How To: Accelerate?

[Baltothewolf]

Originally Posted by Fat Charlie

It depends, and this is where a gauge comes in handy- did you get one yet? Pick a route that won't have much traffic interference and log the short trip mpg when you get there. After a few runs, switch to another method for a few runs. Let us know.

Oh yea, I forgot the OP has a 98 which means OBD-2. OP get a scan gauge or ultragauge depending on what you can afford.

[Thenorm]

Originally Posted by 96CX

So on the on-ramp (25mph up to 55)-- I should use just enough throttle to achieve the maximum rate of acceleration (any throttle more than that merely enriches the A/F ratio?), and get up to 55mph while still on the downhill?

yes.
accelerate (Reasonably) hard, and short shift. keep the rpm between 1500 and 3000 (assuming that the area your make has the best BSFC)

[user removed]

It's like Chess or golf, think of where you want to be and the speed you want when you get there. Use the highest gears that allow you to reach that point with the lowest RPM possible, without going to close to full throttle where you get enrichment. It takes less throttle than you might think to get to 70-80% load when you are shifting at 2000-2500 RPM. Keep the load fairly high but shifting earlier than most people. You want to use the engines torque to get there, not high RPM horsepower. A lot like the big rig drivers.

regards
Mech

[96CX]

No, no gauge yet. I'd love one, but it's not in the budget yet.

[P-hack]

Aside from keeping the engine around bsfc peak, the biggest acceleration tip is to know when to stop accelerating (and coast if traffic/time allow it). If you accelerate then mash the brakes then you just turned all that gas into heat, better to accelerate just enough to coast to the next stop/obstacle. If the obstacle is temporary (light, geese crossing, train, etc) it is better yet to stop accelerating sooner so you can "time" the clearing of the obstacle and keep your momentum.

[Fat Charlie]

Yeah, bump starting and throwing in another pulse beats having to brake.

[96CX]

For scenario #1 (0-35mph), my (admittedly back of the envelope) calculations say that if I keep it in 2nd up to 35mph (3k rpm) before shifting to 5th, I turn a total of 7875* revolutions; whereas if I shift at 1,350rpm** and accelerate more slowly, I only turn 5400* revolutions. So I guess I'll be accelerating more slowly. Oh well.

*Over and above the 12.5 rev/sec that the engine turns at an assumed 750rpm idle, which it'd be turning anyway as long as it is running.

**I'm pulling these RPM levels from a calculation based on gear ratios, wheel diameter, and mph shift points, since I have no tach...

[user removed]

Recheck the math on the first calculation. How many seconds does it take you to get to 35 MPH? How many seconds in each gear?
regards
Mech

[96CX]

I timed myself the other night, and it took 7 seconds to hit 35mph in 2nd; it took 18 seconds when I shifted at 1350rpm every gear.

I did assume (among other things...) a straight slope for my acceleration curve, so that I didn't need calculus to solve for the area under the curve.

[96CX]

Oh...Hang on. I think I forgot to convert revs/minute to revs/second. Oops.