Fuel Blues

We worked on the wiring last night, hooking up the kill switches and start buttons for both the Civic and CB750 motors. The reward at the end should have been the thunderous roar of both motors. The actual result was fuel everywhere.

The Civic motor started up fine. The fan motor at first was not getting spark. After some wiring troubleshooting we got the plugs sparking and moved on to the next problem: no fuel.

Our plan to get fuel to the fan motor was to tee into the high pressure fuel line and run it to a regulator so that the carbs wouldn't get flooded with fuel. With no gas coming we took another look at our setup and realized we had plumbed into the low pressure return line. Another tee into the correct line and we tried again. The result: fuel everywhere. It was leaking from the carbs and from the regulator.

Turns out the cheap Holley regulator we bought is only intended for use with a low pressure fuel pump and can only handle a few psi of input pressure. The fuel injection on the Civic runs closer to 50psi and was overpowering the regulator which in turn overfilled the carbs.

So now we need to find a new regulator that can handle the high input pressure but still deliver only a couple of psi to the carbs.

Update 5 hours later: the tech guy at Aeromotive pointed out that we don't understand how fuel regulators work and put us on the right track. The key is that the bypass type regulators allow fuel to pass until the UPSTREAM pressure has dropped to the set point. Thus, even if we had a regulator that could handle the input pressure, it would have short-circuited all the fuel headed for the Civic motor. He suggested putting a bypass regulator on the return side of the Civic regulator, forcing all of the return fuel through it and raising the return fuel pressure to the 4psi setpoint to feed to the carbs. This will probably boost the Civic FI pressure a bit as a side effect. Either way, the Holley non-bypass regulator was not the one for the job.

Look upon my works and despair...

Our big challenge for the last couple of weeks was figuring out how to mount the fan securely. I was imagining a big water-jet cut piece of .25" steel that we could bolt the fan to that would extend out and attach to the roll cage. This made me sad, as it would be time consuming and expensive.

Then a big lightbulb smashed against my head while I was scrounging scrap metal in the shop. I came across a steel ring we had gotten when we were trying to mount a better vent fan in the server closet. It was essentially a piece of angle iron that had been rolled into a hoop. Fortunately McMaster had a large variety of sizes including a 24" diameter that would perfectly fit our fan's bolt circle. After adding some .125" gusseting around it, I'm pretty sure the car would have to be completely destroyed for that fan to move.

Need New Belts

We've had our racing harness sitting around for a while now. The cage needed to be in before we could install it. More recently we've been putting it off because we still had various bits to be welded, and we didn't want to risk damaging the webbing.

Now that we finally got them in.... they're too long. We have the kind with the bolt plates at the end of the shoulder harnesses and there's too much slack for the adjustment to take up. I've got the ones that loop around the cage on order.

We also noticed that the angle they make with our shoulders is much more than the 15 degrees in the LeMons rules. Partially because the SCCA rules specified 0-20 degrees, and also due to the fact that our shoulders come over the point on the seat back to which I measured. We'll be cutting out those tubes and putting the proper height ones in this weekend.

Magic Hub

Now that the motor runs we need to connect it to our fan. The simplest way seems to be to use the motorcycle's chain and turn the fan like it was the rear wheel of the bike. This lets us use the transmission to have some control over the motor/fan speed and to use the clutch if we need to.

The only trick is to find a way to mount a sprocket on the fan. Unfortunately the fan shaft is a 1-13/16" diameter: not exactly a stock size for a Honda chain ring. Thus we need an adapter hub. This one is designed to be built from a 3" piece of round stock and a 3/8" plate. We're having it built by a local fab shop because we don't want to spend $200 just to buy a broach.

Update 3/24/09: McMaster carries bushing mount sprockets for ANSI 50 chain which is compatible with the 530 chain that most motorcycles use. While McMaster doesn't carry 1-13/16" Taper-Lock bushings, Grainger does.

It Lives!

Our motor lives! After peeling off all of the electrical tape and tracing wires that were joined by twisting together the stripped ends and covering with said tape, we finally got some cylinders to fire! Not all of the cylinders, but enough, and we think we can get the rest going too if we get the ignition wiring figured out.

A Network of Tubes

Our cage install went pretty well. One bit of panic came early. We had tacked the main hoop, halo and front down tubes in place and thought "Gee, if we shift the whole thing forward we'll have better access to the welds". So we did. The panic came when we went to shift it back and saw that the final welds had warped the frame by about 8". Much grunting and pushing followed. Trevor and I eventually persuaded the cage into position using a Hi-Lift jack and a piece of spare tubing. We even still have all of our fingers!

A few more evenings of measuring, cutting and welding got the rest of the tubes in place.

Lucky Cage

Once we started measuring for a custom cage we realized that our measurements were coming out pretty close to what the S&W CRX cage would be. We had initially assumed that the main hoop would sit in the rear passenger footwell and that the S&W cage would be too short. The big Ah-Ha came when we pushed the main hoop back far enough that it sat on the rear seat. This is what the S&W cage was built to do, so it looks like it will fit pretty close.

We traced the design on a cardboard mockup and test fit it to the car. Looks like it will fit up fine.

The extra nice side is that the cage is cheaper than I thought. It's built out of .134 EWS rather than .120 DOM, so it costs about half as much.