Top speed limiter removal?

Is there any discussion about removing the ridiculous 94mph top speed limiter? This car should be capable of at least 120mph. Is there any coding that can be changed in E-SYS to fix this?

Yes, and you're spot on with 'about 120mph'. BMW runs them at this on test. No, I don't know what the coding change is.

(Published motor limit of 11,400 rpm / Transmission Ratio of 9.7:1) * 86.53 inch circumference of 155/70-19 tires = 96 mph

Q-Rated tires that the car ships with are limited to 99mph.

So, step one, find better tires that will fit on a rim that will mount on the i3.

With a Rex Cd of .3, frontal area of 2.36 square meters the aerodynamic drag alone will be about 45 horsepower @ 96mph. Figure several more hp for rolling resistance and other mechanical losses, even with our skinny tires.

Step two, find out where motor power = drag + rolling resistance + other losses. Only published chart I found cuts off @ 7,000 rpm.



Power curves also explain why i3 is so quick to 40mph, then it starts to struggle. Torque is flat (likely controller current limited) until power peak is at ~4,750 rpm (equal to 40 mph with stock tires) then at higher rpm that power output drops as torque falls off faster than the rpms grow.

Do you really want the motor twirling @ over 14,500rpm? It is a single speed transmission. Just how long do you think the bearings will last? And, about battery life as the higher power output means greater heat which means higher cooling load, which means less range? Not sure that the seals and lubricant could stand the pressure, either, at least long-term like maybe on the AutoBahn. Ridiculous limit? Not for what it was designed for.

Some things can be tweaked, but the longevity and safety may not keep up with expectations.

Given the quick steering and jittery feeling at 75, I can't imagine wanting to test stability at 100!

The biggest single improvement in range and performance would be a two speed transmission: city and highway.

WoodlandHills said:

The biggest single improvement in range and performance would be a two speed transmission: city and highway.

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Increased weight, complexity, cost, friction, and may not actually buy you much. The biggest contributor to range degradation is drag from speed, not the rotating components. ANd, if you have to wait for the transmission to shift when you want that instant spurt, that would be lost as well. It doesn't get simpler than a single-speed transmission.

A rotating electrical motor does not have the reciprocation losses (pumping losses) of an ICE, so adding a transmission just means higher current as the motor would then be under a bigger load. Yes, it might make things quieter, but probably not as you'd have a few more gears rotating, and the increased inertia of the assembly. The i8 uses it because it was designed for higher top speeds, and there is a limit on how fast you can run the thing. A commuter, mega city car capable of 94mph, does it really need to go faster? No tires available to do it safely, and nowhere in the USA (and most other places) where it is legal. More and more of Germany has speed limits, so maximum speed capability is more of a bragging right than a functional usefulness. A multi-speed transmission will not make it accelerate faster unless first gear is lower - and, the tires probably won't support that, either. We're talking a major redesign.

Sparky said:

Given the quick steering and jittery feeling at 75, I can't imagine wanting to test stability at 100!

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I'm with Sparky. I remember my '97 Ford Explorer 2-dr Sport. Car felt squiggly over 70MPH. Changed out the Firestones for Michelin and could go 80 before squiggly feeling came. Car was telling me that it didn't want to go over 80. On the other hand, my 528i LOVES to run at 80-90.

The top speed it related to the max (safe) speed of the motor, not an arbitrary point that was picked.

Sparky said:

Given the quick steering and jittery feeling at 75, I can't imagine wanting to test stability at 100!

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As discussed elsewhere on this forum it would appear that some people or some cars suffer more from this than others. My i3 always feels stable even at 70 and in the recent stormy winds!

ive seen 104mph indicated on mine no mods.

busaman said:

ive seen 104mph indicated on mine no mods.

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How did you accomplish this?

Sparky said:

Given the quick steering and jittery feeling at 75, I can't imagine wanting to test stability at 100!

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My daily commute in LA (literally going with the flow of traffic in the HOV lane) is between 80-90 mph. The car feels very stable and sturdy with no jittery feeling what so ever. It's very easy to go well over 90, but I haven't really felt a limiter.

I'm just more worried about the skinny tires giving out if anything.

i3atl said:

busaman said:

ive seen 104mph indicated on mine no mods.

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How did you accomplish this?

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foot flat on the floor for 1 mile it just crept up.. i have not done anything to it although i would like to find where i can release more power because i think it will take 220bhp ok..

its in the EDME somewhere but but im reluctant to try and read the ecu in case it is protected like the f-series and locks it.