EV Hacker

My New Theme Song

2009-09-05T23:11:00.004-05:00

I've been sticking with project-specific posts so far, but thought this new They Might Be Giants video was too cute/optimistic/fun not to share. I hope you don't mind the diversion.

Adapter Parts Have Arrived

2009-08-19T21:20:00.004-05:00

It look a bit longer than expected, but I just picked up the parts Revolt fabricated for me. This includes adapter plate, spacer, and hub. While they were at it, I had them do some work on the flywheel including removing the gear ring (it's there for the starter to spin the crankshaft - so not needed with an electric car) and the flywheel lightened and balanced. The stock flywheel came with an unexpected surprise: a built-in counterweight, which the shop had to remove. I presume this is needed to offset some sort of imbalance inherit to the eccentric shaft of rotary engines.

The next step is to test fit, then get on the ball with the sourcing the next major component: the controller.

Adapter Design Done

2009-06-22T22:10:00.002-05:00

The design for the adapter is done. There are actually 3 components: The adapter plate, motor hub, and spacer ring.

The design's been sent off to the machinist. If all goes well, the parts will be here in 4 weeks.

Flywheel Removed

2009-05-24T21:27:00.003-05:00

I was finally able to remove the flywheel today. There's a big 54mm nut torqued down rather tightly holding the flywheel on the shaft. When I looked for a socket in the past, they were around $50 (!). Today, I found a 2-1/8" socket for $28 at Sears that should work. I'd purchased a cheap little Harbor Freight electric impact wrench years ago and figured I'd try using that to remove the nut (my back up plan was to borrow some air tools). I also bought a set of adapters that would allow me to use the 1/2" drive wrench with the socket, which takes a 3/4" drive.

The impact wrench is 12V, so I connected it to the battery in my Miata.

That's a huge socket, huh? The impact wrench worked surprisingly well. The nut was off within 2 minutes.

Here's the flywheel:

And here's the engine with the flywheel removed:

Now, the folks at Revolt can come over and take the remaining measurements needed to design the adapter plate.

Motor is Here

2009-02-23T20:12:00.006-06:00

My friend, Umar, and I just picked up my motor from the freight dock. It's sitting in my living room for now, but having a major part of the conversion here means it's one step closer to completion.

Here's another view to give some idea of its size:

It's a bit over 15" in length (not counting the shaft), around 9.5" in diameter, and about 150 lbs.

µ-update: Motor

2009-02-16T21:09:00.002-06:00

I just placed a winning bid on a 9" Advanced DC motor!

Get into the Groove

2008-11-30T17:17:00.010-06:00

Inertia. It can be your compadre or it can be a mofo.

There's a certain amount of momentum needed to keep a project like this going. The frictional forces of an unusually busy (and odd) work schedule, wrenching on my other cars, limited availability of parts needed to move forward on the conversion, consulting projects, dealing with my rental property, etc. were all bringing progress to a halt.

Knowing the longer I wait, the harder it is to get started, I figured I should at least work on something. Even if it's not significant, it's a matter of keeping some momentum. The good news is since I'm not constraining myself to significant stuff, I might as well do fun stuff (the two are often mutually exclusive). And as Neanderthal-ish as I'm sure this sounds, power tools can be the source of tremendous amounts of fun.

In this case, it's a Craftsman 8 amp reciprocating saw (bought on sale for $59.99 at Sears).

Install the blade, plug it in, and in no time at all, the floor of the trunk was out.

Eventually, some sort of battery box will go back there. That's a problem for another day. Today it was all about having some fun.

I'd say: Mission accomplished.

But there's more!

Later in the afternoon, Chris and Aaron from Revolt Custom Electric Vehicles came by with their coordinate measuring machine to capture dimensions on my transmission. From these dimensions, a design will be created, from which a machine shop will build the adapter plate and hub. Also, since the design is now in Revolt's library, anyone else doing a conversion on an FD RX-7 will be able to get their own plate and hub through Revolt.

Normally, having the transmission removed from the car is preferred since there's more room to work and it's easier to ensure a stable base (and more accurate samples). Chris and Aaron were beyond accommodating and were willing to give it a shot with my transmission in the car. Overall, the measuring process went pretty smoothly. Although I mostly just sat back and watched, it was very cool to see a 3D model being created from the sampling of points and curves.

Due to not yet removing my flywheel from the engine, there is one remaining measurement pending, but Revolt has what they need to get started on the transmission plate and will come back once I'm ready.

Out: Engine

2008-08-11T21:04:00.005-05:00

The engine is out! This was the final item removed during the stripping process.

An engine lift made it easy for me to remove the engine. Austin EV generously offered to lend me theirs, but in order for me to use it, I would have had to borrow an air compressor and vehicle large enough to transport it. I found a deal at Harbor Freight so figured it was worth the investment.

With some tips from the guys at rx7club.com, the engine was out in no time.

I was able to keep the AC system intact. This should make it easier to have working AC once I'm running on electric.

I plan on keeping the clutch for my EV, so I'll remove it from the engine and reinstall once I get the electric motor and transmission plate.

With ICE completely removed, now the fun really begins.

Out: Exhaust System and More

2008-08-03T17:45:00.003-05:00

The engine is almost ready to come out. Over the last two weeks, I've removed the catalytic converter, downpipe, oil coolers and lines, lots of hoses, starter, power steering pump and lines, brackets and other small parts. The other things that connect to the engine (wiring harnesses, vacuum lines, etc.) have also been disconnected. Once I disconnect the AC compressor from the block, I should be able to pull the engine out.

Here are the parts I've stripped out so far:

Isn't it amazing just how many components (besides the engine itself!) are needed just to run a gasoline-power vehicle? So many parts. So much complexity. I don't know what every part does, but each one must be there to serve some purpose. Which means, each one is a potential point of failure.

By comparison, an electric car is simple and easy to understand. I wonder what they have more in common with: A gasoline-power car or a Stomper?

Out: Fuel Delivery System

2008-07-20T17:00:00.002-05:00

After a few weeks of downtime, I had a chance to work on the car again. The fuel system was next to go.

The fuel tank is the biggest component. It's a good idea to remove the gasoline before removing the tank (for safety and to make things easier by reducing weight), so used a siphon pump from Harbor Freight to transfer the dino-juice to my Miata.

Once the tank was mostly empty, I removed it along with some exhaust bits: heat shields, hangers, etc. (the muffler was already out - removed for clearance when I towed the car home). With the rear pretty much free of the junk we don't need in an EV, now's a good time to take some measurements for the aft battery box.

By the way, today is significant because it marks the first time I made an EV addition to my project:

Yes, it's just a sticker, but we all know stickers belong to a very important class of vehicle modifications: The kind that add lots of horsepower.

Out: Cooling System

2008-06-29T21:00:00.014-05:00

The engine cooling system, like much of the stuff you find in an ICE-powered vehicle, is there only to support the operation of the ICE and, therefore, not needed in an electric car. Since the air intake had already been removed, I had easy access to the cooling system components, so I spent part of the afternoon chucking the radiator, fans, coolant tank, hoses, and few brackets out of the engine bay. Even though I was armed with a service manual, I still thought I had to jump through way too many hoops to get it all out. The angle and placement of the radiator required the front sway bar to be dropped in order to allow the radiator to slide out from below the car. Coming from the Honda world, that's a little weird to me.

The Workspace

2008-06-17T22:20:00.011-05:00

In my ideal world, I'd live in a 1 bedroom house with a 4 car garage. Unfortunately, my garage is in the real world and is at full capacity with two cars. So, I'm a bit short on space for the EV conversion unless I can find some space.

I ended up moving the RX-7 into the backyard to set up a temporary workspace for the conversion. Since it's not running, pushing the car was my only option. Every time I find myself in this situation, I'm quickly reminded how exhausting pushing a car, even on relatively flat surface, can be. And this reminded me of how inefficient the most common mode of transportation (cars and trucks) is in general: ~3000 lbs. of metal to move ~150 lbs. of human. With a 20X ratio, I wonder what we are more addicted to: oil or waste. At least this car's oil consumption days are long gone. It won't be wasting any energy anytime soon either, mostly due to it not going anywhere!

With the car in the backyard, the next task was to set up some sort of covered area to keep the summer sun off the car and to give me some shade. I constructed a semi-permanent canopy over the patio. Over the summer, it'll be my EV conversion workspace. Laissez les bon temps rouler!

Take a Look at What Followed Me Home

2008-05-29T22:17:00.018-05:00

A friend and I took a road trip to Houston. This little gal followed me back home. I guess I'll keep her.

I actually ran across an ad for this Mazda RX-7 online, rented a truck and trailer, and brought it back. It's a 1993 R1 with a bad engine (if you know anything about rotary engines, you know it's quite common), but seems to be in pretty decent shape otherwise. Over the next few months, I'll be removing the ICE (internal combustion engine), along with its supporting systems, to convert it to an EV (electric vehicle).

Although it makes perfect sense to me, the thought of converting such a high performance sport car to electric left a couple of my gearhead friends perplexed: "It's one of the best handling cars, you know you're going to ruin it" ... "But you can build a 500 HP monster for way less" ... "Can't you do that to a cheap Honda instead?"

Well, I think Doc said (eh, sort of said) it best:

Marty: You built a EV... out of an RX-7?!?

Doc: Yes, the way I see it, if you want to build an EV, why not do it with some style?