986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

Greg Holmberg · 05-01-2019, 10:21 AM

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

05-01-2019, 10:21 AM	#1236
Greg Holmberg Registered User Join Date: Jan 2015 Location: San Francisco bay area Posts: 70	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 Last edited by Greg Holmberg; 05-01-2019 at 10:33 AM.