At roughly what RPM's I should be changing gear to get optimum acceleration or how to figure it out from a torque / power graph.

Some people seem to think I should change gear at the readline and others seem to think I should change gear at 5252 RPM's. Then some say a little over 5252. I really don't know when is the right time.

Cheers.

 

Anyone?

 

would't it be a bit dangerous to always be changing up at 7000rpm??

 

Most of my friends change around the 6k mark in there blob eyes, and this works for them with the gearing and torque.

However the jdm classic gearing proves to like and need the higher rev range all the way up their, I know this will make you cringe but the classic jdm pulls hard and usefull right upto the 7.2k and limiter.

obviously the torque and power delivery is some what different on the two models, the gearing on the JDMS is so short you need to utalize the revs

I seriously think gear changing should be guaged by the road and speeds, I don't think it makes you fast to change on the limiter each and every time.

To keep good corner speed up the decision has to be down to experiance and what the bend throws at you, some times short shifting to put you in the right rev range and torque range at the right time.

it all just seems to come together for me, sometimes i hit the limiter on the exit of a bend when trying to get good exit speed, sometimes a quick short shift to use the torque.

To get the best out of my car in a straight('ish) line I am up around the high sixes sometimes hitting the limiter

 

Don't really know. That's why I'm asking. I've never been given an proper answer on this, which is strange given the number of professional racers on here.

 

If you change at the 7k red-line then you will be at around 5.5k-6k revs in the next gear, and have missed out on lots of the flat torque curve and be into diminishing power. By changing at around 6k you will arrive in the next gear at 4k-ish and thus be in building power at the start of the torque flat. You could argue that the gearchange will lose you around 1/2 a second, so in a racing situation you could be better to hang on to the gear longer, but ultimately it is quicker to keep in the torque/power band.

 

What he said

 

Scooter, this is my power graph after the remap in January at Powerstation.



After seeing that, I sat outside and changed my shift light to 5000 rpm. After that, you can see the curve starting to drop down, so for my car, that's the optimum point to change gear, if I change any later, I'm losing power, earlier, and I've not got the most out of it
Each car is different though, and without a rolling road session, you'd only be able to guess what your optimum point was.

 

Yes but what i'm saying is that you should be able to 'feel' when to change up.

Every car/driver combo is different, so nobody will be able to give you the answer that you're looking for.
I come from a kart/formula ford background, but I can't tell you the rpm value when I change up in my 277bhp uk turbo.

I'm too busy looking down the road!

 

cw42 I completely disagree...

UK STI: (02-05)
1st 3.636 - change at least at 6875, drop in at 4491
2nd 2.375 - change at least at 6875, drop in at 5098
3rd 1.761 - change at about 6800, drop in at 5198
4th 1.346 - change at at least 6875, drop in at 4960
5th 0.971 - change at 6750, drop in at 5255
6th 0.756

1-2 and 4-5 (and probably 2-3) it is probably worth changing higher than the graph is plotted to, this is why I like a RR graph that goes to red line.

Your highest average power at wheels will come from being around the middle of the power peak as much as possible on that graph since it is roughly symmetrical around 6000 RPM.

 

This is getting really sad. Just drive the bl*ody car!

 

If he changes from 4th to 5th at 5000 RPM he'll be dropping to 3607 RPM and dropping from 205 WHP to 130 WHP. If he changes at 6875 he'll be dropping from 205 WHP to 205 WHP. Think what that does to the average power. If you rely on the feel of a dropping torque curve you'll feel reducing g-force as you go up the gear, but how do you know it won't drop further from selecting the next gear now or waiting a bit longer?

Generally it is sensible to rev it a little bit beyond peak power as I've shown, not change up as soon as the torque starts falling.

It is because of the huge errors in this thread that I took the time to contribute. I'm sorry that is "sad".

 

Is this aimed at road or track use?

 

A very sensible and valid response mate,

There are so many variables on whats best, knowing the road one of the most important, Track days are good for playing with different styles of driving and gearchanging as the track does not change lap by lap, but the way you drive it can.

The power graphs are good to see what your cars acieving on the rollers, but rollers are a far cry from the ups and downs of the roads on what we drive

IMHO 5k is far to low if were talking enthusiatic driving, At 5k on the road mine would still be pulling hard right upto 7k (94WRX JDM)
High sixes for me every time then it drops in perfect for the next gear still on full boost and pulling strongly

 

Thanks for the excellent insight john. So at what level should I be setting my shift light then based on my graph?

 

6800-6900 as a general rule from the looks of your gearing/graphs, how about setting the buzzer to 6500? Different if you are going to be using a lot of part throttle through bends, then you might want a few revs to spare, but for best straight line acceleration it is average power at the wheels you need to be highest.

 

When on a mapping session with AndyF, he commented i should change about 6k to stay in the band better, as i was going much closer to the red line.

Since, i've reduced my rev limiter to 6200, which equates to about a 6400/500 gear change i would've thought.

That feels right for the car to me.

Lots of variables, but you'll know how you drive & how the car feels.

(All this talk, i haven't driven the scoob for two weeks. I think a drive is on the cards tonight!)

 

I have a MY03 WRX PPP, i tend to change gear around 6,200 rpm.

 

I agree hitting the limiter or changing gear on a bend are but on tightish but long opening out corners like Brands Hatch Melbourne loop sometimes hard not to do, even more so with a 6 speed box.

Reaction time in 1st that 6200 could be 7200 and 6th 6200 could be 6300 , hence why I'm not keen a single setting shiftlight.

That's the important thing


IMHO

Tony

 

The re-entry point depends on how quickly you change. If its slow you will drop further down the rev range reducing average power. 1-2 and 3-4 should be quicker than 2-3 because of the dogleg. A slow changing driver should go higher up the rev range but thus reduces average power. On an aggressive drive you'll want a different shift point. Each change should be assessed on a case-by-case basis

 

Not thought about that. Good point. Have you got a 7sp box?

I don't floor it in first anyway. In 2nd it's all too fast to even get a glimpse of the speedo.

 

I'll give that a go for a while John, cheers

 

CW42; what's the spec of your STI..?

 

This has been a really useful discussion and I thank everyone for contributing.

cw42. Just seen this graph was from January. Is your car back to normal figures now? Was the dip in power purely down to the air temp on the rolling road day?

 

I don't pay too much attention to where the rev counter is, in 1st and 2nd the revs are climbing so quickly, it's probably better to get used to the engine note signifying when to change than watching the counter.

But I do know that sometimes 1st to 2nd results in a dive and loss of forward momentum for the first second in 2nd gear, and sometimes I really nail it and the power is almost seamless. I'll have to pay attention and see if it's speed of shifting the stick, or hitting the sweet rpm spot (or both) that's the reason.

 

my03 sti 53 reg uk
tek 3 remap
3" milltek with sports cat downpipe
k&n panel filter
3 port boost solenoid
whiteline anti-lift kit, front and rear anti-roll bars, rear uprated drop links


scooter, yes

 

Use the force man. Feel it.

 

I haven't had it mapped or actually know a huge amount about the dynamics of driving Subaru's, but my wrx feels faster and I feel I get more out of it if I change at (about) 5500rpm, that puts me dead on 4000rpm in the next gear, in every gear. This feels the best way for me after driving it for a year, I'm sure people will disagree and say 'hit the limiter' or whatever, but my car feels a little flat after about 5700 so I at least feel that I'm making the most out of the power range for my car at least.

Obviously i don't do this very regularly, only when I'm playing with a Skyline or something on the A34 or when I fancy a play!!!!

Dan.