Ran Palomar mountain on Sunday, enjoying the drive up the twisty road, and having power is great fun on steep roads, especially coming out of corners. It’s been a long time since I’d done this and the sportbike crowd was out in force. In fact, about half way up the mountain appeared to be a support station for several bikes, complete with trucks, large trailers, shade, and some guys apparently waiting for their buddies to come in from their last “lap.” I suspect they also radio the guys if a cop passes by… This is a public street and not all that long ago the cops pretty much set up camp on the hill, but today there were none to be seen. Part of me wanted to see if I could keep up with the bikes as they headed up the hill but no one was at the bottom when I came through. A lot of them were coming down though, some dragging their knees around the turns. When I headed back down I got stuck behind a number of cars, most of which nicely waved me by… though there was one exception…
In a not-so-surprising tradition of modern irritation, a Prius was driving painfully slow (and I’m not the only one who notices this behavior; there’s even a term for it – “Prius Rage.”) He/she was really taking his/her sweet time coming down the hill – okay, fair enough, it’s a public road, but they never pulled over in any of the 47 places they could have. More so, they went round the turns at – and I checked so I wouldn’t be exaggerating – 18 mph. The road is double-yellow the entire way and while there were a couple places I could pass, there was a concern that a sportbiker just might be heading up at full power. So I gritted my teeth until the bottom then blasted by it, no doubt confirming in their mind that sports car owners are jerks. Fair enough, ’cause they’d already provided another data point that Prius owners are as well. Or, maybe they were just oblivious, and I don’t envy their choice between the two.
That rant aside, a change of topic: I gave my buddy, Lee, a ride last week and he said something that’s been bugging me ever sense, that if I really have 400 hp, how come I can’t spin the tires in second gear, and I admit to wondering the same thing. Granted, the type of dyno that was used tends to read about 10-12% higher than the inertial-drum type, so for an apples-to-apples number I probably have more like 350 hp or so – but still. Then there’s the wide sticky tires, the rear weight bias, and the limited-slip… but still. Digging back through the dyno information turned up a few interesting things. Back then I only had one wastegate working and as a result, the 409 hp was at 9 psi, and it just hit me that I’m currently running 7.7 lbs! Well… that’ll never do 🙂
Another interesting tidbit is that boost doesn’t always equal spring pressure. Tial, the wastegate manufacturer, notes, “Boost pressures are only an approximation based on intake manifold pressures equaling exhaust manifold pressure.” I never thought about it that way but it make sense, that the turbine is a restriction in the exhaust and only if both the compressor and turbine wheels are doing equal work will an “X psi” spring result in “X psi” boost. Indeed, boost has been lower than the rated spring pressure in the last two changes, with a “5.8 lbs” spring resulting in an actual boost of 4.4 lbs, and a “8.7 lb” spring resulting in an actual boost of 7.7 lbs. Because the engine builder said it can handle 10-12 psi, new springs have been ordered – and the numbers say to expect roughly another 40-50 hp 🙂 A turbocharged engine is a very slippery slope…