build diary

April 13, 2004:
The fuel cell is here!
entry 229

April 14, 2004:
Turns out that Summit sells the same fuel cell under their own brand as well.
The tank fits into the car nicely, but it's a squeeze getting it into place. I had to remove a couple of fittings. No problem there! Since the sump on the bottom of the tank means that the tank isn't flat, I'll have to build some supports for the front of it. Easy enough to do. Last night was spent reading up on surge tanks and generally poking around the back of the car. Ooooh, I'm ready to a lot of work now!
entry 230

The fuel cell in place.
It's a bit difficult to get in place, but it's nicely sized.
entry 231
The sump for the fuel pickups means I'll have to make a support for the tank.
Easy enough.
entry 232
My new, low-profile oil filler cap.
Every little bit helps!
entry 233
Everybody wants a bit of attention.
entry 234

April 16, 2004:
An interesting discovery as I look through my "instructions" - the GRM build photos.
They put the tank in backwards! While this places the pickups at the front of the tank and thus makes them more prone to starvation under acceleration, it should sit the tank down flatter and make it easier to tie down. I'll have to try that. Putting in a surge tank would prevent the possible starvation problems as well as my plumbing problems so that may still happen. Hmmm, so many options.
entry 235

April 19, 2004:
I'm not sure exactly why the GRM tank was installed with the pickups at the front.
It's easier to slip the tank into place but it offers no other packaging benefits - and there's the potential problem of fuel starvation under acceleration (and lots of fuel under braking). So I installed mine with the pickups at the back. A frame of 1/8" and 1/16" aluminum has the tank firmly secured in place with very little weight and a cash outlay of about $12. I'm happy with the way things turned out there.

I also changed the rear end. The super-strong GURU racing diff that was in my street Miata is now in the Seven. The reasoning is that I have to get a custom driveshaft made for the Seven, and I'd rather not discover (like the GRM guys did!) that the smaller, weaker 1.6 ring and pinion isn't up to the abuse the Seven is likely to dish out. My Miata, despite being twice the weight, has survived for years with a 1.6 rear and it's much cheaper to upgrade that car to the 1.8 with off-the-shelf parts should that become necessary. This has added 15 lbs to the weight of the rear end but it's probably worthwhile.
entry 236

The 1.6 viscous LSD (right) and the 1.8 Guru torque-sensing LSD.
entry 237
The weight difference of the two diffs - 56 lbs vs 71 lbs.
entry 238
Remember that Shoe Goo stiffening? Well, it didn't survive very long!
entry 239
When I installed the last diff, the frame was upside down.
Installing it in the correct orientation took a little creativity.
entry 240
The lower support for the fuel tank.
This is an aluminum U-shaped channel for lots of rigidity and light weight.
entry 241
The tank is in.
The upper straps are 1/16" aluminum.
entry 242
The fuel filter is installed.
The pump will be strapped just above it.
entry 243

April 20, 2004:
I had been concerned with the sizes of the fuel lines, given that the Miata runs on 5/16" and the tank has a 1/2" outlet.
It turns out that my fears were unfounded - the pump has a 1/2" inlet and we have the adaptors on the shelf at Flyin' Miata to make the outlet 5/16". That was resolved far more easily than I expected! I'm also going to use fuel hose to feed the engine instead of bending up hard lines. While manufacturers use the latter, I suspect it's not for performance reasons.
entry 244

April 21, 2004:
More fuel line work.
I needed about 18 feet of 5/16" line in total (9' for the feed and the same for the return) as well as maybe 18" of the 1/2". It's all looking pretty good.

To ensure that I don't have problems fitting the lines past the transmission, I've put another transmission and dummy engine in the car. It's impossible to get anything past the bottom of the tranny on the right side which is unfortunate. But I've worked out routing for everything that will keep the wires from chafing as well as keep them clear when the transmission is being removed or installed. I did decide to cut one of the rubber mounts for the rear of the transmission down by about 3/4" as it was putting the tail of the transmission too high.
entry 245

The nice thing about working at a performance shop.
I need fuel line, but I'm not sure how much. So I brought home 60 feet of it.
entry 246
The fuel line routing.
While the pump mounting looks a little cheesy, this does work quite well. We do the same thing on some of our turbo Miatas.
entry 247
Another dummy engine in place so I can do fuel line and wire routing and don't accidentally put the main power feed through the transmission, for example.
This time I've mounted some accessories.
entry 248
These cool little mounts are what I'm using for wire and hose management.
A 1/4" hole and they pop right in. A ziptie fits though. I can't ziptie right around the frame rail because there are often body panels riveted to the other side.
entry 249
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