onefastviking

I'll chime in as well here with some facts that support VR's response.

Temps done properly with a tire probe, and when read properly, will tell you many things, one of which is whether or not tire pressure is where it should be.

Tire pressures will just tell you what the pressure is. Your results on pressure will vary depending on track,driver,car setup,outside conditions, how the car was driven, who's gauge you used, etc, etc.

onefastviking

Only 50 ?

Veloce Raptor

Absolutely! After we made this ONE POUND adjustment, this driver went on to set fastest lap in class, won his class, and bested his previous personal best time at the Glen by a significant margin....a trend that began when we started working together on Thursday.

But had we just gone on hot pressures, we woudl have made no pressure changes, he might have been tempted to mess with shocks, etc., and might never have gotten a rein on the car. As You and Cory F and others said, all of this is an interconnected system...sometimes it makes sense to look at the simplest part of the system!

Veloce Raptor

Below is a scan of the Andy Hollis article I referenced much earlier in this thread. At least one person had asked me to scan & post it, since it is really full of valid points, both for autocross & track driving:

Larry Herman

That is a gem of an article, Dave. Sums up a wealth of knowledge in short read.

Sam N

Thanks for posting. Really gets you thinking about learned habits.

Veloce Raptor

Glad you found this useful! That is the whole point of this thread..

Veloce Raptor

Ii just received a question via PM that I will answer here, and invite others to offer their perspectives as well:

"Why is the draft important in road racing, and how does it work?"



I am sure there are aerodynamicists here on RL....I am not one of them. However, the principle used in NASCAR, where two (or more) vehicles very close to each other nose to tail are often faster together than either would be alone, also applies to road racing. In essence, the lead vehicle creates a "hole" in the air that enables the follow vehicle to have less wind resistance & thus go faster. But in doing so, the lead vehicle also has less drag from the rear & can (sometimes) also go faster. Generally, this 2nd point only works when both vehicles are bumper to bumper or very nearly so. Watch a Spec Miata or SRF race sometime. The top drivers draft often, and are nose to tail.

If the lead vehicle (or its driver) is simply faster, as the gap between it & the follow vehicle grows, both derive less advantage from the draft, to the eventual point when there is no draft any more.

Some vehicles have a difficult time remaining in the draft for a long time, as they get very little cooling air & can overheat. Sometimes you see in NASCAR and even F1 where a following vehicle will momentarily pull a bit into clean air to cool the car.

Drafting can be useful for the follow vehicle to build momentum to make a pass. A skilled driver will be able to pull out from the draft (often on the inside) with just a bit of extra speed to make a pass under braking.

Drafting can also be useful in qualifying, even among widely varying cars. I recently coached a racer in a Porsche 911 in a class that was on track with GT3 Cup cars. On one race day, for qualifying, he was gridded right behind several Cups. On the radiio, I prepared him to use the draft from one of them to get a tow down a long straight at this track, in order to better his time fighting a big head wind with lower HP.

The principle was this: the Cup tires would take most of the out lap to develop temp (cool morning). So he & the Cup would be at about the same pace for th eout lap, and thus the Cup would be easy to stick behind. His tires, on the other hand, would come up in less than that. I had him stick behind one of the Cups as best he could for the entire out lap, since the Cup has a big aero profile in the back due to its wing, and sticking on its bumper would put my guy in a nice big aero hole (as compared with a Spec Boxster, for example, which would have created a smaller hole). I told him that as they completed the out lap, the Cup would accelerate away from him down the long start/finish straight, but my guy would still derive a very nice tow for at least half way, again into a wind. So I told him he really had one lap to git 'er done.

And in fact he did it perfectly, got his flyer by drafting the Cup (as long as he could), and ended up setting a new PB and a track record for his class in the process!

So the draft works...and it amazes me how few folks in many forms of sports car racing use it.

Larry Herman

No doubt using the draft is a key ingredient in a racers cook book. Here is a data point for you. When I ran at the 2007 Daytona PCA club race, my car would be just about 50 RPMs shy of redline going into turn 1. If I got a good tow however, I would hit the rev limiter going over the start/finish line, about 150 yards before the braking area. It made a few MPH difference in my top speed.

cannon1000

Wow, just finished my first DE ever this weekend - and promoted to Group 2 before it was over. What a blast. I have to say that this thread helped me "accelerate" through the novice group 1. My instructor asked if I had done this before - and said I was pretty much ready to solo. I'll enjoy group 2 and the free instructor while I can get it.

Some things that I learned while getting my check ride - and very obvious to you more experienced drivers but not so obvious to us newbie's...is even though the major goal is being smooth - let the car settle, hit your turn in points, apex, etc... we have to retrain our brains to NOT DRIVE IT like you are on the street.

What I mean by that is we are "taught" to gradually apply brakes and apply more pressure until stopped or slowed. We trail brake all the time without even thinking, accelerations are typically gradual. I found myself doing this without even thinking on some turns.

My 2nd instructor called me out on it.
Too much trail braking (i felt uncomfortable and was tapping the brakes on the turn).
Gradually pressing the brakes (I thought it was aggressive-but I was wrong) to hit my entry speed, then turning in instead of waiting longer before hitting the brakes HARD then letting up smoothly (counter to street driving style) before turning in.

Anyways, just trying to throw in some novice advice from a novice point of view. I felt great and the instruction here was in the back of my mind the whole time. I can tell you - I'm all in...this is addicting! Time to look at a dedicated track car now. :-)

Veloce Raptor

Way to go!!!! Another addict!!

forklift

How many track days a year do you think one needs to drive to stay in “shape or sharp”….meaning not get slower? I’m down to only 5-12 days a year now for the last 3-4 years (out of 7 years total) and have been lucky enough to somehow (sometimes) still set new PB’s but I don’t think that can will keep happening w/ the little amount of track time.

Veloce Raptor

Tougher as you get older, obviously, and tougher to remain consistent. It's one thing to set a new PB. It's another thing entirely to do 12 laps within a second of that.

IcemanG17

Careful Cannon...you'll be addicted soon like the rest of us!!

Great color on your turbo...never heard of that one!!

CRex

Question from a relative greenhorn: when is it desirable to short-shift?

Using a tight, 35mph hairpin as example, I'd normally take it in 2nd and track out somewhere around 6k rpm. The hairpin's followed by a straight that'll see me thru the middle of 4th. I'd normally run past trackout in 2nd and hit the 8.5k redline before upshifting. Obviously an alternative would be to short-shift at track-out and spend more time in 3rd. Seems to work great for the guys in cup cars but doesn't seem to make a positive difference to me, at least in terms of max speed. Is this simply a matter of gearing math (shorter R&P in cup cars and higher redline) or is there more logic to it?

Thanks in advance--this has been a great thread and let's keep this going!