Tiburon w/Shark Wing

[cougart]

Not sure on the best shifting spots for the tibby. If anyone has any stock tibby dyno plots or if your tibby is modded and you have dyno plots post them. I personnally try to launch at about 2.7k on my tibby, that may not be the best but you want a good start that doesn't drag the car down and doesn't spin the tires, takes alot of practice to get it right

2001 Tiburon
Black with Blacked out windows
Alpine cd player
More mods to come slowly

[Random]

The tiburons torque curve is nearly totally flat. You want to shift as LATE as possible to ensure you are as high as possible in the next gear, and to get the most out of the gear you are in.

The rev limiter is 6750, so you should take your tibby to 6500 or a tad higher before shifting. Shifting at 6000 RPM WILL slow you down.

Wheel spin while looking cool to some, also slows you down. The perfect lauch has no wheel SPIN, but it does have wheel SLIP. When the wheel SLIPS, it still maintains traction, but the wheel is spinning slightly faster than the forward motion of the car. Wheel SPIN is when the front tires loose traction, and rotate significantly faster than the forward motion of the car.

A perfect lauch would have no wheel SPIN, but would have wheel SLIP.

Some people like reving to 4000, then slip the the clutch out rather slowly. Others like reving to 2500, then "dumping" the clutch rapidly...or any combination inbetween.

You need to practice and see what works best for you. I personally seem to do best with clutch slip. I can control wheelspin with the clutch AND gas, and give more or less of either to keep the car moving and the wheels from spinning. With a clutch "dump" usually, you will either spin the wheels, or bog the engine.

The moral of the story is practice, practice practice.

Leave it to Random to Needlessly complicate things.

[cougart]

thanks random, I didn't know the tibby had a fairly flat torque curve<img src=icon_smile_clown.gif border=0 align=middle>

2001 Tiburon
Black with Blacked out windows
Alpine cd player
More mods to come slowly

[Random]

100 Ft/lbs at 2200 RPM, peak of 117 ft lbs at around 4200 RPM. Very flat.
<img src="http://www.teamsr.org/ForumLinkedImages/dyno_runs/RandomSpecialCAI_Dyno_01.jpg" border=0>

Leave it to Random to Needlessly complicate things.

[4doorGL]

Hehe...Random, remember when we tried graphing the shifting points? They don't even come close to hitting each other.

Pretty much, just shift before the torque falls off at around 6200.

--------------------------------------------
I drive a slow car.
0 to 60 in 11 seconds (look out!)

[cougart]

good deal, that dynoplot is nice, thanks

2001 Tiburon
Black with Blacked out windows
Alpine cd player
More mods to come slowly

[Kevdog]

Thanks for the tips guys.

Random, I like your explanation of the difference between wheel slip and spin. It sounds similar to what I've been doing, except maybe shifting a bit too soon. I'll have to go practice some more <img src=icon_smile_big.gif border=0 align=middle>

From a more academic standpoint, how does the available horsepower affect acceleration vs the available torque? I know torque (especially low-end) will help a lot on launch. How does the variation in horsepower across the range affect the acceleration?

When I had my Pontiac Sunfire GT it had 150hp and 160ft-lbs of torque. I really noticed in a difference in the launch vs the Tibby's lower torque, but once you get moving the Tibby takes off.


2000 Red Tiburon
1999 Blue Tiburon w/Shark Wing

[SilkySpinZ]

I am going to save this page in my history, thank you Random, you're the best.

[overdrive]

i have a question, it might be a stupid one but o-well. on the dyno results that random posted up how come the max horsepower is only at 116.??, when hyundai says the tib should have 140 horses. just wondering. also would it hurt to get ride of the rev limiter, and if not how about doing so.

mess with the best die like the rest