Lap times between a dry and a wet course?
 

I know there are lots of variables (tires/cars/driver/oh $hit factor), but what is the general rule of thumb as far as the difference between a dry and wet course?

.....Setup? Course? Amount of Wet? Oil accumulation? ....ain't no rule of thumb. But since your looking for one I'll say 4 seconds for optimal setup.

How wet is a huge variable. I've been on tracks that where the variation was more than 4 seconds between wet and very wet. Close to 10 seconds on pretty dry vs. very wet.

Aside from all of the other variables mentioned already there's the topography of the track too. Does it puddle? Where? are there areas where water is running accross the track? Where? How rubbered in was the track before it got wet?

Long story short, there's absoluetely no way to even close to accurately guess a dry lap time by looking at a wet one.

Yeah thats what I sort of figures, I just wanted to know if there is some sort of rough estimate.

Really is couse dependent. Course like Laguna with mild wet surface it's not going to be too bad. It's a course with lots of room and some long straights.

Infineon is downright treacherous in the rain and it pools water. I have seen wet times more than 10 seconds slower on that track.

Also our cars really suffer in the wet. They essentially have to be driven like big momentum cars with very light throttle compared to cars with better weight distribution in the back.

Yeah, I was within 8 sec of my dry times at three tracks, yet about 15 sec at my home track. I just couldn't find any consistency and that was the reason I asked the question.

Actually you brought up a good point. Is the Z really that bad of a car in the rain compare to other cars if given the same tires and drivers? I was at Lime Rock last year and for the life of me I can't figure out why a E36 M3 and a 996 GT3 was so much faster off the corner. I don't know if it is me, the tires or just the car. I have looked at the videos and datalogs many times, I really couldn't figure out how they can come off the corner so much quicker (I saw the datalogs and videos, they were killing me off the corner exit). You would think a stock car with soft suspension is good enough, but I suspect the crappy LSD on the 370 has something to do with it.

As a long time Porsche track car driver I can tell you our wet rear grip sucks. I have read journals of racers in 370z race cars in Europe too who experience same thing.

That tendency of the Z to initiate a little mid to late turn oversteer on power doesnt work so well when grip goes away!

The z is geared for steady state understeer, which forces you to use throttle oversteer coming out...it's a much finer balance in the wet.

Yeah I think we can thank the drifters for that....

I just took a look back on lap time data from a time attack event I did in the wet in 2010 at Sonoma. Pretty crazy how drastic the lap time changes were. During the competition portion of the event is when it was at its wettest and I ran a 2:26.548 which sounds super super slow for that track but it was THAT wet. I actually won my class with that time by 12.5 seconds. The fastest lap I set that weekend was a 1:59.058 and the track was still wet, just not nearly as wet. So that shows you right there that even comparing wet lap time to wet lap time can be pointless. Same day, same car, different levels of wetness and still a 26 second difference.

Too many variables. I think the only way to a best guest is to have info on the same car at the same track with different weather conditions. The Top Gear Track is a good example, but even then it's subjective.

Problem is that we don't have a gauge on how wet things are. Unlike a hurricane where we have a category 1-5, there is nothing for rain/wetness. I guess that was a stupid question, sorry. I wasn't sure if someone had some sort of rough guidelines, almost like going from street tires to R comps. I have seen variations from 5 sec per laps to 20 sec too.

I think it generated some good discussion. curious what do you guys do when it rains? I back off compression settings quite a bit. I'm a late braker and I tend to get on throttle early so I adjust to be smoother going in and I'm very light on throttle..

Suck it up, pray and keep driving.

I did a weekend at Road Atlanta in the rain. Learned a lot, but mostly learned, I won't be tracking this car in the rain anymore. Its just too squirrely and I don't enjoy it. I can handle the wet just fine, but its more work than fun, and therefore, there is no point to doing it.

What I did do though, was always stay a gear higher than normal, and brake much earlier.