| Author | Message | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 323 Registered: 11-2002 |
I should add that all 308 series through current models benefit from running 2 to 6 psi higher front cold pressures. Actually, this goes for Porsche's, Beemer's, Honda's; virtually any modern car running street tires and unmodified suspension. Then you just tune to your liking. DOT legal race rubber is different, higher grip and different construction requires a more sophisticated tuning method. Though you can still go by your "as*-o-meter" here too, just doesn't work as well. Race slicks are a different breed altogether, requiring a more disciplined approach to get the ultimate tune. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 321 Registered: 11-2002 |
Of course, please follow factory recommendations. I do my best to be a conservative engineer in this risk-filled racing environment. I'd hate to get fingers pointed at me for following my advice, hence the conservatism. Also, I want everyone to be safe first, then have fun second. There's nothing to win at a track day.  I once heard a Porsche Club instructor tell a room full of novice's, "There's no coasting in racing" (i.e. foot to the floor until you brake for the corner). I think that's BS! Coast all day long for all I'm concerned at a club track day. | ||
| Mr. Doody (Doody)
Member Username: Doody Post Number: 858 Registered: 11-2001 |
stellar commentary rob. very useful information! I don't recommed running less than 30 psi cold on the street, you're always best off on the street following factory recommendations (which yeild understeer). factory spec for some of the tires is 29 (the michelins and maybe the f1's?). do you recommend running these on the street at 30? doody. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 319 Registered: 11-2002 |
Here's the scoop on optimizing your track set-up on a car where the only adjustment you will or can make is tire pressure. One option is you can ask me as I've tracked or advised on just about every modern model. For your car, I suggest 34 front and 30 rear. This is a safe, conservative place to start cold. This will yield a nice balance with general understeer, but not too much. It's also on the higher side, which allows you to set them once in the morning and then bleed pressure off if necessary, which is faster than pumping them up at the track. If you have way too much understeer, the car doesn't want to point into the corner on turn-in, start dropping front pressure in three psi steps per session. Remember, after your first session, you'll be dealing with hot pressures. Hot may be 38 front and 35 rear. Generally, reducing the tire pressure on one axle will yield improved grip on that end of the car, but you can go too low, which is not safe. I would not go below 30 psi HOT in any one tire. I would definitely lower any tire coming in above 40 psi hot, but try to keep the difference side to side within one psi, which is to say, don't run 38 RF and 35 LF, unless you're running Lime Rock and the car feels great (all but one turn is right). OR, method two is to start with Ferrari recommended pressures listed in your manual and doorjamb. Now make adjustments in three-psi increments until you're happy. It's okay to raise pressures to help balance the car, and this technique includes sacrificing some grip to improve balance. This may require a source of compressed air, which is why I go to the track with Nitrogen cylinders. I even have a nice small aluminum one that fits into many cars. Use a nice air pressure gauge, and start a track day log book, noting cold starting pressures, all changes when and why, then note what the tire's cool down to at the end of the day so you know where to start next time (memory never works here). You can add checklists to your track day log, too. Makes a nice owner's history to go with the car. I don't recommed running less than 30 psi cold on the street, you're always best off on the street following factory recommendations (which yeild understeer). Have fun, play safe! | ||
| Roger Arlen (Rogera)
New member Username: Rogera Post Number: 12 Registered: 5-2002 |
Can anyone provide feedback on the best cold pressures for a 550 (with P zeros) on a road course? Much thanks. |