Spec Boxster Build

[Greg Holmberg]

Ya, those parallel arms really make a difference in handling. I never understood why Porsche has stayed with the MacPherson strut for so long. Even the lowly Miata has parallel arms!

As you said, the SRF is several seconds a lap faster than SPB at every track, especially with the new engine in SRF3. At Thunderhill, the records are 1:58.7 vs. 2:02.7--4 seconds.

The SRF3 is 135 HP and 131 ft-lbs at the crank for 1560 lbs (Ratio W/(P+T)=5.86), while the SPB is, I estimate, 232 HP and 209 ft-lbs at the crank for 2650 lbs (ratio=6.01). But it's really about the tires, weight, and handling, and not the acceleration.

And then there's the costs. The SRF3 costs 25% less per hour to operate than the SPB. And it's not even the cheapest purpose-built car--Formula Ford/Club Ford and Formula Vee/First are all cheaper to operate per hour than SRF3, and FF/CF are faster than SRF3. Spreadsheet.

I'm not sure why so many people stick with street-based race cars. Is it the perceived safety issues of an open-top or open-wheel car?


Greg

[thstone]

Originally Posted by Greg Holmberg

Ya, those parallel arms really make a difference in handling. I never understood why Porsche has stayed with the MacPherson strut for so long. Even the lowly Miata has parallel arms!

As you said, the SRF is several seconds a lap faster than SPB at every track, especially with the new engine in SRF3. At Thunderhill, the records are 1:58.7 vs. 2:02.7--4 seconds.

The SRF3 is 135 HP and 131 ft-lbs at the crank for 1560 lbs (Ratio W/(P+T)=5.86), while the SPB is, I estimate, 232 HP and 209 ft-lbs at the crank for 2650 lbs (ratio=6.01). But it's really about the tires, weight, and handling, and not the acceleration.

And then there's the costs. The SRF3 costs 25% less per hour to operate than the SPB. And it's not even the cheapest purpose-built car--Formula Ford/Club Ford and Formula Vee/First are all cheaper to operate per hour than SRF3, and FF/CF are faster than SRF3. Spreadsheet.

I'm not sure why so many people stick with street-based race cars. Is it the perceived safety issues of an open-top or open-wheel car?

Greg, that is a really comprehensive table of race car class info!

I think part of the allure of racing a street-based car is exactly that - it is easy for everyone to relate to it since it looks like a street car. That point notwithstanding, your point about costs is very accurate.

The thought about safety concerns for an open cockpit race car is valid. My wife isn't exactly a fan of open cockpit race cars. But after driving the SRF, I can say that I wouldn't have any safety concerns - the roll bar is super strong and you sit much farther down in the car than it appears when looking at the car.