Best time to change gear (rpm)

[Jorrs]

enchanter, can you do mine plz.

160–165 hp (123–127 kW) at 7800 rpm and 120 ft·lbf (162 N·m) at 5600 rpm

20valve ST

[Jorrs]

enchanter ?
ill pay you in rep !

[Enchanter]

enchanter, can you do mine plz.

160–165 hp (123–127 kW) at 7800 rpm and 120 ft·lbf (162 N·m) at 5600 rpm

20valve ST

Again I have assumed the same gearing, body weight etc

15.9 qtr
0-100 8.2 sec

Optimum shift points 8000rpm (I guessed this is its redline ??) in 1st, 2nd and 3rd. 4th and 5th werent calculated. It seems the recomended thing is simply rev the crap out of it

Nurburgring 10min 8sec
Laguna Seca 2min 23sec

[Jorrs]

yeh redline is about 8200 RPM
if i gave you, a exact body weight can u get more exact ?
cos i weigh my car bout once a week, seems to be about, 1080 KGs - 1100 depending on fuel. and gearing is C52, AW11 box, though im unsure of the gearing for them.

[Enchanter]

yeh redline is about 8200 RPM
if i gave you, a exact body weight can u get more exact ?
cos i weigh my car bout once a week, seems to be about, 1080 KGs - 1100 depending on fuel. and gearing is C52, AW11 box, though im unsure of the gearing for them.

he he, ring the poor things neck all the way to 8200rpm. (as recomened by cartest)

The test car weight was 1150kg so down to 1100kg and the raised redline results in

15.7 qtr
0-100 8.1

Nurburgring 10min 5sec
Laguna Seca 2min 22.7sec

[Vios-GT_07]

Oh yea I get what u mean, Im not too worried I heard corolla engines are pretty bullet proof but knowing my luck something will happen haha

with my luck too but i've flogged my 4A-GE as it is.. when i got it, was low on oil and i've redlined it at least twice... after the service i've flogged it at least once everytime i fill up.. now it's got a bit of a misfire so i don't do it as much but they love to rev.... it just feels so right to rev it hard... mine seems to run out of breath after 5000 rpms (relation to the 4800 on wikipedia for max torque).. but it still loves the high revs...

btw... how's ur synchros?? that's the only thing keeping me away from fast gear changes and 2nd gear chirps..

[gerald1]

It all depends on your driving style. If you are river anytime below 3000rpm

i do it just above the peak torque of my engine which according to wikipedia is 3600rpm :-)

toodles
gerald

[-GT-]

Optimum shift points 8000rpm (I guessed this is its redline ??) in 1st, 2nd and 3rd. 4th and 5th werent calculated. It seems the recomended thing is simply rev the crap out of it

he he, ring the poor things neck all the way to 8200rpm.

That's what i was trying to tell you!

[Jorrs]

well when you drive my rolla you feel that the best time to change is right at redline anyways, if your trying to go as fast as you can
but i have also discovered well i feel that its best torque is somewhere a bit lower.

[suss_slide]

i cahnge my gear at around 2500 3000 whne driving reasnably, when i drive hard its around 5500 onwards, these are all guesses tho, cos my car dont have a rev gauge, also changin gears without using the cluth, i have done that too,its never been smooth but if u get that sweet spot it can get smoothish, altho my car is a pos corona and i dont care what happens to it, still doesnt really hurt it that much altho my cars gone already so eh, if yas really want ill provide a video for ya,

[Enchanter]

well when you drive my rolla you feel that the best time to change is right at redline anyways, if your trying to go as fast as you can
but i have also discovered well i feel that its best torque is somewhere a bit lower.

You need to rev it past its peak torque so that the next gear up has somthing to play with. If you changed gear as soon as you passed your engines peak torque the next gear up would be too far below peak and struggle to do much at all until it finally caught up.

Thats exactly what the cartest program will calculate. With bigger engines the program recomends very different optimum shift points, often well below redline.

[oldeskewltoy]

Michael, have a run on a dyno. The RPM where you have achieved max torque, is a great gearshift point, 'cause anything after that is just noise.

cheers Chuck.

Actually... I disagree with this... You shift the transmission when the NEXT gear will be at or near peak torque when engaged.......

[Roundy]

Howdy Guys,

Well got the graphs that i generated in Excel.

I am no excel wiz so they take a little bit of deciphering but basically i estimated the torque at the engine from a Dyno run (based on 30% drivetrain losses for the GT4) and then multiplied it by the gear ratios. So what you have is the torque at the output shaft of the gearbox, and the revolutions of the output shaft at the gearbox.

I didn't go to the wheels because once it comes out of the gearbox it is all fixed multiplication anyways!

First is my graph, The final mark on each one is 7000rpm, with 500rpm increments, so starts at 3000rpm

As you can see, the torque never interesects so going to redline in each gear seems to be best (and in practise at wakefield that seemed true as well, higher top speed at the end of the straight)



The 2nd graph is one of 'The Mongrel'
This demonstrates how with peak power coming on early it is better to shift well before the redline with his current setup.

Once again, 3000rpm is the starting rpm, but only goes to 6500rpm.



So looking at that, 1-2 is best after 6500rpm, and every other change after that is 6000rpm or below.

Anyways that is what i base my gear-changes off, the way i figure it, it is torque at the wheels that dictates when to change gears, not power or where peak torque is, simply because you are making the same power and torque at the engine in 1st and 5th, but accelerate a lot quicker in 1st due to torque multiplication

Cheers
Nathan

[MR22ZZ]

that's great stuff Nathan

now do one for a 4A-GE with C52 gearbox (I think that's the right one)

[Roundy]

that's great stuff Nathan

now do one for a 4A-GE with C52 gearbox (I think that's the right one)

as requested! (got nothing to do at work )

thanx to Garth for the dyno graph

this one is a touch weird, the revs don't seem to be high enough

because the original dyno graph is at the wheels i guesstimate drivetrain loss (so 15% for fwd ) and then have to calculate the revs based on tyre size and gear ratios....which gives me 7200 at peak power, and where the graph stops....which is, correct me if i'm wrong, but too low

anyways, doesn't intersect anywhere so best to shit at redline based on this dodgy lil job



also best way to find out for sure is to drag race and check the mph, i bet shifting just after peak torque you would be quite a bit slower then at redline with this setup

Cheers
Nathan