Discussion in 'Technical' started by danozgriff, Nov 9, 2005.
When do you switch in 5th?
Under Normal road and Driving conditions on a flat road..
but I got an NA diff so tis a lil different
Sorry didn't think to add an 85+ - Can't edit/change it now sorry.
Depends on the speed limit ....
On normal 60k roads, into 5th at 60kmh - 1st-2nd-5th.
If limit is higher, speed into 5th is higher.
If on a racetrack - NEVER! No racetracks I've been on have a straight long enough to warrant 5th gear ... wish you could do a track day at Bathurst!!!!
1st - 2nd - 5th?
havent you got 3rd and 4th?:unsure:
I change at 80km/h+.
There's a 5th???? hehehhehee
Whenever I hit cruising speed
So yeah if a long stretch of 60kmh road then 60 it is
I shift to 5th at 210 at eastern creek RZM
also on QR (full track) and probably also at phillip Island but im yet to try that track.
...when 4th is bouncing off the rev limiter
9/10 i shift into 5th at 60km, im already in 4th by 40..
i go into 5th downhill at 50km tho..
trying to save the fuel as much as i can..
if im in a hurry ill be in 2nd at 40
Isn't 5th at 50-60km/h a bit low?
Also if trying to save fuel, wouldn't you end up using more by increasing the load on the engine and having to press the accelerator harder to get anywhere?
I wouldn't have thought fuel economy was determained only by how many rpms your doing.
Re: Isn't 5th at 50-60km/h a bit low?
You'd be suprised. If you look at datascan in final drive vs overdrive even at a slow speed like 65 (ie 4th vs fifth in a manual and third vs fouth in an auto), there is a reduction in fuel usage at cruising.
However, under accelleration, you would need to press the gas harder in overdrive, but then again, the ECU controls the fuel usage.
As an example if I am doing 100kmph, locked in third gear (I am auto), and I drop the accelerator pedal to the floor Injector duty goes straight up to 80% and climbs as the revs build, in fourth due to lower engine speed, the injector duty only goes to 50% until the engine speed rises to a point where enough air is passing into the engine to increase the fuel delivery.
:wacko:Anyway, I prefer the feeling of acceleration in third over fourth , as soon as I want to overtake on the HWY, OD is turned off , or if in a manual, I'd be back into 4th or 3rd
Is 50-60km/h a bit low?
Hmm Im glad to see everyones responses...
Most of my zed driving is just cruising, but changing into 5th below 70 feels weird. Not exactly like the engine is struggling, more like the engine is silently carrying a larger burden??
Anyone got any recommended shift points for NA and TT? I try to keep the revs above 2k when I change gears..
Would be interesting to see what is optimal for the engine and also for fuel economy (however these 2 things *should* be one in the same thing?)
just watching your boost/vacuum gauge.
Cool, that clears it up. Thanks
see, i also take that into account, if im at 60km in 5th and a hill shows
up, i'll shift back down to 4th, i dont put my foot more than 1/4 of the way down whislt in 5th at that speed, otherwise it just makes the engine struggle, but pushing the pedal in 1-2cm to keep the speed the same, or slowly increasing the speed is fine, and as the speed climbs i can put my foot down further, ive found it to be a great way to save fuel, also dont let the boost hit positive.
ive got these shoes at home, i call em my fuel saver shoes, they are big clumsy looking things and when i drive part of the shoe hits the plastic near the accel pedal and wont let me push it any further.. quite cool
Re: Isn't 5th at 50-60km/h a bit low?
a question for the tech savvy ones.
in a tt zx, say you're doing 80 in 5th and you boot it, boost winds up forcing more air into cylinders. wouldn't the injector duty shoot straight up to stop the mixture from leaning out, which in turn would make it run rich coz the amount air and fuel in the cylinders would be excessive for the engine speed?
or would the ecu limit the injector duty and let it run lean? does anyone have a fuel map they could post?
Definately use it at the Island.
You guys make more power than me .....
and I haven't done Phillip Island yet ... one day. I've only done 1 track day with the speed limiter removed, that was Wakefield this year. At Sandown and Calder I've raced using the stock ECU, and the speed limiter comes to effect on 1 straight at Calder, and 2 straights at Sandown. So I have yet to go over 200 on a racetrack dammit!
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