when to shift 328i

[noamkrief]

i have a 328ic and wondering what the "recomended" speeds or RPM's that the driver should shift at.

Right now when i'm on a straight level road i shift at 2.5. It seems as if this car has enough power even in low RPMs.

I'm concerened about keeping the engine running good. I know that revving too high is bad, but too low is also bad because you can bogg down the engine.

Also, what would give the absolute best fuel economy?

thanks
Noam

[Turbodefrost]

I'm still confused about why, i'll find out, but my brother is convinced that the absolute best fuel economy would be when throttle is completely floored. And it's not bad for your car to run at high rpms (unless you're revving past your redline, of course).

[TMac325is]

for best fuel economy, shift at 3000-3500.. for extra fun, and to get the most enjoyment from your car at the expense of a dollar or 2 at the pump, rev it to 4500 before shifting

[Hoppy's535i]

shift where it comfortable. best millage isnt when its floored
best milage idealy is when accelerating at you peak point in the power band, but efficientcy is less as you try to get up to that point, and when cruising its obviously lower.

[noamkrief]

here's what i was thinking about shifting for best fuel economy:

It's a two sided dillema really...

Lets say you want to accel to 55mph. You can eaither shift at 2.5 and press lightly on the gas and use an average of about 12mpg as you accelerate to 55 but it will take you for example 15 seconds.

so here we have 15 seconds @ 12mpg


The second way is to accelerate a bit more aggresivly so you can get to the cruising speed faster. I'm not saying floor it but lets say take it up to 3.5rpm, accelerate at around 7mpg on average, but it will only last 10 seconds till you get to 55mph...


Those are all ofcourse figures i just made up but i hope you can see what i'm getting at.

I know I'm picky... If you don't give a @$#$, don't reply.
Noam

[thinair]

I'm with the 'get to your cruising speed quick' crowd. Basically if the limit is 55mph, I'll accelerate fairly agressively until I hit that speed, then shift from 2nd to 5th and set the cruise. Believe it or not, it actually is better on fuel.

[Hoppy's535i]

i do agree with the physics of it.

work= force X time or w/e

so to get to 55mph it will take X for y duration is the same if you do Y at x duration...... HOW EVER

thats assuming there is equal power from the engine. but as we all know engines has power bands. but keeping in mind, more power is at higher rpm, higher rpm = more fuel consumption so... you need to find where you get the best ratio of power to consuption is....


i know what im saying is rambling and probibly wrong...i donno im tired

[noamkrief]

happy535, i think you understand my question.
I'm a pilot so i'm use to the manual having all sort of owesome charts regarding economy, speeds, acceleration etc...

I have the onboard computer and i guess i can test out variouse acceleration methods and see which one gives me the best ecomony to accelerate to 60mph. But just how accurate is this onboard computer? Is there an actua sensor that mesures the exact fuel flow to the engine?

Noam

[Hoppy's535i]

well as a start heres a dyno read out for a 328

i only know the general basics of how to get what you need but i think i do under stand ur question. check your owners manual, my manual ( e28 535i) give you a suggested shift speed chart.

[thekid]

The rule of thumb that I have used when ever I sit in any manual car is shift at 3k rpms (for normal driving). It has not failed me yet, no bogging no nothing. Then after you drive it for a while you adjust the shift points based on your driving habits, never shift below 2.5k rpms (as a rule of thumb) and don't run it up past 3.5k rpms unless it is floored (once again a rule of thumb). This is by no means the absoullte way to drive a stick, this is just what I keep in mind as I am driving any manual car, it has worked for my BMW, a 1976 BMW 2002, and 2002 ti, 2002 Honda Civic Hatch, 95ish' Nissan Sentra SE-R and crap loads of cars I drove while valet parking for a n art exhibit. Once again keep this in mind as you start to drive it and then adjust based on the car and you, after a while you will really feel when to without looking down, and then you'll be able to tell how fast you are going just by the sound/feel of the car and knowing what gear you are in. Sorry this got a little long...

[BLACKBMW]

Good grief if you drive a 328i or 325i and shift at 3000 revs then either: -

1) you are 80 + years old ghead

2) you should buy a 1 litre VW Golf ghead

I drive my car like it is stolen every day...redline every gear and put in Shell Optimax Ron 98 - yes it costs me a fortune in petrol but YOU ONLY LIVE ONCE!!



J...