[brian_]

Engine out and sold.

Did you weigh it, so you know how the weight after conversion will compare?

Need to fit 36 battery modules in here along with the electric motor...

Each bare Leaf module (using the specs from Electric Vehicle Wiki) has a volume of 2.36 litres or 0.083 cubic feet. 36 of them would then be 85 litres (or 3.0 cubic feet). That wouldn't be a problem without the motor, but with the motor and the controller that's a tight squeeze... especially with the extra volume needed to assemble and house the pack, and the inconveniently rigid module dimensions.

36 modules will weigh 137 kg (310 lb)... plus the box they're in, plus wiring, plus the 60 kg (133 pound) motor, plus the controller. It would be nice if more of the modules could go in the back, for the sake of balance and traction; that would presumably intrude on the trunk. It was such a well-balanced car before the conversion...

If you follow the WolfTronix approach you would have three 16-module packs, so a 32-module front pack (and 16-module rear) would make sense.

 

[brian_]

I'm glad to see that weight and balance are getting suitable attention. One thing to watch for is that I see a lot of conversions piling battery boxes far forward under the hood, due to a lack of space. That 296 pound engine is centred well behind the front axle, so if the batteries spill forward as the packaging problems are worked out, the mass distribution could be further forward than the total weight "under the hood" would suggest.

If you really want to keep track of this, pick a reference point and keep a total (I would use a spreadsheet) of the moment for each component - "moment" is the weight multiplied by the distance from the reference. A reference point can be any sensible fixed location, such as an axle, or a bumper; the advantage of an axle is that it is a well-defined point along the car which doesn't get moved in body modifications, while the advantage of a bumper is that all distances from it will be positive (since there are not components on both sides of it). Divide total moment by total weight, and you have the distance to the centre of mass (centre of gravity) of the components. In this case, I would use the rear axle. This is normal practice for race car setup and aircraft loading. I haven't seen anyone do this in this forum (but I have only read a very small fraction of the build threads), but I wouldn't be surprised if there are some small cars with disturbing bias toward the front.

 

[brian_]

I didn't weigh the engine, but according to this site http://www.motoiq.com/MagazineArticles/ID/1645/Project-Miatabusa-Part-3--Let-the-Weight-Weenieing-Begin.aspx
the engine, alternator, and power steering pump, which will all be gone...

The engine-driven power steering pump will be gone, but won't it be replaced by at least a comparable mass of electrically-powered power steering pump? You can de-power the rack (online article about this from Flyin' Miata), but the steering effort will likely be too high, especially with increased load on the front axle. A manual rack can be substituted, with a slower ratio to make it easier, at the expense of quick steering (and still more work, although more manageable).

 

[brian_]

The 12 batteries in the back plus the shelf I made for them are about 120 lbs (that 5/8 HDPE is heavy). A full fuel tank (12.7 gallons at 6.3 lbs per gallon= 80 lbs) is about 100 lbs. Add the charger in the trunk and we are about equal.

Have I missed something, or is the electric setup 20 pounds heavier, plus the charger... not equal to the original?

I don't think I would use a solid horizontal panel of HDPE structurally. Not only is it dense, it's not very stiff and will probably sag in the long run if significantly loaded.