Not just another dyno thread

[bonus12]

i know they tell you where your power band is, but looking at a dyno sheet, is it possible to determine which rpm's are most efficent economically for your car? i am talking about manuals, of course.

in other words, can a dyno sheet tell you at what rpm you need to shift for best fuel economy?

just wondering...

 

[miggles]

just after your power curve drops i'd say.
Stock motor peaks at 5500rpm (iirc)

 

[bonus12]

^^ that was lame

 

[miggles]

sorry, i misread the post, i thought he was refering to when to shift for power.
For economy probably keep under 3000rpm

 

[miekedmr]

for the best fuel economy you should shift as low as you can without putting a strain on the engine, and still having the power available to accel. the less the motor turns, the less energy is wasted turning it.
just be very light on the throttle and shift low. it's a bad idea to shift at low rpm if you are using a lot of throttle, because its stressful to the motor.

BTW assassins's is not a word.
assassin > assassin's
assassins > assassins'

 

[SupraDerk]

Yeah, this is pretty much common sense, lol.

Don't run the car hard and keep it under like 3k like miggles said. There's no need for the ricer takeoff EVER on the street (not saying you do it, it just boggles my mind when I see my friends drive like this and then complain about the price of gas).

Also if you can, slow down before coming to stop lights and keep the car rolling at like 5-10mph. In the long run, you won't waste as much gas as you would taking the car from a dead stop up to speed. And try to keep it at a constant speed. I HATE when people speed up and slow down, speed up and slow down, it wastes gas.

 

[7MGTEsup]

The average petrol engine is most efficent between 1800 and 2500 rpm. Try to read the road as far ahed as you can so you varie the throttle position as little as possible. On a long run crusing at 70 - 75 and driving like I discribe I can get 33 mpg (imperial gallons which is 4.5L as aposed to 3.8L for us gallon)

 

[tissimo]

run 2-3 before shifting dont shift below 2000 its not efficent down there.. keep vacume low and youll get good milage

 

[T34418L3ONE]

Yea low vaccum is more crucial than rpms. The lower load you can keep on your motor the lower the duty cycle of the injectors.

 

[bonus12]

thanks for this help, but i think everyone here misread the post. i know how to drive a car efficiently, but i wanted to know: can you tell exactlywhen to shift looking at a dyno?

looks like nobody who posted above knows either.

 

[miekedmr]

a dyno doesn't tell you by itself. power output is only one variable when determining efficiency.

 

[limequat]

thanks for this help, but i think everyone here misread the post. i know how to drive a car efficiently, but i wanted to know: can you tell exactlywhen to shift looking at a dyno?

looks like nobody who posted above knows either.

You can't tell. Dyno measures output at WOT. For max efficiency you shouldn't be into the throttle very much. Engine mapping varies considerably with throttle.

 

[Nick M]

Shift as far below the torque peak as possible without lugging the engine. As already pointed out in this thread.

Your owners manual gives you the answer also. It calls for exact speeds, and to avoid "jack rabbit" starts.

 

[tubbie]

How to use your dyno graph to shift.....
For instance, your peak hp is at 5500rpm. What you have to look at is, where the rpm will be when you shift to the next gear. You already know that past 5500rpm your dropping power. So when you shift to the next gear and the rpm falls to say, 4500rpm, is the power there higher than the power at the other end of the rpm past 5500rpm where you shifted at.
4000rpm 180hp
4500rpm 200hp
5500rpm 250hp
6000rpm 225hp
6500rpm 195hp

If you shift at 6000rpm, rpm will drop to 4000rpm. Hp at 6000rpm is higher than 4000rpm, so you don't want to shift yet. If you do, your accelerating with less hp.

If you shift at 6500rpm, rpm will drop to 4500rpm. 4500rpm is making more power then 6500 rpm. So you want to shift before 6500rpm where hp is less than the next gear. So you might want to shift at 6300rpm.

You always want to shift where the next gear will have equal to or more power than the current gear, unless your at redline and have no choice.

Just my rambling..... :bigthumb: