Two simple questions - Tilted Forum Project Discussion Community

slimpi66y · 10-09-2004, 09:27 PM

Please help me friends

1) going from 3rd to 4th gear, My car manual says the max torque comes out at 4500 rpm, can I shift up gear at that point or should I shift at around 60KM?

2) When I set the cruise control at 120KM, I can use the cruise stick to accelerate, and I can use it to decelerate, I am just wondering when I reduce speed using the cruise control stick, is it applying my mechanical brakes or is it just easing up the gas pedal?

leftturn109 · 10-10-2004, 01:53 AM

i would think that most likly ist just easing up on the gas.

slimpi66y · 10-10-2004, 09:03 AM

Quote:

Originally Posted by lightmayo

Please help me friends

1) going from 3rd to 4th gear, My car manual says the max torque comes out at 4500 rpm, can I shift up gear at that point or should I shift at around 60KM?

2) When I set the cruise control at 120KM, I can use the cruise stick to accelerate, and I can use it to decelerate, I am just wondering when I reduce speed using the cruise control stick, is it applying my mechanical brakes or is it just easing up the gas pedal?

bum bum bum

MSD · 10-10-2004, 08:01 PM

1: Ideally, the transmission should be tuned so that if the torque curve were to be plotted out, it would form a bell curve, with the ratios set so that each shift would take you from the graph's upper point of inflection to the lower point of inflection. This would keep you in the torque band the whole time. For practical everyday driving, you should shift as low as possible. For maximum speed, you should shift so that you begin each gear near the peak torque.

2: Your cruise control does not apply the brakes, it can only control the throttle.

slimpi66y · 10-10-2004, 10:49 PM

Quote:

Originally Posted by MrSelfDestruct

1: Ideally, the transmission should be tuned so that if the torque curve were to be plotted out, it would form a bell curve, with the ratios set so that each shift would take you from the graph's upper point of inflection to the lower point of inflection. This would keep you in the torque band the whole time. For practical everyday driving, you should shift as low as possible. For maximum speed, you should shift so that you begin each gear near the peak torque.

2: Your cruise control does not apply the brakes, it can only control the throttle.

beautiful answers

1）I thought shifting around 4500 (peak torque) make sense, but it seems that the acceleration slows down at around 65KM, I haven't hit 4500rpm in 3rd gear because that will mean a speed of 120ish...., so what's the right thing to do for better acceleration?

2) I got cha

jamessh1 · 10-12-2004, 02:39 PM

well, i would typically think it would be best to shift when your car seems to be running out of steam in the higher rpms, but at the same time you don't want to drop out of your powerband. When racing you are basically trying to maximize your time in your car's powerband, so i personally shift at an rpm that will drop me straight back into my powerband.

eg, I have a hybrid vtec motor that redlines at 8400 rpms. My max torque is at 7300 rpms. I shift at 8000+ rpms to keep my car above the vtec point of 5700 rpms (where my car starts to really make power). If i were to shift at 7300 rpms i would be sitting around 5300 rpms in the next gear which is outside my optimal power range.

10-09-2004, 09:27 PM	#1 (permalink)
slimpi66y Upright	Two simple questions Please help me friends 1) going from 3rd to 4th gear, My car manual says the max torque comes out at 4500 rpm, can I shift up gear at that point or should I shift at around 60KM? 2) When I set the cruise control at 120KM, I can use the cruise stick to accelerate, and I can use it to decelerate, I am just wondering when I reduce speed using the cruise control stick, is it applying my mechanical brakes or is it just easing up the gas pedal?

10-10-2004, 01:53 AM	#2 (permalink)
leftturn109 Crazy Location: Olalla washington	i would think that most likly ist just easing up on the gas.

10-10-2004, 08:01 PM	#4 (permalink)
MSD The sky calls to us ... Super Moderator Location: CT	1: Ideally, the transmission should be tuned so that if the torque curve were to be plotted out, it would form a bell curve, with the ratios set so that each shift would take you from the graph's upper point of inflection to the lower point of inflection. This would keep you in the torque band the whole time. For practical everyday driving, you should shift as low as possible. For maximum speed, you should shift so that you begin each gear near the peak torque. 2: Your cruise control does not apply the brakes, it can only control the throttle.

10-12-2004, 02:39 PM	#6 (permalink)
jamessh1 Crazy	well, i would typically think it would be best to shift when your car seems to be running out of steam in the higher rpms, but at the same time you don't want to drop out of your powerband. When racing you are basically trying to maximize your time in your car's powerband, so i personally shift at an rpm that will drop me straight back into my powerband. eg, I have a hybrid vtec motor that redlines at 8400 rpms. My max torque is at 7300 rpms. I shift at 8000+ rpms to keep my car above the vtec point of 5700 rpms (where my car starts to really make power). If i were to shift at 7300 rpms i would be sitting around 5300 rpms in the next gear which is outside my optimal power range.