4 Aug 2013

The new wastegate springs were installed earlier this week and boost is now 10.7 psi – I’m not going any higher on pump gas. Tried another 0-60 mph run, one using first and second gear and the other using second only, which won out slightly with a best of 3.6 seconds. Hmmm, fast, but like my buddy asked, why isn’t it something nuts like 2.5 seconds or so? Traction was not an issue, with only slight wheel-spin. Putting on the engineering hat, since the weight is known the only explanation is that the car isn’t making the claimed power. The type of dyno used is known to consistently indicate about 10-12% higher than the drum type, so the “430 hp” is probably more like 380 hp or so. Even then I’d expect it to be faster. Perhaps I’m not “driving it like I stole it” – side-stepping the clutch at 8000 rpm. As an aside, one of the displayed engine parameters is lambda (air/fuel ratio) and during the above pulls it stays right at 0.8, or about 11.8:1, which seems about right, so it doesn’t look as if there’s anything to be found there.

The dog-engagement transmission is growing on me; I guess I’m getting used to it. During the runs above, there were still the occasional “BANG”, yet to be explained, and which I really hope is external to the transmission. In related news I’ve lost excitement for the Quaife sequential gearbox. Cost aside – which is large – while they offer a helical gear set for road/track cars, for some reason they don’t offer a helical 4.36 ring and pinion ratio to go with it, only a 4.75. That doesn’t seem like much but it lowers the top speed from about 150 to 137 mph, which on large tracks like Fontana becomes a limitation. It’s not just top speed, but how long the engine is held at high rpm, something I want to avoid. Between that and Quaife rating its torque capacity as “300 hp” (yes, hp), it makes me think it’s intended for high-rpm normally aspirated engines. Given its price I think I’ll let others find its limitations… it’s too much money to be a beta tester.

It wasn’t easy working on the book instead of going for a drive, but good progress was made.