Ideal RPM for gear change... I know but...

14th June 2007, 01:41

Ok i have read already that its different for various cars and depends on many other variables etc but...

I was driving my car myself and just before the red-bit i changed gear and it was quick but when i went just inside the red-bit and changed it was alot faster because it still picked up speed when i changed to 2nd gear.

I told my brother this and he said he wouldnt do that again because going into the red bit can fuck my enginge quite easily. Obviously i wouldnt do it all the time but every now and again i would like to get the fastest speed possible but without fucking my car

So any advice on RPM thats good and safe 2 shift gear at? 1.1 saxo desire

14th June 2007, 01:47

i dont know exactly what revs is the optimum for gear change in a 1.1 but am pretty sure it aint in the red

14th June 2007, 01:58

optimum gear change in a 1.1 is 5200 RPM

14th June 2007, 01:58

Quote:

Originally Posted by craigy_87

i dont know exactly what revs is the optimum for gear change in a 1.1 but am pretty sure it aint in the red

correcto man

without going all techno on your ass just change at 5500rpm (peak hp) no point in going further.... sounds like your not giving much care to the engine, chill out man. dont boot it from cold, wait until the water temp is at normal. then have fun (within reason)

14th June 2007, 01:59

Quote:

Originally Posted by snewham

optimum gear change in a 1.1 is 5200 RPM

Quote:

Originally Posted by adsayer

without going all techno on your ass just change at 5500rpm (peak hp) no point in going further

oooooo controversy... I just pulled the figure off the net? is 5200rpm for defo?

14th June 2007, 02:21

Quote:

Originally Posted by adsayer

oooooo controversy... I just pulled the figure off the net? is 5200rpm for defo?

unless people have been spouting shite to me yer lol

14th June 2007, 02:26

Quote:

Originally Posted by snewham

unless people have been spouting shite to me yer lol

probably. seem low like not far off mine...

I've got the specs at home... I post them up later.

14th June 2007, 02:47

i tend to find that just passed 6k-rpm makes alot of difference rather than short shifting as when u change up a gear u land at the peak amount, not sure tho...

14th June 2007, 02:55

Quote:

Originally Posted by b0t13

i tend to find that just passed 6k-rpm makes alot of difference rather than short shifting as when u change up a gear u land at the peak amount, not sure tho...

different engines, different rpms darling.

14th June 2007, 03:28

on sum nites iv been known to take her to 7 / 7.5k rpm lol

14th June 2007, 09:41

believe it or not the optimum gear change is a different rpm for each gear

14th June 2007, 09:43

Quote:

Originally Posted by redbullet07

on sum nites iv been known to take her to 7 / 7.5k rpm lol

7,5? My VTS revs to approx 7,250 - did you have a remap or your limiter raised?

14th June 2007, 09:47

For my little 1360, its when the shift light comes on at 8250 rpm....... LOL

14th June 2007, 09:48

Videos of In car entertainment please Foggy!

14th June 2007, 09:48

Quote:

Originally Posted by Foggy

For my little 1360, its when the shift light comes on at 8250 rpm....... LOL

show off

14th June 2007, 13:00

Quote:

Originally Posted by adsayer

correcto man

without going all techno on your ass just change at 5500rpm (peak hp) no point in going further.... sounds like your not giving much care to the engine, chill out man. dont boot it from cold, wait until the water temp is at normal. then have fun (within reason)

100% correct mate

Quote:

Originally Posted by KamRacing

believe it or not the optimum gear change is a different rpm for each gear

Sorry to deny you, but the optimum gear change (if you want acceleration) is when you have the top engine power. The engine torque or power doesnt depend on the gearbox. If that was so, the dyno test was made in different gear and not in the top gear or in the most direct gear (the gear after top gear)

14th June 2007, 15:10

Ok, thanks, so going into the red bit is bad tho correct? As i said b4 its not as if i drive like that much, very limited, never actually lol. I also take alot of care of my enginge, i was just curious incase i decided to actually try n race it around abit. I wanted to make sure i wasnt going to damage anything before i knew what was goning on.

Atm the moment i;m under the impression its 5,200 - 5,500?

14th June 2007, 15:19

Quote:

Originally Posted by stevcatristicas

Sorry to deny you, but the optimum gear change (if you want acceleration) is when you have the top engine power. The engine torque or power doesn’t depend on the gearbox. If that was so, the dyno test was made in different gear and not in the top gear or in the most direct gear (the gear after top gear)

gearing and therefore which gear you are in does affect your torque. The dyno test is done in the gear nearest a 1:1 ratio. Try doing a dyno run in each gear and then ask yourself why there is a difference. You should not be looking at engine revs when its what is happening at the wheels that provides the forward movement.

14th June 2007, 16:12

It wont be the same for each car but I’m sure it depends on the power curve and gear ratios … especially on the 1.1 as it has a longer 5th gear so I’m sure it would be better to hold it in 4th till the red line than go into 5th as you will be getting more torque to the wheels for a bit longer

It would be interesting to see a graph of speed vs time through all the gears for both cases – changing at peak power and holding to the redline

14th June 2007, 17:30

Enter the sayer....

I didnt really want to go all out but nevermind.
Kamster is right... the 'shifting rpm' will vary depending on gear chosen.

power in this instance means NAFF all, nothing whatsoever. Its torque, and more specifically the torque profile across the rpm range.

this is the apparent rough torque and power profile of the TU5JP4 (VTS/GTI) engine (doesnt look right to me but nevermind)

The blue curve is the torque...

and i cant be arsed to say anymore but ask questions if need be...

the torque created by the engine goes through a 'Torque Multiplier' (Gearbox) hence why 1st gives more acceleration than 2nd and second give you more acceleration that 3rd etc etc.

this means that each gear produces its own Torque profile across the rev range.

towards the high end of the engines rpm you can see that the torque begins to drop. they'll be a point where say... the torque profile of the 2nd gear goes lower than the torque profile of 3rd gear. at that point you want to shift...

i made that crap. sorry.

14th June 2007, 20:15

Quote:

Originally Posted by KamRacing

gearing and therefore which gear you are in does affect your torque. The dyno test is done in the gear nearest a 1:1 ratio. Try doing a dyno run in each gear and then ask yourself why there is a difference. You should not be looking at engine revs when its what is happening at the wheels that provides the forward movement.

Sorry again, but you can do a test in 1st gear if you want to. The dyno will calculate the mechanical loses and add them to the power at the wheels… It can be done in any gear...

But this is not what we are discussing here.

I have a 1.1i Sx, and when I want to go faster, normally I change gear redline in, because when I change gear the engine is already in almost maximum power.

My gear box (standard) in 4th gear the engine cuts off at 160km/h (+/- 96mil/h). If I change to 5th, it drops to 150km/h (+/- 90mil/h). I don’t know the top speed because I’m afraid to do it, but I know that is more than 180km/h (+/- 108mil/h).

14th June 2007, 22:41

Good work Mr Sayer!! Where did you find the graph it doesn’t look quite right to me either? And what’s the crack with the CEE?

The 1.1 will hit the limiter at approximately 125mph in 5th thought I very much doubt it will ever get there!

14th June 2007, 22:49

Quote:

Originally Posted by Joesnow

Good work Mr Sayer!! Where did you find the graph it doesnt look quite right to me either? And whats the crack with the CEE?

CEE dude? i searched google images i think 'torque profile TU'

for the graph... just to give an idea more than anything.

14th June 2007, 23:04

Ahh rite no worries! Just the scale on the graph was just wondering what it stands for! I guessed its power on the left, torque on the right and rpm on the bottom. Just never seen CEE before!

15th June 2007, 09:20

Quote:

Originally Posted by stevcatristicas

Sorry again, but you can do a test in 1st gear if you want to. The dyno will calculate the mechanical loses and add them to the power at the wheels It can be done in any gear...

But this is not what we are discussing here.

I have a 1.1i Sx, and when I want to go faster, normally I change gear redline in, because when I change gear the engine is already in almost maximum power.

My gear box (standard) in 4th gear the engine cuts off at 160km/h (+/- 96mil/h). If I change to 5th, it drops to 150km/h (+/- 90mil/h). I dont know the top speed because Im afraid to do it, but I know that is more than 180km/h (+/- 108mil/h).

it is relevant in a roundabout way because a RR will highlight the torque differences in every gear and therefore shows that your optimum power band is not constant in every gear. The reason for doing the RR in fourth is to get that ratio or near 1:1 which will mean your torque and bhp curve cross at 5252 rpm so you can take a stab in the dark at working out your bhp at the flywheel. If you do it in a lower gear your bhp calculation for the flywheel figure will increase which is not correct.

15th June 2007, 19:54

so i still cant find an answer? red zone = broken enginge? 5500 or 5200?

15th June 2007, 21:06

Quote:

Originally Posted by lighters

so i still cant find an answer? red zone = broken enginge? 5500 or 5200?

No my 1.1 cuts off after the start of redline and the engine is stock, and still didnt brake in 8 years.

I still with my theory and spoken to my school mates and all of them agree with me that the ideal rpm is a little bit after the top engine power. So is at 6200 rpm

16th June 2007, 00:06

Quote:

Originally Posted by stevcatristicas

No… my 1.1 cuts off after the start of redline and the engine is stock, and still didn’t brake in 8 years.

I still with my theory and spoken to my school mates and all of them agree with me that the ideal rpm is a little bit after the top engine power. So is at 6200 rpm…

usually by peak power the torque will be a on steep downward slope... i'd change just before peak tbh if we're keeping things simple

16th June 2007, 16:51

Quote:

The 1.1 will hit the limiter at approximately 125mph in 5th thought I very much doubt it will ever get there!

lol true.. my gf's 1.1 106 (same engine as the saxo 1.1).. has done 115mph. standard.. with 2 ppl in it.. and it took aaages to get from 100 -> 115.. mustav biin lyk 30 seconds or something.. was fun trying to get it up to tht though tehe..

16th June 2007, 22:48

Ok i will test myself going into the red a little bit etc, just didnt wanna brake (intended sp) my car. I am also sure it is faster at 6000 ish because the one time i did test it my car went very fast when i changed my gear and picked up speed

16th June 2007, 23:37

wats the optimum for a black top vtr??

16th June 2007, 23:38

whats the potimum for a black top vtr?? cheers

17th June 2007, 00:04

Quote:

Originally Posted by james_roxburgh123

whats the potimum for a black top vtr?? cheers

I didnt know that, but has Itsafastworld85 said in here, the blacktop has 90bhp, so like the Revue Technique Citroen Saxo says, the max bhp is at 5600 rpm, so is a little beat upper than that

17th June 2007, 03:36

If you give me a decent torque/rpm graph for the vtr.. ill have a bash at working out the optimum shift point for you.