30 Mar 2008

The molds were sold this weekend; the new owners will be building a couple of track cars for themselves and selling shells. They’ll be providing me with an e-mail address for anyone who’s interested. With the molds gone it frees up space, both in the backyard and in the rafters, which is already filled with Midlana’s fenders and nosecone and whatever other stuff will fit.

Rear suspension design is progressing and it looks like A-arms will fit with pushrod suspension. That won’t be for certain until everything is mocked-up on the table.

Using a detailed spreadsheet the current weight estimate is around 1500lbs. I’m trying hard to be honest and objective with all component weights but it’s hard to not miss something. On-hand parts have been weighed so they’re known quantities, except for the engine. That’ll have to wait until the table is built and I borrow my brother’s engine hoist and scales. For now I’m assuming 450lbs, same as the H22A1 in Kimini. Midlana’s engine, an Acura K24A2, will have an aluminum flywheel added which will save weight, though the turbo will add it right back on again.

The spreadsheet also calculates weight distribution, 64% rear. I’d prefer 60% but if that’s what it ends up being, oh well. Currently, the fuel tank is placed laterally behind the seats – it’s dead space otherwise. It puts the tank right at the CG and keeps PMOI low, all good things. I think I’m going to make my own tank this time instead of using a fuelcell, mostly for cost reasons. Because the tank will be confined behind a bulkhead, and protected laterally by the engine and wheels, I’m taking the calculated risk that fuel won’t end up in the cockpit. That’s my choice, though builders will have a choice of either making their own or buying a ready-made fuelcell.

29 Mar 2008

Received the oh-so-cool but expensive Tilton bottom-pivot brake assembly. Still waiting on the shocks, and while they aren’t really “needed” for a while, they’ll serve as a nice psychological push forward. Also, the seats should be showing up in the next few weeks. Once that happens everything will be present to push forward, which means I’ll be itching to get parts on a table. And that means moving Kimini out of the garage one way or another.

22 Mar 2008

Checked out my brother’s nearly-completed Super Stalker. All that’s needed is paint, installing the fenders and painting the engine cover. He’s been driving it a few weeks now so first he took me for a ride, then let me drive, then I let him drive Kimini.

Driving observations:
His car has TONS of low-end power thanks to the supercharger, the problem is getting it to the ground. The long wheelbase and steering rack results in a rate about half of mine, and I may have the same issue with Midlana. A slower ratio is better for the street, though I’m curious what he’ll think about it on-track. Probably the biggest difference though is ride quality. He went on a road that has two bumps in it, one upward and another downward. His seats have less padding than mine, but when we hit those bumps, it was a real harsh blow to the backside, enough to make you clamp your teeth together when approaching it. The wind whipping around the windshield wasn’t as bad as I had previously experienced in a Caterham. He said that’s probably because he made the windshield both 2″ wider and taller. The exhaust sound is pretty loud, obviously due to its proximity to our ears, but made worse by the low frequency nature of the V6. At a certain speed and engine load, it all resonates, like someone feeding 100Hz into your headphones and cranking the volume way up. He said it’s loud even with earplugs because they don’t filter out low frequencies well. He may try pointing the exhaust tips differently to see what happens. Oh, and now that I’ve driven both a high and low-pivot pedal setup, I’m not concerned about the differences. Yes, the brake pedal arc does lift your shoe off the floor, but it simply isn’t a big deal. After a couple minutes I didn’t even notice the difference.

His observations of Kimini were that it was much more refined, much quieter, and that the steering was much more sensitive. When he drove over the same two bumps he couldn’t believe the difference. That’s the day-to-day consequence of high unsprung weight and little suspension travel. Examining the rear suspension showed that it has only about 1.5″ of compression travel so he may try relocating the shocks to free up some travel (allowing softer springs and shocks.) He’s also looking into stiffening the shocks and swapping in stiffer springs.

No we didn’t drag-race. We both agreed that the two cars are very different animals and we both respect the other’s car enough that there’s nothing to prove – each has its strengths. I think his is faster in a straight line, but only if he can get the power down. In the curves, who knows. There’s no way to properly compare the two outside of a racetrace. Having driven his car, I can’t understand why anyone would want more power. First and second are useless if you hammer it, and third is a dicey proposition if it’s not pointed straight or if the road’s not smooth. All more power does is make more smoke, so he’s getting wider and stickier tires to help cure that.