43 MPH in Second Gear without noticing it! - Fuel Economy, Hypermiling, EcoModding News and Forum

bennelson · 10-21-2009, 11:49 PM

I upped the system voltage in my electric car to 108V. I can go 43mph in second.

Driving home tonight, with my wife in the car, going from the 25mph to 45mph, I never even thought about shifting.

That means I can just drive my car like an automatic - never shifting for going from home to town and back.

Not sure how many other cars can go 43 mph in second without sounding like they are about to explode!

IsaacCarlson · 10-22-2009, 12:15 AM

sure feels like first when tested with my butt-o-meter...

99LeCouch · 10-22-2009, 01:03 AM

Nice! I bet the spousal unit likes going a wee bit faster!

Heh, my car will downshift to 1st at 35 mph if it's floored. I notice it when it snaps my head back into the headrest as the hood suddenly claws skyward. It's pretty darned noticeable. Completely not like your car. I get roughly 2 mpg doing that, so it almost never happens. It's still better than a Hummer.

gascort · 10-22-2009, 01:17 AM

Very cool, Ben..
although I must mention I run up to 70 mph in 2nd in my mustang (only when racing) and a camaro I rode in went up to 95 in 2nd....
Obviously these were both pretty loud, as you stated!!
Congrats on the success!
Do you use all of your gears still?

Christ · 10-22-2009, 01:38 AM

I don't remember exactly, but in my Civic, I had a range of 2nd to 5th that I could be using in 2nd gear. 2nd was pretty high, unless I had the HF tranny installed.

In Cara, 45 is doable in 2nd, but that's a nil comparo, since she's auto. I think I can do 45 in my Father's S10 in 2nd, but it don't like it. (Ignition kill kicks on somewhere close to there, I think).

Doofus McFancypants · 10-22-2009, 08:58 AM

my old Civic Hatch (1990 - 4sp MT) would redline in 2 at about 60 mph. and it DID sould exactly like it was going to explore
Did that once or twice then never again.

MadisonMPG · 10-22-2009, 12:54 PM

I knew a guy that could regularly run up to 55 or so in first gear, it was a Vette though.

chuckm · 10-22-2009, 12:55 PM

Awesome job, Ben!
Just curious, were you limited by voltage or motor rpm?

bennelson · 10-22-2009, 01:20 PM

I think the limitation for speed in any of the lower gears is magnetic saturation - at some point, the motor just can't get any more magnetic, and spin any faster or harder.

In the higher gears, how many amps you can pull from the batteries limits how fast you can go. Just because I can go 65mph, doesn't mean I want to, because it drains the batteries SO fast. Also, my main fuse right now is a slow-blow 300 amp, so I don't want to sustain anything over 300 for anything other than brief accelerating.

Upshifting puts more load on the motor, allowing it to draw more amps, allowing greater acceleration.

Driving in a lower gear at higher RPM draws nice low current (good for the batteries!) I would imagine that it also makes increased brush wear.

The other thing is that the motor does seem to have a "sweet-spot". There is a point in the speed of the car and the RPM of the motor where is seems to perform really well, and not pull as much amperage as some other points of the RPM/Speed/Gear curve.

However, since I have no tachometer and having been playing with different system voltages, I couldn't say exactly what it is.

I may just try driving around using just third for a while and see how that goes.

almightybmw · 10-23-2009, 02:54 AM

Well I can say the only vehicles I drive that have 43mph not sounding like an explosion under the hood are bikes. My brother's 750 nighthawk would do 60mph in first. My brother-in-law's bike with a "torque" chain gear (vs. high speed) would do 110mph in second. But that was at 13000 rpm :P

But you're right, MOST vehicles you will notice 43mph in second.