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Old 11-12-2002, 02:03 PM   #1
sdecker
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Default Lap time percentages -- your opinions

Hey all,

This seems to be the most likely place to get reasonable answers...if not, mods feel free to move it.

I'm looking for opinions on generic lap times around a track. This is sort of hard to explain, but I'll give it my best shot. Please be kind since you know I'm a n00b to all this track stuff.

I, a racing n00b, own a ~300 hp AWD car with lightly modified suspension (RSB/springs) and R compound tires. A buddy who is a racing instructor owns a 227 hp AWD car with coilovers and street tires. I turn lap time 'x', he turns lap time 'x minus 7 seconds' on a 2.5 mile course. The approximate weights of the cars are 3050 pounds, +/- 50. A second buddy, also a racer, owns a 120 horsepower FWD car with coilovers, full roll cage, stock brakes, and 2050 pounds, and turns lap times identical to my car ('x').

So, this tells me that simply raw horsepower is most definitely NOT the answer to obtaining great lap times. What I'm trying to figure out is (percentage-wise) what makes the most difference?

1) Driver skill, the obvious choice
2) Suspension
3) Weight
4) Fear factor
5) Track knowledge
6) Others?

I know there are an awful lot of variables here that I'm not taking into account, and I didn't list them on purpose. I'm just interested in your opinions and I appreciate them all. By the way, I'm talking road racing, not rally or auto-x, but don't let that limit your responses...

Thanks all!

Scott
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Old 11-12-2002, 02:46 PM   #2
HoRo1
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In my opinion, the order of importance is...
1 Driver skill
2 Horsepower:weight ratio
3 Tyres
4 Track knowledge
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Old 11-12-2002, 02:46 PM   #3
enduroshark
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In order of importance, in my opinion:

1)Driver skill
2)tires
3)suspension
4)weight/power
5)track knowledge

Fear factor goes inside driver skill, I think. The more track time you get, the more you get used to the speeds and what it takes to control things. To me, once I take a corner at 'X' speed, then I know I can do that same speed every single time afterwards. Also, the more track time you get, the less concentration it will take to drive at the limit, so you are able to "expand your senses" in a way and everything seems to "slow down" making it feel easier.

At the track, the most important thing is speeds out of the corners. A car that takes a corner slower than another will have a hard time catching up down the straight, even if it has more power. It takes a lot of power and a longer straight to overcome a few mph exiting a corner.
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Old 11-12-2002, 03:03 PM   #4
sdecker
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Thanks guys, keep 'em coming!

Horo: what do you think about suspension with regards to the percentages? Do you feel that taking advantage of the available suspension is part and parcel of driver skill, or is it possible for an excellent suspension setup to overcome a less skilled driver?

Again, just looking for opinions. This is why I-club is what it is.

Thanks!

Scott
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Old 11-12-2002, 03:10 PM   #5
sdecker
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Enduroshark : thanks for your comments. I agree, fear factor is rolled into driver skill to a point. It's also related to track knowledge. A really skilled driver at a totally alien track will definitely take it easier at first, but the learning curve would be much easier to get on top of.

To be honest, I'm just wondering what the biggest factor is that allows a 17:1 hp to weight car to keep up with a 10.1:1 car on a road course. I'm learning (and I'm not ashamed to admit it).

Thanks guys!

Scott
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Old 11-12-2002, 03:26 PM   #6
enduroshark
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Another factor is how easy is the car to drive at the limit. A well balanced car will allow you to be closer to the limit more of the time. A car that's too twitchy might not inspire as much confidence.

But I still think that the biggest factor is driver skill.
Driver skill being equal, the 10.1:1 ratio car would have to handle pretty bad to be beaten by the 17:1 ratio car.

And a lot of it is not how early to get on the gas, but how less braking you do before a corner.
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Old 11-12-2002, 03:34 PM   #7
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Scott - Assuming both drivers are fairly knowledgeable about the track, there are all these factors that can make one faster than the other, despite a disadvantage of horsepower/weight ratio.

Going into a turn: Braking. That depends on tires, braking power and weight of the car; and technique/guts of the driver. The later one has to brake, and trail-braking (when applicable) means shorter lap times.

In the turn: Tires and suspension will decide the ultimate speed one can "make" that turn. But the better and more experienced driver can go closer to that ultimate limit.

Knowing the proper line through the turns and getting as close to that limit (including the fastest exit speed) will allow the higher speed on the straights.

-Ray
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Old 11-12-2002, 03:52 PM   #8
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Tyres, track knowledge and power:weight are all more important than suspension. Suspension, IMO, is what you worry about when you know what you're competent and you have tyres and power - this assumes that your car is fairly well sorted when it comes from the factory. The WRX is pretty good stock. Sure, you can reach the limit of the springs at a really fast track, but most average drivers will find the engine or tyres or track knowledge to be their limiting factor before they encounter a suspension problem.
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Old 11-12-2002, 06:16 PM   #9
sdecker
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Smile This is great!

Thanks guys, this is super stuff for everyone. Maybe it's not highly technical in a mechanical sense but it sure is helpful.

A common thread that I'm seeing here is brakes.
Quote:
Going into a turn: Braking. That depends on tires, braking power and weight of the car; and technique/guts of the driver. The later one has to brake, and trail-braking (when applicable) means shorter lap times.
Quote:
And a lot of it is not how early to get on the gas, but how less braking you do before a corner.
So is it fair to say that knowing and finding braking points and total brake pedal pressure before (and into) a turn can have just as much impact as some of the things I mentioned above? I mean, I can believe it because of some of the things I have done in the past. For example, I made about 4-5 seconds a lap at Road Atlanta between my first and second HPDE's, virtually all due to braking. This all makes sense intellectually. The less time you are on the brake pedal or coasting, the faster your lap will become.

And the biggest thread here is still DRIVER SKILL. I've got probably 250-300 track day laps under my belt now and many more on the schedule. It all comes down to seat time, doesn't it gentlemen? I have no illusions about my lack of ability but I'm working on it.

Oh, and Ray -- thanks a lot! You pretty much made my summer with your comments to me going all the way back to like, May. I've done virtually every HPDE/track day at Road Atlanta since then. Racing school over the winter, perhaps a little mild 'real' competition next spring assuming money holds out.

I truly appreciate it guys. Any other things you can think of, I'd love to hear it.

How about a 'Spec Impreza' class to go along with Spec Miata?

Scott
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Old 11-12-2002, 06:30 PM   #10
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As an instructor, I've noticed that braking is one of the hardest things for new students to understand.

On the highway, you brake with more and more effort as you get closer and closer to the car in front or the stop light, etc.

On the track you do the opposite. Your initial pedal application is the highest effort part (without upsetting the car) and then, as you slow down, you can use less pressure. The real trick is in learning how LITTLE braking to use and still be able to take the corner.

A lot of people get focused into braking at the very last possible moment, but what ends up happening is that you end up braking way more than you need to, thus losing corner entry speed, thus losing corner exit speed.

Have you read "Going Faster"? It explains it very well.

And yes, it all comes down to track time, as long as you go into it with specific goals. Choose something to practice every time you go out. Use your tach or speedometer (on track out points, for example) or shift points to gauge your progress.

Can you tell how much I love this stuff??

I've been racing mostly Miatas since 1998 and I've had to learn (due to the lack of power) that momentum is the key to racing, no matter how much power you have under you.
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Old 11-12-2002, 06:48 PM   #11
sdecker
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All right, I'm going to hijack my own thread here. It's my thread, I can do what I want with it.

Enduroshark, that is an excellent way of describing it. In fact, I have read 'Going Faster' multiple times but somehow I never really got that exact chunk of information from it.

It's a heavier initial bite and then a taper off to the exact amount needed and then a smooth quick release. I have been discouraged from trail braking by all HPDE instructors, and I know why. I'm just wondering how to maximize the entry speed down to the apex if a trail brake is unavailable. For example, the entry to turn 2 at RA is a tough spot not to trail brake if you're carrying enough speed through 1.

I do have specific goals every time out. I do a lot of talking (no kidding huh) to people more knowledgeable than I am about this stuff and get input. Believe it or not I plan to work this entire next track day on one corner complex (the esses, since I think you know RA).

By the way, is there any better place to post this sort of stuff? I have lots of questions but I hate to put it in the wrong place. I could just send private e-mails but then nobody else would benefit...that sucks.

If you don't know RA, sorry for the references, just let me know and I'll describe for you what the setup is.

Thanks again,

Scott
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Old 11-12-2002, 09:13 PM   #12
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Actually, I remember discussing this with Gary Sheehan a long time ago (remember this, Gary?) and we agree in that we both think that trail braking is one of the last things to learn, since it carries the most consequences if you make a mistake.

What I would recommend is that you get good at doing your braking in a straight line and be ready to get on the gas by the time you get to your corner entry point.

The way I learned trail braking was when trying to increase my corner entry speed. Little by little I tried braking a bit less until I noticed that I didn't have the grip on corner entry to add throttle to the traction that the tires were giving me. Everything was being used to turn on corner entry and then, as the car rotated, it would free up a bit of grip to start using more gas.

Like I said before, with experience you'll see how it takes less mental effort to drive and then you can feel more about what the car is doing in terms of grip and the whole physics of it.

Check out "Speed Secrets" by Ross Bentley, if you haven't. It's another great book that has helped me a lot and describes this pretty well.

I think that if you focus on doing your braking early enough so that you can start to slowly feed power from corner entry, you'll be able to get 9/10ths of the way to a "fastest lap". Trail braking is the other 10th. You'll slowly see how much more grip there is there than you thought, just by driving the line, being smooth and trusting the car.

I can talk about this and Road Atlanta all day!
Especially now, after racing the whole enduro this past Sunday.
As for the esses, that entry into turn 5 is one where I'm always
working to get consistenly good, since it's quite busy. The entry into the esses from turn 4 is pretty exiting because the car feels pretty light as you change direction and plow down the hill, huh!


Are you going to the PCA event this weekend? I wish I could go, but I'll be out of town due to work.

I think that my friend Rob Ebersol will be instructing there. Look for a Miata race car and ask for him. He has a lot of experience at Road Atlanta.

We can meet and bench race any time! We are practically neighbors. I live about 20 miles from the track myself.

--
Ony

Last edited by enduroshark; 11-13-2002 at 12:49 PM.
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Old 11-13-2002, 07:55 AM   #13
sdecker
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Hi Ony:

I was wondering where I had heard the name Rob Ebersol before, and now I remember...he was scheduled to be by instructor at a BMWCCA event earlier this summer but had to cancel for some reason.

This weekend's event is actually just an open track day, not a PCA event...

I'm going to stop hijacking my own thread here and start another one related specifically to RA. See ya there!

Scott
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Old 11-13-2002, 10:52 AM   #14
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Driver Skill is clearly the most important factor...

Sticky tires are good for at least a second or two on a 60 second track.

Track knowledge also good for a second or so on a 60 second track.

Power/weight can make a huge difference from car to car... Why is a Z06 faster than a Miata..., but not such a huge difference tweeking a single type of car (your overboosted WRX isn't going to be much faster than your buddies stock boosted WRX).

Suspension design and car balance also makes a huge difference car to car... (stock S2000 much faster than stock WRX) but very hard to expertly tweak on a single car (throw some coilovers and 17" wheels on your WRX and you may or may not actually be faster!)
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Old 11-13-2002, 11:15 AM   #15
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Default some random thoughts

Power to weight is a good generic measure of lap time potential but it ignores one issue. That is the intangible of how well the track suits the strengths weakness of a particular car.

Example, on a tight enough track the old minicooper S would hold its own quite nicely against the AC Cobra. Get on a more open track and the Cobra would eat up the mini.

Mini had better cornering on very tight circuits but gave up the brutal acceleration out of the turns the Cobra could generate. Pretty much a classic example of the hold your speed through the turns compared to the difficulty of catching that lost time back up.



I think my favorite axiom of racing is Sterling Moss's " better in slow and out fast, than in fast and out slow"


Larry
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Old 11-13-2002, 12:51 PM   #16
sdecker
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Excellent, this is just what I'm looking for...let's keep em coming!

Scott
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Old 11-13-2002, 01:22 PM   #17
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Driver, driver, driver. I see people who want to go faster all the time and they way they do it is to focus on the car and not their skills (I believe that with technology that driver skill is playing less of a role but is still the most important factor). Obviously if you add more hp and suspension you should go faster. But the question is, "are you driving your car to its potential?"

I also think there is a variable that is missing. Familiarity with the handling characteristics of the car. A person who drives a front engined rwd car would probably take a while to adjust to the handling of a front engined fwd car.

I don't know how many times I've been to the track and have passed cars with twice the hp and a lot better hp/weight ratio than my car (not difficult considering I only have 95 bhp and a hp/weight ratio of 23:1 ).
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Old 11-13-2002, 02:06 PM   #18
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Thanks Sea Dragon Rex...that's what I'm looking for. Driver, driver, driver, and car/track knowledge. In other words, a good driver in a car he/she understands can quickly do well at almost any track. Of course, within the limitations of the vehicle as you describe.

This is great stuff. Thanks to everybody, keep it coming.

Scott
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